Ered significant.Enterohemolysin Induced Release of IL-1bFigure 2. AN-3199 chemical information Cytotoxicity of human macrophages as indicated by the release of lactate dehydrogenase (LDH). Differentiated THP-1 cells were exposed to different bacterial strains (EDL933, DpO157, DehxA, DehxA/pehxA) for 2 and 4 h. The release of LDH was assessed at specific times during incubation. Data are shown as mean 6 S.D. of experiments performed in triplicate. Significant differences (* P,0.05) are indicated. n.s., no significant differences (P.0.05). doi:10.1371/journal.pone.0050288.gFigure 1. Construction of the mutant strains. (A) The genes 15900046 ehx and ecf were detected in EDL933 but not in DpO157. Lane M: marker; Lanes 1 and 3: EDL933; Lanes 2 and 4: DpO157 mutant. (B) Comparison of Solvent Yellow 14 web genomic DNA of EDL933 and DpO157 using 1326631 PFGE of XbaI-digested. Lane M: marker; Lane 1: EDL933; Lane 2: DpO157 mutant. (C) Using primer ehxA-3,4, EDL933 was amplified as a <3.3 kb fragment. DehxA and DehxA/pehxA were amplified as a reduced fragment to <1.6 kb. Using primer ehxA-5,6, DehxA showed no PCR product. EDL933 and DehxA/pehxA were amplified as a <360 bp fragment. Lane 1: EDL933; Lane 2: DehxA; Lane 3: DehxA/pehxA. doi:10.1371/journal.pone.0050288.gsignificantly higher levels of mature-form IL-1b (p17) in the supernatant than cells stimulated by its virulence plasmid elimination derivative strain DpO157 or its ehxA gene deletion mutant DehxA (Figure 4). The reduced release of mature IL-1b (p17) from the ehxA gene deletion mutant was restored when complemented with ehxA gene (DehxA/pehxA) (Figure 4). However, neither the expression of intracellular IL-1b mRNA (Figure S1) nor pro-IL-1b protein in cell lysis differed across the four strains (Figure 4). Overall, these results suggest that EhxA encoding on pO157 was responsible for the higher levels of extracellular production of mature IL-1b in THP-1 cells but had no effect on intracellular production of biologically inactive pro-IL-1b in THP1 cells.EHEC O157:H7-Ehx Induced IL-1b Release in THP-1 CellsThe IL-1b production in the supernatants of cell culture and cell extract infected with different bacterial strains (EDL933, DpO157, DehxA, DehxA/pehxA) was tested by ELISA and Western-blot. The ELISA results showed that the THP-1 cells stimulated by EDL933 produced higher level of IL-1b in supernatant compared with the cells stimulated by its virulence plasmid elimination derivative strain DpO157 (P,0.05), and its ehxA gene deletion mutant DehxA (P,0.05). The reduced release of IL-1b from the ehxA gene deletion mutant can be restored when complemented with ehxA gene (DehxA/pehxA) (P,0.05) (Figure 3A). We also assessed production of IL-6, IL-8, RANETS/CCL5, MCP-1, TNF-a, and IFN-c in THP-1 cells stimulated by those strains, and results showed that EhxA had no effect on production of the other cytokines we examined (Figure 3B ). To confirm whether the presence of IL-1b production we analyzed in the supernatant using ELISA was the biologically active mature form or the biologically inactive pro-IL-1b, which can be released passively during cell lysis due to cytotoxicity, we examined the production of pro-IL-1b and mature-form IL-1b in both supernatants and cell lysis using immunoblotting after the cells had been infected with different strains (EDL933, DpO157, DehxA, and DehxA/pehxA). Results showed that the IL-1b in the supernatant was mainly mature-form p17 and the IL-1b in the cell lysis was mainly inactive-form pro-IL1b, as shown in Figure 4. We als.Ered significant.Enterohemolysin Induced Release of IL-1bFigure 2. Cytotoxicity of human macrophages as indicated by the release of lactate dehydrogenase (LDH). Differentiated THP-1 cells were exposed to different bacterial strains (EDL933, DpO157, DehxA, DehxA/pehxA) for 2 and 4 h. The release of LDH was assessed at specific times during incubation. Data are shown as mean 6 S.D. of experiments performed in triplicate. Significant differences (* P,0.05) are indicated. n.s., no significant differences (P.0.05). doi:10.1371/journal.pone.0050288.gFigure 1. Construction of the mutant strains. (A) The genes 15900046 ehx and ecf were detected in EDL933 but not in DpO157. Lane M: marker; Lanes 1 and 3: EDL933; Lanes 2 and 4: DpO157 mutant. (B) Comparison of genomic DNA of EDL933 and DpO157 using 1326631 PFGE of XbaI-digested. Lane M: marker; Lane 1: EDL933; Lane 2: DpO157 mutant. (C) Using primer ehxA-3,4, EDL933 was amplified as a <3.3 kb fragment. DehxA and DehxA/pehxA were amplified as a reduced fragment to <1.6 kb. Using primer ehxA-5,6, DehxA showed no PCR product. EDL933 and DehxA/pehxA were amplified as a <360 bp fragment. Lane 1: EDL933; Lane 2: DehxA; Lane 3: DehxA/pehxA. doi:10.1371/journal.pone.0050288.gsignificantly higher levels of mature-form IL-1b (p17) in the supernatant than cells stimulated by its virulence plasmid elimination derivative strain DpO157 or its ehxA gene deletion mutant DehxA (Figure 4). The reduced release of mature IL-1b (p17) from the ehxA gene deletion mutant was restored when complemented with ehxA gene (DehxA/pehxA) (Figure 4). However, neither the expression of intracellular IL-1b mRNA (Figure S1) nor pro-IL-1b protein in cell lysis differed across the four strains (Figure 4). Overall, these results suggest that EhxA encoding on pO157 was responsible for the higher levels of extracellular production of mature IL-1b in THP-1 cells but had no effect on intracellular production of biologically inactive pro-IL-1b in THP1 cells.EHEC O157:H7-Ehx Induced IL-1b Release in THP-1 CellsThe IL-1b production in the supernatants of cell culture and cell extract infected with different bacterial strains (EDL933, DpO157, DehxA, DehxA/pehxA) was tested by ELISA and Western-blot. The ELISA results showed that the THP-1 cells stimulated by EDL933 produced higher level of IL-1b in supernatant compared with the cells stimulated by its virulence plasmid elimination derivative strain DpO157 (P,0.05), and its ehxA gene deletion mutant DehxA (P,0.05). The reduced release of IL-1b from the ehxA gene deletion mutant can be restored when complemented with ehxA gene (DehxA/pehxA) (P,0.05) (Figure 3A). We also assessed production of IL-6, IL-8, RANETS/CCL5, MCP-1, TNF-a, and IFN-c in THP-1 cells stimulated by those strains, and results showed that EhxA had no effect on production of the other cytokines we examined (Figure 3B ). To confirm whether the presence of IL-1b production we analyzed in the supernatant using ELISA was the biologically active mature form or the biologically inactive pro-IL-1b, which can be released passively during cell lysis due to cytotoxicity, we examined the production of pro-IL-1b and mature-form IL-1b in both supernatants and cell lysis using immunoblotting after the cells had been infected with different strains (EDL933, DpO157, DehxA, and DehxA/pehxA). Results showed that the IL-1b in the supernatant was mainly mature-form p17 and the IL-1b in the cell lysis was mainly inactive-form pro-IL1b, as shown in Figure 4. We als.

He leading edge. An attractive hypothesis is that proliferation is only beneficial to epithelialization if present at the initial wound margin away from the leading edge, and detrimental if detected in cells at the leading edge. Interestingly, we did not detect altered proliferation in Tgfb3-deficient keratinocytes and wild type keratinocytes grown in the presence of NAB, as well as in the basal layer of embryonic skin, suggesting that the proliferation defect in injured skin may be unique to a condition of tissue repair. Furthermore, it supports a role for a TGF-?dependent paracrine effect on keratinocytes, mediated by cells from the granulation tissue. Recent reports have identified a TGF 2-Smad-independent TGF-? signaling in palatogenesis [43]. This non-canonical SPDP Crosslinker pathway utilizes the MAPK signaling, known to regulate the production of numerous downstreamtargets, including interleukin 6 [44], a well-known critical regulator of keratinocyte migration [45,46]. TGF-? is probably best-known for its antiscarring effect [24], and recombinant TGF-? has been used in clinical JI 101 custom synthesis trials as prophylactic treatment of human scars [25]. TGF- ?-injected wounds exhibit decreased expression of a-smooth muscle actin in the granulation tissue, consistent with an antiscarring effect. However, the collagen fiber network was unchanged. Interestingly, despite the low level of a-smooth muscle actin, TGF-?-injected wounds show the same wound volume compared to controls, suggesting that perhaps a-smooth muscle actin expression is more related to granulation tissue remodeling and myofibroblast differentiation than tissue contraction. The absence of TGF-?, however, leads to larger and deeper wounds. When stained for asmooth muscle actin, however, wounds injected with TGF-? neutralizing antibody show very small areas with a-smooth muscle actin positive myofibroblasts at 7 and 11 days post-wounding. Furthermore, collagen fiber network was not fully mature. These results would suggest that TGF-? is required for fibroblast/ myofibroblast transdifferentiation and proper granulation tissueTGFB3 and Wound Healingmaturation in the wound area and are consistent with the effect of the injection of a viral construct containing a mutant TGF-? into cutaneous wounds [26]. Both studies would be consistent with a mathematical model that predicts an increase in wound size after early elimination of TGF-?[47]. Several reports describe the expression of TGF-? in tissues and cells throughout development and during adulthood, yet not consistently in the same tissues and cells [8,22,48,49]. We took advantage of a new allele with Cre recombinase knocked in the TGF-? locus [27] to determine spatial and temporal expression of Tgfb3 during cutaneous wound healing. X-gal staining indicated the presence of positive signal in the suprabasal layers of the epidermis and hair follicle cells in wounded and unwounded tissues. Although the staining reflects the transformation of cells that have expressed or continue to transcribe from the TGF-? promoter, its pattern in the epidermis and hair follicle is similar to the expression of Cre-recombinase shown previously [31]. These observations only partially mirror previous studies that indicated the presence of Tgfb3 throughout the epidermis, in the granulation tissue and in mesenchymal derivatives [15]. Differences in animal models and method of detection could be at the origin of these discrepancies.In summary, our study indicates the requirement of a.He leading edge. An attractive hypothesis is that proliferation is only beneficial to epithelialization if present at the initial wound margin away from the leading edge, and detrimental if detected in cells at the leading edge. Interestingly, we did not detect altered proliferation in Tgfb3-deficient keratinocytes and wild type keratinocytes grown in the presence of NAB, as well as in the basal layer of embryonic skin, suggesting that the proliferation defect in injured skin may be unique to a condition of tissue repair. Furthermore, it supports a role for a TGF-?dependent paracrine effect on keratinocytes, mediated by cells from the granulation tissue. Recent reports have identified a TGF 2-Smad-independent TGF-? signaling in palatogenesis [43]. This non-canonical pathway utilizes the MAPK signaling, known to regulate the production of numerous downstreamtargets, including interleukin 6 [44], a well-known critical regulator of keratinocyte migration [45,46]. TGF-? is probably best-known for its antiscarring effect [24], and recombinant TGF-? has been used in clinical trials as prophylactic treatment of human scars [25]. TGF- ?-injected wounds exhibit decreased expression of a-smooth muscle actin in the granulation tissue, consistent with an antiscarring effect. However, the collagen fiber network was unchanged. Interestingly, despite the low level of a-smooth muscle actin, TGF-?-injected wounds show the same wound volume compared to controls, suggesting that perhaps a-smooth muscle actin expression is more related to granulation tissue remodeling and myofibroblast differentiation than tissue contraction. The absence of TGF-?, however, leads to larger and deeper wounds. When stained for asmooth muscle actin, however, wounds injected with TGF-? neutralizing antibody show very small areas with a-smooth muscle actin positive myofibroblasts at 7 and 11 days post-wounding. Furthermore, collagen fiber network was not fully mature. These results would suggest that TGF-? is required for fibroblast/ myofibroblast transdifferentiation and proper granulation tissueTGFB3 and Wound Healingmaturation in the wound area and are consistent with the effect of the injection of a viral construct containing a mutant TGF-? into cutaneous wounds [26]. Both studies would be consistent with a mathematical model that predicts an increase in wound size after early elimination of TGF-?[47]. Several reports describe the expression of TGF-? in tissues and cells throughout development and during adulthood, yet not consistently in the same tissues and cells [8,22,48,49]. We took advantage of a new allele with Cre recombinase knocked in the TGF-? locus [27] to determine spatial and temporal expression of Tgfb3 during cutaneous wound healing. X-gal staining indicated the presence of positive signal in the suprabasal layers of the epidermis and hair follicle cells in wounded and unwounded tissues. Although the staining reflects the transformation of cells that have expressed or continue to transcribe from the TGF-? promoter, its pattern in the epidermis and hair follicle is similar to the expression of Cre-recombinase shown previously [31]. These observations only partially mirror previous studies that indicated the presence of Tgfb3 throughout the epidermis, in the granulation tissue and in mesenchymal derivatives [15]. Differences in animal models and method of detection could be at the origin of these discrepancies.In summary, our study indicates the requirement of a.

R labeling, the leaves were washed twice with homogenization buffer (50 mM Tris-HCl, pH 7.5, 150 mM NaCl, and 2 mM EDTA) and ground with 300 mL of the same buffer. The thylakoid membranes were isolated and separated by SDS-PAGE, and the labeled proteins were visualized by autoradiography.Chloroplast and Thylakoid Membrane PreparationIntact chloroplasts 25033180 were fractionated into envelope, stromal and thylakoid membrane fractions as described previously [27?9]. The thylakoid membranes were isolated according to Cai et al [30]. The chlorophyll contents were measured as described previously [31].Photoinhibitory TreatmentDetached wild type and cplepa-1 mutant leaves were floated face down on water and illuminated under a photon flux density of 1,000 mmol m22 s21, and the chlorophyll fluorescence was measured at 0.5 h, 1 h, 2 h, 3 h, and 4 h after exposure to high light using a PAM-2000 fluorometer (Walz). The temperature wascpLEPA in Chloroplast TranslationFigure 6. Northern Blot Analysis for Chloroplast Transcripts in Wild-Type and cplepa-1 Plants. Northern blot analysis of the chloroplast transcripts psbA, psbB, psbD, atpB, psaA, petB, rbcL, rpoA, rpoB and rrn23 in wild-type and cplepa-1 mutant plants. Each lane was loaded with 10 mg of total RNA. The (��)-Hexaconazole cost Plants were grown on soil for 3 weeks under 120 mmol m22 s21 illumination. Additionally, 25S rRNA stained with EtBr was loaded as a control. The size of the transcript (in kb) is shown. doi:10.1371/journal.pone.0049746.gcpLEPA in Chloroplast TranslationFigure 7. Photosensitivity Analysis of cplepa-1 Plants. A: The phenotypes of wild-type (WT) and cplepa-1 mutant plants grown in a growth chamber at 120 mmol m22 s21 in the first two weeks, then transferred to low light (40 mmol m22 s21) or high light (500 mmol m22 s21) for another two weeks. B: The Fv/Fm ratio was measured for detached leaves from wild-type (WT) plants (red circles) and cplepa-1 mutant plants (black squares) following high-light illumination (1,000 mmol m22 s21) in the absence of lincomycin (Lin). C: The Fv/Fm ratio was measured for detached leaves from wild-type (WT) plants (red circles) and cplepa-1 mutant plants (black squares) following high-light illumination (1,000 mmol m22 s21) in the Fexinidazole web presence of lincomycin (Lin). doi:10.1371/journal.pone.0049746.gProtein Localization AnalysisThe thylakoid membranes from wild type plants were suspended to a final concentration of 0.1 mg chlorophyll/mL in 10 mM HEPES-KOH, Ph 8.0, 10 mM MgCl2, 330 mM sorbitol, and 1 mM PMSF supplemented with either 250 mM NaCl, 1 M CaCl2, 200 mM Na2CO3 or 6 M urea. The membrane fractions without treatment were used as controls. All of the samples were kept on ice during the experiment. The treated samples were washed with 10 mM HEPES-KOH, pH 8.0, 10 mM MgCl2, 330 mM sorbitol, and 1 mM PMSF, and the pellets were collected by centrifugation for western blot analysis [32,33].the signals from secondary conjugated antibodies were detected by the enhanced chemiluminescence method. The anti-cpLEPA antibody was raised against the N-terminus of the cpLEPA protein (cpLEPA56?70). The procedures involved in generating an antibody were performed according to Sun et al [35].RT-PCR, Northern Blot and Polysome Association AnalysesFor the RT-PCR analysis, the total RNA was isolated from 3week-old leaves using the Total RNA Isolation Kit (U-Gene), and RT-PCR was performed with the SuperScript III First-Strand Synthesis System for RT-PCR (Invitrogen) using the primers LEPA RTF.R labeling, the leaves were washed twice with homogenization buffer (50 mM Tris-HCl, pH 7.5, 150 mM NaCl, and 2 mM EDTA) and ground with 300 mL of the same buffer. The thylakoid membranes were isolated and separated by SDS-PAGE, and the labeled proteins were visualized by autoradiography.Chloroplast and Thylakoid Membrane PreparationIntact chloroplasts 25033180 were fractionated into envelope, stromal and thylakoid membrane fractions as described previously [27?9]. The thylakoid membranes were isolated according to Cai et al [30]. The chlorophyll contents were measured as described previously [31].Photoinhibitory TreatmentDetached wild type and cplepa-1 mutant leaves were floated face down on water and illuminated under a photon flux density of 1,000 mmol m22 s21, and the chlorophyll fluorescence was measured at 0.5 h, 1 h, 2 h, 3 h, and 4 h after exposure to high light using a PAM-2000 fluorometer (Walz). The temperature wascpLEPA in Chloroplast TranslationFigure 6. Northern Blot Analysis for Chloroplast Transcripts in Wild-Type and cplepa-1 Plants. Northern blot analysis of the chloroplast transcripts psbA, psbB, psbD, atpB, psaA, petB, rbcL, rpoA, rpoB and rrn23 in wild-type and cplepa-1 mutant plants. Each lane was loaded with 10 mg of total RNA. The plants were grown on soil for 3 weeks under 120 mmol m22 s21 illumination. Additionally, 25S rRNA stained with EtBr was loaded as a control. The size of the transcript (in kb) is shown. doi:10.1371/journal.pone.0049746.gcpLEPA in Chloroplast TranslationFigure 7. Photosensitivity Analysis of cplepa-1 Plants. A: The phenotypes of wild-type (WT) and cplepa-1 mutant plants grown in a growth chamber at 120 mmol m22 s21 in the first two weeks, then transferred to low light (40 mmol m22 s21) or high light (500 mmol m22 s21) for another two weeks. B: The Fv/Fm ratio was measured for detached leaves from wild-type (WT) plants (red circles) and cplepa-1 mutant plants (black squares) following high-light illumination (1,000 mmol m22 s21) in the absence of lincomycin (Lin). C: The Fv/Fm ratio was measured for detached leaves from wild-type (WT) plants (red circles) and cplepa-1 mutant plants (black squares) following high-light illumination (1,000 mmol m22 s21) in the presence of lincomycin (Lin). doi:10.1371/journal.pone.0049746.gProtein Localization AnalysisThe thylakoid membranes from wild type plants were suspended to a final concentration of 0.1 mg chlorophyll/mL in 10 mM HEPES-KOH, Ph 8.0, 10 mM MgCl2, 330 mM sorbitol, and 1 mM PMSF supplemented with either 250 mM NaCl, 1 M CaCl2, 200 mM Na2CO3 or 6 M urea. The membrane fractions without treatment were used as controls. All of the samples were kept on ice during the experiment. The treated samples were washed with 10 mM HEPES-KOH, pH 8.0, 10 mM MgCl2, 330 mM sorbitol, and 1 mM PMSF, and the pellets were collected by centrifugation for western blot analysis [32,33].the signals from secondary conjugated antibodies were detected by the enhanced chemiluminescence method. The anti-cpLEPA antibody was raised against the N-terminus of the cpLEPA protein (cpLEPA56?70). The procedures involved in generating an antibody were performed according to Sun et al [35].RT-PCR, Northern Blot and Polysome Association AnalysesFor the RT-PCR analysis, the total RNA was isolated from 3week-old leaves using the Total RNA Isolation Kit (U-Gene), and RT-PCR was performed with the SuperScript III First-Strand Synthesis System for RT-PCR (Invitrogen) using the primers LEPA RTF.

Rs, covering the full range of BMI and M-values. As with western blot we found that there was a great deal of inter-individual variability in the basal level of activity. There was no significant correlation between either basal activity or post-insulin p42/p44 MAPK activity levels, and JI-101 biological activity M-value or BMI (Figure 5). However there was an inverse correlation between fold-induction of p42/44 MAPK activity by insulin and body mass index (r = 0.73; p = 0.0009) (Figure 5A) and 15857111 a significant correlation between p42/44 MAPK activity in response to insulin and M value (r = 0.52; p = 0.04) (Figure 5B). Thus, whether measured against the degree of obesity or IR, the data indicates a close relationship between defective response to insulin of p42/44 MAPK activity in muscle and the clinical measures of pre-diabetes. This suggests that abnormal p42/p44 MAPK response to insulin in skeletal muscle is a better marker of whole body insulin resistance than the response of the PI3K-PKB pathway, at least in obese non-diabetic individuals. FOXO, GSK3 and ribosomal S6. There were no correlations between the basal or insulin-induced levels of phosphorylation of FOXO, GSK3 and ribosomal S6 protein with either BMI or M value (data not shown).Phosphorylation statusPKB. The induction of PKB phosphorylation by insulin was apparent in most volunteers (Figure 3 A and B). There was a tendency for the degree of insulin-induced phosphorylation of PKB to reduce with increasing BMI (r = 2.38; p = 0.09) (C) and to increase with increasing M value (r = 0.4; p = 0.08) (D) but these failed to reach significance. In contrast to the analysis of p42/p44 MAPK, direct assay of PKB activity rather than western blotting of phosphorylation failed to improve the correlation between PKB activity and insulin sensitivity (data not shown). p42/44 MAPK. There were no significant correlations between basal p42/44 MAPK phosphorylation and either BMI or M value (Figure 4). There was a tendency for p42/44 MAPK phosphorylation following insulin exposure to correlate with BMI (Spearman r = 0.4; p = 0.07) (C) or with M value (Spearman r = 0.59; p = 0.08) (D) but these both failed to reach significance.Figure 2. Relationship of IRS1 expression with body mass index or M value. Relative IRS1 protein expression according to body mass index (A) or to M value (B) and fold increase in IRS1 expression according to body mass index (r = 20.36; p = 0.10) (C) or to M value (r = 0.27; p = 0.23) (D). doi:10.1371/journal.pone.0056928.gSkeletal Muscle Lixisenatide chemical information signalling Defects in ObesityFigure 3. Relationship of PKB phosphorylation with body mass index or M value. Relative PKB phosphorylation according to body mass index (A) or to M value (B) and fold increase in PKB phosphorylation by insulin according to body mass index (r = 2.38; p = 0.09) (C) or to M value (r = 0.4; p = 0.08) (D). doi:10.1371/journal.pone.0056928.gSummary of signalling analysis (Table 1)The study group was stratified incrementally according to their whole body insulin resistance, determined by the M value, and the responses of each individual signalling protein to insulin were ranked and the four individuals with the greatest (Green numbers, ranking 1 to 4)) or least (Red numbers, ranking 1 to 4) responses for each protein were noted. Representative blots are shown (Figure 6). The responses of interest were insulin-induced changes in IRS1 protein expression, in PKB or p42/p44 MAP kinase phosphorylation or in p42/p44 MAP kinase activity. We observed a.Rs, covering the full range of BMI and M-values. As with western blot we found that there was a great deal of inter-individual variability in the basal level of activity. There was no significant correlation between either basal activity or post-insulin p42/p44 MAPK activity levels, and M-value or BMI (Figure 5). However there was an inverse correlation between fold-induction of p42/44 MAPK activity by insulin and body mass index (r = 0.73; p = 0.0009) (Figure 5A) and 15857111 a significant correlation between p42/44 MAPK activity in response to insulin and M value (r = 0.52; p = 0.04) (Figure 5B). Thus, whether measured against the degree of obesity or IR, the data indicates a close relationship between defective response to insulin of p42/44 MAPK activity in muscle and the clinical measures of pre-diabetes. This suggests that abnormal p42/p44 MAPK response to insulin in skeletal muscle is a better marker of whole body insulin resistance than the response of the PI3K-PKB pathway, at least in obese non-diabetic individuals. FOXO, GSK3 and ribosomal S6. There were no correlations between the basal or insulin-induced levels of phosphorylation of FOXO, GSK3 and ribosomal S6 protein with either BMI or M value (data not shown).Phosphorylation statusPKB. The induction of PKB phosphorylation by insulin was apparent in most volunteers (Figure 3 A and B). There was a tendency for the degree of insulin-induced phosphorylation of PKB to reduce with increasing BMI (r = 2.38; p = 0.09) (C) and to increase with increasing M value (r = 0.4; p = 0.08) (D) but these failed to reach significance. In contrast to the analysis of p42/p44 MAPK, direct assay of PKB activity rather than western blotting of phosphorylation failed to improve the correlation between PKB activity and insulin sensitivity (data not shown). p42/44 MAPK. There were no significant correlations between basal p42/44 MAPK phosphorylation and either BMI or M value (Figure 4). There was a tendency for p42/44 MAPK phosphorylation following insulin exposure to correlate with BMI (Spearman r = 0.4; p = 0.07) (C) or with M value (Spearman r = 0.59; p = 0.08) (D) but these both failed to reach significance.Figure 2. Relationship of IRS1 expression with body mass index or M value. Relative IRS1 protein expression according to body mass index (A) or to M value (B) and fold increase in IRS1 expression according to body mass index (r = 20.36; p = 0.10) (C) or to M value (r = 0.27; p = 0.23) (D). doi:10.1371/journal.pone.0056928.gSkeletal Muscle Signalling Defects in ObesityFigure 3. Relationship of PKB phosphorylation with body mass index or M value. Relative PKB phosphorylation according to body mass index (A) or to M value (B) and fold increase in PKB phosphorylation by insulin according to body mass index (r = 2.38; p = 0.09) (C) or to M value (r = 0.4; p = 0.08) (D). doi:10.1371/journal.pone.0056928.gSummary of signalling analysis (Table 1)The study group was stratified incrementally according to their whole body insulin resistance, determined by the M value, and the responses of each individual signalling protein to insulin were ranked and the four individuals with the greatest (Green numbers, ranking 1 to 4)) or least (Red numbers, ranking 1 to 4) responses for each protein were noted. Representative blots are shown (Figure 6). The responses of interest were insulin-induced changes in IRS1 protein expression, in PKB or p42/p44 MAP kinase phosphorylation or in p42/p44 MAP kinase activity. We observed a.

Easured using realtime PCR. B. Electron transport system abnormalities are more abundant in rats treated with the AMP kinase activator b-guanidinopropionic acid. Each Vastus lateralis skeletal muscle was stained for cytochrome C oxidase and succinate dehydrogenase every 60 microns for one millimeter. Regions of skeletal muscle fibers lacking COX activity 25033180 and hyper-reactive for SDH (the ETS abnormal phenotype) were counted. doi:10.1371/journal.pone.0059006.gDiscussionDespite the identification of the relationship between mitochondrial DNA deletion mutation BIBS39 accumulation and metabolic dysfunction, the specific mechanism(s) that originate and allow clonal accumulation of mtDNA deletion mutations with aging are enigmatic. The loss of electron transport activity in muscle fiber segments harboring intracellular clonal expansions of mtDNA deletion mutations suggests that many metabolic pathways, both anabolic and catabolic, would be affected by the inability to dispose of reducing equivalents generated by respiration. Since many of the enzymes in the citric acid cycle are susceptible to product (NADH) inhibition, the electron flux would decrease, and the central hub of metabolism would be compromised. This would have a direct effect on mitochondrial ATP synthesis, and result in the requirement for the use of inefficient compensatory biochemtransport and oxidative phosphorylation. To test the hypothesis, we stained for activated AMP kinase and overexpression of the peroxisome proliferator activated receptor alpha (ppara) using immunohistochemistry with antibodies specific to these factors, their cofactors and their target genes. AMP kinase was phosphorylated on threonine-172, an indication of its activation, in ETS abnormal fibers. Moreover, a primary downstream target of activated AMP kinase, acetyl-coA carboxylase, was phosphorylated on serine 79, inhibiting fatty acid synthesis, an energy intensive process, consistent with an increase in AMP concentration (Figure 2). Immunohistochemical analysis of ppara, pgc-1a (peroxisome proliferator activated receptor gamma coactivator 1 alpha) andMitobiogenesis Drives mtDNA Deletion MutationsFigure 4. Model of positive feedback loop in ETS abnormal fibers. Signal transduction pathways detect mitochondrial dysfunction and drive transcriptional activation leading to up-regulation of mitochondrial DNA replication and subsequent deletion mutation accumulation. Genes in green were up-regulated in ETS abnormal fibers. Proteins in blue were found to be up-regulated by immunohistochemistry in ETS abnormal fibers. Proteins in purple were detected by both purchase Castanospermine assays. wt: wild-type mitochondrial genomes, D deletion mutation containing mitochondrial genomes. doi:10.1371/journal.pone.0059006.gical pathways, depleting cellular ATP concentration. We tested whether the response to electron transport dysfunction induced by the expansion of mtDNA deletion mutations was non-adaptive and consistent with the proposed role for mitochondrial deletion mutations in sarcopenia. To better understand the molecular basis of sarcopenia, we profiled (Tables S1 and S2) muscle fibers containing intracellular expansions of deletion-mutation containing mitochondrial DNA. The profile obtained suggested that AMP kinase, the ubiquitous energy sensing molecule, was activated as was nuclear hormone signaling, a response indicating a program of mitochondrial biogenesis was activated, consistent with the observed mitochondrial dysfunction in deletio.Easured using realtime PCR. B. Electron transport system abnormalities are more abundant in rats treated with the AMP kinase activator b-guanidinopropionic acid. Each Vastus lateralis skeletal muscle was stained for cytochrome C oxidase and succinate dehydrogenase every 60 microns for one millimeter. Regions of skeletal muscle fibers lacking COX activity 25033180 and hyper-reactive for SDH (the ETS abnormal phenotype) were counted. doi:10.1371/journal.pone.0059006.gDiscussionDespite the identification of the relationship between mitochondrial DNA deletion mutation accumulation and metabolic dysfunction, the specific mechanism(s) that originate and allow clonal accumulation of mtDNA deletion mutations with aging are enigmatic. The loss of electron transport activity in muscle fiber segments harboring intracellular clonal expansions of mtDNA deletion mutations suggests that many metabolic pathways, both anabolic and catabolic, would be affected by the inability to dispose of reducing equivalents generated by respiration. Since many of the enzymes in the citric acid cycle are susceptible to product (NADH) inhibition, the electron flux would decrease, and the central hub of metabolism would be compromised. This would have a direct effect on mitochondrial ATP synthesis, and result in the requirement for the use of inefficient compensatory biochemtransport and oxidative phosphorylation. To test the hypothesis, we stained for activated AMP kinase and overexpression of the peroxisome proliferator activated receptor alpha (ppara) using immunohistochemistry with antibodies specific to these factors, their cofactors and their target genes. AMP kinase was phosphorylated on threonine-172, an indication of its activation, in ETS abnormal fibers. Moreover, a primary downstream target of activated AMP kinase, acetyl-coA carboxylase, was phosphorylated on serine 79, inhibiting fatty acid synthesis, an energy intensive process, consistent with an increase in AMP concentration (Figure 2). Immunohistochemical analysis of ppara, pgc-1a (peroxisome proliferator activated receptor gamma coactivator 1 alpha) andMitobiogenesis Drives mtDNA Deletion MutationsFigure 4. Model of positive feedback loop in ETS abnormal fibers. Signal transduction pathways detect mitochondrial dysfunction and drive transcriptional activation leading to up-regulation of mitochondrial DNA replication and subsequent deletion mutation accumulation. Genes in green were up-regulated in ETS abnormal fibers. Proteins in blue were found to be up-regulated by immunohistochemistry in ETS abnormal fibers. Proteins in purple were detected by both assays. wt: wild-type mitochondrial genomes, D deletion mutation containing mitochondrial genomes. doi:10.1371/journal.pone.0059006.gical pathways, depleting cellular ATP concentration. We tested whether the response to electron transport dysfunction induced by the expansion of mtDNA deletion mutations was non-adaptive and consistent with the proposed role for mitochondrial deletion mutations in sarcopenia. To better understand the molecular basis of sarcopenia, we profiled (Tables S1 and S2) muscle fibers containing intracellular expansions of deletion-mutation containing mitochondrial DNA. The profile obtained suggested that AMP kinase, the ubiquitous energy sensing molecule, was activated as was nuclear hormone signaling, a response indicating a program of mitochondrial biogenesis was activated, consistent with the observed mitochondrial dysfunction in deletio.

F the transient to the baseline to Sodium laureth sulfate site determine the decay time constant as described by Laurita et al.. Average Ca2+ transient parameters were taken at 30 min after a perfusate switch to ensure the response had reached a steady-state. We conducted parallel studies, as described above; with the exception that fNADH instead of Rhod-2AM was imaged. The objective was to determine if the inhibition of the actinmyosin ATPase with 4.75 M of blebbistatin affected the dynamics of fNADH after administering DCA or pyruvate. Measurement of SR calcium load The effect of DCA and pyruvate on SR Ca2+ load was measured using purchase TMS Neonatal myocyte monolayers and a caffeine surge protocol. Neonatal rat ventricular myocytes were isolated and plated from a heterogeneous population of hearts, as previously described. Intracellular Ca2+ transients were imaged using Fluo-4 and confocal fluorescence microscopy. Cells were field stimulated at 0.2 Hz for 30 s, followed by an injection of 20 mM caffeine to induce total SR calcium release. The injection of caffeine was supplemented with 20 mM KCl and 1 mM verapamil to prevent rapid contractions. The average area under the curve of three baseline transients was compared to the area of the large transient induced by the caffeine surge. Arrhythmia scoring Pressure and electrogram signals were examined to identify premature ventricular contractions and episodes of non-sustained ventricular tachycardia. Arrhythmias were scored using a modified method from Jin et al., where hearts having 20 or less PVCs received a score of 0 and hearts having more than 20 PVCs or one episode of NSVT for less than 2 s received a score of 1. We did not observe any heart to have NSVT longer than 2 s. We also did not observe VF or other significant arrhythmias, so scores beyond 1 were not necessary. All hearts received arrhythmia scores of either 0 or 1. Statistics Statistical analyses were performed in R. Data are presented as meanstandard error of mean. Significance was defined by p<0.05, unless noted as p<0.01. One-way ANOVAs with Tukey post hoc tests were used to identify significant differences between groups. A threeway ANOVA with Tukey post hoc tests were used to compare calcium transient Author Manuscript Author Manuscript Author Manuscript Author Manuscript Pflugers Arch. Author manuscript; available in PMC 2016 January 06. Jaimes et al. Page 7 characteristics between baseline and treatments, pacing rates, and between treatments. All data were determined to be normal using the ShapiroWilk test. Author Manuscript Author Manuscript Author Manuscript Author Manuscript Results Control studies with identical KH solutions in each side of the dual perfusion apparatus confirmed that perfusate switching did not cause artifacts or alter heart function. Perfusate switching introduced a maximum temperature variation of less than 1 C and a heart rate change of less than 5 %. No other changes in heart function were detected. HR changes of less than 5 % were also measured when administering DCA or pyruvate. LVDP and nNADH signals in all contracting heart studies consisted of three phases: a baseline phase, a transient phase, and a steady-state phase. The BP was the 10 min of baseline perfusion before a perfusate switch occurred. The TP was the period from the perfusate switch to when changes in LVDP or nNADH subsided. The SSP began when a given variable reached steady-state and corresponded to the time from the end of the TP to the end PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19850718,22102576 of study. Measureme.F the transient to the baseline to determine the decay time constant as described by Laurita et al.. Average Ca2+ transient parameters were taken at 30 min after a perfusate switch to ensure the response had reached a steady-state. We conducted parallel studies, as described above; with the exception that fNADH instead of Rhod-2AM was imaged. The objective was to determine if the inhibition of the actinmyosin ATPase with 4.75 M of blebbistatin affected the dynamics of fNADH after administering DCA or pyruvate. Measurement of SR calcium load The effect of DCA and pyruvate on SR Ca2+ load was measured using neonatal myocyte monolayers and a caffeine surge protocol. Neonatal rat ventricular myocytes were isolated and plated from a heterogeneous population of hearts, as previously described. Intracellular Ca2+ transients were imaged using Fluo-4 and confocal fluorescence microscopy. Cells were field stimulated at 0.2 Hz for 30 s, followed by an injection of 20 mM caffeine to induce total SR calcium release. The injection of caffeine was supplemented with 20 mM KCl and 1 mM verapamil to prevent rapid contractions. The average area under the curve of three baseline transients was compared to the area of the large transient induced by the caffeine surge. Arrhythmia scoring Pressure and electrogram signals were examined to identify premature ventricular contractions and episodes of non-sustained ventricular tachycardia. Arrhythmias were scored using a modified method from Jin et al., where hearts having 20 or less PVCs received a score of 0 and hearts having more than 20 PVCs or one episode of NSVT for less than 2 s received a score of 1. We did not observe any heart to have NSVT longer than 2 s. We also did not observe VF or other significant arrhythmias, so scores beyond 1 were not necessary. All hearts received arrhythmia scores of either 0 or 1. Statistics Statistical analyses were performed in R. Data are presented as meanstandard error of mean. Significance was defined by p<0.05, unless noted as p<0.01. One-way ANOVAs with Tukey post hoc tests were used to identify significant differences between groups. A threeway ANOVA with Tukey post hoc tests were used to compare calcium transient Author Manuscript Author Manuscript Author Manuscript Author Manuscript Pflugers Arch. Author manuscript; available in PMC 2016 January 06. Jaimes et al. Page 7 characteristics between baseline and treatments, pacing rates, and between treatments. All data were determined to be normal using the ShapiroWilk test. Author Manuscript Author Manuscript Author Manuscript Author Manuscript Results Control studies with identical KH solutions in each side of the dual perfusion apparatus confirmed that perfusate switching did not cause artifacts or alter heart function. Perfusate switching introduced a maximum temperature variation of less than 1 C and a heart rate change of less than 5 %. No other changes in heart function were detected. HR changes of less than 5 % were also measured when administering DCA or pyruvate. LVDP and nNADH signals in all contracting heart studies consisted of three phases: a baseline phase, a transient phase, and a steady-state phase. The BP was the 10 min of baseline perfusion before a perfusate switch occurred. The TP was the period from the perfusate switch to when changes in LVDP or nNADH subsided. The SSP began when a given variable reached steady-state and corresponded to the time from the end of the TP to the end PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19850718,22102576 of study. Measureme.

Cantly higher than when compared against all genes with specific transcription in parasitic and free-living stages, respectively. These findings suggest that, while most ES proteins are deployed during the lifecycle, a considerable number are specifically associated with particular functions in either the parasitic- or free-living stages of the worm. A total of 162 genes were predicted to encode ES proteins likely to have immunomodulatory or immunogenic functions, many of which were transcribed at high levels in both parasitic stages; 27% of them are `over-transcribed’ in parasitic stages. Conspicuous were transcripts encoding numerous peptidases, SCP/Tpx-1/Ag5/PR-1/Sc7, transthyretin-like and FAR binding proteins as well as eicosanoids. A set of 160 genes was inferred to encode ES peptidases in the L4 and adult stages with abundant transcription. These genes encoded mainly cysteine-type, serine-type and metallopeptidases as well as some aspartate- and threoninetype peptidases. In addition, transcription of genes encoding 75 peptidase inhibitors was assessed. Many secreted peptidases likely to represent the `degradome’ and respective inhibitors are known to enable parasitic worms to invade, penetrate tissue HC-030031 biological activity barriers and feed; some of them have been reported to induce or modulate the host’s immune response against the parasite. A large repertoire of genes encoding SCP/TAPS proteins was predicted; these molecules are characterized by the Aphrodine web presence of SCP-like domains. Of the 284 predicted SCP/TAPS proteins, 167 were inferred to be ES molecules and 119 were transcribed exclusively in the parasitic stages as compared with only 19 transcribed exclusively Biotechnol Adv. Author manuscript; available in PMC 2016 November 01. Tyagi et al. Page 9 in free-living stages. In total, 179 of the predicted SCP/TAPS proteins did not have orthologs in H. contortus, N. americanus or C. elegans, and only 16 had C. elegans orthologs, similar to recent observations in Necator. The large number of genes encoding SCP/TAPS proteins in O. dentatum compared with only 34 such genes in C. elegans suggests that many of these proteins are involved in functions specific to O. dentatum, with potential relevance to parasitism and/or disease. Some of the SCP/ TAPS proteins predicted were classified as NIFs, 30 of which were predicted to be ES proteins with immunobiological roles. Although NIFs had not been reported previously for O. dentatum, the SCP-1 homolog in Ancylostoma caninum binds the canine integrin CR3 and inhibits the oxidative burst by neutrophils. While the functional significance of most SCP/TAPS proteins is still unknown, they deserve detailed curation and investigation, given that they have been explored as vaccine candidates for other nematodes. Although not yet curated, SCP/TAPS genes are expanded in N. americanus compared with some other parasitic nematodes of animals studied to date. One representative, Na-ASP-2, has been tested in humans as a vaccine candidate, but induced allergic responses following natural exposure to hookworm. The crystal structure of NaASP-2 reveals charge segregation, like that of mammalian chemokines, suggesting that this protein is a ligand or agonist of selected GPCRs . Another set of molecules likely to be PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/1985460 involved in host-parasite interactions are TTL proteins, 64 of which were ES proteins and 28 were transcribed only in parasitic stages of O. dentatum. TTLs are relatively conserved, and some are enzymes that catalyze the h.Cantly higher than when compared against all genes with specific transcription in parasitic and free-living stages, respectively. These findings suggest that, while most ES proteins are deployed during the lifecycle, a considerable number are specifically associated with particular functions in either the parasitic- or free-living stages of the worm. A total of 162 genes were predicted to encode ES proteins likely to have immunomodulatory or immunogenic functions, many of which were transcribed at high levels in both parasitic stages; 27% of them are `over-transcribed’ in parasitic stages. Conspicuous were transcripts encoding numerous peptidases, SCP/Tpx-1/Ag5/PR-1/Sc7, transthyretin-like and FAR binding proteins as well as eicosanoids. A set of 160 genes was inferred to encode ES peptidases in the L4 and adult stages with abundant transcription. These genes encoded mainly cysteine-type, serine-type and metallopeptidases as well as some aspartate- and threoninetype peptidases. In addition, transcription of genes encoding 75 peptidase inhibitors was assessed. Many secreted peptidases likely to represent the `degradome’ and respective inhibitors are known to enable parasitic worms to invade, penetrate tissue barriers and feed; some of them have been reported to induce or modulate the host’s immune response against the parasite. A large repertoire of genes encoding SCP/TAPS proteins was predicted; these molecules are characterized by the presence of SCP-like domains. Of the 284 predicted SCP/TAPS proteins, 167 were inferred to be ES molecules and 119 were transcribed exclusively in the parasitic stages as compared with only 19 transcribed exclusively Biotechnol Adv. Author manuscript; available in PMC 2016 November 01. Tyagi et al. Page 9 in free-living stages. In total, 179 of the predicted SCP/TAPS proteins did not have orthologs in H. contortus, N. americanus or C. elegans, and only 16 had C. elegans orthologs, similar to recent observations in Necator. The large number of genes encoding SCP/TAPS proteins in O. dentatum compared with only 34 such genes in C. elegans suggests that many of these proteins are involved in functions specific to O. dentatum, with potential relevance to parasitism and/or disease. Some of the SCP/ TAPS proteins predicted were classified as NIFs, 30 of which were predicted to be ES proteins with immunobiological roles. Although NIFs had not been reported previously for O. dentatum, the SCP-1 homolog in Ancylostoma caninum binds the canine integrin CR3 and inhibits the oxidative burst by neutrophils. While the functional significance of most SCP/TAPS proteins is still unknown, they deserve detailed curation and investigation, given that they have been explored as vaccine candidates for other nematodes. Although not yet curated, SCP/TAPS genes are expanded in N. americanus compared with some other parasitic nematodes of animals studied to date. One representative, Na-ASP-2, has been tested in humans as a vaccine candidate, but induced allergic responses following natural exposure to hookworm. The crystal structure of NaASP-2 reveals charge segregation, like that of mammalian chemokines, suggesting that this protein is a ligand or agonist of selected GPCRs . Another set of molecules likely to be PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/1985460 involved in host-parasite interactions are TTL proteins, 64 of which were ES proteins and 28 were transcribed only in parasitic stages of O. dentatum. TTLs are relatively conserved, and some are enzymes that catalyze the h.

Partially active in the fasted state in DKO mice, BQ 123 web glucose should contribute more carbon to the synthesis of ketone bodies in these mice. This was examined by measuring the incorporation of carbon from glucose into ketone bodies in wild-type and DKO mice. As anticipated, greater hydroxybutyrate enrichment with two carbons was found in the plasma of the DKO mice, which, combined with the greater concentration of ketone bodies in the DKO mice, established that more ketone bodies were produced from glucose in the DKO mice than in the wild-type mice. This finding is consistent with greater flux through the PDH complex with subsequent conversion of acetyl-CoA into ketone bodies. However, the relative contribution of glucose carbon to the formation of ketone bodies was minuscule relative to other carbon sources, which presumably were almost entirely fatty acids. Since serum levels of NEFAs were similar between DKO and wild-type mice, greater availability of fatty acids for oxidation does not explain the increase in ketone bodies. Fasting induces ketoacidosis and hypothermia PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19847069 in the DKO mice PDHK4-KO mice tolerate fasting without evidence of metabolic decompensation. Since preliminary studies suggested that DKO mice are more sensitive to fasting, the metabolic effects of fasting for various periods of time were determined with wild-type, single-KO and DKO mice. Relative to wild-type mice, a modest, but Biochem J. Author manuscript; available in PMC 2015 February 10. Jeoung et al. Page 10 significant, increase in -hydroxybutyrate occurred after 12 h, but not after 24 and 36 h, of fasting in PDHK2-KO mice. In PDHK4-KO mice, acetoacetate was significantly increased after 24 and 36 h of fasting and -hydroxybutyrate after 36 h of fasting. In the DKO mice, fasting induced much higher levels of both ketone bodies throughout the study than observed in the other genotypes. Fasting for 36 h induced nearly a 5-fold increase in acetoacetate in DKO mice compared with wild-type mice and a 2.5-fold increase compared with PDHK4 KO. In addition, the concentration of hydroxybutyrate was elevated approximately 4-fold in the DKO mice compared with wildtype mice and 2-fold compared with PDHK4-KO mice. Because ketosis can induce metabolic acidosis, the blood pH of the DKO mice was determined. Fasting for 4 h significantly lowered blood pH in the DKO mice compared with wild-type mice. After 24 h of fasting, blood pH of the DKO mice reached dangerously low levels owing to severe ketoacidosis. Unlike the response of the DKO mice, 36 h of fasting did not lower blood pH of PDHK2-KO and PDHK4-KO mice. As LY3039478 cost expected, with the presence of acidosis, the concentration of bicarbonate was dramatically reduced in the DKO mice compared with wild- type mice . Furthermore, pCO2 was significantly reduced in DKO mice. In addition to suffering from ketoacidosis, the DKO mice experienced hypothermia after 36 h of fasting, leading ultimately to their death. Expression of PDHK4 does not compensate for a lack of PDHK2 in PDHK2-KO mice and vice versa PDHK2 and PDHK4 were measured by Western blot analysis to assess whether altered expression of these proteins compensates for the lack of PDHK2 and PDHK4 in the corresponding KO mice. Protein levels of PDHK2 were not changed in the tissues of the PDHK4-KO mice compared with wild-type mice. Protein levels of PDHK4 were likewise similar in heart, liver and skeletal muscle of PDHK2-KO mice and wild-type mice. These findings suggest that, in the fast.Partially active in the fasted state in DKO mice, glucose should contribute more carbon to the synthesis of ketone bodies in these mice. This was examined by measuring the incorporation of carbon from glucose into ketone bodies in wild-type and DKO mice. As anticipated, greater hydroxybutyrate enrichment with two carbons was found in the plasma of the DKO mice, which, combined with the greater concentration of ketone bodies in the DKO mice, established that more ketone bodies were produced from glucose in the DKO mice than in the wild-type mice. This finding is consistent with greater flux through the PDH complex with subsequent conversion of acetyl-CoA into ketone bodies. However, the relative contribution of glucose carbon to the formation of ketone bodies was minuscule relative to other carbon sources, which presumably were almost entirely fatty acids. Since serum levels of NEFAs were similar between DKO and wild-type mice, greater availability of fatty acids for oxidation does not explain the increase in ketone bodies. Fasting induces ketoacidosis and hypothermia PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19847069 in the DKO mice PDHK4-KO mice tolerate fasting without evidence of metabolic decompensation. Since preliminary studies suggested that DKO mice are more sensitive to fasting, the metabolic effects of fasting for various periods of time were determined with wild-type, single-KO and DKO mice. Relative to wild-type mice, a modest, but Biochem J. Author manuscript; available in PMC 2015 February 10. Jeoung et al. Page 10 significant, increase in -hydroxybutyrate occurred after 12 h, but not after 24 and 36 h, of fasting in PDHK2-KO mice. In PDHK4-KO mice, acetoacetate was significantly increased after 24 and 36 h of fasting and -hydroxybutyrate after 36 h of fasting. In the DKO mice, fasting induced much higher levels of both ketone bodies throughout the study than observed in the other genotypes. Fasting for 36 h induced nearly a 5-fold increase in acetoacetate in DKO mice compared with wild-type mice and a 2.5-fold increase compared with PDHK4 KO. In addition, the concentration of hydroxybutyrate was elevated approximately 4-fold in the DKO mice compared with wildtype mice and 2-fold compared with PDHK4-KO mice. Because ketosis can induce metabolic acidosis, the blood pH of the DKO mice was determined. Fasting for 4 h significantly lowered blood pH in the DKO mice compared with wild-type mice. After 24 h of fasting, blood pH of the DKO mice reached dangerously low levels owing to severe ketoacidosis. Unlike the response of the DKO mice, 36 h of fasting did not lower blood pH of PDHK2-KO and PDHK4-KO mice. As expected, with the presence of acidosis, the concentration of bicarbonate was dramatically reduced in the DKO mice compared with wild- type mice . Furthermore, pCO2 was significantly reduced in DKO mice. In addition to suffering from ketoacidosis, the DKO mice experienced hypothermia after 36 h of fasting, leading ultimately to their death. Expression of PDHK4 does not compensate for a lack of PDHK2 in PDHK2-KO mice and vice versa PDHK2 and PDHK4 were measured by Western blot analysis to assess whether altered expression of these proteins compensates for the lack of PDHK2 and PDHK4 in the corresponding KO mice. Protein levels of PDHK2 were not changed in the tissues of the PDHK4-KO mice compared with wild-type mice. Protein levels of PDHK4 were likewise similar in heart, liver and skeletal muscle of PDHK2-KO mice and wild-type mice. These findings suggest that, in the fast.