Ce (Figure 3A, bottom panel). In the livers of VHL-KO (VHLf/fCreERTM with tamoxifen) mice, the fluorescence level of a glucose analogue, 2NBDG [2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose], which was injected intravenously, was much higher thanFigure 2. NO production due to VHL deletion does not contribute to hypoglycemia in VHL-KO mice. There were no significant increases in blood glucose levels (BS) in both L-NAME-treated VHL-KO mice (n = 5) and eNOS-deficient VHL-KO mice (n = 5). The hypoglycemic levels of both these mouse groups were not different from those of VHL-KO mice (n = 6?) (L-NAME-treated VHL-KO mice vs. VHL-KO mice, p = 0.210: N.S.; eNOS-deficient VHL-KO mice vs. VHL-KO mice, p = 0.523: N.S.). DBS was determined by subtracting BS before the tamoxifen injection from BS after the injection. Data were used to determine DBS values: DBS = BSafter ?BSbefore. doi:10.1371/journal.pone.0069139.gthat in the livers of control (VHLf/fCreERTM without tamoxifen) mice (Figure 3B). This result indicated that glucose uptake into hepatocytes was enhanced by VHL deletion. The fluorescence intensity in the liver of VHL-KO mice was the highest among the organs ML 281 web examined, including skeletal muscle and heart, although, compared with the levels in control mice, the fluorescence levels in the skeletal muscle and heart of VHL-KO mice were markedly higher (data not shown).In vivo Association of CI-1011 biological activity IGF-IR with RACK-I in the Liver with VHL-deletionThe insulin-like 18204824 growth factor 1315463 I receptor (IGF-IR), receptor for activated C kinase 1 (RACK1), insulin receptor (IR), phospho-Akt (p-Akt) and VHL expression in the livers of VHL-KO (VHLf/ f CreERTM with tamoxifen) and control (VHLf/fCreERTM without tamoxifen) mice were evaluated by Western blot analysis (Figure 4A). VHL-KO livers resulted in downregulation of VHL expression (Figure 4A, top panel). VHL-KO livers had significantlyVHL Deletion Causes HypoglycemiaFigure 3. VHL deletion induces accelerated hepatic glucose uptake and storage of PAS-positive substances. (A) H E stained liver sections from VHL-KO mice showed characteristic appearances of hepatocytes (top panel); translucent hepatocytes with conserved cellular architectures. These translucent hepatocytes were strongly positive for PAS staining (middle panel) compared to those cells from WT Tamoxifen+and VHL-KO Tamoxifen 2, which suggested marked glycogen accumulation. VHL immunostaining showed mosaic loss of VHL expression in the liver in VHL-KO mice (bottom panel). (B) In VHL-KO mice, 2-NBDG fluorescence intensity in the liver was considerably increased compared to control mice (VHL-KO Tamoxifen 2). doi:10.1371/journal.pone.0069139.gVHL Deletion Causes Hypoglycemiahigher levels of IGF-IR compared to control livers, as also supported by immunohistochemical analysis (Figure 4B). PhosphoAkt expression was also enhanced in the livers of VHL-KO mice. On the other hand, RACK1 and IR expression levels in VHL-KO livers were comparable with those in control livers. To evaluate the interaction of IGF-IR with RACK1 in VHL-KO livers, we conducted co-immunoprecipitation (co-IP) experiments using liver cell lysates from VHL-KO and control mice. On using an anti-IGFIR antibody, it was observed that immunoprecipitates from VHLKO livers included more RACK1 protein compared with those from control mice (Figure 4C). In contrast, the IR immunoprecipitates from VHL-KO and control livers did not include RACK1 (Figure 4D). Taken together, IGF-IR formed a com.Ce (Figure 3A, bottom panel). In the livers of VHL-KO (VHLf/fCreERTM with tamoxifen) mice, the fluorescence level of a glucose analogue, 2NBDG [2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose], which was injected intravenously, was much higher thanFigure 2. NO production due to VHL deletion does not contribute to hypoglycemia in VHL-KO mice. There were no significant increases in blood glucose levels (BS) in both L-NAME-treated VHL-KO mice (n = 5) and eNOS-deficient VHL-KO mice (n = 5). The hypoglycemic levels of both these mouse groups were not different from those of VHL-KO mice (n = 6?) (L-NAME-treated VHL-KO mice vs. VHL-KO mice, p = 0.210: N.S.; eNOS-deficient VHL-KO mice vs. VHL-KO mice, p = 0.523: N.S.). DBS was determined by subtracting BS before the tamoxifen injection from BS after the injection. Data were used to determine DBS values: DBS = BSafter ?BSbefore. doi:10.1371/journal.pone.0069139.gthat in the livers of control (VHLf/fCreERTM without tamoxifen) mice (Figure 3B). This result indicated that glucose uptake into hepatocytes was enhanced by VHL deletion. The fluorescence intensity in the liver of VHL-KO mice was the highest among the organs examined, including skeletal muscle and heart, although, compared with the levels in control mice, the fluorescence levels in the skeletal muscle and heart of VHL-KO mice were markedly higher (data not shown).In vivo Association of IGF-IR with RACK-I in the Liver with VHL-deletionThe insulin-like 18204824 growth factor 1315463 I receptor (IGF-IR), receptor for activated C kinase 1 (RACK1), insulin receptor (IR), phospho-Akt (p-Akt) and VHL expression in the livers of VHL-KO (VHLf/ f CreERTM with tamoxifen) and control (VHLf/fCreERTM without tamoxifen) mice were evaluated by Western blot analysis (Figure 4A). VHL-KO livers resulted in downregulation of VHL expression (Figure 4A, top panel). VHL-KO livers had significantlyVHL Deletion Causes HypoglycemiaFigure 3. VHL deletion induces accelerated hepatic glucose uptake and storage of PAS-positive substances. (A) H E stained liver sections from VHL-KO mice showed characteristic appearances of hepatocytes (top panel); translucent hepatocytes with conserved cellular architectures. These translucent hepatocytes were strongly positive for PAS staining (middle panel) compared to those cells from WT Tamoxifen+and VHL-KO Tamoxifen 2, which suggested marked glycogen accumulation. VHL immunostaining showed mosaic loss of VHL expression in the liver in VHL-KO mice (bottom panel). (B) In VHL-KO mice, 2-NBDG fluorescence intensity in the liver was considerably increased compared to control mice (VHL-KO Tamoxifen 2). doi:10.1371/journal.pone.0069139.gVHL Deletion Causes Hypoglycemiahigher levels of IGF-IR compared to control livers, as also supported by immunohistochemical analysis (Figure 4B). PhosphoAkt expression was also enhanced in the livers of VHL-KO mice. On the other hand, RACK1 and IR expression levels in VHL-KO livers were comparable with those in control livers. To evaluate the interaction of IGF-IR with RACK1 in VHL-KO livers, we conducted co-immunoprecipitation (co-IP) experiments using liver cell lysates from VHL-KO and control mice. On using an anti-IGFIR antibody, it was observed that immunoprecipitates from VHLKO livers included more RACK1 protein compared with those from control mice (Figure 4C). In contrast, the IR immunoprecipitates from VHL-KO and control livers did not include RACK1 (Figure 4D). Taken together, IGF-IR formed a com.