mortality/aging
N |
• mice are born in the expected Mendelian ratio and survive to adulthood, unlike Mad2l1bptm1.2Itl homozygotes
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homeostasis/metabolism
• at 2 months of age, mice show hyperglycemia in the fed state
• surprisingly, blood glucose levels become normal by 6 months of age
• adeno-associated virus (AAV)-mediated expression of MAD2L1BP (but not of GFP) in the liver rescues the hyperglycemia phenotype
|
• at 2 months of age, mice show hyperinsulinemia in the fed state that is less severe than that in Insrtm1Khn/Insrtm1Khn
Speer6-ps1Tg(Alb-cre)21Mgn/Speer6-ps1+ mice
|
• at 2 months of age, serum triglyceride levels are moderately increased
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• at 2 months of age, male mice develop glucose intolerance that is less severe than that in Insrtm1Khn/Insrtm1Khn
Speer6-ps1Tg(Alb-cre)21Mgn/Speer6-ps1+ mice
• AAV-mediated expression of MAD2L1BP (but not of GFP) in the liver rescues the glucose intolerance phenotype
|
• at E18.5, liver glycogen levels are decreased but to a much lesser extent than in Mad2l1bptm1.2Itl homozygotes, thus enabling survival
• at 2 months of age, liver glycogen levels are reduced but to a lesser extent than in Insrtm1Khn/Insrtm1Khn
Speer6-ps1Tg(Alb-cre)21Mgn/Speer6-ps1+ mice
• however, no liver developmental defects are noted at E18.5 or at 2 months of age
|
• at 2 months of age, male mice develop insulin intolerance that is less severe than that in Insrtm1Khn/Insrtm1Khn
Speer6-ps1Tg(Alb-cre)21Mgn/Speer6-ps1+ mice
• AAV-mediated expression of MAD2L1BP (but not of GFP) in the liver rescues the insulin intolerance phenotype
|
• at 2 months of age, hepatic triglyceride levels are decreased by about 50%
|
• insulin treatment fails to stimulate glycogen synthase activity (GS) in hepatocytes, unlike in wild-type hepatocytes
|
liver/biliary system
• at E18.5, liver glycogen levels are decreased but to a much lesser extent than in Mad2l1bptm1.2Itl homozygotes, thus enabling survival
• at 2 months of age, liver glycogen levels are reduced but to a lesser extent than in Insrtm1Khn/Insrtm1Khn
Speer6-ps1Tg(Alb-cre)21Mgn/Speer6-ps1+ mice
• however, no liver developmental defects are noted at E18.5 or at 2 months of age
|
• at 2 months of age, hepatic triglyceride levels are decreased by about 50%
|
• insulin receptor (IR) autophosphorylation and activating phosphorylation of AKT (pT308) are significantly reduced whereas inhibitory phosphorylation of GSK3 (pS9) is modestly reduced in whole-liver lysates from insulin-treated mice
• AAV-mediated expression of MAD2L1BP (but not of GFP) in the liver rescues the insulin signaling defects
|
• insulin-dependent glycogen synthase (GS) activation is abolished in hepatocytes
• freshly isolated primary hepatocytes display weakened and delayed IR autophosphorylation and AKT pT308 at multiple time points and over a wide range of insulin concentrations
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cellular
aneuploidy
(
J:234643
)
• only 10% (1 out of 10) live hepatocytes is aneuploid relative to none (0 of 15) wild-type hepatocytes
• AAV-mediated expression of MAD2L1BP does not eliminate aneuploidy: 5% (2 of 39) hepatocytes are aneuploid vs only 2.5% (1 of 40) hepatocytes in the AAV-GFP control group
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• hepatocytes show defective insulin endocytosis as a result of a reduced level of functional IR at the plasma membrane, due to premature internalization of IR prior to insulin stimulation
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