Altered hepatic triglyceride content after partial hepatectomy without impaired liver regeneration in multiple murine genetic models.
Liver regeneration is impaired following partial hepatectomy (PH) in mice with genetic obesity and hepatic steatosis and also in wild-type mice fed a high-fat diet. These findings contrast with other data showing that liver regeneration is impaired in mice in which hepatic lipid accumulation is suppressed by either pharmacologic leptin administration or by disrupted glucocorticoid signaling. These latter findings suggest that hepatic steatosis may actually be required for normal liver regeneration. We have reexamined this relationship using several murine models of altered hepatic lipid metabolism. Liver fatty acid (FA) binding protein knockout mice manifested reduced hepatic triglyceride (TG) content compared to controls, with no effect on liver regeneration or hepatocyte proliferation. Examination of early adipogenic messenger RNAs revealed comparable induction in liver from both genotypes despite reduced hepatic steatosis. Following PH, hepatic TG was reduced in intestine-specific microsomal TG transfer protein deleter mice, which fail to absorb dietary fat, increased in peroxisome proliferator activated receptor alpha knockout mice, which exhibit defective FA oxidation, and unchanged (from wild-type mice) in liver-specific FA synthase knockout mice in which endogenous hepatic FA synthesis is impaired. Hepatic TG increased in the regenerating liver in all models, even in animals in which lipid accumulation is genetically constrained. However, in no model -- and over a >90-fold range of hepatic TG content -- was liver regeneration significantly impaired following PH.


CONCLUSIONS
Although hepatic TG content is widely variable and increases during liver regeneration, alterations in neither exogenous or endogenous lipid metabolic pathways, demonstrated to promote or diminish hepatic steatosis, influence hepatocyte proliferation.
Newberry
Elizabeth P
EP
Department of Medicine, School of Medicine, Washington University, St Louis, MO 63110, USA.
Kennedy
Susan M
SM
Xie
Yan
Y
Luo
Jianyang
J
Stanley
Susan E
SE
Semenkovich
Clay F
CF
Crooke
Roseanne M
RM
Graham
Mark J
MJ
Davidson
Nicholas O
NO
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D049109:Cell Proliferation; D004195:Disease Models, Animal; D050556:Fatty Acid-Binding Proteins / Q000235:genetics*; D005227:Fatty Acids / Q000378:metabolism; D005234:Fatty Liver / Q000235:genetics / Q000378:metabolism; D006498:Hepatectomy; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology; D008099:Liver / Q000378:metabolism* / Q000601:surgery; D008115:Liver Regeneration / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009765:Obesity / Q000235:genetics / Q000378:metabolism; D047493:PPAR alpha / Q000235:genetics*; D014280:Triglycerides / Q000378:metabolism*
D002352:Carrier Proteins; C493320:Fabp1 protein, mouse; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D047493:PPAR alpha; D014280:Triglycerides; C106092:microsomal triglyceride transfer protein