Proteomic and phosphoproteomic analysis of PKCe KO

ABSTRACT: Activation of protein kinase C epsilon (PKCε) in the liver has been widely associated with hepatic insulin resistance. PKCε is proposed to inhibit insulin signalling through phosphorylation of the insulin receptor. We have tested this directly by breeding PKCε floxed mice with mice expressing Cre recombinase under the control of the cytomegalovirus, albumin or adiponectin promoters to generate global, liver- and adipose tissue-specific PKCε knockout (KO) mice. Global deletion of PKCε recapitulated the benefits for diet-induced glucose intolerance that we previously described using conventional PKCε KO mice. However, we did not detect PKCε-dependent alterations in hepatic insulin receptor phosphorylation. Furthermore, liver-specific KO mice were not protected against diet-induced glucose intolerance or insulin resistance determined by euglycemic clamp. In contrast, adipose tissue-specific KO mice exhibited improved glucose tolerance and mildly increased hepatic triglyceride storage, but no change in liver insulin sensitivity. Phosphoproteomic analysis of insulin signalling in PKCε KO adipocytes revealed no defect in the canonical INSR/AKT/mTOR pathways. However, PKCε KO resulted in changes in phosphorylation of several proteins associated with the endosome and cell junctions suggesting regulation in secretory pathways and a potential role of PKCε in endocrine function. Indeed, RNA-seq analysis revealed adipose-tissue PKCε-dependent changes in the hepatic expression of several genes linked to glucose homeostasis and hepatic lipid metabolism. The primary effect of PKCε on glucose homeostasis is therefore not exerted directly in the liver as currently assumed. However, PKCε in adipose tissue modulates glucose tolerance and is involved in crosstalk with the liver that affects gene expression and lipid accumulation.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Subcutaneous Fat Cell

SUBMITTER: Benjamin Parker  

LAB HEAD: Benjamin Parker

PROVIDER: PXD010212 | Pride | 2018-10-04

REPOSITORIES: Pride