Oral Presentation ANZOS-ASLM-ICCR 2019

The effect of PKCɛ deletion on the adipose tissue tricarboxylic acid cycle and electron transport chain (#49)

A. Gabrielle J. van der Kraan 1 , Ashleigh M. Philp 1 , Stephen P. Ashcroft 2 , Maria Findeisen 1 , Andrew Philp 1 , Carsten Schmitz-Peiffer 1 3
  1. Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
  2. University of Birmingham, Birmingham, UK
  3. University of New South Wales, Sydney, NSW, Australia

Protein Kinase C epsilon (PKCɛ) is a signalling enzyme that has been shown to play a negative role in diet-induced insulin sensitivity and glucose tolerance, which has been thought to be exerted directly in the liver. Recently, our laboratory has shown that adipose tissue- (AdPKCɛKO) but not liver-specific PKCɛ deletion mediates a protective effect against whole body glucose intolerance (Brandon et al., 2019). The signalling pathways whereby PKCɛ is mediating these effects is not clear. However, mitochondrial dysfunction has been previously implicated in the development of insulin resistance (Gonzalez-Franquesa and Patti, 2017). PKCɛ has also been shown to regulate the phosphorylation of proteins involved in the tricarboxylic Acid Cycle (TCA) and the Electron Transport Chain (ETC) and also have proteins involved in these processes within PKCɛ signalling complexes (Budas et al., 2012, Edmondson et al., 2002). Using adipose tissue from fat-fed wildtype and ADPKCɛKO mice (n=7), we performed mitochondrial respirometry and citrate synthase activity assays, and also measured proteins involved in oxidative phosphorylation (OXPHOS) by immunoblotting. Mitochondrial respiration in ADPKCɛKO adipose tissue showed minor increases in the ETC leak, complex I and complexes I + II activity and there was a significant increase in uncoupled ETC respiration (1.3 fold, P<0.05). Citrate synthase activity, a marker of mitochondrial content, was not different between groups. Markers of OXPHOS Complex II or Complex IV protein expression were also not different. However, there were tendencies for a decrease in Complex I and an increase in Complex V protein markers. In addition, the OXPHOS Complex III subunit, Ubiquinol-cytochrome c reductase core protein, protein expression was significantly increased in ADPKCɛKO tissue (2.75 fold, P<0.05). These data suggest that PKCe deletion in adipose tissue increases mitochondrial ETC capacity without affecting mitochondrial content and may contribute to improved glucose tolerance in ADPKCɛKO mice.