Distinguishing Properties of mitochondrial glycerol‐3‐phosphate acyltransferase distal and proximal promoter.

Abstract

As shown previously, we have identified two promoter regions for rat mitochondrial glycerol-3-phosphate acyltransferase. The distal promoter is located ~30 kb upstream whereas the proximal promoter is right next to the first translational codon. In an effort to functionally distinguish these two promoter regions, the COS-1 cells were transfected with pGL3 basic containing either the distal or the proximal promoter region with luciferase as the reporter gene. The cells were starved and then treated with 50 mM glucose and 100nM insulin. There was 5 to 6- fold increase in luciferase activity with the plasmid containing the distal promoter region but not with the plasmid containing the proximal promoter region. The antibody specific for carbohydrate response element binding protein further retarded or supershifted the migration of the complex of distal promoter incubated with the glucose treated COS-1 cell nuclear extracts. No such differences in the migration were observed when similar experiments were done with the proximal promoter. Taken together, these results suggest that the glucose-insulin response is mediated via the distal and not the proximal promoter region of mtGPAT. This work has been supported by NIH grant GM-57643.