The long-term objective of this study is to understand how tissue- specific gene expression is controlled. Previous studies in transgenic mice showed that cis-acting elements required to drive phosphoenolpyruvate carboxykinase (PEPCK) transcription in fat cells are different from those in liver cells. Specifically, a distal """"""""fat- specific"""""""" enhancer (from -1240 to -830 bp upstream of the PEPCK gene) is absolutely required for PEPCK expression in adipocytes. In contrast, this fat-specific enhancer is dispensable in hepatocytes. Recent studies show that: 1) a PPARgamma2/RXRalpha (peroxisome proliferator-activated receptor/9-cis retinoic acid receptor) heterodimer binds to and activates the fat-specific PEPCK enhancer via an element at -993 bp designated as PCK2; 2) PPARgamma2/RXRalpha also binds to a second site at -445 bp (designated as PCK1/AF1) which is part of a complex hormone response unit in liver; and 3) Linoleic acid induces PEPCK in cultured adipocytes.
Three specific aims are proposed to address two hypotheses regarding the mechanisms that control fat-specific PEPCK expression. This information will lead to a better understanding of how different tissue-specific factors regulate transcription from the same promoter of the PEPCK gene.. * Hypothesis l: The PPARgamma2/RXRalpha heterodimer is the critical fat- specific factor that drives PEPCK expression through PCK2, the element centered at -993 bp, within the fat-specific enhancer.
Aim l: To determine whether PPARgamma2 is the principal pairing partner for RXRalpha bound to PCK2 and whether this heterodimer drives fat- specific PEPCK expression. * Hypothesis 2: The PPARgamma2/RXRalpha heterodimer binds to PCK2 with a fixed polarity that provides an essential topology for it to interact with transcription factors bound to other sites.
Aim 2 : To determine the overall architecture of the fat-specific enhancer.
Aim 3 : To map the domain outside of the fat-specific enhancer which is needed for All enhancer activity. and to clone factors that interact with PPARgamma2.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM039895-08
Application #
2444680
Study Section
Metabolism Study Section (MET)
Project Start
1988-09-16
Project End
2000-12-31
Budget Start
1997-07-01
Budget End
2000-12-31
Support Year
8
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Texas Tech University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
609980727
City
Lubbock
State
TX
Country
United States
Zip Code
79430
Beale, Elmus G (2013) Insulin signaling and insulin resistance. J Investig Med 61:11-4
Tordjman, Joan; Chauvet, Genevieve; Quette, Joelle et al. (2003) Thiazolidinediones block fatty acid release by inducing glyceroneogenesis in fat cells. J Biol Chem 278:18785-90
Beale, Elmus G; Forest, Claude; Hammer, Robert E (2003) Regulation of cytosolic phosphoenolpyruvate carboxykinase gene expression in adipocytes. Biochimie 85:1207-11
Devine, J H; Eubank, D W; Clouthier, D E et al. (1999) Adipose expression of the phosphoenolpyruvate carboxykinase promoter requires peroxisome proliferator-activated receptor gamma and 9-cis-retinoic acid receptor binding to an adipocyte-specific enhancer in vivo. J Biol Chem 274:13604-12