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Mol. Cell. Biol., Jan 1995, 351-357, Vol 15, No. 1
P Tontonoz, E Hu, J Devine, EG Beale and BM Spiegelman
Phosphoenolpyruvate carboxykinase (PEPCK) is expressed at high levels in
liver, kidney, and adipose tissue. This enzyme catalyzes the rate- limiting
step in hepatic and renal gluconeogenesis and adipose glyceroneogenesis.
The regulatory factors important for adipose expression of the PEPCK gene
are not well defined. Previous studies with transgenic mice established
that the region between bp -2086 and - 888 is required for expression in
adipose tissue but not for expression in liver or kidney tissue. We show
here that a DNA fragment containing this region can function as an enhancer
and direct differentiation- dependent expression of a chloramphenicol
acetyltransferase gene from a heterologous promoter in cultured 3T3-F442A
preadipocytes and adipocytes. We further demonstrate that the
adipocyte-specific transcription factor PPAR gamma 2, previously identified
as a regulator of the adipocyte P2 enhancer, binds in a heterodimeric
complex with RXR alpha to the PEPCK 5'-flanking region at two sites, termed
PCK1 (bp - 451 to -439) and PCK2 (bp -999 to -987). Forced expression of
PPAR gamma 2 and RXR alpha activates the PEPCK enhancer in non-adipose
cells. This activation is potentiated by peroxisome proliferators and fatty
acids but not by 9-cis retinoic acid. Mutation of the PPAR gamma 2 binding
site (PCK2) abolishes both the activity of the enhancer in adipocytes and
its ability to be activated by PPAR gamma 2 and RXR alpha. These results
establish a role for PPAR gamma 2 in the adipose expression of the PEPCK
gene and suggest that this factor functions as a coordinate regulator of
multiple adipocyte-specific genes.
Copyright © 1995, American Society for Microbiology
PPAR gamma 2 regulates adipose expression of the phosphoenolpyruvate carboxykinase gene
Dana-Farber Cancer Institute, Boston, Massachusetts 02115.
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