Combinatorial Transcription Factor Regulation of the Cyclic AMP-response Element on the Pgc-1α Promoter in White 3T3-L1 and Brown HIB-1B Preadipocytes

Abstract

Cold stress in rodents increases the expression of UCP1 and PGC-1␣ in brown and white adipose tissue. We have previously reported that C/EBP␤ specifically binds to the CRE on the proximal Pgc-1␣ promoter and increases forskolin-sensitive Pgc-1␣ and Ucp1 expression in white 3T3-L1 preadipocytes. Here we show that in mice exposed to a cold environment for 24 h, Pgc-1␣, Ucp1, and C/ebp␤ but not C/ebp␣ or C/ebp␦ expression were increased in BAT. Conversely, expression of the C/EBP dominant negative Chop10 was increased in WAT but not BAT during cold exposure. Reacclimatization of cold-exposed mice to a warm environment for 24 h completely reversed these changes in gene expression. In HIB-1B, brown preadipocytes, forskolin increased expression of Pgc-1␣, Ucp1, and C/ebp␤ early in differentiation and inhibited Chop10 expression. Employing chromatin immunoprecipitation, we demonstrate that C/EBP␤, CREB, ATF-2, and CHOP10 are bound to the Pgc-1␣ proximal CRE, but CHOP10 does not bind in HIB-1B cell lysates. Forskolin stimulation and C/EBP␤ overexpression in 3T3-L1 cells increased C/EBP␤ and CREB but displaced ATF-2 and CHOP10 binding to the Pgc-1␣ proximal CRE. Overexpression of ATF-2 and CHOP10 in 3T3-L1 cells decreased Pgc-1␣ transcription. Knockdown of Chop10 in 3T3-L1 cells using siRNA increased Pgc-1␣ transcription, whereas siRNA against C/ebp␤ in HIB-1B cells decreased Pgc-1␣ and Ucp1 expression. We conclude that the increased cAMP stimulation of Pgc-1␣ expression is regulated by the combinatorial effect of transcription factors acting at the CRE on the proximal Pgc-1␣ promoter.

Basal adrenergic tone is required for maximal stimulation of rat brown adipose tissue UCP1 expression by chronic PPAR-γ activation

“…Expression of PGC-␣ and its transcriptional regulator C/EBP-␤ followed a pattern of modulation similar to that of the mitochondrial markers (no effect of rosiglitazone and reduction by denervation). These findings are in accordance with in vitro and in vivo studies showing that BAT PGC-␣ expression is under adrenergic control through cAMP response-element binding protein and C/EBP-␤ activation and correlates with mitochondrial mass (18,26,37). Interestingly, rosiglitazone increased mRNA levels of the orphan nuclear receptor SHP (NROB2), a negative regulator of PGC-␣ expression and energy expenditure in brown adipocytes (40), and reduced those of both SIRT3, a protein involved in the control of BAT PGC-␣ expression and mitochondrial biogenesis (31), and PRDM16, a zinc-finger protein that exerts its action in BAT by interacting with and modulating PPAR-␥ transcriptional activity (17,28,29).…”

NR4A orphan nuclear receptors as mediators of CREB-dependent neuroprotection

“…CREB has also been found to induce PGC-1α expression (3,14,(44)(45)(46). We show here that PGC-1α is expressed in neurons exposed to oxidative stress, as previously observed in fibroblasts (14), but it failed to be induced by excitotoxic insult induced by ionomycin and glutamate.…”

Association of single nucleotide polymorphism Rs2236518 in PRDM16 gene with BMI in Chinese males

“…In recent years, a wealth of studies have focused on the role of PRDM16 in BAT and white adipose tissue (WAT) and on the possible mechanisms by which PRDM16 directs cell fate to skeletal myoblasts or brown fat cells [9,[11][12][13] . To our knowledge, no study has been performed on the genetic association of PRDM16 polymorphisms with obesity-related phenotypic variation in humans.…”