USF2 inhibits C/EBP-mediated transcriptional regulation of the RIIβ subunit of cAMP-dependent protein kinase

• Published in: BMC molecular biology 2002-06, Vol.3 (1), p.10-10, Article 10
• Main Authors: Dahle, Maria Krudtaa, Taskén, Kjetil, Taskén, Kristin Austlid
• Format: Article
• Language: English
• ISSN: 1471-2199; 1471-2199
• DOI: 10.1186/1471-2199-3-10

Cyclic AMP-dependent protein kinase (PKA) plays a central role in regulation of energy metabolism. Upon stimulation of testicular Sertoli cells by follicle stimulating hormone (FSH), glycolysis is activated to increase the production of nutrients for the germ cells, and a new regulatory subunit of cAMP-dependent protein kinase, RII beta , is induced. We have previously shown that production of the transcription factor C/EBP beta is rapidly increased by FSH and cAMP in primary Sertoli cell cultures, and that C/EBP beta induces the RII beta promoter. In this work we show that USF1, USF2 and truncated USF isoforms bind to a conserved E-box in the RII beta gene. Interestingly, overexpression of USF2, but not USF1, led to inhibition of both cAMP- and C/EBP beta -mediated induction of RII beta . Furthermore, Western blots show that a novel USF1 isoform is induced by cAMP in Sertoli cells. These results indicate that the expression of various USF isoforms may be regulated by cAMP, and that the interplay between USF and C/EBP beta is important for cAMP-mediated regulation of RII beta expression. The counteracting effects of USF2 and C/EBP beta observed on the RII beta promoter is in accordance with the hypothesis that C/EBP and USF play opposite roles in regulation of glucose metabolism.