PARENT SESSION
PLATFORM SESSION 17: GENE REGULATION AND FUNCTION IN THE REPRODUCTIVE TRACT
Chair: Asselin, Eric¹, ¹
Co-chair: Boerboom, Derek¹, ¹
Harborside A
2:00 PM-4:00 PM

(422) IDENTIFICATION OF A FUNCTIONAL FORKHEAD RESPONSE ELEMENT IN THE ACTIVIN _A PROMOTER: A POSSIBLE MECHANISM FOR PROLACTIN REGULATION OF ACTIVIN EXPRESSION .

Bowen-Shauver, Jennifer¹, Zhang, Xiaohui², Mao, Jifang¹, Unterman, Terry^1,2, Gibori, Geula¹, ¹ Dept of Physiology and Biophysics, Chicago, IL² Dept of Medicine, Chicago, IL

ABSTRACT- Activin A is a pro-apoptotic factor in the decidua, in which tissue its expression is inhibited by prolactin and placental lactogens. This suggests that the documented anti-apoptotic effects of prolactin/lactogens in decidua may be due in part to inhibition of activin A production. In this study, we investigated a potential pathway by which prolactin may regulate the activin _A gene. Our laboratory has previously shown that the anti-apoptotic effect of prolactin in decidual tissue is mediated through the PI3K/PKB system. PKB is known to phosphorylate the FOXO forkhead family of transcription factors, causing their exclusion from the nucleus and disrupting their DNA-binding ability. This leads to the down-regulation of genes containing active forkhead response elements. Using the MatInspector program and TRANSFAC database, we identified three clusters of putative forkhead response elements in a -761 bp 5′-flanking region of the activin _A gene. Gel-shift analysis determined that the most distal of these regions (at -689) was capable of strong binding to bacterially expressed recombinant protein containing the DNA-binding domain of FOXO1 (FKHR). Several bands were detected when the -689 region was incubated with lysate from cells over-expressing FOXO1 and one of these bands was eliminated by incubation with an antibody to FOXO1, indicating specific binding. Gel-shift studies performed with nuclear and cytosolic protein fractions from rat decidua and a rat decidual cell line (GGAD) also revealed endogenous proteins capable of binding to the -689 region of the activin _A promoter. We have confirmed the presence of FOXO proteins in decidua and GGAD cells by western blotting with antibodies to FOXO1 and FOXO3 (FKHR and FKHRL1, Upstate Biotechnology). Currently, we are carrying out experiments to determine 1) whether phosphorylation and translocation of these transcription factors in decidual cells is affected by prolactin and 2) the role of forkhead transcription factors in regulation of activin expression. Supported by NIH HD12356, HD11119 and HL07692-12.

KEY WORDS: forkhead, prolactin, activin, decidua