308. FOLLISTATIN SPLICE VARIANTS FST288 AND FST315 INCREASE DURING EARLY MOUSE PREGNANCY: REGULATION BY PROGESTERONE?
R. G. Craythorn A B , W. R. Winnall B , M. P. Hedger B , P. A. W. Rogers A , D. M. De Kretser B and J. E. Girling AA Centre for Women’s Health Research, Monash University Department of Obstetrics and Gynaecology and Monash Institute, Melbourne, VIC, Australia.
B Centre for Reproduction and Development, Monash Institute of Medical Research, Melbourne, VIC, Australia.
Reproduction, Fertility and Development 22(9) 108-108 https://doi.org/10.1071/SRB10Abs308
Published: 6 September 2010
Abstract
Follistatin acts by binding and neutralising the activity of activin-A, which has important regulatory roles in development, reproduction and inflammation. There are two isoforms of follistatin comprising 288 and 315 amino acids (FST288 and FST315), resulting from alternative gene splicing. FST288 binds spontaneously to heparan sulphate and is largely bound to cell surface proteoglycans. FST315 is the predominant circulating form and can only bind to heparan sulphate after binding activin-A. The regulation of these splice variants in the female reproductive tract have not been investigated in detail. In this study, our aim was to quantify the expression of FST288 and FST315 mRNA in the mouse uterus during early pregnancy (days 1–4, pre-implantation), and in response to exogenous oestradiol-17b (100 ng × single s.c. injection, dissection after 24 h) and progesterone (1 mg × three daily s.c. injections, dissection 24 h after last injection) in ovariectomised mice. Gene expression was analysed using quantitative RT-PCR. Primers amplifying a product from exon 5 to 6a (unique to FST288) or from exon 5 to 6b (unique to FST315) were used to discriminate the isoforms. In early pregnancy, expression of both FST288 and FST315 increased significantly (approximately 35-fold and 100-fold, respectively) on days 3–5, relative to days 1–2, corresponding with the increase in circulating progesterone levels that occurs at day 3. A significant increase in FST288 and FST315 mRNA expression (both approximately 35-fold) was also observed in ovariectomised mice in response to exogenous progesterone, but there was no increase in response to oestradiol-17β. In contrast to the similar rate of increase in response to exogenous progesterone, FST315 mRNA expression increased more rapidly than FS288 in early pregnancy, indicating that differential regulation of the two isoforms also occurs. We conclude that progesterone regulates both FST288 and FST315 mRNA expression during early pregnancy in the mouse uterus.
