Identification of growth-differentiation factor 8 (GDF-8) in endometrium of the golden hamster

Abstract

Growth-differentiation factor 8 (GDF-8) currently reported to be present in skeletal muscle only, belongs to the TGF-£] superfamily. Dysregulation of GDF-8 is associated with muscular diseases like muscular dystrophy. In the hamster, we have identified GDF-8 in uterine fluid 72 hours post coitus (h.p.c.) by 2D SDS-Gel electrophoresis and MALDI-TOF. Using RT-PCR, the presence of GDF-8 was confirmed in uterine tissue and its mRNA level was transiently upregulated at 72 h. p.c. by real-time PCR, in situ hybridization and immunohistological staining localized the transcript and protein to endometrium. We speculated that GDF-8 may be secreted by endometrial cells to regulate development of myometrium. To verify this, primary cultures of myometial cells was treated with GDF-8 for 60h and 72h. Using immunostaining, the number of cells expressing proliferating cell nuclear antigen (PCNA) and smooth muscle actin (SMA) was determined. Preliminary results showed that GDF-8 reduced the proportion of SMA-positive cells expressing PCNA but had no effect on the number of cells expressing SMA only. We propose that GDF-8 may inhibit smooth muscle cell proliferation and thus regulate muscular development in particular at the time of implantation which is 72 h p.c. in the hamster.

Acknowledgement

Supported by a CERG grant (CUHK442205/M) from Research Grant Council of Hong Kong.