Effect of Hsp27 on early embryonic development in the mouse

Previous studies by this study group have showed that heat shock protein 27 (Hsp27), expressed in the oocyte of growing follicles, is down-regulated in polycystic ovary syndrome ovaries and that down-regulation of Hsp27 improves the maturation of mouse oocytes and increases early apoptosis of oocytes. In this study, the effect of Hsp27 on early embryo development in the mouse was observed. Following microinjection of AdCMV-Hsp27 or AdsiRNA-Hsp27 into the cytoplasm of mouse zygotes, blastocyst morphology was observed and cell apoptosis of blastocysts was detected by TUNEL. After culture in vitro for 96 h, blastocysts were analysed for Hsp27 expression by real-time PCR and immunofluorescence. The blastocyst formation rate and embryo quality were evaluated. The expression of Hsp27 was significantly increased in embryos with Hsp27 overexpression (AdCMV-Hsp27), while it was significantly suppressed by 75% in embryos with the gene silenced (AdsiRNA-Hsp27; both P < 0.05). Cell apoptosis in blastocysts, blastocyst formation rate and embryo quality were unaffected by Hsp27 overexpression or gene silencing. In conclusion, overexpression or down-regulation of Hsp27 in zygotes, as a single factor, does not significantly affect the subsequent embryonic development.Heat shock protein 27 (Hsp27), a member of the small heat shock protein family, has been shown to play an important role in a variety of physiological processes including protein chaperoning, steroidogenesis and, especially, protection against apoptosis. Our previous studies showed that the Hsp27 expressed in the oocyte of growing follicles was down-regulated in polycystic ovary syndrome ovaries and that down-regulation of Hsp27 improved the maturation of mouse oocytes by regulating early apoptosis of oocytes. In this study, we observed the effect of Hsp27 on early embryo development in the mouse. But following microinjection with adenoviruses AdCMV-Hsp27 (Hsp27 overexpression) or AdsiRNA-Hsp27 (Hsp27 silencing) into the cytoplasm of mouse zygotes, cell apoptotsis in blastocysts, blastocyst formation rate and embryo quality were unaffected. In conclusion, overexpression or down-regulation of Hsp27 in zygotes, as single factors, does not significantly affect the subsequent embryonic development. Further studies are required to elucidate the role of Hsp27 in embryonic development and differentiation.