Objective: To investigate the effect of heat shock protein 10 (HSP10) on apoptosis induced by testosterone in granulosa cells (GCs) of mouse ovaries in order to define the possible roles of HSP10 in ovarian pathological development of polycystic ovarian syndrome (PCOS) and hyperandrogenic conditions.
Study design: Cultured mouse ovarian GCs were treated with testosterone (10(-5) mol/l). Apoptosis was assessed using flow cytometry, and proliferation was assessed using the MTT assay. HSP10 expression in the treated GCs was detected by real-time polymerase chain reaction (PCR). HSP10 gene was downregulated in the cultured GCs by AdCMV-H1-SiRNA/HSP10 or overexpressed by AdCMV-HSP10. PD98059 [phosphorylated ERK (p-ERK) inhibitor] was used to treat GCs to induce a high apoptosis index. Critical apoptotic factors and proliferation factors, including P-ERK, Bcl-2, Bax, caspase 9, caspase 3 and Ki67, were monitored by real-time reverse transcriptase PCR (RT-PCR) and Western blot.
Results: Compared with the control group, the apoptosis index was higher (p<0.05) and HSP10 expression was lower (p<0.05) in the testosterone-treated groups. In the AdCMV-H1-SiRNA/HSP10-treated group, cell viability was decreased (p<0.05) and the cell cycle was arrested at G2. Expression of p-ERK, Bcl-2 and Ki67, and the Bcl-2:Bax ratio were lower, while expression of apoptotic factors, including Bax, caspase 9 and caspase 3, was higher (p<0.05). Compared with the control group, Bcl-2 expression in the GCs that overexpressed HSP10 was increased (p<0.05), while the reduction of p-ERK and Bcl-2 and the elevation of caspase 9 and caspase 3 induced by PD98059 were significantly suppressed (p<0.05).
Conclusions: Hyperandrogenic conditions induced apoptosis of mouse GCs. Testosterone may have reduced HSP10 expression in GCs, leading to reduced Bcl-2 expression and increased Bax expression.
Keywords: Apoptosis; Granulosa cells; HSP10; Polycystic ovarian syndrome.
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