Evaluation of HSPA2 in fertile and infertile individuals

Heat-shock protein A2 (HSPA2) is a testis-specific member of the HSP70 family known to correlate with sperm maturity, function and fertility. The aim of this study was to compare expression of HSPA2 in fertile and infertile individuals using a recently marketed highly purified polyclonal antibody. Thus, after analysing sperm concentration, motility and morphology in semen sample of 49 individuals with male factor infertility and 47 fertile individuals according to World Health Organization guidelines, we evaluated HSPA2 by microscope florescence, flow cytometry, Western blot and RT-PCR. We observed higher percentage of sperm expressing HSPA2 in anterior and equatorial regions in fertile than infertile individuals by microscope fluorescence. Percentage of sperm expressing HSPA2 in two conditions (fixed permeabilised and capacitated) by flow cytometry showed that percentage of HSPA2-positive sperm in fixed permeabilised and also capacitated samples was significantly different between fertile and infertile individuals. Western blot analysis of HSPA2 in semen samples revealed high variation within the fertile and infertile population. The results of RT-PCR revealed higher expression of HSPA2 in the fertile compared to infertile individuals, but this difference was not significant. According to the results, we suggest that HSPA2 expression is heterogeneously expressed on different part of fixed permeabilised sperm and its expression is significantly higher in fertile compared to infertile individuals. The surface expression of this protein significantly increases following capacitation in both fertile and infertile individuals. HSPA2 expression significantly correlates with sperm concentration and morphology. Therefore, aberrant HSPA2 expression may play an important role in capacitation and fertilisation processes.