Comparative Immunolocalization of Heat Shock Proteins (Hsp)‐60, ‐70, ‐90 in Boar, Stallion, Dog and Cat Spermatozoa

Abstract

Heat shock proteins (Hsp)-60, -70 and -90 are important testis chaperones that fulfil several functions during sperm cell maturation. In post-meiotic cells, their expression may change or may be undetectable and in some species it may be evident in mature spermatozoa. The aims of this study were to verify whether Hsp60, -70 and -90 are present in the sperm, and to compare their localization in boar, stallion, cat and dog spermatozoa by immunofluorescence. Hsp-60 immunoreactivity was detected in sperm midpiece in all the species examined. In stallion sperm, Hsp70 signal was localized in the sub-equatorial band, whereas immunoreactivity was evident on the neck of dog spermatozoa and on both neck and sub-equatorial region of cat spermatozoa. In agreement with our previous observations, a triangular fluorescent signal in the equatorial segment of fresh boar sperm was detected. Hsp90 immunoreactivity was present in different portions of sperm tail: in the midpiece of both boar and cat spermatozoa and in the neck and throughout the tail in dog and stallion spermatozoa, respectively. When capacitation and acrosome reaction were induced in boar, stallion and dog spermatozoa, no changes in both Hsp60 and -90 were recorded by either Western blot or immunofluorescence. After induction of acrosome reaction, a Hsp70 redistribution in boar spermatozoa and an increased percentage of stallion spermatozoa showing the post-acrosomal signal were observed although no changes were recorded by Western blot; in dog spermatozoa, no changes in Hsp70 were found by Western blot and immunofluorescence after capacitation and acrosome reaction.

Developmental expression of heat shock proteins 60, 70, 90, and A2 in rabbit testis

“…These results differ from those showing HSP60 immunoreactivity in boar, stallion, dog, and cat spermatozoa at mitochondrial positions (Volpe et al 2008). However, they are in agreement with the acrosomal HSP60 localization observed in mouse spermatozoa (Asquith et al 2004).…”

“…Moreover, our data demonstrate the presence of HSC70 in rabbit spermatids. Although no direct evidence is available concerning the presence of HSC70 in spermatids, many investigations have demonstrated the localization of HSP70 immunolabeling in spermatozoa (Matwee et al 2001;Spinaci et al 2005;Volpe et al 2008).…”

Relative abundance of heat shock proteins and clusterin transcripts in spermatozoa collected from boar routinely utilised in an artificial insemination centre: preliminary results

“…The presence of HSP70 and HSP90 proteins in porcine spermatozoa has been described as playing a role in sperm-oocyte interaction and sperm motility respectively (Huang et al 2000b;Spinaci et al 2005;Volpe et al 2008). No correlation between HSP70 and semen quality was found (Turba et al 2007) while HSP90 was investigated only in relation to the quality of cryopreserved semen (Wang et al 2014;Zhang et al 2015).…”

The ’omics revolution and our understanding of sperm cell biology

“…Several HSPs, including HSP60, HSP90 and HSP70, undergo phosphorylation during capacitation. [28][29][30][31][32][33][34] Recent evidence has shown that HSP60 and HSP90 (ERp99 and Grp94) migrate to the surface of the sperm head during capacitation, in concert with the ability of sperm to bind to the egg. In addition, although circumstantial, it was interesting to note that the only tyrosine-phosphorylated sperm heads were able to bind to the zona pellucida.…”