Sperm activation by heat shock protein 70 supports the migration of sperm released from sperm storage tubules in Japanese quail (Coturnix japonica)

Abstract

Systems for maintaining the viability of ejaculated sperm in the female reproductive tract are widespread among vertebrates and invertebrates. In birds, this sperm storage function is performed by specialized simple tubular invaginations called sperm storage tubules (SSTs) in the uterovaginal junction (UVJ) of the oviduct. Although the incidence and physiological reasons for sperm storage in birds have been reported extensively, the mechanisms of sperm uptake by the SSTs, sperm maintenance within the SSTs, and control of sperm release from the SSTs are poorly understood. In this study, we demonstrated that the highly conserved heat shock protein 70 (HSP70) stimulates sperm motility in vitro and also that HSP70 expressed in the UVJ may facilitate the migration of sperm released from the SSTs.Quantitative RT-PCR analysis demonstrated that the expression of HSP70 mRNA in the UVJ increases before ovulation/oviposition. Gene-specific in situ hybridization and immunohistochemical analysis with a specific antibody to HSP70 demonstrated that HSP70 is localized in the surface epithelium of the UVJ. Furthermore, injection of anti-HSP70 antibody into the vagina significantly inhibited fertilization in vivo. In addition, we found that recombinant HSP70 activates flagellar movement in the sperm and that the binding of recombinant HSP70 to the sperm surface is mediated through an interaction with voltage-dependent anion channel protein 2 (VDAC2). Our results suggest that HSP70 binds to the sperm surface by interacting with VDAC2 and activating sperm motility. This binding appears to play an important role in sperm migration within the oviduct.

Proteome-wide identification of HSP70/HSC70 chaperone clients in human cells

“…Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), perilipin 3 (PLIN3), dihydropyrimidinase like 2 (DPYSL2), and annexin A1 (ANXA1) are all known to be regulated through CMA [53][54][55][56], so these and potentially other factors on this list of V438F-specific binding partners may be CMA targets. Other factors in this set are known to be stable binding partners of HSC70, likely through other interfaces [57][58][59][60][61][62][63][64][65][66][67][68]. Overall, this analysis of the V438F interactome suggests that about half of the UBAIT targets are bound in a V438-sensitive manner, while half are not, with the latter group including co-chaperones as well as binding partners in other complexes.…”

Avian uterine fluid proteome: Exosomes and biological processes potentially involved in sperm survival

“…Most of these components have already been shown to regulate sperm function, as reviewed in mammals (Dun et al, 2012; Yu & Huang, 2015) and avian species (Breque, Surai, & Brillard, 2003; Hiyama et al, 2014).…”

A unique mechanism of successful fertilization in a domestic bird

“…We predicted that paternal PGF 2α , transported into the female vagina at the time of copulation does not reach to the uterus beyond the UVJ. This is because our previous findings in which Hoechst 33342 DNA dye injected into the vagina was able to stain the nucleus of the surface epithelium of the vagina and UVJ, but not those of the uterus 22 . From these findings, we predicted that PGF 2α -R expressed in the vagina and UVJ would only be involved in sperm transport and uptake into the SST.…”