title: 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.
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture.
authors.forename: Gen
authors.initials: G
authors.lastname: Hiyama
authors.forename: Mei
authors.initials: M
authors.lastname: Matsuzaki
authors.forename: Shusei
authors.initials: S
authors.lastname: Mizushima
authors.forename: Hideo
authors.initials: H
authors.lastname: Dohra
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ikegami
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Kogiku
authors.initials: K
authors.lastname: Shiba
authors.forename: Kazuo
authors.initials: K
authors.lastname: Inaba
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sasanami
mesh_terms: D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D003370:Coturnix; D005260:Female; D005306:Fertilization / Q000187:drug effects; D005307:Fertilization in Vitro / Q000187:drug effects; D015870:Gene Expression; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D008297:Male; D010057:Oviducts / Q000737:chemistry / Q000502:physiology*; D010058:Oviposition; D010060:Ovulation; D012333:RNA, Messenger / Q000032:analysis; D013081:Sperm Motility / Q000187:drug effects; D013083:Sperm Transport / Q000502:physiology*; D013094:Spermatozoa / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*; D014599:Uterus / Q000187:drug effects; D050996:Voltage-Dependent Anion Channel 2 / Q000502:physiology
chemical_list: D000906:Antibodies; D018840:HSP70 Heat-Shock Proteins; D012333:RNA, Messenger; D050996:Voltage-Dependent Anion Channel 2