title: Trypsin is a multifunctional factor in spermatogenesis.
abstract: Trypsin is well known as a pancreatic enzyme that is typically secreted into the intestine to digest proteins. We show in our current study, however, that trypsin is also a key factor in the control of spermatogenesis. A progestin in teleost fish, 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP), is an essential component of the spermatogenesis pathway, particularly during the initiation of the first meiotic division. In the course of our investigations into the mechanisms underlying progestin-stimulated spermatogenesis, we identified that eel trypsinogen is upregulated in eel testis by DHP treatment. Trypsinogen is expressed in the Sertoli cells surrounding spermatogonia and in the membranes of spermatids and spermatozoa. Using an in vitro eel testicular culture system, we further analyzed the roles of trypsin in spermatogenesis. The inhibition of trypsin using specific antibodies or serine protease inhibitors was found to compromise DHP-induced spermatogenesis. A low dose of trypsin induces DNA synthesis and the expression of Spo11, a molecular marker of meiosis, in germ cells. By comparison, a higher dose of trypsin partially induced spermiogenesis. Furthermore, trypsin was detectable in the membranes of the spermatozoa and found to be associated with fertilization in fish. Our results thus demonstrate that trypsin and/or a trypsin-like protease is an essential and multifunctional factor in spermatogenesis.
authors.affiliation: Research Group for Reproductive Physiology, Southern Ehime Fisheries Research Center, Ehime University, 1289-1 Funakoshi, Ainan, Ehime 798-4292, Japan.
authors.forename: Chiemi
authors.initials: C
authors.lastname: Miura
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohta
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ozaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miura
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003001:Cloning, Molecular; D004524:Eels / Q000235:genetics / Q000378:metabolism*; D005306:Fertilization / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008297:Male; D008540:Meiosis / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013077:Sperm Head / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D013082:Sperm Tail / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013091:Spermatogenesis / Q000187:drug effects; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D014357:Trypsin / Q000378:metabolism* / Q000494:pharmacology; D014362:Trypsinogen / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000906:Antibodies; D015415:Biomarkers; D015842:Serine Proteinase Inhibitors; D014362:Trypsinogen; D014357:Trypsin