title: The IP3 R Binding Protein Released With Inositol 1,4,5-Trisphosphate Is Expressed in Rodent Reproductive Tissue and Spermatozoa.
abstract: Besides its capacity to inhibit the 1,4,5-trisphosphate (IP3) receptor, the regulatory protein IRBIT (IP3 receptor binding protein released with IP3) is also able to control the activity of numerous ion channels and electrolyte transporters and thereby creates an optimal electrolyte composition of various biological fluids. Since a reliable execution of spermatogenesis and sperm maturation critically depends on the establishment of an adequate microenvironment, the expression of IRBIT in male reproductive tissue was examined using immunohistochemical approaches combined with biochemical fractionation methods. The present study documents that IRBIT is expressed in Leydig and Sertoli cells. In addition, pronounced IRBIT expression was detected in sperm precursors during early stages of spermatogenesis as well as in spermatozoa. Analyzing tissue sections of rodent epididymides, IRBIT was found to co-localize with the proton pumping V-ATPase and the cystic fibrosis transmembrane conductance regulator (CFTR) at the apical surface of narrow and clear cells. A similar co-localization of IRBIT with CFTR was also observed for Sertoli cells and developing germ cells. Remarkably, assaying caudal sperm in immunogold electron microscopy, IRBIT was found to localize to the acrosomal cap and the flagellum as well as to the sperm nucleus; moreover, a prominent oligomerization was observed for spermatozoa. The pronounced occurrence of IRBIT in the male reproductive system and mature spermatozoa indicates a potential role for IRBIT in establishing the essential luminal environment for a faithful execution of spermatogenesis and epididymal sperm maturation, and suggest a participation of IRBIT during maturation steps after ejaculation and/or the final fertilization process.
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Borth
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Nele
authors.initials: N
authors.lastname: Weber
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Dorke
authors.initials: D
authors.lastname: Meyer
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Wartenberg
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Arlt
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Susanna
authors.initials: S
authors.lastname: Zierler
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Breit
authors.affiliation: Department of Anatomy, University Clinic Essen, University of Duisburg-Essen, Germany.
authors.forename: Gunther
authors.initials: G
authors.lastname: Wennemuth
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gudermann
authors.affiliation: Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universit, ä, t M, ü, nchen, München, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Boekhoff
mesh_terms: D043383:Adenosylhomocysteinase / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D004822:Epididymis / Q000166:cytology / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism; D008297:Male; D017207:Rats, Sprague-Dawley; D012098:Reproduction; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000648:ultrastructure; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D015544:Inositol 1,4,5-Trisphosphate; D043383:Adenosylhomocysteinase; C000608140:Ahcyl1 protein, rat; D025262:Vacuolar Proton-Translocating ATPases