title: IQ motif-containing G (Iqcg) is required for mouse spermiogenesis.
abstract: Spermiogenesis in mammals is the process by which the newly formed products of meiosis, haploid spermatids, undergo a dramatic morphological transformation from round cells into flagellated spermatozoa. The underlying genetic control of spermiogenesis is complicated and not well-characterized. We have used forward genetic screens in mice to illuminate the mechanisms of spermatozoon development. Here, we report that the oligoasthenoteratospermia in a male-specific infertility mutant (esgd12d) is attributable to disruption of a gene called Iqcg (IQ motif-containing G). The causality of the mutation was confirmed with a targeted null allele. Loss of Iqcg disrupts spermiogenesis such that tail formation either occurs incompletely or breaks apart from the sperm heads. Orthologs are present in diverse species as distant as hemichordates, mollusks, and green algae. Consistent with a conserved role in flagellar formation and/or function, the orthologous Chlamydomonas protein is present in that organism's flagella. Because IQ motif-containing genes typically regulate calmodulin (CaM), which in turn can impact the actin cytoskeleton, these findings suggest a potential role for localized calcium signaling in sperm flagellum morphogenesis.
authors.affiliation: Department of Biomedical Sciences and the Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853.
authors.forename: Tanya P
authors.initials: TP
authors.lastname: Harris
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Schimenti
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Munroe
authors.forename: John C
authors.initials: JC
authors.lastname: Schimenti
mesh_terms: D000818:Animals; D007248:Infertility, Male / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D013091:Spermatogenesis / Q000235:genetics*
chemical_list: C588374:IQCE protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins
keywords: flagellum; forward genetics; mouse; reproductive biology; spermatogenesis