title: CLIP-50 immunolocalization during mouse spermiogenesis suggests a role in shaping the sperm nucleus.
abstract: The spermatid nucleus and cytoplasm undergo dramatic morphological modifications during spermatid differentiation into mature sperm. Some of the external force causing this nuclear shaping is generated by a microtubular structure termed the manchette, which attaches to the perinuclear ring of the spermatid. Here, we report the isolation and characterization of a protein component of this perinuclear ring in an immunological screening of a mouse testis cDNA library. We termed this protein CLIP-50 because of its high similarity at the amino acid level to the C-terminal region of the microtubule-binding protein CLIP-170/restin. CLIP-50 lacks the characteristic microtubule-binding motif, but retains a portion of the predicted coiled-coiled domain and the metal-binding motif. The CLIP-50 transcript and protein are abundant in testis. The protein is also expressed in heart, lung, kidney, and skin. A distinct size variant exists in brain. In the spermatids, CLIP-50 protein localizes specifically to the centriolar region where the sperm tail originates and to the perinuclear ring from which the manchette emerges. CLIP-50 staining is retained in the ring throughout its migration over the surface of the nucleus which accompanies the nuclear shaping into its characteristic sperm configuration. This localization pattern indicates a very specific function for this novel CLIP derivative during mouse spermiogenesis.
authors.affiliation: Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada. m.tarsounas@icrf.icnet.uk
authors.forename: M
authors.initials: M
authors.lastname: Tarsounas
authors.forename: R E
authors.initials: RE
authors.lastname: Pearlman
authors.forename: P B
authors.initials: PB
authors.lastname: Moens
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000737:chemistry; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D013087:Spermatids / Q000166:cytology / Q000378:metabolism; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology* / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000378:metabolism*
chemical_list: C435524:CLIP-50 protein, mouse; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; C076744:cytoplasmic linker protein 170