title: Interplay of PIWI/Argonaute protein MIWI and kinesin KIF17b in chromatoid bodies of male germ cells.
abstract: Chromatoid bodies are thought to act as male-germ-cell-specific platforms for the storing and processing of haploid transcripts. The molecular mechanisms governing the formation and function of these germ-cell-specific structures have remained elusive. In this study, we show that the kinesin motor protein KIF17b, which is involved in the nucleocytoplasmic transport of RNA and of a transcriptional coactivator, localizes in chromatoid bodies. The chromatoid body moves actively and non-randomly in the cytoplasm of round spermatids, making frequent contacts with the nuclear envelope. The localization of KIF17b thereby offers a potential mechanism for microtubule-dependent mobility of chromatoid bodies, as well as for the transport of the specific components in and out of the chromatoid body. Interestingly, we demonstrate that KIF17b physically interacts with a testis-specific member of the PIWI/Argonaute family, MIWI, a component of chromatoid bodies implicated in RNA metabolism. A functional interplay between KIF17b and MIWI might be needed for the loading of haploid RNAs in the chromatoid body. Importantly, chromatoid bodies from round spermatids of miwi-null mice are not fully compacted and remain as a diffuse chromatoid material, revealing the essential role played by MIWI in the formation of chromatoid bodies. These results shed new light on the function of chromatoid bodies in the post-transcriptional regulation of gene expression in haploid germ cells.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, B.P. 10142, 67404 Illkirch-Strasbourg, France.
authors.forename: Noora
authors.initials: N
authors.lastname: Kotaja
authors.forename: Haifan
authors.initials: H
authors.lastname: Lin
authors.forename: Martti
authors.initials: M
authors.lastname: Parvinen
authors.forename: Paolo
authors.initials: P
authors.lastname: Sassone-Corsi
mesh_terms: D000818:Animals; D060565:Argonaute Proteins; D005854:Germ Cells / Q000378:metabolism*; D016547:Kinesins / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D013087:Spermatids / Q000648:ultrastructure; D013090:Spermatocytes / Q000648:ultrastructure*; D014018:Tissue Distribution
chemical_list: D060565:Argonaute Proteins; C409642:KIF17 protein, mouse; D020409:Molecular Motor Proteins; C448522:Piwil1 protein, mouse; D011506:Proteins; D016547:Kinesins