title: Importin alpha2-interacting proteins with nuclear roles during mammalian spermatogenesis.
abstract: Spermatogenesis, the process of generating haploid sperm capable of fertilizing the female gamete, requires the timely transport into the nucleus of transcription and chromatin-remodeling factors, mediated by members of the importin (IMP) superfamily. Previous IMP expression profiling implies a role for IMPalpha2 in testicular germ cells late in spermatogenesis. To identify interacting proteins of IMPalpha2 that are potential drivers of germ cell development, we performed yeast two-hybrid screening of an adult mouse testis library. IMPalpha2 interactions were verified by coimmunoprecipitation approaches, whereas immunohistochemical staining of testis sections confirmed their coexpression with IMPalpha2 in specific testicular cell types. Key interactors identified were a novel isoform of a cysteine and histidine rich protein (Chrp), a protein inhibitor of activated STAT (PIAS) family member involved in transcriptional regulation and sumoylation, Androgen receptor interacting protein 3 (Arip3), and Homologous protein 2 (Hop2), known to be involved in homologous chromosome pairing and recombination, all of which are highly expressed in the testis and show mRNA expression profiles similar to that of IMPalpha2 throughout testicular development. This is the first study to identify binding partners of IMPalpha2 in the developmental context of germ line development, and we propose that the regulated expression and timely IMPalpha2-mediated nuclear transport of these proteins may coordinate events during spermatogenesis, with IMPalpha2-mediated nuclear localization representing a potentially critical developmental switch in the testis.
authors: Nuclear Signalling Laboratory, Monash University, Clayton, Victoria, Australia.
authors: Jennifer D
authors: JD
authors: Ly-Huynh
authors: Kim G
authors: KG
authors: Lieu
authors: Andrew T
authors: AT
authors: Major
authors: Penelope A F
authors: PA
authors: Whiley
authors: Janet E
authors: JE
authors: Holt
authors: Kate L
authors: KL
authors: Loveland
authors: David A
authors: DA
authors: Jans
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000378:metabolism*; D050828:Protein Inhibitors of Activated STAT / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013091:Spermatogenesis; D013737:Testis / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases; D028901:alpha Karyopherins
chemical_list: D018797:Cell Cycle Proteins; C406869:Cyhr1 protein, mouse; C501202:Hop2 protein, mouse; C490631:Kpna2 protein, mouse; D009687:Nuclear Proteins; D050828:Protein Inhibitors of Activated STAT; D011506:Proteins; D012333:RNA, Messenger; D028901:alpha Karyopherins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C485521:Miz1 protein, mouse; D044767:Ubiquitin-Protein Ligases