title: Drosophila polypyrimidine tract-binding protein is necessary for spermatid individualization.
abstract: Although mammalian polypyrimidine tract-binding (PTB) protein functions in most or all cell types to regulate a wide spectrum of transcripts, Drosophila PTB encodes an abundant male germline-specific mRNA isoform (dmPTB) whose expression correlates with male fertility. The biological function of this isoform is unknown. Using selection-amplification, we show that mammalian and Drosophila PTB have similar RNA sequence preference, suggesting that cell-specific expression rather than unique RNA-binding properties account for the sex-specific function of dmPTB. We also show that the dmPTB protein isoform expressed in the male germline is by far the most abundant isoform, and reduction of its levels correlates with male sterility. Finally, we show that dmPTB expression is necessary for proper spermatid individualization, the terminal step necessary for production of motile sperm. Loss of dmPTB results in severe disruption of the actin cones of the spermatid individualization complex. This represents a cytological defect resulting from PTB loss. We discuss the basis for functional differences between mammalian and Drosophila PTB orthologs.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Robida
authors.forename: Vinod
authors.initials: V
authors.lastname: Sridharan
authors.forename: Sheridan
authors.initials: S
authors.lastname: Morgan
authors.forename: Timsi
authors.initials: T
authors.lastname: Rao
authors.forename: Ravinder
authors.initials: R
authors.lastname: Singh
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D005298:Fertility / Q000235:genetics; D008297:Male; D038941:Polypyrimidine Tract-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013087:Spermatids / Q000378:metabolism
chemical_list: D000199:Actins; D020033:Protein Isoforms; D012333:RNA, Messenger; D038941:Polypyrimidine Tract-Binding Protein