title: Transgenic expression of testis-specific poly(A) polymerase TPAP in wild-type and TPAP-deficient mice.
abstract: We have previously identified a testis-specific poly(A) polymerase, TPAP (PAPbeta), involved in poly(A) tail extension of specific mRNAs in the cytoplasm of round spermatids. Targeted disruption of the mouse TPAP gene resulted in the arrest of spermiogenesis due to reduced expression of haploid-specific genes required for morphogenesis of germ cells. To further elucidate the role(s) of TPAP in spermatogenesis, transgenic mice expressing an exogenous TPAP transgene on wild-type and TPAP-deficient backgrounds were generated and characterized. The transgenic mice overexpressing TPAP exhibited normal spermatogenesis and fertility. The sizes of some transcription factor mRNAs as the substrates of TPAP were also unaffected. Transgenic expression of the TPAP gene in the TPAP-deficient mice complemented both the incomplete elongation of the poly(A) tails of specific transcription factor mRNAs, and reduced expression of haploid-specific genes, resulting in the resumption of normal spermiogenesis. These data conclusively show that spermatogenesis requires the cytoplasmic elongation of the mRNA poly(A) tails catalyzed by TPAP, and imply the presence of a regulatory mechanism(s) defining the extent of the cytoplasmic mRNA polyadenylation.
authors.affiliation: Institute of Applied Biochemistry, University of Tsukuba, Tsukuba Science City, Ibaraki, Japan.
authors.forename: Tiangang
authors.initials: T
authors.lastname: Zhuang
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Kashiwabara
authors.forename: Junko
authors.initials: J
authors.lastname: Noguchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Baba
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D003593:Cytoplasm / Q000378:metabolism; D004822:Epididymis / Q000473:pathology; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D005816:Genetic Complementation Test; D006238:Haploidy; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics* / Q000502:physiology*; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D013087:Spermatids / Q000378:metabolism; D013091:Spermatogenesis; D013737:Testis / Q000201:enzymology* / Q000473:pathology; D019076:Transgenes
chemical_list: D012333:RNA, Messenger; D012313:RNA; D011062:Polynucleotide Adenylyltransferase