title: A targeted mutation of Nkd1 impairs mouse spermatogenesis.
abstract: Nkd1 is an antagonist of the canonical Wnt/beta-catenin signaling pathway. The EF-hand motif of Nkd1 is required for its inhibitory function. Early studies suggested that Nkd1 might play important roles in mouse embryonic development and tumorigenesis. We constructed Nkd1(-/-) mice whose Nkd1 protein lacked the EF-hand and was unable to inhibit Wnt/beta-catenin signaling. The homozygotes were viable and grew normally, but their fertility in males was reduced. In wild-type adult testes, Nkd1 mRNA was expressed more abundantly in the elongating spermatids than in the round spermatids. Lack of EF-hand caused reductions in the testis weight and sperm count by 30 and 60%, respectively. During testis development, Nkd1 mRNA expression started at the 25th day after birth, coincident with the onset of Wnt1 expression. Nuclear localization of beta-catenin increased in the elongating spermatids, suggesting that the mutant Nkd1 failed to inhibit the Wnt/beta-catenin pathway. These results suggest that deletion of the EF-hand from Nkd1 reduces the number of the elongating spermatids at haploid stage. In contrast, the mutant Nkd1 did not affect intestinal polyposis in Apc(Delta716) mice.
authors.affiliation: Department of Pharmacology, Graduate School of Medicine, Kyoto University, Yoshida-konoé-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Qin
authors.initials: Q
authors.lastname: Li
authors.forename: Tomo-O
authors.initials: TO
authors.lastname: Ishikawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Masanobu
authors.initials: M
authors.lastname: Oshima
authors.forename: Makoto M
authors.initials: MM
authors.lastname: Taketo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006238:Haploidy; D006579:Heterozygote; D006720:Homozygote; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D044483:Intestinal Polyposis / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013076:Sperm Count; D013091:Spermatogenesis; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; C424446:Nkd1 protein, mouse; D012333:RNA, Messenger; D012313:RNA