Testis

Characterization of a Novel Postacrosomal Perinuclear Theca-Specific Protein, CYPT1

Abstract
The perinuclear theca (PT) is a unique cytoskeletal structure that surrounds the nucleus of the sperm. The posterior acrosome segment of the PT (postacrosomal PT) is thought to play roles in shaping the nucleus during differentiation of the spermatid and in activating the oocyte during fertilization. We isolated a cDNA clone that encoded a novel haploid germ cell-specific cysteine-rich perinuclear theca protein, CYPT1. The transcripts were expressed exclusively in testicular germ cells after meiotic division. Sequence analysis revealed that CYPT1 comprised 168 amino acids and that the N-terminal was rich in basic amino acids, including cysteine clusters. Immunohistochemical and biochemical analyses localized CYPT1 to the postacrosomal PT of elongated spermatids and mature sperm. Cypt1 had three paralogs that were expressed in adult testis. A comparison of genomic structure suggested that two of the three cypt1 paralogs were generated by gene triplication on the X chromosome, while one paralog was retrotransposed to an autosome. Interestingly, the 5' flanking regions of these genes were highly homologous with the promoter region of the spermatid-specific gene Zfy-2. CYPT1 and the proteins of the paralogous genes constitute a novel, basic cysteine-rich sperm protein family that contributes to the function of the postacrosomal PT during nuclear shaping.

Key words: Testis • Gametogenesis • Gene regulation • Sperm maturation • Spermatogenesis

This article has been cited by other articles:

				V.A. Westbrook, P.D. Schoppee, G.R. Vanage, K.L. Klotz, A.B. Diekman, C.J. Flickinger, M.A. Coppola, and J.C. Herr Hominoid-specific SPANXA/D genes demonstrate differential expression in individuals and protein localization to a distinct nuclear envelope domain during spermatid morphogenesis Mol. Hum. Reprod., November 1, 2006; 12(11): 703 - 716. [Abstract] [Full Text] [PDF]

				Y. Nishimune and H. Tanaka Infertility Caused by Polymorphisms or Mutations in Spermatogenesis-Specific Genes J Androl, May 1, 2006; 27(3): 326 - 334. [Full Text] [PDF]

				P. J.I. Ellis, E. J. Clemente, P. Ball, A. Toure, L. Ferguson, J. M.A. Turner, K. L. Loveland, N. A. Affara, and P. S. Burgoyne Deletions on mouse Yq lead to upregulation of multiple X- and Y-linked transcripts in spermatids Hum. Mol. Genet., September 15, 2005; 14(18): 2705 - 2715. [Abstract] [Full Text] [PDF]