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Spermatid-specific expression of the novel X-linked gene product SPAN-X localized to the nucleus of human spermatozoa.

Authors
  • Westbrook, V A
  • Diekman, A B
  • Klotz, K L
  • Khole, V V
  • von Kap-Herr, C
  • Golden, W L
  • Eddy, R L
  • Shows, T B
  • Stoler, M H
  • Lee, C Y
  • Flickinger, C J
  • Herr, J C
Type
Published Article
Journal
Biology of reproduction
Publication Date
Aug 01, 2000
Volume
63
Issue
2
Pages
469–481
Identifiers
PMID: 10906052
Source
Medline
License
Unknown

Abstract

Formation of mature spermatozoa involves a series of dramatic molecular and morphological changes in the male germ cell lineage. These changes result from the temporally regulated transcription and translation of several testis-specific gene products. Here, we describe a novel, testis-specific protein designated SPAN-X for sperm protein associated with the nucleus on the X chromosome. SPAN-X sequences showed no significant similarity with known cDNA or peptide sequences. The SPAN-X peptide sequences contained three overlapping consensus nuclear localization signals, a high percentage (33%-37%) of charged amino acid residues, and a relatively acidic isoelectric point (pI; 4.88-6.05). Northern analysis of mRNA from multiple human tissues identified a SPAN-X transcript exclusively in the testis. In situ hybridization of human testes sections showed SPAN-X mRNA expression in haploid, round, and elongating spermatids. The SPANX gene was mapped to chromosome Xq27. 1 by fluorescence in situ hybridization and by Southern blot analysis of human/mouse somatic cell hybrids. On Western blots of human sperm proteins, antirecombinant SPAN-X antibodies reacted with broad bands migrating between 15-20 kDa. Immunofluorescent labeling of human spermatozoa demonstrated SPAN-X localization to nuclear craters and cytoplasmic droplets. Expression of SPAN-X, an X-linked gene product, exclusively in haploid spermatids leads to interesting questions regarding the transcription of sex-linked genes during spermiogenesis.

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