Identification and localization of T-type voltage-operated calcium channel subunits in human male germ cells. Expression of multiple isoforms

Suchitra Jagannathan, Emma L. Punt, Yuchun Gu, Christophe Arnoult, Denny Sakkas, Christopher L. R. Barratt, Stephen J. Publicover

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

Low voltage activated, voltage-operated Ca(2+) channels are expressed in rodent male germ cells and are believed to be pivotal in induction of the acrosome reaction in mouse spermatozoa. However, in humans, very little is known about expression of voltage-operated Ca(2+) channels in male germ cells or their function. We have used reverse transcription-polymerase chain reaction, in situ hybridization, and patch clamp recording to investigate the expression of low voltage activated voltage-operated Ca(2+) channels in human male germ cells. We report that full-length transcripts for both alpha(1G) and alpha(1H) low voltage activated channel subunits are expressed in human testis. Multiple isoforms of alpha(1G) are present in the testis and at least two isoforms of alpha(1H), including a splice variant not previously described in the human. Transcripts for all the isoforms of both alpha(1G) and alpha(1H) were detected by reverse transcription-polymerase chain reaction on mRNA isolated from human spermatogenic cells. In situ hybridization for alpha(1G) and alpha(1H) localized transcripts both in germ cells and in other cell types in the testis. Within the seminiferous tubules, alpha(1H) was detected primarily in germ cells. Using the whole cell patch clamp technique, we detected T-type voltage-operated Ca(2+) channel currents in isolated human male germ cells, although the current amplitude and frequency of occurrence were low in comparison to the occurrence of T-currents in murine male germ cells. We conclude that low voltage activated voltage-operated Ca(2+) channels are expressed in cells of the human male germ line.

Original languageEnglish
Pages (from-to)8449-56
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number10
DOIs
Publication statusPublished - 8 Mar 2002

Keywords

  • Animals
  • Calcium/metabolism
  • Calcium Channels, T-Type/biosynthesis
  • Cells, Cultured
  • DNA, Complementary/metabolism
  • Humans
  • In Situ Hybridization
  • Male
  • Mice
  • Models, Genetic
  • Molecular Sequence Data
  • Patch-Clamp Techniques
  • Polymerase Chain Reaction
  • Protein Binding
  • Protein Isoforms/metabolism
  • RNA, Messenger/metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Seminiferous Tubules/metabolism
  • Spermatozoa/metabolism
  • Testis/metabolism

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