Trisk 32 regulates IP 3 receptors in rat skeletal myoblasts

Tamás Oláh, János Fodor, Sarah Oddoux, Olga Ruzsnavszky, Isabelle Marty, László Csernoch

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

To date, four isoforms of triadins have been identified in rat skeletal muscle. While the function of the 95-kDa isoform in excitation-contraction coupling has been studied in detail, the role of the 32-kDa isoform (Trisk 32) remains elusive. Here, Trisk 32 overexpression was carried out by stable transfection in L6.G8 myoblasts. Co-localization of Trisk 32 and IP 3 receptors (IP 3R) was demonstrated by immunocytochemistry, and their association was shown by co-immunoprecipitation. Functional effects of Trisk 32 on IP 3-mediated Ca 2+ release were assessed by measuring changes in [Ca 2+] i following the stimulation by bradykinin or vasopressin. The amplitude of the Ca 2+ transients evoked by 20 μM bradykinin was significantly higher in Trisk 32-overexpressing (p∈<∈0.01; 426∈±∈84 nM, n∈=∈27) as compared to control cells (76∈±∈12 nM, n∈=∈23). The difference remained significant (p∈<∈0.02; 217∈±∈ 41 nM, n∈=∈21, and 97∈±∈29 nM, n∈=∈31, respectively) in the absence of extracellular Ca 2+. Similar observations were made when 0.1 μM vasopressin was used to initiate Ca 2+ release. Possible involvement of the ryanodine receptors (RyR) in these processes was excluded, after functional and biochemical experiments. Furthermore, Trisk 32 overexpression had no effect on store-operated Ca 2+ entry, despite a decrease in the expression of STIM1. These results suggest that neither the increased activity of RyR, nor the amplification of SOCE, is responsible for the differences observed in bradykinin- or vasopressin-evoked Ca 2+ transients; rather, they were due to the enhanced activity of IP 3R. Thus, Trisk 32 not only co-localizes with, but directly contributes to, the regulation of Ca 2+ release via IP 3R.

Original languageEnglish
Pages (from-to)599-610
Number of pages12
JournalPflugers Archiv European Journal of Physiology
Volume462
Issue number4
DOIs
Publication statusPublished - Oct 1 2011

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Keywords

  • Calcium transient
  • Endoplasmic reticulum
  • Inositol 1,4,5-trisphosphate
  • Myoblasts
  • Skeletal muscle

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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