Trisk 32 regulates IP(3) receptors in rat skeletal myoblasts. - Archive ouverte HAL Access content directly
Journal Articles Pflügers Archiv European Journal of Physiology Year : 2011

Trisk 32 regulates IP(3) receptors in rat skeletal myoblasts.

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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(3)R) 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(3)R. Thus, Trisk 32 not only co-localizes with, but directly contributes to, the regulation of Ca(2+) release via IP(3)R.
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inserm-00763318 , version 1 (10-12-2012)

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Tamás Oláh, János Fodor, Sarah Oddoux, Olga Ruzsnavszky, Isabelle Marty, et al.. Trisk 32 regulates IP(3) receptors in rat skeletal myoblasts.. Pflügers Archiv European Journal of Physiology, 2011, 462 (4), pp.599-610. ⟨10.1007/s00424-011-1001-y⟩. ⟨inserm-00763318⟩

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