Full length ryanodine receptor subtype 3 encodes spontaneous calcium oscillations in native duodenal smooth muscle cells.
Two isoforms of the ryanodine receptor subtype 3 (RYR3) have been described in smooth muscle. The RYR3 short isoform (RYR3S) negatively regulates the calcium-induced calcium release mechanism encoded by the RYR2, whereas the role of the full length isoform of RYR3 (RYR3L) was still unclear. Here, we describe RYR-dependent spontaneous Ca(2+) oscillations measured in 10% of native duodenum myocytes. We investigated the role of RYR3 isoforms in these spontaneous Ca(2+) signals. Inhibition of RYR3S expression by antisense oligonucleotides revealed that both RYR2 and RYR3L were able to propagate spontaneous Ca(2+) waves that were distinguishable by frequency analysis. When RYR3L expression was inhibited, the spontaneous Ca(2+) oscillations were never observed, indicating that RYR3S inhibited the function of RYR2. RYR2 expression inhibition led to Ca(2+) oscillations identical to those observed in control cells suggesting that RYR3S did not functionally interact with RYR3L. The presence and frequency of RYR3L-dependent Ca(2+) oscillations were dependent on sarcoplasmic reticulum Ca(2+) content as revealed by long-term changes of the extracellular Ca(2+) concentration. Our study shows that, in native duodenal myocytes, the spontaneous Ca(2+) waves are encoded by the RYR3L alone, which activity is regulated by sarcoplasmic reticulum Ca(2+) loading.
Dabertrand
Fabrice
F
Centre de Neurosciences Intégratives et Cognitives, CNRS UMR5228, Universités de Bordeaux, avenue des facultés, 33405 Talence, France.
Mironneau
Jean
J
Macrez
Nathalie
N
Morel
Jean-Luc
JL
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002478:Cells, Cultured; D004386:Duodenum / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D020033:Protein Isoforms; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002118:Calcium