Full length ryanodine receptor subtype 3 encodes spontaneous calcium oscillations in native duodenal smooth muscle cells
Cell Calcium. 2008-08-01; 44(2): 180-189
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1. Cell Calcium. 2008 Aug;44(2):180-9. doi: 10.1016/j.ceca.2007.11.009. Epub 2008
Full length ryanodine receptor subtype 3 encodes spontaneous calcium oscillations
in native duodenal smooth muscle cells.
Dabertrand F(1), Mironneau J, Macrez N, Morel JL.
(1)Centre de Neurosciences Intégratives et Cognitives, CNRS UMR5228, Universités
de Bordeaux, avenue des facultés, 33405 Talence, France.
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.
PMID: 18207571 [Indexed for MEDLINE]