Altered stored calcium release in skeletal myotubes deficient of triadin and junctin.

Published

Journal Article

Triadin and junctin are integral sarcoplasmic reticulum membrane proteins that form a macromolecular complex with the skeletal muscle ryanodine receptor (RyR1) but their roles in skeletal muscle calcium homeostasis remain incompletely understood. Here we report that delivery of siRNAs specific for triadin or junctin into C2C12 skeletal myoblasts reduced the expression of triadin and junctin in 8-day-old myotubes by 80 and 100%, respectively. Knocking down either triadin or junctin in these cells reduced Ca2+ release induced by depolarization (10mM KCl) by 20-25%. Unlike triadin knockdown myotubes, junctin knockdown and junctin/triadin double knockdown myotubes also had reduced Ca2+ release induced by 400 microM 4-chloro-m-cresol, 10mM caffeine, 400 microM UTP, or 1 microM thapsigargin. Thus, knocking down junctin compromised the Ca2+ stores in the sarcoplasmic reticulum of these cells. Our subsequent studies showed that in junctin knockdown myotubes at least two sarcoplasmic reticulum proteins (RyR1 and skeletal muscle calsequestrin) were down-regulated while these proteins' mRNA expression was not affected. The results suggest that triadin has a role in facilitating KCl depolarization-induced Ca2+ release in contrast to junctin which has a role in maintaining sarcoplasmic reticulum Ca2+ store size in C2C12 myotubes.

Full Text

Duke Authors

Cited Authors

  • Wang, Y; Li, X; Duan, H; Fulton, TR; Eu, JP; Meissner, G

Published Date

  • January 2009

Published In

Volume / Issue

  • 45 / 1

Start / End Page

  • 29 - 37

PubMed ID

  • 18620751

Pubmed Central ID

  • 18620751

Electronic International Standard Serial Number (EISSN)

  • 1532-1991

International Standard Serial Number (ISSN)

  • 0143-4160

Digital Object Identifier (DOI)

  • 10.1016/j.ceca.2008.05.006

Language

  • eng