Effect of Calstabin1 depletion on calcium transients and energy utilization in muscle fibers and treatment opportunities with RyR1 stabilizers

PLoS One. 2013 Nov 26;8(11):e81277. doi: 10.1371/journal.pone.0081277. eCollection 2013.

Abstract

Depletion of calstabin1 (FKBP12) from the RyR1 channel and consequential calcium leakage from the sarcoplasmic reticulum (SR) is found in certain disease conditions such as dystrophy, aging or muscle overuse. Here, we first assessed the effect of calstabin1 depletion on resting Ca(2+) levels and transients. We found that depletion of calstabin1 with the calstabin1-dissociation compound FK506 increased the release of calcium from the SR by 14 % during tetanic stimulation (50 Hz, 300 ms) and delayed cytosolic calcium removal. However, we did not find a significant increase in resting cytosolic Ca(2+) levels. Therefore, we tested if increased SERCA activity could counterbalance calcium leakage. By measuring the energy utilization of muscle fibers with and without FK506 treatment, we observed that FK506-treatment increased oxygen consumption by 125% compared to baseline levels. Finally, we found that pretreatment of muscle fibers with the RyR1 stabilizer JTV-519 led to an almost complete normalization of calcium flux dynamics and energy utilization. We conclude that cytosolic calcium levels are mostly preserved in conditions with leaky RyR1 channels due to increased SERCA activity. Therefore, we suggest that RyR1 leakiness might lead to chronic metabolic stress, followed by cellular damage, and RyR1 stabilizers could potentially protect diseased muscle tissue.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling / drug effects
  • Cytoplasm / metabolism
  • Energy Metabolism*
  • Male
  • Mice
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Ryanodine Receptor Calcium Release Channel / metabolism*
  • Tacrolimus / pharmacology
  • Tacrolimus Binding Protein 1A / metabolism*
  • Thiazepines / pharmacology

Substances

  • Ryanodine Receptor Calcium Release Channel
  • Thiazepines
  • K201 compound
  • Tacrolimus Binding Protein 1A
  • Calcium
  • Tacrolimus

Grants and funding

No external funding was received for this study. The funder had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.