Ca2+-induced sarcoplasmic reticulum Ca2+ release in myotubularin-deficient muscle fibers.

Ca2+-induced sarcoplasmic reticulum Ca2+ release in myotubularin-deficient muscle fibers. Cell Calcium. 2019 Apr 10;80:91-100 Authors: Kutchukian C, Szentesi P, Allard B, Buj-Bello A, Csernoch L, Jacquemond V Abstract Skeletal muscle deficiency in the 3-phosphoinositide (PtdInsP) phosphatase myotubularin (MTM1) causes myotubular myopathy which is associated with severe depression of voltage-activated sarcoplasmic reticulum Ca2+ release through ryanodine receptors. In the present study we aimed at further understanding how Ca2+ release is altered in MTM1-deficient muscle fibers, at rest and during activation. While in wild-type muscle fibers, SR Ca2+ release exhibits fast stereotyped kinetics of activation and decay throughout the voltage range of activation, Ca2+ release in MTM1-deficient muscle fibers exhibits slow and unconventional kinetics at intermediate voltages, suggestive of partial loss of the normal control of ryanodine receptor Ca2+ channel activity. In addition, the diseased muscle fibers at rest exhibit spontaneous elementary Ca2+ release events at a frequency 30 times greater than that of control fibers. Eighty percent of the events have spatiotemporal properties of archetypal Ca2+ sparks while the rest take either the form of lower amplitude, longer duration Ca2+ release events or of a combination thereof. The events occur at preferred locations in the fibers, indicating spatially uneven distribution of the parameters ...
Source: Cell Calcium - Category: Cytology Authors: Tags: Cell Calcium Source Type: research