ON THE COVER
Bright-field (lower left) and fluorescence images of skeletal muscle fibers from wild type (top) and malignant hyperthermia model R2509C-RYR1 heterozygous (bottom) mice. Fibers are co-stained with Ca2+ indicator Cal-520 (green) and thermometer ERthermAC (magenta). Lower right panels show higher magnification of the area indicated by white-outlined rectangles in upper right panels. Image © Tsuboi et al., 2022 https://doi.org/10.1085/jgp.202113136.
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Kv1 channel inactivation: Slow and slower
JGP study suggests that Kv1 channels share a common mechanism of slow inactivation, but that some family members are less prone to inactivate than others.
The road to the brain in Timothy syndrome is paved with enhanced CaV1.2 activation gating
Specific gating effects of Timothy syndrome CaV1.2 channel mutations determine cardiovascular versus nervous system deficits.
CaV1.2 channelopathic mutations evoke diverse pathophysiological mechanisms
Human mutations in CaV1.2 underlie life-threatening arrhythmias and neurodevelopmental disorders. Through in-depth biophysical analysis, this study identifies divergent mechanistic alterations linked to CaV1.2 channelopathies and reveals an association between changes in channel function and patient phenotypes.
Mutations within the selectivity filter reveal that Kv1 channels have distinct propensities to slow inactivate
Slow inactivation in Kv channels is a mechanism of short-term memory wherein the availability of conducting channels depends on recent channel activity. Here, we compare how mutations near the selectivity filter influence slow inactivation in Shaker and Kv1.2 channels and find that Kv1.2 channels are less prone to inactivate compared with Shaker, yet support common mechanisms of inactivation in the two channels.
Nerve-dependent distribution of subsynaptic type 1 inositol 1,4,5-trisphosphate receptor at the neuromuscular junction
The present study reports on a novel effect of denervation at the neuromuscular junction level. It shows that the absence of nerve causes a reduction in the subsynaptic type 1 inositol 1,4,5-trisphosphate-stained region likely involved in the stabilization of the endplate.
Mice with R2509C-RYR1 mutation exhibit dysfunctional Ca2+ dynamics in primary skeletal myocytes
Tsuboi et al. analyze skeletal myocytes from R2509C-RYR1 mice. They find depressed Ca2+ transients, increased resting [Ca2+]cyt, and shortened sarcomeres to the A-band length in homozygous myocytes.