Nanoscale coupling of junctophilin-2 and ryanodine receptors regulates vascular smooth muscle cell contractility.
Harry A T PritchardCaoimhin S GriffinEvan YamasakiPratish ThakoreConor LaneAdam S GreensteinScott EarleyPublished in: Proceedings of the National Academy of Sciences of the United States of America (2019)
Junctophilin proteins maintain close contacts between the endoplasmic/sarcoplasmic reticulum (ER/SR) and the plasma membrane in many types of cells, as typified by junctophilin-2 (JPH2), which is necessary for the formation of the cardiac dyad. Here, we report that JPH2 is the most abundant junctophilin isotype in native smooth muscle cells (SMCs) isolated from cerebral arteries and that acute knockdown diminishes the area of sites of interaction between the SR and plasma membrane. Superresolution microscopy revealed nanometer-scale colocalization of JPH2 clusters with type 2 ryanodine receptor (RyR2) clusters near the cell surface. Knockdown of JPH2 had no effect on the frequency, amplitude, or kinetics of spontaneous Ca2+ sparks generated by transient release of Ca2+ from the SR through RyR2s, but it did nearly abolish Ca2+ spark-activated, large-conductance, Ca2+-activated K+ (BK) channel currents. We also found that JPH2 knockdown was associated with hypercontractility of intact cerebral arteries. We conclude that JPH2 maintains functional coupling between RyR2s and BK channels and is critically important for cerebral arterial function.
Keyphrases
- smooth muscle
- subarachnoid hemorrhage
- cell surface
- cerebral ischemia
- protein kinase
- single cell
- induced apoptosis
- liver failure
- room temperature
- cell cycle arrest
- heart failure
- high resolution
- brain injury
- high throughput
- oxidative stress
- single molecule
- intensive care unit
- cell death
- drug induced
- cell proliferation
- high speed
- binding protein
- mechanical ventilation