Two distinct phases of calcium signalling under flow

Area of Science:

• Cardiovascular Biology
• Cellular Mechanotransduction
• Endothelial Cell Physiology

Background:

• High shear stress (HSS) significantly impacts vascular health, influencing angiogenesis and atherosclerosis.
• Understanding cellular responses to HSS is crucial for cardiovascular disease research.

Purpose of the Study:

• To investigate the spatiotemporal pattern of intracellular calcium alterations induced by HSS.
• To elucidate the subcellular mechanisms and molecular players involved in HSS-mediated calcium dynamics.

Main Methods:

• Utilized genetically encoded fluorescence resonance energy transfer (FRET) biosensors to monitor cytoplasmic and endoplasmic reticulum (ER) calcium dynamics.
• Applied HSS (65 dyn/cm(2)) to bovine aortic endothelial cells.
• Manipulated extracellular calcium and employed pharmacological inhibitors to probe calcium influx and efflux pathways.

Main Results:

• HSS caused an immediate increase in intracellular calcium concentration ([Ca(2+)](i)) and a delayed decrease in ER-stored calcium.
• The early phase of [Ca(2+)](i) increase was dependent on extracellular calcium influx, mechanical impact, and cytoskeletal integrity.
• The late phase of [Ca(2+)](i) increase was regulated by Src, phospholipase C (PLC), and inositol 1,4,5-trisphosphate receptor (IP(3)R)-mediated ER calcium efflux.

Conclusions:

• HSS-induced calcium increase involves distinct early (influx-dependent) and late (ER efflux-dependent) phases.
• Mechanisms involve direct mechanical effects and signaling pathways including Src, PLC, and IP(3)R.
• Provides molecular insights into mechanotransduction in cardiovascular systems.