title: Two distinct phases of calcium signalling under flow.
abstract: OBJECTIVE
  High shear stress (HSS) can have significant impact on angiogenesis and atherosclerosis in collateral arteries near the bifurcation and curvature regions. Here, we investigate the spatiotemporal pattern of HSS-induced intracellular calcium alteration.
  
  
  RESULTS
  Genetically encoded biosensors based on fluorescence resonance energy transfer were targeted in the cytoplasm and the endoplasmic reticulum (ER) to visualize the subcellular calcium dynamics in bovine aortic endothelial cells under HSS (65 dyn/cm(2)). Upon HSS application, the intracellular Ca(2+) concentration ([Ca(2+)](i)) increased immediately and maintained a sustained high level, while the ER-stored calcium had a significant decrease only after 300 s. The perturbation of calcium influx across the plasma membrane (PM) by the removal of extracellular calcium or the blockage of membrane channels inhibited the early phase of [Ca(2+)](i) increase upon HSS application, which was further shown to be sensitive to the magnitudes of shear stress and the integrity of cytoskeletal support. In contrast, Src, phospholipase C(PLC), and the inositol 1,4,5-trisphosphate receptor (IP(3)R) can regulate the late phase of HSS-induced [Ca(2+)](i) increase via the promotion of the ER calcium efflux.
  
  
  CONCLUSIONS
  The HSS-induced [Ca(2+)](i) increase consists of two well-co-ordinated phases with different sources and mechanisms: (i) an early phase due to the calcium influx across the PM which is dependent on the mechanical impact and cytoskeletal support and (ii) a late phase originated from the ER-calcium efflux which is regulated by the Src, PLC, and IP(3)R signalling pathway. Therefore, our work presented new molecular-level insights into systematic understanding of mechanotransduction in cardiovascular systems.
authors.affiliation: Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Shaoying
authors.initials: S
authors.lastname: Lu
authors.forename: Shuai
authors.initials: S
authors.lastname: Zheng
authors.forename: Zonglai
authors.initials: Z
authors.lastname: Jiang
authors.forename: Yingxiao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D015374:Biosensing Techniques; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008164:Luminescent Proteins; C434479:citrine protein, bacteria; C527701:enhanced cyan fluorescent protein; D049452:Green Fluorescent Proteins; D019061:src-Family Kinases; D010738:Type C Phospholipases