Journal
CIRCULATION
Volume 117, Issue 9, Pages 1161-1171Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1161/CIRCULATIONAHA.107.710111
Keywords
blood flow; blood pressure; endothelium; endothelium-derived factors; physiology; polycystic kidney diseases
Funding
- NCI NIH HHS [P01 CA045548, CA45548] Funding Source: Medline
- NHLBI NIH HHS [HL64867, R01 HL064867, R21 HL084451, HL084451] Funding Source: Medline
- NIDDK NIH HHS [R37 DK051050, R01 DK040703, DK40703, DK51050, R01 DK080640-04, P30 DK074038, R01 DK051050, R01 DK080640] Funding Source: Medline
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Background-When challenged with extracellular fluid shear stress, vascular endothelial cells are known to release nitric oxide, an important vasodilator. Here, we show that the ability of cultured endothelial cells to sense a low range of fluid shear depends on apical membrane organelles, called cilia, and that cilia are compartments required for proper localization and function of the mechanosensitive polycystin-1 molecule. Methods and Results-Cells with the PkdI(null/null) or Tg737(orpk/orpk) mutation encoded for polycystin-1 or polaris, respectively, are unable to transmit extracellular shear stress into intracellular calcium signaling and biochemical nitric oxide synthesis. Cytosolic calcium and nitric oxide recordings further show that fluid shear sensing is a cilia-specific mechanism because other mechanical or pharmacological stimulation does not abolish calcium and nitric oxide signaling in polycystin-1 and polaris mutant endothelial cells. Polycystin-1 localized in the basal body of Tg737(orpk/orpk) endothelial cells is insufficient for a fluid shear stress response. Furthermore, the optimal shear stress to which the cells respond best does not alter the apical cilia structure but modifies the responsiveness of cells to higher shear stresses through proteolytic modification of polycystin-1. Conclusions-We demonstrate for the first time that polycystin-1 (required for cilia function) and polaris (required for cilia structure) are crucial mechanosensitive molecules in endothelial cells. We propose that a distinctive communication with the extracellular microenvironment depends on the proper localization and function of polycystin-1 in cilia.
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