title: A novel role for calpain in the endothelial dysfunction induced by activation of angiotensin II type 1 receptor signaling.
abstract: BACKGROUND
  The cytosolic protease calpain has been recently implicated in the vascular remodeling of angiotensin II (Ang II) type 1 receptor (AT(1)R) signaling. The role of Ang II/AT(1)R/calpain signaling on endothelial function, an important and early determinant of vascular pathology, remains though totally unknown. Accordingly, we investigated the role of calpain in the endothelial dysfunction of Ang II.
  
  
  OBJECTIVE
  To demonstrate a mechanistic role for calpain in the endothelial dysfunction induced by Ang II/AT(1)R signaling. To establish endothelial-expressed calpains as an important target of AT(1)R signaling.
  
  
  RESULTS
  Subchronic administration of nonpressor doses of Ang II to rats and mice significantly increased vascular calpain activity via AT(1)R signaling. Intravital microscopy studies revealed that activation of vascular expressed calpains causes endothelial dysfunction with increased leukocyte-endothelium interactions and albumin permeability in the microcirculation. Western blot and immunohistochemistry studies confirmed that Ang II/AT(1)R signaling preferentially activates the constitutively expressed μ-calpain isoform and demonstrated a calpain-dependent degradation of IκBα, along with upregulation of nuclear factor κB-regulated endothelial cell adhesion molecules. These physiological and biochemical parameters were nearly normalized following inhibition of AT(1)R or calpain in vivo. RNA silencing studies in microvascular endothelial cells, along with knockout and transgenic mouse studies, further confirmed the role of μ-calpain in the endothelial adhesiveness induced by Ang II.
  
  
  CONCLUSIONS
  This study uncovers a novel role for calpain in the endothelial dysfunction of Ang II/AT(1)R signaling and establishes the calpain system as a novel molecular target of the vascular protective action of renin-angiotensin system inhibition. Our results may have significant clinical implications in vascular disease.
authors.affiliation: Department of Physiology, and The Cardiovascular Research Center, Temple University, Philadelphia, PA 19140, USA. rscalia@temple.edu
authors.forename: Rosario
authors.initials: R
authors.lastname: Scalia
authors.forename: Yulan
authors.initials: Y
authors.lastname: Gong
authors.forename: Brett
authors.initials: B
authors.lastname: Berzins
authors.forename: Brin
authors.initials: B
authors.lastname: Freund
authors.forename: Danielle
authors.initials: D
authors.lastname: Feather
authors.forename: Gavin
authors.initials: G
authors.lastname: Landesberg
authors.forename: Gourav
authors.initials: G
authors.lastname: Mishra
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002154:Calpain / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D004730:Endothelium, Vascular / Q000276:immunology / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D008638:Mesenteric Arteries / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D000072000:NF-KappaB Inhibitor alpha; D034622:RNA Interference; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D012084:Renin-Angiotensin System / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014657:Vasculitis / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D020672:I-kappa B Proteins; C000606205:Nfkbia protein, mouse; C000606206:Nfkbia protein, rat; D044140:Receptor, Angiotensin, Type 1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D000072000:NF-KappaB Inhibitor alpha; D002154:Calpain; C449000:m-calpain; C112682:Capn1 protein, mouse