Lauren A Biwer1, Miranda E Good1, Kwangseok Hong1, Rahul K Patel1, Neha Agrawal1, Robin Looft-Wilson1, Swapnil K Sonkusare1, Brant E Isakson2. 1. From the Robert M. Berne Cardiovascular Research Center (L.A.B., M.E.G., K.H., R.K.P., S.K.S., B.E.I.) and Department of Molecular Physiology and Biophysics (L.A.B., S.K.S., B.E.I.), University of Virginia School of Medicine, Charlottesville; and Department of Kinesiology, College of William and Mary, Williamsburg, VA (N.A., R.L.-W.). 2. From the Robert M. Berne Cardiovascular Research Center (L.A.B., M.E.G., K.H., R.K.P., S.K.S., B.E.I.) and Department of Molecular Physiology and Biophysics (L.A.B., S.K.S., B.E.I.), University of Virginia School of Medicine, Charlottesville; and Department of Kinesiology, College of William and Mary, Williamsburg, VA (N.A., R.L.-W.). brant@virginia.edu.
Abstract
OBJECTIVE: In resistance arteries, endothelial cell (EC) extensions can make contact with smooth muscle cells, forming myoendothelial junction at holes in the internal elastic lamina (HIEL). At these HIEL, calcium signaling is tightly regulated. Because Calr (calreticulin) can buffer ≈50% of endoplasmic reticulum calcium and is expressed throughout IEL holes in small arteries, the only place where myoendothelial junctions form, we investigated the effect of EC-specific Calr deletion on calcium signaling and vascular function. APPROACH AND RESULTS: We found Calr expressed in nearly every IEL hole in third-order mesenteric arteries, but not other ER markers. Because of this, we generated an EC-specific, tamoxifen inducible, Calr knockout mouse (EC Calr Δ/Δ). Using this mouse, we tested third-order mesenteric arteries for changes in calcium events at HIEL and vascular reactivity after application of CCh (carbachol) or PE (phenylephrine). We found that arteries from EC Calr Δ/Δ mice stimulated with CCh had unchanged activity of calcium signals and vasodilation; however, the same arteries were unable to increase calcium events at HIEL in response to PE. This resulted in significantly increased vasoconstriction to PE, presumably because of inhibited negative feedback. In line with these observations, the EC Calr Δ/Δ had increased blood pressure. Comparison of ER calcium in arteries and use of an ER-specific GCaMP indicator in vitro revealed no observable difference in ER calcium with Calr knockout. Using selective detergent permeabilization of the artery and inhibition of Calr translocation, we found that the observed Calr at HIEL may not be within the ER. CONCLUSIONS: Our data suggest that Calr specifically at HIEL may act in a non-ER dependent manner to regulate arteriolar heterocellular communication and blood pressure.
OBJECTIVE: In resistance arteries, endothelial cell (EC) extensions can make contact with smooth muscle cells, forming myoendothelial junction at holes in the internal elastic lamina (HIEL). At these HIEL, calcium signaling is tightly regulated. Because Calr (calreticulin) can buffer ≈50% of endoplasmic reticulum calcium and is expressed throughout IEL holes in small arteries, the only place where myoendothelial junctions form, we investigated the effect of EC-specific Calr deletion on calcium signaling and vascular function. APPROACH AND RESULTS: We found Calr expressed in nearly every IEL hole in third-order mesenteric arteries, but not other ER markers. Because of this, we generated an EC-specific, tamoxifen inducible, Calr knockout mouse (EC Calr Δ/Δ). Using this mouse, we tested third-order mesenteric arteries for changes in calcium events at HIEL and vascular reactivity after application of CCh (carbachol) or PE (phenylephrine). We found that arteries from EC Calr Δ/Δ mice stimulated with CCh had unchanged activity of calcium signals and vasodilation; however, the same arteries were unable to increase calcium events at HIEL in response to PE. This resulted in significantly increased vasoconstriction to PE, presumably because of inhibited negative feedback. In line with these observations, the EC Calr Δ/Δ had increased blood pressure. Comparison of ER calcium in arteries and use of an ER-specific GCaMP indicator in vitro revealed no observable difference in ER calcium with Calr knockout. Using selective detergent permeabilization of the artery and inhibition of Calr translocation, we found that the observed Calr at HIEL may not be within the ER. CONCLUSIONS: Our data suggest that Calr specifically at HIEL may act in a non-ER dependent manner to regulate arteriolar heterocellular communication and blood pressure.
Authors: Lea Scheppke; Eric A Murphy; Alessandro Zarpellon; Jennifer J Hofmann; Alona Merkulova; David J Shields; Sara M Weis; Tatiana V Byzova; Zaverio M Ruggeri; M Luisa Iruela-Arispe; David A Cheresh Journal: Blood Date: 2011-12-01 Impact factor: 22.113
Authors: Paul M Kerr; Raymond Tam; Katarina Ondrusova; Rohan Mittal; Deepak Narang; Cam Ha T Tran; Donald G Welsh; Frances Plane Journal: Microcirculation Date: 2012-07 Impact factor: 2.628
Authors: Randolph S Faustino; Anca Chiriac; Nicolas J Niederlander; Timothy J Nelson; Atta Behfar; Prasanna K Mishra; Slobodan Macura; Marek Michalak; Andre Terzic; Carmen Perez-Terzic Journal: Stem Cells Date: 2010-07 Impact factor: 6.277
Authors: Hong S Lu; Ann Marie Schmidt; Robert A Hegele; Nigel Mackman; Daniel J Rader; Christian Weber; Alan Daugherty Journal: Arterioscler Thromb Vasc Biol Date: 2019-12-23 Impact factor: 8.311
Authors: Lauren A Biwer; Henry R Askew-Page; Kwangseok Hong; Jenna Milstein; Scott R Johnstone; Edgar Macal; Miranda E Good; Pooneh Bagher; Swapnil K Sonkusare; Brant E Isakson Journal: Am J Physiol Heart Circ Physiol Date: 2020-03-20 Impact factor: 4.733