title: Intermedin induces loss of coronary microvascular endothelial barrier via derangement of actin cytoskeleton: role of RhoA and Rac1.
abstract: OBJECTIVE
  Intermedin (IMD) is a novel member of the calcitonin gene-related peptide family, which acts via calcitonin receptor-like receptors (CLRs), mediating activation of cAMP signalling. The main objective of the present study was to analyse the molecular mechanisms of the differential effects of IMD on the macromolecule permeability of endothelial cells of different vascular beds.
  
  
  RESULTS
  Here we demonstrate that IMD increases permeability of rat coronary microvascular endothelial cells (RCECs) and reduces permeability of human umbilical vein endothelial cells (HUVECs) and rat aortic endothelial cells via CLRs and cAMP. Intermedin causes a derangement of the actin cytoskeleton accompanied by loss of vascular endothelial cadherin (VE-cadherin) in RCECs, while it causes a rearrangement of the actin cytoskeleton and VE-cadherin at cell-cell junctions in HUVECs. Intermedin inactivates the RhoA/Rho-kinase (Rock) pathway in both cell types; however, it inactivates Rac1 in RCECs but not in HUVECs. Inhibition and rescue experiments demonstrate that both RhoA and Rac1 are required for the RCEC barrier stability, while in HUVECs the inhibition of RhoA/Rock signalling does not interfere with basal permeability.
  
  
  CONCLUSIONS
  The opposite effects of IMD on permeability of RCECs and HUVECs are due to differential regulation of actin cytoskeleton dynamics via RhoA and Rac1. Moreover, Rac1 activity is regulated by the RhoA/Rock pathway in RCECs but not in HUVECs.
authors.affiliation: Physiologisches Institut, Justus-Liebig-Universität, Aulweg 129, D-35392 Giessen, Germany. muhammad.aslam@physiologie.med.uni-giessen.de
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aslam
authors.forename: Dursun
authors.initials: D
authors.lastname: Gündüz
authors.forename: Dominik
authors.initials: D
authors.lastname: Schuler
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Sharifpanah
authors.forename: Daniel
authors.initials: D
authors.lastname: Sedding
authors.forename: Hans Michael
authors.initials: HM
authors.lastname: Piper
authors.forename: Thomas
authors.initials: T
authors.lastname: Noll
mesh_terms: D008841:Actin Cytoskeleton / Q000201:enzymology*; D053607:Adrenomedullin / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D058286:Calcitonin Receptor-Like Protein / Q000378:metabolism; D002199:Capillary Permeability; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000201:enzymology*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000201:enzymology*; D006801:Humans; D008297:Male; D055806:Microvessels / Q000166:cytology / Q000201:enzymology*; D009479:Neuropeptides / Q000378:metabolism*; D036361:Peptide Hormones / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018003:Receptors, Calcitonin / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D000099152:Cadherin 5
chemical_list: D053607:Adrenomedullin; D015703:Antigens, CD; D015820:Cadherins; D058286:Calcitonin Receptor-Like Protein; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D009479:Neuropeptides; D036361:Peptide Hormones; D018003:Receptors, Calcitonin; D020830:rac1 GTP-Binding Protein; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D000099152:Cadherin 5; C484330:ADM2 protein, human; C499411:Adm2 protein, rat; C545578:CALCRL protein, human; C545580:Calcrl protein, rat; C107953:RAC1 protein, human; C066737:RHOA protein, human; C499134:Rac1 protein, rat