Soluble adenylyl cyclase-dependent microtubule disassembly reveals a novel mechanism of endothelial cell retraction

• Published in: American journal of physiology. Lung cellular and molecular physiology Vol. 297; no. 1; pp. L73 - L83
• Main Authors: Prasain, Nutan, Alexeyev, Mikhail, Balczon, Ron, Stevens, Troy
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.07.2009
• Subjects: Adenylyl Cyclases - metabolism; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Membrane Permeability - drug effects; Colforsin - pharmacology; Cyclic AMP - metabolism; Cytosol - drug effects; Endothelial Cells - cytology; Endothelial Cells - drug effects; Endothelial Cells - enzymology; Enzyme Activation - drug effects; Microtubules - chemistry; Microtubules - drug effects; Microtubules - metabolism; Solubility - drug effects; Stress Fibers - drug effects; Stress Fibers - enzymology
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.90577.2008

Departments of 1 Pharmacology, 2 Cell Biology and Neuroscience, and 3 Medicine, 4 Center for Lung Biology, University of South Alabama, Mobile, Alabama Submitted 25 November 2008 ; accepted in final form 19 April 2009 Soluble adenylyl cyclase toxins, such as Pseudomonas aeruginosa exoY, generate a cAMP pool that retracts cell borders. However, the cytoskeletal basis by which this cAMP signal retracts cell borders is not known. We sought to determine whether activation of chimeric, soluble adenylyl cyclase I/II (sACI/II) reorganizes either microtubules or peripheral actin. Endothelial cells were stably transfected with either green fluorescent protein-labeled -tubulin or β-actin, and then infected with adenovirus to express sACI/II. Forskolin, which stimulates both the endogenously expressed transmembrane adenylyl cyclases and sACI/II, induced cell retraction accompanied by the reorganization of peripheral microtubules. However, cortical filamentous-actin (f-actin) did not reorganize into stress fibers, and myosin light-chain-20 phosphorylation was decreased. Isoproterenol, which activates endogenous adenylyl cyclases but does not activate sACI/II, did not induce endothelial cell gaps and did not influence microtubule or f-actin architecture. Thus, sACI/II generates a cAMP signal that reorganizes microtubules and induces cell retraction, without inducing f-actin stress fibers. These findings illustrate that endothelial cell gap formation can proceed without f-actin stress fiber formation, and provide mechanistic insight how bacterial adenylyl cyclase toxins reorganize the cytoskeleton to induce cell rounding. cAMP; actin; cytoskeleton; exoY; stress fibers Address for reprint requests and other correspondence: T. Stevens, Depts. of Pharmacology and Medicine, Center for Lung Biology, Univ. of South Alabama College of Medicine, Mobile, AL 36688 (e-mail: tstevens{at}jaguar1.usouthal.edu )