Cyclic AMP-rap1A signaling activates RhoA to induce α2c-adrenoceptor translocation to the cell surface of microvascular smooth muscle cells

Selvi C. Jeyaraj, Nicholas T. Unger, Ali H. Eid, Srabani Mitra, N. Paul El-Dahdah, Lawrence Quilliam, Nicholas A. Flavahan, Maqsood A. Chotani

Research output: Contribution to journalArticle

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Abstract

Intracellular signaling by the second messenger cyclic AMP (cAMP) activates the Ras-related small GTPase Rap1 through the guanine exchange factor Epac. This activation leads to effector protein interactions, activation, and biological responses in the vasculature, including vasorelaxation. In vascular smooth muscle cells derived from human dermal arterioles (micro-VSM), Rap1 selectively regulates expression of G protein-coupled α2C-adrenoceptors (α2C-ARs) through JNK-c-jun nuclear signaling. The α2C-ARs are generally retained in the trans-Golgi compartment and mobilize to the cell surface and elicit vasoconstriction in response to cellular stress. The present study used human microVSM to examine the role of Rap1 in receptor localization. Complementary approaches included murine microVSM derived from tail arteries of C57BL6 mice that express functional α2C-ARs and mice deficient in Rap1A (Rap1A-null). In human microVSM, increasing intracellular cAMP by direct activation of adenylyl cyclase by forskolin (10 μM) or selectively activating Epac-Rap signaling by the cAMP analog 8-pCPT-2′-O-Me-cAMP (100 μM) activated RhoA, increased α2C-AR expression, and reorganized the actin cytoskeleton, increasing F-actin. The α2C-ARs mobilized from the perinuclear region to intracellular filamentous structures and to the plasma membrane. Similar results were obtained in murine wild-type microVSM, coupling Rap1-Rho-actin dynamics to receptor relocalization. This signaling was impaired in Rap1A-null murine microVSM and was rescued by delivery of constitutively active (CA) mutant of Rap1A. When tested in heterologous HEK293 cells, Rap1A-CA or Rho-kinase (ROCK-CA) caused translocation of functional α2C-ARs to the cell surface (~4- to 6-fold increase, respectively). Together, these studies support vascular bed-specific physiological role of Rap1 and suggest a role in vasoconstriction in microVSM.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume303
Issue number5
DOIs
StatePublished - Sep 1 2012

Fingerprint

Cyclic AMP
Adrenergic Receptors
Smooth Muscle Myocytes
Monomeric GTP-Binding Proteins
Vasoconstriction
Actins
rho-Associated Kinases
HEK293 Cells
Guanine
Arterioles
Second Messenger Systems
Colforsin
Actin Cytoskeleton
Vascular Smooth Muscle
GTP-Binding Proteins
Adenylyl Cyclases
Vasodilation
Blood Vessels
Tail
Arteries

Keywords

  • 8-pcpt-2′-o-me-camp
  • Actin cytoskeleton
  • G protein-coupled receptor
  • Rap1a-null

ASJC Scopus subject areas

  • Cell Biology
  • Physiology

Cite this

Cyclic AMP-rap1A signaling activates RhoA to induce α2c-adrenoceptor translocation to the cell surface of microvascular smooth muscle cells. / Jeyaraj, Selvi C.; Unger, Nicholas T.; Eid, Ali H.; Mitra, Srabani; El-Dahdah, N. Paul; Quilliam, Lawrence; Flavahan, Nicholas A.; Chotani, Maqsood A.

In: American Journal of Physiology - Cell Physiology, Vol. 303, No. 5, 01.09.2012.

Research output: Contribution to journalArticle

Jeyaraj, Selvi C. ; Unger, Nicholas T. ; Eid, Ali H. ; Mitra, Srabani ; El-Dahdah, N. Paul ; Quilliam, Lawrence ; Flavahan, Nicholas A. ; Chotani, Maqsood A. / Cyclic AMP-rap1A signaling activates RhoA to induce α2c-adrenoceptor translocation to the cell surface of microvascular smooth muscle cells. In: American Journal of Physiology - Cell Physiology. 2012 ; Vol. 303, No. 5.
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