Integrin ligands mobilize Ca2+ from ryanodine receptor-gated stores and lysosome-related acidic organelles in pulmonary arterial smooth muscle cells

Anita Umesh, Michael A. Thompson, Eduardo Nunes Chini, Kay Pong Yip, James S K Sham

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Extracellular matrix (ECM) protein receptors, or integrins, participate in vascular remodeling and the systemic myogenic response. Synthetic ligands and ECM fragments regulate the vascular smooth muscle cell contractile state by altering intracellular Ca2+levels ([Ca2+]i). Information on the Ca2+effect of integrins in vascular smooth muscle cells is limited, but nonexistent in pulmonary arterial smooth muscle cells (PASMCs). We therefore characterized integrin expression in endothelium-denuded pulmonary arteries, and explored [Ca2+]i mobilization pathways induced by soluble ligands in rat PASMCs. Reverse transcriptase-PCR showed mRNA expression of integrins α1, α2, α3, α4, α5, α7, α8, αv, β1, β3, and β4, and immunoblots of α5, αv, β1, and β3 confirmed protein expression. Exposure of PASMCs to integrin-binding peptides (0.5 mM) containing the arginine-glycine-aspartate (RGD) motif elicited [Ca2+]i responses with an order of potency of GRGDNP > GRGDSP > GRGDTP = cyclo-RGD. Pharmacological analysis revealed that the GRGDSP-induced Ca2+ response was unrelated to Ca2+ influx and the inositol triphosphate receptor-gated Ca 2+ store, but partially blocked by ryanodine or inhibition of lysosome-related acidic organelles with bafilomycin A1. Simultaneous inhibition of both pathways was necessary to abolish the response. GRGDSP treatment increased cyclic ADP-ribose , the endogenous activator of ryanodine receptors, by 70%. GRGDSP also rapidly reduced Lysotracker Red accumulation, confirming direct modulation of acidic organelles. These data are the first demonstration of integrin-mediated Ca2+ regulation in PASMCs. The presence of an array of integrins, and activation of ryanodine-sensitive Ca2+ stores and lysosome-like organelles by GRGDSP suggest important roles for integrin-dependent Ca2+ signaling in regulating PASMC function.

Original languageEnglish (US)
Pages (from-to)34312-34323
Number of pages12
JournalJournal of Biological Chemistry
Volume281
Issue number45
DOIs
StatePublished - Nov 10 2006

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Ryanodine Receptor Calcium Release Channel
glycyl-arginyl-glycyl-aspartyl-seryl-proline
Lysosomes
Integrins
Organelles
Smooth Muscle Myocytes
Muscle
Cells
Ligands
Lung
Ryanodine
glycyl-arginyl-glycyl-aspartyl-asparaginyl-proline
fibronectin attachment peptide
Vascular Smooth Muscle
Cyclic ADP-Ribose
Inositol 1,4,5-Trisphosphate Receptors
Extracellular Matrix Proteins
RNA-Directed DNA Polymerase
Reverse Transcriptase Polymerase Chain Reaction
Aspartic Acid

ASJC Scopus subject areas

  • Biochemistry

Cite this

Integrin ligands mobilize Ca2+ from ryanodine receptor-gated stores and lysosome-related acidic organelles in pulmonary arterial smooth muscle cells. / Umesh, Anita; Thompson, Michael A.; Chini, Eduardo Nunes; Yip, Kay Pong; Sham, James S K.

In: Journal of Biological Chemistry, Vol. 281, No. 45, 10.11.2006, p. 34312-34323.

Research output: Contribution to journalArticle

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T1 - Integrin ligands mobilize Ca2+ from ryanodine receptor-gated stores and lysosome-related acidic organelles in pulmonary arterial smooth muscle cells

AU - Umesh, Anita

AU - Thompson, Michael A.

AU - Chini, Eduardo Nunes

AU - Yip, Kay Pong

AU - Sham, James S K

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