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Caveolar localization and caveolin‐1 regulation of PDE5 in human pulmonary artery smooth muscle cells
Author(s) -
Murray Fiona,
Patel Hemal H,
Suda Ryan Y.S.,
Thistlethwaite Partricia A,
Yuan Jason XY,
Insel Paul A
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a543-a
Subject(s) - caveolae , caveolin 1 , caveolin , caveolin 3 , microbiology and biotechnology , signal transduction , chemistry , biology
Caveolae are cholesterol‐enriched invaginations in plasma membranes that concentrate signaling molecules. The protein caveolin is an important component of caveolae that binds and negatively regulates key signal transduction molecules. Phosphodiesterases (PDE) catalyze the hydrolysis of cyclic nucleotides but their localization in caveolae is not well‐defined. The objective of this study was to assess if PDE5 is in caveolae from human pulmonary artery smooth muscle cells (PASMC) and if perturbing caveolin‐1 expression alters expression of PDE5. Caveolae were prepared from PASMC by subcellular fractionation, and fractions probed with antibodies for caveolin‐1 and PDE5. We found that PDE5 was found in caveolin‐enriched fractions of PASMC, results that were confirmed by immunofluorescence. Immunoprecipation provided further evidence for interaction/co‐localization of caveolin‐1 and PDE5. Overexpression of caveolin‐1 by use of a caveolin‐1 adenovirus (24 hr incubation) decreased the level of PDE5 protein 70 ± 12% while use of siRNA specific for caveolin‐1 (48 hr) increased PDE5 expression 50 ± 8%. Consistent with those results, whole lung isolated from caveolin‐1 ‐/‐ mice have a 2‐fold increase in cGMP‐PDE activity compared to control. Thus, caveolin‐1 and PDE5 co‐localize in hPASMC and caveolin‐1 appears to negatively regulate PDE5 expression. This interaction between caveolin‐1 and PDE5 may enhance pulmonary arterial pressure (due to lower cGMP) and hence contribute to the development of PHT in caveolin‐1 knockout mice. Supported by ALA and NIH.