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Rap1 GTPase stimulates translocation of α2C‐adrenoceptors from the trans Golgi to the plasma membrane
Author(s) -
Chotani Maqsood A.,
Mitra Srabani,
Eid Ali H.,
Miller Trevor J.,
Flavahan Nicholas 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.20.5.a1177-a
Subject(s) - rap1 , rhoa , microbiology and biotechnology , forskolin , rho associated protein kinase , small gtpase , chemistry , chromosomal translocation , guanine nucleotide exchange factor , gtpase , biology , signal transduction , receptor , biochemistry , gene
In cutaneous arteries, α 2C ‐adrenoceptors (α 2C ‐ARs) are normally silent at warm temperature, but mediate cold‐induced constriction following their translocation from the trans Golgi to the cell surface. We have previously demonstrated that activation of Rap1 by intracellular cyclic AMP increases transcription and expression of α 2C ‐ARs in cutaneous smooth muscle cells. The aim of the present study was to determine if Rap1 also regulates α 2C ‐AR translocation. In HEK293 cells expressing exogenous α 2C ‐ARs, a constitutively‐active mutant of Rap1 (Rap1CA) stimulated translocation of functional α 2C ‐ARs from the Golgi to the plasma membrane (quantified using a live‐cell labeling technique, Circ Res 2004 94:1367) at 37 o C. Activation of Rap1, using Rap1CA or EPAC ( e xchange p rotein directly a ctivated by c AMP) activators forskolin (10μM) or 8‐pCPT‐2′‐O‐Me‐cAMP (100μM), was associated with stimulation of RhoA (detected by pulldown assay) and Rho kinase (ROCK, detected by phosphorylation of a ROCK substrate, the myosin phosphatase subunit MYPT). Indeed, selective ROCK inhibitors, fasudil (3 μM) or Y27632 (1 μM), markedly reduced the translocation of α 2C ‐ARs to the plasma membrane in response to Rap1CA. In a similar manner to Rap1CA, constitutively‐active ROCK‐CA stimulated translocation of α 2C ‐ARs from the Golgi to the cell surface. These results suggest that Rap1 regulates α 2C ‐AR activity at multiple levels by increasing transcription and expression of the receptors and by stimulating their translocation to the cell surface, via activation of RhoA and ROCK. Activation of Rap1 may contribute to abnormal constriction during vascular disease.