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Truncated β 2 subunits increase membrane expression of LTCC subunits in A7r5 cells
Author(s) -
Telemaque Sabine,
Flynn Shawn E,
Liu Meeiyueh,
Grain Terrie,
Marsh James D
Publication year - 2011
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.25.1_supplement.1026.14
Subject(s) - protein subunit , cytosol , intracellular , microbiology and biotechnology , chemistry , vascular smooth muscle , biology , biochemistry , gene , endocrinology , enzyme , smooth muscle
Cytosolic Ca 2+ is regulated by Ca 2+ entry through L‐type calcium channels (LTCC) and release from intracellular Ca 2+ stores via the IP 3 receptors (IP 3 R) in vascular smooth muscle cells (VSMC). The β 2 subunit of the LTCC is an intracellular chaperone that interacts with the α 1C subunit via its beta interaction domain (BID) to regulate membrane localization and channel function. In order to alter assembly of the LTCC at the cell surface of VSMC, we used adenovirus constructs to overexpress either the β 2 subunit (Full‐β 2 ) or truncated β 2 subunits lacking either the C‐, N‐terminus or both (N‐BID, C‐BID or BID, respectively) fused to GFP. Immunoblot analysis confirmed that Full‐β 2 was primarily expressed in the membrane fraction while C‐BID and N‐BID expression at the membrane was reduced to 70% and 52%, respectively. BID was in the cytosol, like GFP. Full‐β 2 significantly increased α 1C subunit expression at the membrane, as did C‐BID and N‐BID. Membrane levels of α 2 subunit were also increased by the 3 constructs. BID did not modify localization of the LTCC subunits. Membrane levels of IP 3 R were significantly increased only by Full‐β 2 . Our study showed that truncated β 2 subunits can alter expression of the LTCC subunits at the cell surface and suggest that LTCC function could be regulated by these decoys. Development of VSMC‐specific constructs may represent a viable gene‐based treatment to regulate vascular reactivity.