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Spatial Association between L‐type Calcium Channels and Integrins
Author(s) -
Chao JunTzu,
Gui P,
Zamponi G W,
Davis M J
Publication year - 2007
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.21.6.a914-b
Subject(s) - integrin , cav1.2 , immunoprecipitation , integrin, beta 6 , mutant , patch clamp , transfection , chemistry , microbiology and biotechnology , hek 293 cells , voltage dependent calcium channel , calcium channel , wild type , biology , calcium , receptor , biochemistry , gene , organic chemistry
Current through the L‐type calcium channel (Cav1.2) is enhanced by α 5 β 1 integrin activation in vascular smooth muscle cells and neurons. We examined the spatial association between α 5 β 1 integrin and Cav1.2 using Cav1.2 mutants either with truncation of the Cav1.2 C‐terminal region just proximal to the PKA phosphorylation site at Ser 1901 (stop5) or missing the two C‐terminal proline rich domains between amino acids 1955–1973 (dp1/p2). The effects on Cav1.2 current and integrin interaction were determined using co‐immunoprecipitation (IP) and patch clamp recording of Cav1.2 current in HEK293 cells transfected with wild type (WT) or mutant neuronal Cav1.2 cDNA. After integrin activation with α 5 β 1 integrin antibody, current was potentiated by 107% in WT Cav1.2, by 10% in the stop5 mutant, and by 88% in the dp1/p2 mutant. Co‐association of Cav1.2 with β 1 integrin was detected by IP in cells plated on fibronectin (FN), but not on poly‐l‐lysine. On FN, notably less co‐association of Cav1.2 with β 1 integrin was seen in the dp1/p2 mutant (59% of WT, p<0.05), but only slightly less co‐association with β 1 integrin was seen in the stop5 mutant (79% of WT). Lack of correlation between the patch clamp and IP data may result either from the differences in the timing of integrin activation in the two protocols and/or by a requirement for other regulatory regions in Cav1.2 that mediate acute signaling events upon integrin activation. Overall, our data suggest that regions in the C‐terminal of Cav1.2 are crucial for association with β 1 integrin, but their roles in modulating the effects of integrin activation on Cav1.2 need further investigation.