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Integrin‐dependent and ‐independent potentiation of L‐type Calcium Current (Cav1.2) by cell stretch
Author(s) -
Gui Peichun,
Zamponi Gerald W,
Davis George E,
Davis Michael J
Publication year - 2009
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.23.1_supplement.1000.18
Subject(s) - mechanosensitive channels , cav1.2 , biophysics , integrin , patch clamp , chemistry , fibronectin , microbiology and biotechnology , l type calcium channel , gene isoform , pipette , voltage dependent calcium channel , calcium channel , extracellular matrix , calcium , ion channel , biochemistry , cell , biology , receptor , organic chemistry , gene
Recent studies in our lab using both native and heterologously expressed calcium channels (Cav1.2) indicate that L‐type calcium current is potentiated by activation of a5b1 integrin and requires PKA‐ and Src‐ phosphorylation of Cav1.2 C‐terminal residues. To test whether Cav1.2 channels are mechanosensitive and the possible role of integrins in this process, patch clamp methods were used to investigate the properties of Cav1.2 expressed in HEK 293 cells during intracellular application of positive pressure or more physiological, longitudinal two‐pipette stretch of a flexible membrane onto which cells were plated. The membrane was coated with either fibronectin or poly‐lysine to assess integrin‐dependent or ‐independent responses, respectively. In cells expressing the smooth muscle calcium channel isoform (Cav1.2b) alone or in combination with b2a/a2d‐1 accessory subunits, positive pipette pressures of 10~30 mmHg resulted in 20~45% increases in peak inward current. Similar results were found for the neuronal L‐type channel isoform Cav1.2c. Longitudinal stretch between 110 to 130% of resting cell length induced 25 to 60% graded increases in Cav1.2c current. The magnitude of the increase was significantly greater on fibronectin‐coated substrate than on poly‐lysine coated substrate. Preliminary findings showed that native L‐type calcium currents from VSMC exhibit similar mechanical sensitivity. Our results suggest that the Cav1.2 channel subunit shows a limited amount of intrinsic mechanosensitivity and that enhanced channel activity in response to longitudinal stretch may involve the integrin‐extracellular matrix axis.