Regulation of L-type calcium channels by [alpha]5[beta]1 integrin activation in rat basal forebrain neurons : a thesis /
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University System Health Science Center],
[2005]
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| Subjects: |
| Abstract: | ABSTRACT: Currents through L-type Ca²⁺ channels (CaL) in vascular smooth muscle cells, or HEK cells transfected with the neuronal isoform of CaL (Cav1.2c), can be potentiated by activation of α5β1 integrin. ⁽²¹⁾⁽⁴²⁾⁽⁴³⁾ Integrin-induced potentiation is mediated by dual phosphorylation of the α₁c channel subunit by a signaling cascade involving protein kinase A (PKA) and c-Src. ⁽²¹⁾ We tested if integrin activation regulates native neuronal CaL currents by this mechanism. Using whole-cell patch clamp methods, Ba²⁺ currents were recorded from rat medial septum/nucleus of the diagonal band (MS/nDB) neurons in the presence of w-Conotoxin MVIIC and with Vhold=-40 mV to block N-, P/Q-type currents (Cav2.1, Cav2.2) and in the presence of Tetrodotoxin (TTX) to block Na⁺ currents. Integrin ligation and cross-linking by application of microbeads coated with α5β1-integrin antibody (Ab), but not soluble α5β1-Ab, resulted in 6.4 ± 1.6 fold potentiation that peaked after 10 min. Beads coated with control Ab (MHC) served as a control. Current density at the peak of the I-V curve after α5β1-Ab bead application was -20.39 ± 2.4 pA/pF (n=6). Peak current density was -7.1 ± 1.4 pA/pF (n=6) in the presence of the Src-family tyrosine kinase inhibitor PP2, and -7.0 ± .04 pA/pF (n=6) in the presence of PKA inhibitor peptide (PKA-I). With PP2 and PKA-I in combination, peak current density was -2.0 ± 0.1 pA/pF (n=6) after integrin activation. We conclude that CaL currents in rat neurons are potentiated following α5β1 integrin activation and that PKA and c-Src are involved. As the result is similar to that observed in smooth muscle, this may represent a common mechanim for acute regulation of nerve and muscle Ca²⁺ entry by interactions between integrins and the extracellular matrix. |
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| Item Description: | "Major Subject: Medical Sciences". "Submitted to the Graduate School of Biomedical Sciences of The Texas A&M University System Health Science Center in partial fulfillment for the requirements for the degree of Master of Science August 2005." Approved as to style and content by: Michael J. Davis, Emily Wilson, Gerald A. Meininger, William H. Griffin. |
| Physical Description: | x, 52 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 49-52). |