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MLCK/actin interaction in contracting rat aortic smooth muscle
Author(s) -
Thatcher Sean Eric,
Black Jason Edward,
Tanaka Hideyuki,
Wright Gary L.
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.a1301-b
Subject(s) - myosin light chain kinase , actin , myosin , vascular smooth muscle , protein kinase c , chemistry , microbiology and biotechnology , contraction (grammar) , phorbol , rho associated protein kinase , phosphorylation , biophysics , medicine , biology , endocrinology , smooth muscle
Myosin light chain kinase (MLCK) plays an important role in vascular smooth muscle contraction. Its primary role is phosphorylation of the regulatory light chains which in turn activates the ATPase of myosin. MLCK also has an additional role as an actin‐binding protein. It is unclear how this binding occurs in aortic tissue under the protein kinase C‐α (PKC‐α) mediated pathway. Therefore, we used the contractile agonist, phorbol 12, 13‐dibutryate (PDBu), to study the MLCK/actin interaction in rat aortic smooth muscle using fluorescent resonance energy transfer (FRET) microscopy. Through FRET analysis, the MLCK/α‐actin interaction was increased ten minutes after the addition of PDBu (% of zero time point, 100 ± 5.1; 10 minutes, 120.8 ±3.2∗; 20 minutes, 90.0 ± 2.2∗; endpoint, 101.2 ± 3.3, asterisk indicates significance at p<0.05). By comparison, the MLCK/β‐actin interaction was constant during tissue contraction but was significantly reduced during the plateau phase in force development (% of zero time point 100.0 ± 2.6, 10 minutes 95.1 ± 1.7, 20 minutes 97.0 ± 2.5, endpoint 72.6 ± 0.9∗; p<0.05). Co‐immunoprecpitation results were consistent with those found with FRET microscopy. Taken together, these results suggest that MLCK interacts differently with the two predominant isoforms of actin found in vascular smooth muscle during phorbol ester‐induced contraction.