Universität zu Köln

Puetz, Sandra, Schroeter, Mechthild M., Piechura, Heike, Reimann, Lena, Hunger, Mona S., Lubomirov, Lubomir T., Metzler, Doris, Warscheid, Bettina ORCID: 0000-0001-5096-1975 and Pfitzer, Gabriele (2012). New insights into myosin phosphorylation during cyclic nucleotide-mediated smooth muscle relaxation. J. Muscle Res. Cell Motil., 33 (6). S. 471 - 484. DORDRECHT: SPRINGER. ISSN 1573-2657

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Abstract

Nitrovasodilators and agonists, via an increase in intracellular cyclic nucleotide levels, can induce smooth muscle relaxation without a concomitant decrease in phosphorylation of the regulatory light chains (RLC) of myosin. However, since cyclic nucleotide-induced relaxation is associated with a decrease in intracellular [Ca2+], and hence, a decreased activity of MLCK, we tested the hypothesis that the site responsible for the elevated RLC phosphorylation is not Ser19. Smooth muscle strips from gastric fundus were isometrically contracted with ET-1 which induced an increase in monophosphorylation from 9 +/- A 1 % under resting conditions (PSS) to 36 +/- A 1 % determined with 2D-PAGE. Electric field stimulation induced a rapid, largely NO-mediated relaxation with a half time of 8 s, which was associated with an initial decline in RLC phosphorylation to 18 % within 2 s and a rebound to 34 % after 30 s whereas relaxation was sustained. In contrast, phosphorylation of RLC at Ser19 probed with phosphospecific antibodies declined in parallel with force. LC/MS and western blot analysis with phosphospecific antibodies against monophosphorylated Thr18 indicate that Thr18 is significantly monophosphorylated during sustained relaxation. We therefore suggest that (i) monophosphorylation of Thr18 rather than Ser19 is responsible for the phosphorylation rebound during sustained EFS-induced relaxation of mouse gastric fundus, and (ii) that relaxation can be ascribed to dephosphorylation of Ser19, the site considered to be responsible for regulation of smooth muscle tone.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Puetz, Sandra UNSPECIFIED UNSPECIFIED UNSPECIFIED Schroeter, Mechthild M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Piechura, Heike UNSPECIFIED UNSPECIFIED UNSPECIFIED Reimann, Lena UNSPECIFIED UNSPECIFIED UNSPECIFIED Hunger, Mona S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lubomirov, Lubomir T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Metzler, Doris UNSPECIFIED UNSPECIFIED UNSPECIFIED Warscheid, Bettina UNSPECIFIED orcid.org/0000-0001-5096-1975 UNSPECIFIED Pfitzer, Gabriele UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-477319
DOI:	10.1007/s10974-012-9306-9
Journal or Publication Title:	J. Muscle Res. Cell Motil.
Volume:	33
Number:	6
Page Range:	S. 471 - 484
Date:	2012
Publisher:	SPRINGER
Place of Publication:	DORDRECHT
ISSN:	1573-2657
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LIGHT-CHAIN PHOSPHORYLATION; CA2+ SENSITIVITY; CA2+-INDEPENDENT CONTRACTION; SIGNAL-TRANSDUCTION; DISTINCT SITES; CROSS-BRIDGES; OKADAIC ACID; DEPHOSPHORYLATION; PROTEIN; KINASE Multiple languages Cell Biology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/47731