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Mol. Cells 2007; 23(2): 175-181

Published online January 1, 1970

© The Korean Society for Molecular and Cellular Biology

SM22α Is Required for Agonist-induced Regulation of Contractility: Evidence from SM22α Knockout Mice

Hyun Dong Je, Uy Dong Sohn

Abstract

The present study was undertaken to determine whether SM22? participates in the regulation of vascular smooth muscle contractility using SM22? knockout mice and, if so, to investigate the mechanisms involved. Aortic ring preparations were mounted and equilibrated in organ baths for 60 min before observing contractile responses to 50 mM KCl, and then exposed to contractile agents such as phenylephrine and phorbol ester. Measurement of isometric contractions using a computerized data acquisition system was combined with molecular or cellular experiments. Interestingly, the aortas from SM22?-deficient mice (SM22-/-LacZ) displayed an almost three-fold increase in the level of SM22?? protein compared to wild-type mice, but no change in the levels of caldesmon, actin, desmin or calponin. Ca2+-independent contraction in response to phenylephrine or phorbol ester was significantly decreased in the SM22?-deficient mice, whereas in the presence of Ca2+ neither contraction nor subcellular translocation of myosin light chain kinase (MLCK) in response to phenylephrine or 50 mM KCl was significantly affected. A decrease in phosphorylation of extracellular signal regulated kinase (ERK) 1/2 was observed in the SM22? -deficient mice and this may be related to the decreased vascular contractility. Taken together, this study provides evidence for a pivotal role of SM22? in the regulation of Ca2+-independent vascular contractility.

Keywords EGTA; ERK; KCl; MLCK; Phenylephrine;, Phorbol Ester; SM22α; SM22β; Transgenic Mouse.

Article

Research Article

Mol. Cells 2007; 23(2): 175-181

Published online April 30, 2007

Copyright © The Korean Society for Molecular and Cellular Biology.

SM22α Is Required for Agonist-induced Regulation of Contractility: Evidence from SM22α Knockout Mice

Hyun Dong Je, Uy Dong Sohn

Abstract

The present study was undertaken to determine whether SM22? participates in the regulation of vascular smooth muscle contractility using SM22? knockout mice and, if so, to investigate the mechanisms involved. Aortic ring preparations were mounted and equilibrated in organ baths for 60 min before observing contractile responses to 50 mM KCl, and then exposed to contractile agents such as phenylephrine and phorbol ester. Measurement of isometric contractions using a computerized data acquisition system was combined with molecular or cellular experiments. Interestingly, the aortas from SM22?-deficient mice (SM22-/-LacZ) displayed an almost three-fold increase in the level of SM22?? protein compared to wild-type mice, but no change in the levels of caldesmon, actin, desmin or calponin. Ca2+-independent contraction in response to phenylephrine or phorbol ester was significantly decreased in the SM22?-deficient mice, whereas in the presence of Ca2+ neither contraction nor subcellular translocation of myosin light chain kinase (MLCK) in response to phenylephrine or 50 mM KCl was significantly affected. A decrease in phosphorylation of extracellular signal regulated kinase (ERK) 1/2 was observed in the SM22? -deficient mice and this may be related to the decreased vascular contractility. Taken together, this study provides evidence for a pivotal role of SM22? in the regulation of Ca2+-independent vascular contractility.

Keywords: EGTA, ERK, KCl, MLCK, Phenylephrine,, Phorbol Ester, SM22α, SM22β, Transgenic Mouse.

Mol. Cells
Jun 30, 2023 Vol.46 No.6, pp. 329~398
COVER PICTURE
The cellular proteostasis network is adaptively modulated upon cellular stress, thereby protecting cells from proteostasis collapse. Heat shock induces the translocation of misfolded proteins and the chaperone protein HSP70 into nucleolus, where nuclear protein quality control primarily occurs. Nuclear RNA export factor 1 (green), nucleolar protein fibrillarin (red), and nuclei (blue) were visualized in NIH3T3 cells under basal (left) and heat shock (right) conditions (Park et al., pp. 374-386).

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