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A role for the p38 mitogen-activated protein kinase pathway in myocardial cell growth, sarcomeric organization, and cardiac-specific gene expression.

Zechner D, Thuerauf DJ, Hanford DS, McDonough PM, Glembotski CC - J. Cell Biol. (1997)

Bottom Line: While activation of JNK and/or ERK with MEKK1COOH or Raf-1 BXB, respectively, augmented cell size and effected relatively modest increases in NP and alpha-SkA promoter activities, neither upstream kinase conferred sarcomeric organization.However, transfection with MKK6 (Glu), which specifically activated p38, augmented cell size, induced NP and alpha-Ska promoter activities by up to 130-fold, and elicited sarcomeric organization in a manner similar to PE.Moreover, all three growth features induced by MKK6 (Glu) or PE were blocked with the p38-specific inhibitor, SB 203580.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Molecular Biology Institute, San Diego State University, California 92182, USA.

ABSTRACT
Three hallmark features of the cardiac hypertrophic growth program are increases in cell size, sarcomeric organization, and the induction of certain cardiac-specific genes. All three features of hypertrophy are induced in cultured myocardial cells by alpha1- adrenergic receptor agonists, such as phenylephrine (PE) and other growth factors that activate mitogen- activated protein kinases (MAPKs). In this study the MAPK family members extracellular signal-regulated kinase (ERK), c-jun NH2-terminal kinase (JNK), and p38 were activated by transfecting cultured cardiac myocytes with constructs encoding the appropriate kinases possessing gain-of-function mutations. Transfected cells were then analyzed for changes in cell size, sarcomeric organization, and induction of the genes for the A- and B-type natriuretic peptides (NPs), as well as the alpha-skeletal actin (alpha-SkA) gene. While activation of JNK and/or ERK with MEKK1COOH or Raf-1 BXB, respectively, augmented cell size and effected relatively modest increases in NP and alpha-SkA promoter activities, neither upstream kinase conferred sarcomeric organization. However, transfection with MKK6 (Glu), which specifically activated p38, augmented cell size, induced NP and alpha-Ska promoter activities by up to 130-fold, and elicited sarcomeric organization in a manner similar to PE. Moreover, all three growth features induced by MKK6 (Glu) or PE were blocked with the p38-specific inhibitor, SB 203580. These results demonstrate novel and potentially central roles for MKK6 and p38 in the regulation of myocardial cell hypertrophy.

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Fluorescent microscopic analyses of the effects  of SB 203580 on size and sarcomeric organization in myocardial cells. Myocardial cells  were cotransfected with MKK6  (Glu) or an empty vector  control (pCEP and pCEP +  PE) and CMV–β-galactosidase and then plated on glass  slides, as described in the legend for Fig. 3. After maintenance for 48 h in serum-free  control medium with or without SB 203580 (20 μM) or  DMSO (vehicle control) and  with or without PE (10 μM)  + propranolol (1 μM), as  shown, cultures were fixed in  paraformaldehyde and immunostained for β-galactosidase expression (Gal) (A– F), and the same cultures  were stained for actin with  BODIPY-phalloidin (Phall)  (A′–F′). Bar, 50 μm.
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Figure 7: Fluorescent microscopic analyses of the effects of SB 203580 on size and sarcomeric organization in myocardial cells. Myocardial cells were cotransfected with MKK6 (Glu) or an empty vector control (pCEP and pCEP + PE) and CMV–β-galactosidase and then plated on glass slides, as described in the legend for Fig. 3. After maintenance for 48 h in serum-free control medium with or without SB 203580 (20 μM) or DMSO (vehicle control) and with or without PE (10 μM) + propranolol (1 μM), as shown, cultures were fixed in paraformaldehyde and immunostained for β-galactosidase expression (Gal) (A– F), and the same cultures were stained for actin with BODIPY-phalloidin (Phall) (A′–F′). Bar, 50 μm.

Mentions: The SB 203580 compound also had potent inhibitory effects on myocardial cell size and sarcomeric organization induced by PE or MKK6 (Glu) (Fig. 7). PE- or MKK6 (Glu)–mediated sarcomeric organization and increases in cell size were reduced by >90% by SB 203580 (Fig. 8). These results are consistent with a central role for a p38-like pathway in myocardial cell growth conferred by PE or by MKK6 (Glu).


A role for the p38 mitogen-activated protein kinase pathway in myocardial cell growth, sarcomeric organization, and cardiac-specific gene expression.

Zechner D, Thuerauf DJ, Hanford DS, McDonough PM, Glembotski CC - J. Cell Biol. (1997)

Fluorescent microscopic analyses of the effects  of SB 203580 on size and sarcomeric organization in myocardial cells. Myocardial cells  were cotransfected with MKK6  (Glu) or an empty vector  control (pCEP and pCEP +  PE) and CMV–β-galactosidase and then plated on glass  slides, as described in the legend for Fig. 3. After maintenance for 48 h in serum-free  control medium with or without SB 203580 (20 μM) or  DMSO (vehicle control) and  with or without PE (10 μM)  + propranolol (1 μM), as  shown, cultures were fixed in  paraformaldehyde and immunostained for β-galactosidase expression (Gal) (A– F), and the same cultures  were stained for actin with  BODIPY-phalloidin (Phall)  (A′–F′). Bar, 50 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139826&req=5

Figure 7: Fluorescent microscopic analyses of the effects of SB 203580 on size and sarcomeric organization in myocardial cells. Myocardial cells were cotransfected with MKK6 (Glu) or an empty vector control (pCEP and pCEP + PE) and CMV–β-galactosidase and then plated on glass slides, as described in the legend for Fig. 3. After maintenance for 48 h in serum-free control medium with or without SB 203580 (20 μM) or DMSO (vehicle control) and with or without PE (10 μM) + propranolol (1 μM), as shown, cultures were fixed in paraformaldehyde and immunostained for β-galactosidase expression (Gal) (A– F), and the same cultures were stained for actin with BODIPY-phalloidin (Phall) (A′–F′). Bar, 50 μm.
Mentions: The SB 203580 compound also had potent inhibitory effects on myocardial cell size and sarcomeric organization induced by PE or MKK6 (Glu) (Fig. 7). PE- or MKK6 (Glu)–mediated sarcomeric organization and increases in cell size were reduced by >90% by SB 203580 (Fig. 8). These results are consistent with a central role for a p38-like pathway in myocardial cell growth conferred by PE or by MKK6 (Glu).

Bottom Line: While activation of JNK and/or ERK with MEKK1COOH or Raf-1 BXB, respectively, augmented cell size and effected relatively modest increases in NP and alpha-SkA promoter activities, neither upstream kinase conferred sarcomeric organization.However, transfection with MKK6 (Glu), which specifically activated p38, augmented cell size, induced NP and alpha-Ska promoter activities by up to 130-fold, and elicited sarcomeric organization in a manner similar to PE.Moreover, all three growth features induced by MKK6 (Glu) or PE were blocked with the p38-specific inhibitor, SB 203580.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Molecular Biology Institute, San Diego State University, California 92182, USA.

ABSTRACT
Three hallmark features of the cardiac hypertrophic growth program are increases in cell size, sarcomeric organization, and the induction of certain cardiac-specific genes. All three features of hypertrophy are induced in cultured myocardial cells by alpha1- adrenergic receptor agonists, such as phenylephrine (PE) and other growth factors that activate mitogen- activated protein kinases (MAPKs). In this study the MAPK family members extracellular signal-regulated kinase (ERK), c-jun NH2-terminal kinase (JNK), and p38 were activated by transfecting cultured cardiac myocytes with constructs encoding the appropriate kinases possessing gain-of-function mutations. Transfected cells were then analyzed for changes in cell size, sarcomeric organization, and induction of the genes for the A- and B-type natriuretic peptides (NPs), as well as the alpha-skeletal actin (alpha-SkA) gene. While activation of JNK and/or ERK with MEKK1COOH or Raf-1 BXB, respectively, augmented cell size and effected relatively modest increases in NP and alpha-SkA promoter activities, neither upstream kinase conferred sarcomeric organization. However, transfection with MKK6 (Glu), which specifically activated p38, augmented cell size, induced NP and alpha-Ska promoter activities by up to 130-fold, and elicited sarcomeric organization in a manner similar to PE. Moreover, all three growth features induced by MKK6 (Glu) or PE were blocked with the p38-specific inhibitor, SB 203580. These results demonstrate novel and potentially central roles for MKK6 and p38 in the regulation of myocardial cell hypertrophy.

Show MeSH
Related in: MedlinePlus