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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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Morphometric analyses of the effects of SB 203580 on  size and sarcomeric organization in myocardial cells. (A) Photographic images of β-galactosidase–positive myocardial cells transfected and treated as described in the legend to Fig. 3 were digitized, and the areas were determined as described in the legend  to Fig. 4 A. Shown are the mean area values for each treatment ±  SE (n = 3 cultures). The SB 203580 vehicle, DMSO, was included  in all controls and had a slight inhibitory effect itself on the ability  of PE and the test constructs to increase cell area. (B) The myofilament structure was evaluated using BODIPY-phalloidin to  stain actin, as described in the legend to Fig. 4 B. Shown are the  mean area values for each treatment ± SE (n = 3 cultures).
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Figure 8: Morphometric analyses of the effects of SB 203580 on size and sarcomeric organization in myocardial cells. (A) Photographic images of β-galactosidase–positive myocardial cells transfected and treated as described in the legend to Fig. 3 were digitized, and the areas were determined as described in the legend to Fig. 4 A. Shown are the mean area values for each treatment ± SE (n = 3 cultures). The SB 203580 vehicle, DMSO, was included in all controls and had a slight inhibitory effect itself on the ability of PE and the test constructs to increase cell area. (B) The myofilament structure was evaluated using BODIPY-phalloidin to stain actin, as described in the legend to Fig. 4 B. Shown are the mean area values for each treatment ± SE (n = 3 cultures).

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)

Morphometric analyses of the effects of SB 203580 on  size and sarcomeric organization in myocardial cells. (A) Photographic images of β-galactosidase–positive myocardial cells transfected and treated as described in the legend to Fig. 3 were digitized, and the areas were determined as described in the legend  to Fig. 4 A. Shown are the mean area values for each treatment ±  SE (n = 3 cultures). The SB 203580 vehicle, DMSO, was included  in all controls and had a slight inhibitory effect itself on the ability  of PE and the test constructs to increase cell area. (B) The myofilament structure was evaluated using BODIPY-phalloidin to  stain actin, as described in the legend to Fig. 4 B. Shown are the  mean area values for each treatment ± SE (n = 3 cultures).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 8: Morphometric analyses of the effects of SB 203580 on size and sarcomeric organization in myocardial cells. (A) Photographic images of β-galactosidase–positive myocardial cells transfected and treated as described in the legend to Fig. 3 were digitized, and the areas were determined as described in the legend to Fig. 4 A. Shown are the mean area values for each treatment ± SE (n = 3 cultures). The SB 203580 vehicle, DMSO, was included in all controls and had a slight inhibitory effect itself on the ability of PE and the test constructs to increase cell area. (B) The myofilament structure was evaluated using BODIPY-phalloidin to stain actin, as described in the legend to Fig. 4 B. Shown are the mean area values for each treatment ± SE (n = 3 cultures).
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