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Cited by 38Cardiac Fibrosis and RemodelingSignaling Pathways in DiseaseProtein Tyrosine Phosphatases

Overexpression of protein phosphatase 2A in a murine model of chronic myocardial infarction leads to increased adverse remodeling but restores the regulation of β-catenin by glycogen synthase kinase 3β

Hoehn, M., Zhang, Y., Xu, J., Gergs, U., Boknik, Peter, Werdan, K., Neumann, J., Ebelt, H.·2015·International Journal of Cardiology
DOI 10.1016/j.ijcard.2015.01.087
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Abstract

Background/objectives Increased activity of cardiac protein phosphatases is an important feature in human heart failure. Several different protein phosphatases (PP) are involved in the regulation of excitation-contraction-coupling of the myocardium. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase consisting of a dimeric core enzyme and tissue-specific subunits. In this study we used transgenic mice overexpressing PP2A to further investigate the role of PP2A in cardiac remodeling after myocardial infarction.Methods and results Adult male CD-1 mice overexpressing the catalytic subunit α of PP2A (αMHC-PP2A; TG) underwent chronic LAD-ligation or sham surgery, respectively; wildtype littermates (WT) were used as controls. Cardiac function was determined by echocardiography before and 28 days after LAD-ligation. 28 days after MI, the animals were sacrificed and cardiac remodeling was analyzed in histological sections and by Western blots. PP2A overexpression leads to dilated cardiomyopathy in mice, and increased cardiomyocyte hypertrophy and fibrosis of the remote myocardium can be seen after myocardial infarction. However, we found an improved survival of TG in the subacute phase after MI in comparison to WT. On the molecular level, TG shows reduced expression of SERCA and CaMKII alpha both under basal condition as well 28 days after MI. Additionally, the regulation of the Akt/GSK3β/β-catenin pathway is severely disturbed in TG at baseline where a significant activation of Akt is found that coincides with the typical phosphorylation of GSK3β. However, this does not lead to the accumulation of β-catenin - on the contrary: phosphorylation-induced degradation of β-catenin is significantly enhanced.Conclusion Transgenic overexpression of myocardial PP2A causes adverse remodeling which coincides with a disruption of the classical Akt/GSK3/β-catenin pathway under baseline conditions that is restored to normal values in chronic myocardial infarction. Even so overall survival of TG after myocardial infarction was not constrained and survival after day 2 post MI was improved.

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Crossref · 10.1016/j.ijcard.2015.01.087

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  • Cα transgenic mice showed increased AKT and GSK-3β phosphorylation and increased β-catenin degradation.

    “Conversely, increased AKT and GSK-3β phosphorylation, and increased β-catenin degradation were seen in the Cα transgenic mice [63].”

    From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [63]

  • This increased infarct size was not associated with decreased survival and unexpectedly improved survival in the subacute phase after infarction, potentially due to restoration of normal AKT and GSK-3β phosphorylation and β-catenin levels.

    “This was however not associated with a decreased survival, and unexpectedly, even resulted in improved survival in the subacute phase after infarction -potentially, because upon myocardial infarction, restoration of normal AKT and GSK-3β phosphorylation, and β-catenin levels could be noted [63].”

    From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [63]

  • Chronic myocardial infarction in Cα transgenic mice increased left ventricle infarct size, suggesting impaired post-myocardial infarction remodeling capacity.

    “an increased left ventricle infarct size was observed, suggestive for impaired post-myocardial infarction remodeling capacity.”

    From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [63]

  • The observed decline in phospholamban phosphorylation, possibly due to reduced CaMKIIα expression or increased PP2A activity, could reinforce SERCA inhibition and further exacerbate the phenotype.

    “the observed decline in PLB phosphorylation, possibly subsequent to reduced CaMKIIα expression or increased PP2A activity, could reinforce its inhibition of SERCA, further exacerbating the phenotype [63].”

    From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [63]

  • RyR2 Ser2808 hypophosphorylation was also seen in the cardiac Ppp2ca overexpression model, co-occurring with reductions in CaMKIIα and SERCA protein expression.

    “RyR 2 Ser2808 hypophosphorylation was also seen in the Ppp2ca cardiac overexpression model, co-occurring with reductions of CaMKIIα and sarcoplasmic reticulum Ca 2+ -ATPase (SERCA) protein expression [63].”

    From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [63]

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Authors
Hoehn, M., Zhang, Y., Xu, J., Gergs, U., Boknik, P., Werdan, K., Neumann, J., & Ebelt, H.
Affiliations
Martin Luther University Halle-Wittenberg (DE)
Corresponding author
Ebelt, H.
ORCID
Venue
International Journal of Cardiology
Publisher
Elsevier BV
Published
2015-03
Volume
183
Pages
39-46
ISSN
0167-5273 (ISSN-L)
DOI
10.1016/j.ijcard.2015.01.087
OpenAlex
W1992840448
Cited by
38
References
49
Citations by year
2026: 5 · 2025: 1 · 2024: 3 · 2023: 4 · 2022: 3 · 2021: 3 · 2020: 3 · 2019: 3 · 2018: 3 · 2017: 4 · 2016: 5 · 2015: 1
FWCI
3.15
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • International Journal of Cardiology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac Fibrosis and Remodeling
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Signaling Pathways in Disease
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
Keywords
protein phosphatase 2A, chronic myocardial infarction, cardiac remodeling, β-catenin, glycogen synthase kinase-3β, Akt signaling, dilated cardiomyopathy, cardiomyocyte hypertrophy, myocardial fibrosis, SERCA, CaMKIIα, heart failure, transgenic mice
MeSH terms
Glycogen Synthase Kinase 3 beta, Animals, Cardiomyopathy, Dilated, Cardiomyopathy, Hypertrophic, Electrocardiography, Male, Mice, Transgenic, Myocardial Infarction, Blotting, Western, Gene Expression, Glycogen Synthase Kinase 3, beta Catenin, Mice, Protein Phosphatase 2, Atrial Remodeling

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