P38α mitogen-activated kinase mediates cardiomyocyte apoptosis induced by palmitate

Charles C. Oh, Michael Q. Nguy, Dawn C. Schwenke, Raymond Q. Migrino, Kent Thornburg, Peter Reaven

    Research output: Contribution to journalArticle

    13 Citations (Scopus)

    Abstract

    Rationale The mechanisms underlying lipotoxic/diabetic cardiomyopathy remain poorly understood. Saturated fatty acid (SFA) levels, elevated in obesity and type 2 diabetes, induce apoptosis in many cell types including cardiomyocytes. Signaling pathways, including the p38α mitogen-activated kinase (MAPK)-dependent pathway, have been implicated in apoptosis due to a diverse range of insults. Objective We tested the hypothesis that SFA-induced cardiomyocyte apoptosis is dependent on p38α activation. Methods and results Human adult ventricular cardiomyocytes (AC16 cells) were exposed to high physiological levels of palmitate (PA), a SFA. The apoptotic response was measured using annexin-V by flow cytometry, and the p38α-dependent pathway was evaluated using a p38 inhibitor PD169316, and by p38α small interfering RNA (siRNA) knockdown. PA exposure for 16 h dose-dependently increased apoptosis in AC16 cardiomyocytes (control: 2.6 ± 0.6%, 150 μM PA: 3.5 ± 0.9%, 300 μM PA: 11.5 ± 1.6%, n = 4, p <0.01). PA did not change total p38α protein levels, but increased p38α phosphorylation dose-dependently (n = 5, p <0.01). PD169316 tended to reduce PA-induced apoptosis (n = 4, p = 0.05). Specific p38α siRNA markedly reduced the expression of p38α but not p38β (n = 3, p <0.0001), and dose-dependently attenuated PA-induced apoptosis (control siRNA: 7.7 ± 1.0%, 300 μM PA: 34.4 ± 5.0%, 300 μM PA + 30 pmol siRNA: 23.7 ± 4.4%, 300 μM PA + 60 pmol siRNA: 19.7 ± 2.6%, 300 μM PA + 120 pmol siRNA: 17.3 ± 2.8%, n = 4, p <0.0001). Conclusions These results demonstrate that PA induces p38α activation, and reducing p38α expression attenuates PA-induced cardiomyocyte apoptosis. Our results support a potential mechanism by which high plasma SFA levels through p38α activation may lead to the development of lipotoxic/diabetic cardiomyopathy.

    Original languageEnglish (US)
    Pages (from-to)628-633
    Number of pages6
    JournalBiochemical and Biophysical Research Communications
    Volume450
    Issue number1
    DOIs
    StatePublished - Jul 18 2014

    Fingerprint

    Palmitates
    Mitogens
    Cardiac Myocytes
    Phosphotransferases
    Apoptosis
    Small Interfering RNA
    Fatty Acids
    Diabetic Cardiomyopathies
    Chemical activation
    Phosphorylation
    Flow cytometry
    Annexin A5
    Mitogen-Activated Protein Kinase Kinases
    Medical problems
    Type 2 Diabetes Mellitus
    Flow Cytometry
    Obesity

    Keywords

    • Apoptosis
    • Cardiomyopathy
    • Diabetes
    • Lipotoxic
    • p38α MAPK

    ASJC Scopus subject areas

    • Biochemistry
    • Biophysics
    • Cell Biology
    • Molecular Biology

    Cite this

    P38α mitogen-activated kinase mediates cardiomyocyte apoptosis induced by palmitate. / Oh, Charles C.; Nguy, Michael Q.; Schwenke, Dawn C.; Migrino, Raymond Q.; Thornburg, Kent; Reaven, Peter.

    In: Biochemical and Biophysical Research Communications, Vol. 450, No. 1, 18.07.2014, p. 628-633.

    Research output: Contribution to journalArticle

    Oh, Charles C. ; Nguy, Michael Q. ; Schwenke, Dawn C. ; Migrino, Raymond Q. ; Thornburg, Kent ; Reaven, Peter. / P38α mitogen-activated kinase mediates cardiomyocyte apoptosis induced by palmitate. In: Biochemical and Biophysical Research Communications. 2014 ; Vol. 450, No. 1. pp. 628-633.
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    abstract = "Rationale The mechanisms underlying lipotoxic/diabetic cardiomyopathy remain poorly understood. Saturated fatty acid (SFA) levels, elevated in obesity and type 2 diabetes, induce apoptosis in many cell types including cardiomyocytes. Signaling pathways, including the p38α mitogen-activated kinase (MAPK)-dependent pathway, have been implicated in apoptosis due to a diverse range of insults. Objective We tested the hypothesis that SFA-induced cardiomyocyte apoptosis is dependent on p38α activation. Methods and results Human adult ventricular cardiomyocytes (AC16 cells) were exposed to high physiological levels of palmitate (PA), a SFA. The apoptotic response was measured using annexin-V by flow cytometry, and the p38α-dependent pathway was evaluated using a p38 inhibitor PD169316, and by p38α small interfering RNA (siRNA) knockdown. PA exposure for 16 h dose-dependently increased apoptosis in AC16 cardiomyocytes (control: 2.6 ± 0.6{\%}, 150 μM PA: 3.5 ± 0.9{\%}, 300 μM PA: 11.5 ± 1.6{\%}, n = 4, p <0.01). PA did not change total p38α protein levels, but increased p38α phosphorylation dose-dependently (n = 5, p <0.01). PD169316 tended to reduce PA-induced apoptosis (n = 4, p = 0.05). Specific p38α siRNA markedly reduced the expression of p38α but not p38β (n = 3, p <0.0001), and dose-dependently attenuated PA-induced apoptosis (control siRNA: 7.7 ± 1.0{\%}, 300 μM PA: 34.4 ± 5.0{\%}, 300 μM PA + 30 pmol siRNA: 23.7 ± 4.4{\%}, 300 μM PA + 60 pmol siRNA: 19.7 ± 2.6{\%}, 300 μM PA + 120 pmol siRNA: 17.3 ± 2.8{\%}, n = 4, p <0.0001). Conclusions These results demonstrate that PA induces p38α activation, and reducing p38α expression attenuates PA-induced cardiomyocyte apoptosis. Our results support a potential mechanism by which high plasma SFA levels through p38α activation may lead to the development of lipotoxic/diabetic cardiomyopathy.",
    keywords = "Apoptosis, Cardiomyopathy, Diabetes, Lipotoxic, p38α MAPK",
    author = "Oh, {Charles C.} and Nguy, {Michael Q.} and Schwenke, {Dawn C.} and Migrino, {Raymond Q.} and Kent Thornburg and Peter Reaven",
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    T1 - P38α mitogen-activated kinase mediates cardiomyocyte apoptosis induced by palmitate

    AU - Oh, Charles C.

    AU - Nguy, Michael Q.

    AU - Schwenke, Dawn C.

    AU - Migrino, Raymond Q.

    AU - Thornburg, Kent

    AU - Reaven, Peter

    PY - 2014/7/18

    Y1 - 2014/7/18

    N2 - Rationale The mechanisms underlying lipotoxic/diabetic cardiomyopathy remain poorly understood. Saturated fatty acid (SFA) levels, elevated in obesity and type 2 diabetes, induce apoptosis in many cell types including cardiomyocytes. Signaling pathways, including the p38α mitogen-activated kinase (MAPK)-dependent pathway, have been implicated in apoptosis due to a diverse range of insults. Objective We tested the hypothesis that SFA-induced cardiomyocyte apoptosis is dependent on p38α activation. Methods and results Human adult ventricular cardiomyocytes (AC16 cells) were exposed to high physiological levels of palmitate (PA), a SFA. The apoptotic response was measured using annexin-V by flow cytometry, and the p38α-dependent pathway was evaluated using a p38 inhibitor PD169316, and by p38α small interfering RNA (siRNA) knockdown. PA exposure for 16 h dose-dependently increased apoptosis in AC16 cardiomyocytes (control: 2.6 ± 0.6%, 150 μM PA: 3.5 ± 0.9%, 300 μM PA: 11.5 ± 1.6%, n = 4, p <0.01). PA did not change total p38α protein levels, but increased p38α phosphorylation dose-dependently (n = 5, p <0.01). PD169316 tended to reduce PA-induced apoptosis (n = 4, p = 0.05). Specific p38α siRNA markedly reduced the expression of p38α but not p38β (n = 3, p <0.0001), and dose-dependently attenuated PA-induced apoptosis (control siRNA: 7.7 ± 1.0%, 300 μM PA: 34.4 ± 5.0%, 300 μM PA + 30 pmol siRNA: 23.7 ± 4.4%, 300 μM PA + 60 pmol siRNA: 19.7 ± 2.6%, 300 μM PA + 120 pmol siRNA: 17.3 ± 2.8%, n = 4, p <0.0001). Conclusions These results demonstrate that PA induces p38α activation, and reducing p38α expression attenuates PA-induced cardiomyocyte apoptosis. Our results support a potential mechanism by which high plasma SFA levels through p38α activation may lead to the development of lipotoxic/diabetic cardiomyopathy.

    AB - Rationale The mechanisms underlying lipotoxic/diabetic cardiomyopathy remain poorly understood. Saturated fatty acid (SFA) levels, elevated in obesity and type 2 diabetes, induce apoptosis in many cell types including cardiomyocytes. Signaling pathways, including the p38α mitogen-activated kinase (MAPK)-dependent pathway, have been implicated in apoptosis due to a diverse range of insults. Objective We tested the hypothesis that SFA-induced cardiomyocyte apoptosis is dependent on p38α activation. Methods and results Human adult ventricular cardiomyocytes (AC16 cells) were exposed to high physiological levels of palmitate (PA), a SFA. The apoptotic response was measured using annexin-V by flow cytometry, and the p38α-dependent pathway was evaluated using a p38 inhibitor PD169316, and by p38α small interfering RNA (siRNA) knockdown. PA exposure for 16 h dose-dependently increased apoptosis in AC16 cardiomyocytes (control: 2.6 ± 0.6%, 150 μM PA: 3.5 ± 0.9%, 300 μM PA: 11.5 ± 1.6%, n = 4, p <0.01). PA did not change total p38α protein levels, but increased p38α phosphorylation dose-dependently (n = 5, p <0.01). PD169316 tended to reduce PA-induced apoptosis (n = 4, p = 0.05). Specific p38α siRNA markedly reduced the expression of p38α but not p38β (n = 3, p <0.0001), and dose-dependently attenuated PA-induced apoptosis (control siRNA: 7.7 ± 1.0%, 300 μM PA: 34.4 ± 5.0%, 300 μM PA + 30 pmol siRNA: 23.7 ± 4.4%, 300 μM PA + 60 pmol siRNA: 19.7 ± 2.6%, 300 μM PA + 120 pmol siRNA: 17.3 ± 2.8%, n = 4, p <0.0001). Conclusions These results demonstrate that PA induces p38α activation, and reducing p38α expression attenuates PA-induced cardiomyocyte apoptosis. Our results support a potential mechanism by which high plasma SFA levels through p38α activation may lead to the development of lipotoxic/diabetic cardiomyopathy.

    KW - Apoptosis

    KW - Cardiomyopathy

    KW - Diabetes

    KW - Lipotoxic

    KW - p38α MAPK

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