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The role of mAKAPβ in the process of cardiomyocyte hypertrophy induced by angiotensin II.

Guo H, Liu B, Hou L, The E, Li G, Wang D, Jie Q, Che W, Wei Y - Int. J. Mol. Med. (2015)

Bottom Line: The cell size of the AngII-treated cardiaomyocytes was significantly larger than that of the untreated cardiomyocytes.The expression of hypertrophic markers and p-ERK2, the cell surface area and the [3H]Leucine incorporation rate were all significantly increased in the AngII‑treated cells.However, the expression of mAKAPβ remained unaltered in this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China.

ABSTRACT
Angiotensin II (AngII) is the central product of the renin-angiotensin system (RAS) and this octapeptide contributes to the pathophysiology of cardiac hypertrophy and remodeling. mAKAPβ is an A-kinase anchoring protein (AKAP) that has the function of binding to the regulatory subunit of protein kinase A (PKA) and confining the holoenzyme to discrete locations within the cell. In this study, we aimed to investigate the role of mAKAPβ in AngII‑induced cardiomyocyte hypertrophy and the possible mechanisms involved. Cultured cardiomyocytes from neonatal rats were treated with AngII. Subsequently, the morphology of the cardiomyocytes was observed and the expression of mAKAPβ and cardiomyocyte hypertrophic markers was measured. mAKAPβ‑shRNA was constructed for RNA interference; the expression of mAKAPβ and hypertrophic markers, the cell surface area and the [3H]Leucine incorporation rate in the AngII‑treated rat cardiomyocytes were detected following RNA interference. Simultaneously, changes in the expression levels of phosphorylated extracellular signal-regulated kinase (p-ERK)2 in the cardiomyocytes were assessed. The cell size of the AngII-treated cardiaomyocytes was significantly larger than that of the untreated cardiomyocytes. The expression of hypertrophic markers and p-ERK2, the cell surface area and the [3H]Leucine incorporation rate were all significantly increased in the AngII‑treated cells. However, the expression of mAKAPβ remained unaltered in this process. RNA interference simultaneously inhibited the protein expression of mAKAPβ and p‑ERK2, and the hypertrophy of the cardiomyocytes induced by AngII was attenuated. These results demonstrate that AngII induces hypertrophy in cardiomyocytes, and mAKAPβ is possibly involved in this process. The effects of mAKAPβ on AngII‑induced cardiomyocyte hypertrophy may be associated with p-ERK2 expression.

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Expression of mAKAPβ in cardiomyocytes treated with angiotensin II (AngII) at different concentrations and for different periods of time. (A) Representative results of assays of mAKAPβ and GAPDH abundance in cardiomyocytes treated with AngII at different concentrations and different periods of time by western blot analysis. (B) The protein expression levels of mAKAPβ and GAPDH were analyzed by western blot analysis using polyclonal antibodies to mAKAPβ and GAPDH to quantify the expression in these groups. No statistically significant differences were observed in the expression of mAKAPβ between the controls and the cells treated with AngII at the designated concentration (all P>0.05). GAPDH was used as an equal loading control. The band value was quantified by densitometric analysis. Experiments were repeated at least 3 times. Data are expressed as the means ± SD in the corresponding bar graph and statistical significance was determined by the Student’s t-test. Ctrl, control; Phe, phenylephrine; ns, not significant. Columns, mean; error bars, ± SD.
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f4-ijmm-35-05-1159: Expression of mAKAPβ in cardiomyocytes treated with angiotensin II (AngII) at different concentrations and for different periods of time. (A) Representative results of assays of mAKAPβ and GAPDH abundance in cardiomyocytes treated with AngII at different concentrations and different periods of time by western blot analysis. (B) The protein expression levels of mAKAPβ and GAPDH were analyzed by western blot analysis using polyclonal antibodies to mAKAPβ and GAPDH to quantify the expression in these groups. No statistically significant differences were observed in the expression of mAKAPβ between the controls and the cells treated with AngII at the designated concentration (all P>0.05). GAPDH was used as an equal loading control. The band value was quantified by densitometric analysis. Experiments were repeated at least 3 times. Data are expressed as the means ± SD in the corresponding bar graph and statistical significance was determined by the Student’s t-test. Ctrl, control; Phe, phenylephrine; ns, not significant. Columns, mean; error bars, ± SD.

Mentions: The size of the cardiomyocytes treated with or without AngII is shown in Fig. 3. The results revealed that AngII promoted the process of cardiomyocyte hypertrophy. mAKAPβ was localized to the nuclear envelope of the myocytes; however, the expression of mAKAPβ in the AngII-treated groups was similar to that of the control group according to the results of western blot analysis (all P>0.05 vs. control; Fig. 4). These results demonstrated that mAKAPβ was involved in the process of AngII-induced cardiomyocyte hypertrophy; however, its expression remained unaltered.


The role of mAKAPβ in the process of cardiomyocyte hypertrophy induced by angiotensin II.

Guo H, Liu B, Hou L, The E, Li G, Wang D, Jie Q, Che W, Wei Y - Int. J. Mol. Med. (2015)

Expression of mAKAPβ in cardiomyocytes treated with angiotensin II (AngII) at different concentrations and for different periods of time. (A) Representative results of assays of mAKAPβ and GAPDH abundance in cardiomyocytes treated with AngII at different concentrations and different periods of time by western blot analysis. (B) The protein expression levels of mAKAPβ and GAPDH were analyzed by western blot analysis using polyclonal antibodies to mAKAPβ and GAPDH to quantify the expression in these groups. No statistically significant differences were observed in the expression of mAKAPβ between the controls and the cells treated with AngII at the designated concentration (all P>0.05). GAPDH was used as an equal loading control. The band value was quantified by densitometric analysis. Experiments were repeated at least 3 times. Data are expressed as the means ± SD in the corresponding bar graph and statistical significance was determined by the Student’s t-test. Ctrl, control; Phe, phenylephrine; ns, not significant. Columns, mean; error bars, ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380120&req=5

f4-ijmm-35-05-1159: Expression of mAKAPβ in cardiomyocytes treated with angiotensin II (AngII) at different concentrations and for different periods of time. (A) Representative results of assays of mAKAPβ and GAPDH abundance in cardiomyocytes treated with AngII at different concentrations and different periods of time by western blot analysis. (B) The protein expression levels of mAKAPβ and GAPDH were analyzed by western blot analysis using polyclonal antibodies to mAKAPβ and GAPDH to quantify the expression in these groups. No statistically significant differences were observed in the expression of mAKAPβ between the controls and the cells treated with AngII at the designated concentration (all P>0.05). GAPDH was used as an equal loading control. The band value was quantified by densitometric analysis. Experiments were repeated at least 3 times. Data are expressed as the means ± SD in the corresponding bar graph and statistical significance was determined by the Student’s t-test. Ctrl, control; Phe, phenylephrine; ns, not significant. Columns, mean; error bars, ± SD.
Mentions: The size of the cardiomyocytes treated with or without AngII is shown in Fig. 3. The results revealed that AngII promoted the process of cardiomyocyte hypertrophy. mAKAPβ was localized to the nuclear envelope of the myocytes; however, the expression of mAKAPβ in the AngII-treated groups was similar to that of the control group according to the results of western blot analysis (all P>0.05 vs. control; Fig. 4). These results demonstrated that mAKAPβ was involved in the process of AngII-induced cardiomyocyte hypertrophy; however, its expression remained unaltered.

Bottom Line: The cell size of the AngII-treated cardiaomyocytes was significantly larger than that of the untreated cardiomyocytes.The expression of hypertrophic markers and p-ERK2, the cell surface area and the [3H]Leucine incorporation rate were all significantly increased in the AngII‑treated cells.However, the expression of mAKAPβ remained unaltered in this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China.

ABSTRACT
Angiotensin II (AngII) is the central product of the renin-angiotensin system (RAS) and this octapeptide contributes to the pathophysiology of cardiac hypertrophy and remodeling. mAKAPβ is an A-kinase anchoring protein (AKAP) that has the function of binding to the regulatory subunit of protein kinase A (PKA) and confining the holoenzyme to discrete locations within the cell. In this study, we aimed to investigate the role of mAKAPβ in AngII‑induced cardiomyocyte hypertrophy and the possible mechanisms involved. Cultured cardiomyocytes from neonatal rats were treated with AngII. Subsequently, the morphology of the cardiomyocytes was observed and the expression of mAKAPβ and cardiomyocyte hypertrophic markers was measured. mAKAPβ‑shRNA was constructed for RNA interference; the expression of mAKAPβ and hypertrophic markers, the cell surface area and the [3H]Leucine incorporation rate in the AngII‑treated rat cardiomyocytes were detected following RNA interference. Simultaneously, changes in the expression levels of phosphorylated extracellular signal-regulated kinase (p-ERK)2 in the cardiomyocytes were assessed. The cell size of the AngII-treated cardiaomyocytes was significantly larger than that of the untreated cardiomyocytes. The expression of hypertrophic markers and p-ERK2, the cell surface area and the [3H]Leucine incorporation rate were all significantly increased in the AngII‑treated cells. However, the expression of mAKAPβ remained unaltered in this process. RNA interference simultaneously inhibited the protein expression of mAKAPβ and p‑ERK2, and the hypertrophy of the cardiomyocytes induced by AngII was attenuated. These results demonstrate that AngII induces hypertrophy in cardiomyocytes, and mAKAPβ is possibly involved in this process. The effects of mAKAPβ on AngII‑induced cardiomyocyte hypertrophy may be associated with p-ERK2 expression.

Show MeSH
Related in: MedlinePlus