Limits...
Src is required for mechanical stretch-induced cardiomyocyte hypertrophy through angiotensin II type 1 receptor-dependent β-arrestin2 pathways.

Wang S, Gong H, Jiang G, Ye Y, Wu J, You J, Zhang G, Sun A, Komuro I, Ge J, Zou Y - PLoS ONE (2014)

Bottom Line: These results collectively suggest that MS-induced ERK1/2 activation through AT1-R might be independent of G-protein coupling.Furthermore, MS-, but not AngII-induced ERK1/2 phosphorylation is attenuated by Src inhibition, which also significantly improves pressure overload-induced cardiac hypertrophy and dysfunction in mice lacking AngII.Our results suggest that Src plays a critical role in MS-induced cardiomyocyte hypertrophy through β-arrestin2-associated angiotensin II type 1 receptor signaling.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China; Institutes of Biomedical Science, Fudan University, Shanghai, China.

ABSTRACT
Angiotensin II (AngII) type 1 receptor (AT1-R) can be activated by mechanical stress (MS) without the involvement of AngII during the development of cardiomyocyte hypertrophy, in which G protein-independent pathways are critically involved. Although β-arrestin2-biased signaling has been speculated, little is known about how AT1-R/β-arrestin2 leads to ERK1/2 activation. Here, we present a novel mechanism by which Src kinase mediates AT1-R/β-arrestin2-dependent ERK1/2 phosphorylation in response to MS. Differing from stimulation by AngII, MS-triggered ERK1/2 phosphorylation is neither suppressed by overexpression of RGS4 (the negative regulator of the G-protein coupling signal) nor by inhibition of Gαq downstream protein kinase C (PKC) with GF109203X. The release of inositol 1,4,5-triphosphate (IP3) is increased by AngII but not by MS. These results collectively suggest that MS-induced ERK1/2 activation through AT1-R might be independent of G-protein coupling. Moreover, either knockdown of β-arrestin2 or overexpression of a dominant negative mutant of β-arrestin2 prevents MS-induced activation of ERK1/2. We further identifies a relationship between Src, a non-receptor tyrosine kinase and β-arrestin2 using analyses of co-immunoprecipitation and immunofluorescence after MS stimulation. Furthermore, MS-, but not AngII-induced ERK1/2 phosphorylation is attenuated by Src inhibition, which also significantly improves pressure overload-induced cardiac hypertrophy and dysfunction in mice lacking AngII. Finally, MS-induced Src activation and hypertrophic response are abolished by candesartan but not by valsartan whereas AngII-induced responses can be abrogated by both blockers. Our results suggest that Src plays a critical role in MS-induced cardiomyocyte hypertrophy through β-arrestin2-associated angiotensin II type 1 receptor signaling.

Show MeSH

Related in: MedlinePlus

In vivo analyses of the cardiac function by echocardiography and hemodynamic measurements.Both AGT KO mice and the C57BL/6 WT littermates were pretreated with or without Src kinase inhibitor (SU6656), followed by TAC for 2 weeks. (A) Quantifications of LVAWd, LVPWd, LVEF and LVESP by representative M-mode tracing and hemodynamic recording from five mice. (B) Quantifications of cardiac immediate-early response genes in C57BL/6 mice and AGT KO mice with or without pretreatment of SU6656 (n = 5 separated experiments). * P<0.05 vs. saline-treated TAC-operated AGT KO mice.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3974699&req=5

pone-0092926-g004: In vivo analyses of the cardiac function by echocardiography and hemodynamic measurements.Both AGT KO mice and the C57BL/6 WT littermates were pretreated with or without Src kinase inhibitor (SU6656), followed by TAC for 2 weeks. (A) Quantifications of LVAWd, LVPWd, LVEF and LVESP by representative M-mode tracing and hemodynamic recording from five mice. (B) Quantifications of cardiac immediate-early response genes in C57BL/6 mice and AGT KO mice with or without pretreatment of SU6656 (n = 5 separated experiments). * P<0.05 vs. saline-treated TAC-operated AGT KO mice.

Mentions: We then investigated the in vivo consequence of the inhibition of β-arrestin2/Src signaling on pressure overload-induced myocardial hypertrophy in AGT KO mice. At 2 weeks after TAC, echocardiography assessment showed a significant increase of left ventricular anterior wall at end-diastolic (LVAWd) and posterior wall at end-diastolic (LVPWd) thickerness in both C57BL/6 mice and AGT KO mice, accompanied by higher left ventricular ejection fraction (LVEF) and left ventricular end-systolic pressure (LVESP). However, Efficacy of attenuating myocardial hypertrophy by pretreatment with SU6656 was more pronounced in AGT KO mice than in C57BL/6 mice (Fig. 4A). Cardiac reprogramming of specific genes expressions were activated during pressure overload, we therefore determined the immediate-early response genes and fetal genes in the heart after TAC. Pressure overload enhanced the transcriptional levels of ANP, BNP and α-skeleton in AGT KO mice and C57BL/6 littermates, but expression of these re-enhanced genes was significantly lower in AGT KO mice than in C57BL/6 mice after SU6656 treatment, except for sarcoplasmic reticulum Ca2+-ATPase (SERCA) (Fig. 4B).


Src is required for mechanical stretch-induced cardiomyocyte hypertrophy through angiotensin II type 1 receptor-dependent β-arrestin2 pathways.

Wang S, Gong H, Jiang G, Ye Y, Wu J, You J, Zhang G, Sun A, Komuro I, Ge J, Zou Y - PLoS ONE (2014)

In vivo analyses of the cardiac function by echocardiography and hemodynamic measurements.Both AGT KO mice and the C57BL/6 WT littermates were pretreated with or without Src kinase inhibitor (SU6656), followed by TAC for 2 weeks. (A) Quantifications of LVAWd, LVPWd, LVEF and LVESP by representative M-mode tracing and hemodynamic recording from five mice. (B) Quantifications of cardiac immediate-early response genes in C57BL/6 mice and AGT KO mice with or without pretreatment of SU6656 (n = 5 separated experiments). * P<0.05 vs. saline-treated TAC-operated AGT KO mice.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3974699&req=5

pone-0092926-g004: In vivo analyses of the cardiac function by echocardiography and hemodynamic measurements.Both AGT KO mice and the C57BL/6 WT littermates were pretreated with or without Src kinase inhibitor (SU6656), followed by TAC for 2 weeks. (A) Quantifications of LVAWd, LVPWd, LVEF and LVESP by representative M-mode tracing and hemodynamic recording from five mice. (B) Quantifications of cardiac immediate-early response genes in C57BL/6 mice and AGT KO mice with or without pretreatment of SU6656 (n = 5 separated experiments). * P<0.05 vs. saline-treated TAC-operated AGT KO mice.
Mentions: We then investigated the in vivo consequence of the inhibition of β-arrestin2/Src signaling on pressure overload-induced myocardial hypertrophy in AGT KO mice. At 2 weeks after TAC, echocardiography assessment showed a significant increase of left ventricular anterior wall at end-diastolic (LVAWd) and posterior wall at end-diastolic (LVPWd) thickerness in both C57BL/6 mice and AGT KO mice, accompanied by higher left ventricular ejection fraction (LVEF) and left ventricular end-systolic pressure (LVESP). However, Efficacy of attenuating myocardial hypertrophy by pretreatment with SU6656 was more pronounced in AGT KO mice than in C57BL/6 mice (Fig. 4A). Cardiac reprogramming of specific genes expressions were activated during pressure overload, we therefore determined the immediate-early response genes and fetal genes in the heart after TAC. Pressure overload enhanced the transcriptional levels of ANP, BNP and α-skeleton in AGT KO mice and C57BL/6 littermates, but expression of these re-enhanced genes was significantly lower in AGT KO mice than in C57BL/6 mice after SU6656 treatment, except for sarcoplasmic reticulum Ca2+-ATPase (SERCA) (Fig. 4B).

Bottom Line: These results collectively suggest that MS-induced ERK1/2 activation through AT1-R might be independent of G-protein coupling.Furthermore, MS-, but not AngII-induced ERK1/2 phosphorylation is attenuated by Src inhibition, which also significantly improves pressure overload-induced cardiac hypertrophy and dysfunction in mice lacking AngII.Our results suggest that Src plays a critical role in MS-induced cardiomyocyte hypertrophy through β-arrestin2-associated angiotensin II type 1 receptor signaling.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China; Institutes of Biomedical Science, Fudan University, Shanghai, China.

ABSTRACT
Angiotensin II (AngII) type 1 receptor (AT1-R) can be activated by mechanical stress (MS) without the involvement of AngII during the development of cardiomyocyte hypertrophy, in which G protein-independent pathways are critically involved. Although β-arrestin2-biased signaling has been speculated, little is known about how AT1-R/β-arrestin2 leads to ERK1/2 activation. Here, we present a novel mechanism by which Src kinase mediates AT1-R/β-arrestin2-dependent ERK1/2 phosphorylation in response to MS. Differing from stimulation by AngII, MS-triggered ERK1/2 phosphorylation is neither suppressed by overexpression of RGS4 (the negative regulator of the G-protein coupling signal) nor by inhibition of Gαq downstream protein kinase C (PKC) with GF109203X. The release of inositol 1,4,5-triphosphate (IP3) is increased by AngII but not by MS. These results collectively suggest that MS-induced ERK1/2 activation through AT1-R might be independent of G-protein coupling. Moreover, either knockdown of β-arrestin2 or overexpression of a dominant negative mutant of β-arrestin2 prevents MS-induced activation of ERK1/2. We further identifies a relationship between Src, a non-receptor tyrosine kinase and β-arrestin2 using analyses of co-immunoprecipitation and immunofluorescence after MS stimulation. Furthermore, MS-, but not AngII-induced ERK1/2 phosphorylation is attenuated by Src inhibition, which also significantly improves pressure overload-induced cardiac hypertrophy and dysfunction in mice lacking AngII. Finally, MS-induced Src activation and hypertrophic response are abolished by candesartan but not by valsartan whereas AngII-induced responses can be abrogated by both blockers. Our results suggest that Src plays a critical role in MS-induced cardiomyocyte hypertrophy through β-arrestin2-associated angiotensin II type 1 receptor signaling.

Show MeSH
Related in: MedlinePlus