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

The effects of different ARBs on the cardiac function and Src expression in AGT KO mice.AGT KO mice were induced by AngII or TAC for 2 weeks with or without the pretreatment of valsartan or candesartan. (A) Representative M-mode tracings of AGT KO hearts stimulated by AngII (10−5 mol/L, top line) or by TAC for 2 weeks (bottom line). (B) Representative recording of LVAWd, LVPWd and LVEF in AGT KO mice from each group. (C) The expression of Src in myocardium of AGT KO mice from each group was determined. Data were presented as mean ± s.e.m. from five to eight mice. * P<0.05 vs. AngII-treated AGT KO mice; # P<0.05 vs. TAC-treated AGT KO mice.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0092926-g005: The effects of different ARBs on the cardiac function and Src expression in AGT KO mice.AGT KO mice were induced by AngII or TAC for 2 weeks with or without the pretreatment of valsartan or candesartan. (A) Representative M-mode tracings of AGT KO hearts stimulated by AngII (10−5 mol/L, top line) or by TAC for 2 weeks (bottom line). (B) Representative recording of LVAWd, LVPWd and LVEF in AGT KO mice from each group. (C) The expression of Src in myocardium of AGT KO mice from each group was determined. Data were presented as mean ± s.e.m. from five to eight mice. * P<0.05 vs. AngII-treated AGT KO mice; # P<0.05 vs. TAC-treated AGT KO mice.

Mentions: We further compared the effects of candesartan and valsartan on myocardial hypertrophic response induced by TAC and AngII stimulation in AGT KO mice. Results showed that both candesartan and valsartan exerted inhibitory impacts on AngII-induced cardiac hypertrophy, but only candesartan effectively reversed TAC-induced hypertrophic response (Fig. 5A–B). Furthermore, Src was weakly upregulated by AngII but robustly enhanced by TAC for 2 weeks, and AngII-induced upregulation of Src was inhibited by both candesartan and valsartan, while TAC-induced Src activation was inhibited only by candesartan (Fig. 5C).


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)

The effects of different ARBs on the cardiac function and Src expression in AGT KO mice.AGT KO mice were induced by AngII or TAC for 2 weeks with or without the pretreatment of valsartan or candesartan. (A) Representative M-mode tracings of AGT KO hearts stimulated by AngII (10−5 mol/L, top line) or by TAC for 2 weeks (bottom line). (B) Representative recording of LVAWd, LVPWd and LVEF in AGT KO mice from each group. (C) The expression of Src in myocardium of AGT KO mice from each group was determined. Data were presented as mean ± s.e.m. from five to eight mice. * P<0.05 vs. AngII-treated AGT KO mice; # P<0.05 vs. TAC-treated AGT KO mice.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0092926-g005: The effects of different ARBs on the cardiac function and Src expression in AGT KO mice.AGT KO mice were induced by AngII or TAC for 2 weeks with or without the pretreatment of valsartan or candesartan. (A) Representative M-mode tracings of AGT KO hearts stimulated by AngII (10−5 mol/L, top line) or by TAC for 2 weeks (bottom line). (B) Representative recording of LVAWd, LVPWd and LVEF in AGT KO mice from each group. (C) The expression of Src in myocardium of AGT KO mice from each group was determined. Data were presented as mean ± s.e.m. from five to eight mice. * P<0.05 vs. AngII-treated AGT KO mice; # P<0.05 vs. TAC-treated AGT KO mice.
Mentions: We further compared the effects of candesartan and valsartan on myocardial hypertrophic response induced by TAC and AngII stimulation in AGT KO mice. Results showed that both candesartan and valsartan exerted inhibitory impacts on AngII-induced cardiac hypertrophy, but only candesartan effectively reversed TAC-induced hypertrophic response (Fig. 5A–B). Furthermore, Src was weakly upregulated by AngII but robustly enhanced by TAC for 2 weeks, and AngII-induced upregulation of Src was inhibited by both candesartan and valsartan, while TAC-induced Src activation was inhibited only by candesartan (Fig. 5C).

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