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The orphan receptor TR3 participates in angiotensin II-induced cardiac hypertrophy by controlling mTOR signalling.

Wang RH, He JP, Su ML, Luo J, Xu M, Du XD, Chen HZ, Wang WJ, Wang Y, Zhang N, Zhao BX, Zhao WX, Shan ZG, Han J, Chang C, Wu Q - EMBO Mol Med (2012)

Bottom Line: TR3 was shown to form a trimer with the TSC1/TSC2 complex that specifically promoted TSC2 degradation via a proteasome/ubiquitination pathway.As a result, mTORC1, but not mTORC2, was activated; this was accompanied by increased protein synthesis, enhanced production of reactive oxygen species and enlarged cell size, thereby resulting in cardiac hypertrophy.The elimination or reduction of TR3 may reduce cardiac hypertrophy; therefore, TR3 is a potential target for clinical therapy.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian Province, China.

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Related in: MedlinePlus

TSC2, but not TSC1, is degraded by TR3 through a proteasome/ubiquitination pathwayTop, the expression of TSC2 is higher in TR3-KO mice than in WT mice. Hearts dissected from three individual mice were lysed, and TSC2 was detected by Western blotting. Bottom, TR3−/− MEFs expressed higher levels of TSC2 than WT (TR3+/+) MEFs.AngII promotes the degradation of endogenous TSC2 in MEFs and NRCMs. The cells were treated with 500 nM AngII for the indicated durations and then lysed for the measurement of TSC2 protein by Western blotting.TR3 downregulates TSC2 via the proteasomal pathway. Top, HA-TR3 and HA-TSC2 were cotransfected into 293T cells; before harvesting, the cells were treated with 40 µM ALLN or 10 µM MG132 for 3 h. DMSO was used as a control. TSC2 protein levels were assessed by Western blotting. Bottom, MG132 stabilizes TSC2 protein levels in the MEFs but not the TR3−/− MEFs. The cells were treated with 10 µM MG132 for the indicated durations and then harvested for Western blotting analysis.TR3 (left) or AngII (right) facilitates the recruitment of ubiquitin to TSC2. Myc-ubiquitin was introduced with TR3 into 293T (left) or H9C2 (right) cells. The cells were pretreated with 10 µM MG132 for 3 h and subsequently treated with 500 nM AngII for 3 h. TSC2 was immunoprecipitated, and a Myc antibody was used to detect ubiquitin-conjugated TSC2.AngII-treated mice exhibited higher TR3 and lower TSC2 expression than the sham-treated animals. Male mice (n = 3) were euthanized, and total protein was extracted for Western blotting.Patients with left ventricular hypertrophy exhibit higher TR3 and lower TSC2 expression. Protein lysates extracted from the left ventricular heart tissue of patients were immunoblotted with TR3 and TSC2 antibodies. Normal (N) and hypertrophic (H) hearts were determined as described in the Materials and Methods section.
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fig05: TSC2, but not TSC1, is degraded by TR3 through a proteasome/ubiquitination pathwayTop, the expression of TSC2 is higher in TR3-KO mice than in WT mice. Hearts dissected from three individual mice were lysed, and TSC2 was detected by Western blotting. Bottom, TR3−/− MEFs expressed higher levels of TSC2 than WT (TR3+/+) MEFs.AngII promotes the degradation of endogenous TSC2 in MEFs and NRCMs. The cells were treated with 500 nM AngII for the indicated durations and then lysed for the measurement of TSC2 protein by Western blotting.TR3 downregulates TSC2 via the proteasomal pathway. Top, HA-TR3 and HA-TSC2 were cotransfected into 293T cells; before harvesting, the cells were treated with 40 µM ALLN or 10 µM MG132 for 3 h. DMSO was used as a control. TSC2 protein levels were assessed by Western blotting. Bottom, MG132 stabilizes TSC2 protein levels in the MEFs but not the TR3−/− MEFs. The cells were treated with 10 µM MG132 for the indicated durations and then harvested for Western blotting analysis.TR3 (left) or AngII (right) facilitates the recruitment of ubiquitin to TSC2. Myc-ubiquitin was introduced with TR3 into 293T (left) or H9C2 (right) cells. The cells were pretreated with 10 µM MG132 for 3 h and subsequently treated with 500 nM AngII for 3 h. TSC2 was immunoprecipitated, and a Myc antibody was used to detect ubiquitin-conjugated TSC2.AngII-treated mice exhibited higher TR3 and lower TSC2 expression than the sham-treated animals. Male mice (n = 3) were euthanized, and total protein was extracted for Western blotting.Patients with left ventricular hypertrophy exhibit higher TR3 and lower TSC2 expression. Protein lysates extracted from the left ventricular heart tissue of patients were immunoblotted with TR3 and TSC2 antibodies. Normal (N) and hypertrophic (H) hearts were determined as described in the Materials and Methods section.

Mentions: Unexpectedly, we found that the endogenous and exogenous expression of TSC2 but not TSC1 decreased when TR3 was introduced into various cell types (Fig 4D and Supporting Information Fig S5A). TR3-KO mice consistently expressed TSC2 at much higher levels than WT mice (Fig 5A, top); this was also observed when comparing TR3−/− MEFs with TR3+/+ MEFs (Fig 5A, bottom). This decrease of TSC2 by AngII was attenuated in TR3−/− MEFs and TR3-KD NRCMs (Fig 5B). Similarly, CHX significantly decreased TSC2 expression in TR3+/+ MEFs but not in TR3−/− MEFs (Supporting Information Fig S5B), which indicates that TSC2 is more stable in TR3−/− MEFs than in TR3+/+ MEFs. These results strongly suggest a possible role for TR3 in the degradation of TSC2.


The orphan receptor TR3 participates in angiotensin II-induced cardiac hypertrophy by controlling mTOR signalling.

Wang RH, He JP, Su ML, Luo J, Xu M, Du XD, Chen HZ, Wang WJ, Wang Y, Zhang N, Zhao BX, Zhao WX, Shan ZG, Han J, Chang C, Wu Q - EMBO Mol Med (2012)

TSC2, but not TSC1, is degraded by TR3 through a proteasome/ubiquitination pathwayTop, the expression of TSC2 is higher in TR3-KO mice than in WT mice. Hearts dissected from three individual mice were lysed, and TSC2 was detected by Western blotting. Bottom, TR3−/− MEFs expressed higher levels of TSC2 than WT (TR3+/+) MEFs.AngII promotes the degradation of endogenous TSC2 in MEFs and NRCMs. The cells were treated with 500 nM AngII for the indicated durations and then lysed for the measurement of TSC2 protein by Western blotting.TR3 downregulates TSC2 via the proteasomal pathway. Top, HA-TR3 and HA-TSC2 were cotransfected into 293T cells; before harvesting, the cells were treated with 40 µM ALLN or 10 µM MG132 for 3 h. DMSO was used as a control. TSC2 protein levels were assessed by Western blotting. Bottom, MG132 stabilizes TSC2 protein levels in the MEFs but not the TR3−/− MEFs. The cells were treated with 10 µM MG132 for the indicated durations and then harvested for Western blotting analysis.TR3 (left) or AngII (right) facilitates the recruitment of ubiquitin to TSC2. Myc-ubiquitin was introduced with TR3 into 293T (left) or H9C2 (right) cells. The cells were pretreated with 10 µM MG132 for 3 h and subsequently treated with 500 nM AngII for 3 h. TSC2 was immunoprecipitated, and a Myc antibody was used to detect ubiquitin-conjugated TSC2.AngII-treated mice exhibited higher TR3 and lower TSC2 expression than the sham-treated animals. Male mice (n = 3) were euthanized, and total protein was extracted for Western blotting.Patients with left ventricular hypertrophy exhibit higher TR3 and lower TSC2 expression. Protein lysates extracted from the left ventricular heart tissue of patients were immunoblotted with TR3 and TSC2 antibodies. Normal (N) and hypertrophic (H) hearts were determined as described in the Materials and Methods section.
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Related In: Results  -  Collection

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fig05: TSC2, but not TSC1, is degraded by TR3 through a proteasome/ubiquitination pathwayTop, the expression of TSC2 is higher in TR3-KO mice than in WT mice. Hearts dissected from three individual mice were lysed, and TSC2 was detected by Western blotting. Bottom, TR3−/− MEFs expressed higher levels of TSC2 than WT (TR3+/+) MEFs.AngII promotes the degradation of endogenous TSC2 in MEFs and NRCMs. The cells were treated with 500 nM AngII for the indicated durations and then lysed for the measurement of TSC2 protein by Western blotting.TR3 downregulates TSC2 via the proteasomal pathway. Top, HA-TR3 and HA-TSC2 were cotransfected into 293T cells; before harvesting, the cells were treated with 40 µM ALLN or 10 µM MG132 for 3 h. DMSO was used as a control. TSC2 protein levels were assessed by Western blotting. Bottom, MG132 stabilizes TSC2 protein levels in the MEFs but not the TR3−/− MEFs. The cells were treated with 10 µM MG132 for the indicated durations and then harvested for Western blotting analysis.TR3 (left) or AngII (right) facilitates the recruitment of ubiquitin to TSC2. Myc-ubiquitin was introduced with TR3 into 293T (left) or H9C2 (right) cells. The cells were pretreated with 10 µM MG132 for 3 h and subsequently treated with 500 nM AngII for 3 h. TSC2 was immunoprecipitated, and a Myc antibody was used to detect ubiquitin-conjugated TSC2.AngII-treated mice exhibited higher TR3 and lower TSC2 expression than the sham-treated animals. Male mice (n = 3) were euthanized, and total protein was extracted for Western blotting.Patients with left ventricular hypertrophy exhibit higher TR3 and lower TSC2 expression. Protein lysates extracted from the left ventricular heart tissue of patients were immunoblotted with TR3 and TSC2 antibodies. Normal (N) and hypertrophic (H) hearts were determined as described in the Materials and Methods section.
Mentions: Unexpectedly, we found that the endogenous and exogenous expression of TSC2 but not TSC1 decreased when TR3 was introduced into various cell types (Fig 4D and Supporting Information Fig S5A). TR3-KO mice consistently expressed TSC2 at much higher levels than WT mice (Fig 5A, top); this was also observed when comparing TR3−/− MEFs with TR3+/+ MEFs (Fig 5A, bottom). This decrease of TSC2 by AngII was attenuated in TR3−/− MEFs and TR3-KD NRCMs (Fig 5B). Similarly, CHX significantly decreased TSC2 expression in TR3+/+ MEFs but not in TR3−/− MEFs (Supporting Information Fig S5B), which indicates that TSC2 is more stable in TR3−/− MEFs than in TR3+/+ MEFs. These results strongly suggest a possible role for TR3 in the degradation of TSC2.

Bottom Line: TR3 was shown to form a trimer with the TSC1/TSC2 complex that specifically promoted TSC2 degradation via a proteasome/ubiquitination pathway.As a result, mTORC1, but not mTORC2, was activated; this was accompanied by increased protein synthesis, enhanced production of reactive oxygen species and enlarged cell size, thereby resulting in cardiac hypertrophy.The elimination or reduction of TR3 may reduce cardiac hypertrophy; therefore, TR3 is a potential target for clinical therapy.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian Province, China.

Show MeSH
Related in: MedlinePlus