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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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The interaction of TR3 with TSC1/TSC2 affects mTORC1 activityCytoplasmic TR3 is upregulated after AngII stimulation in H9C2 cells (top), NRCMs (middle) and freshly isolated murine cardiomyocytes (bottom). The cells were treated with 500 nM AngII for 3 h. After the preparation of total (T), nuclear (N) and cytoplasmic (C) extracts, the expression of TR3 was determined by Western blotting. Histone 4 (H4) was used as a nuclear loading control, and tubulin was used as total and cytoplasmic loading controls.TR3 interacts with either TSC1 or TSC2 in the cytoplasmic fraction of mouse hearts (n = 3 per group). Heart cytoplasmic fractions were immunoprecipitated with a TSC1 (top) or TSC2 (bottom) antibody; the precipitates were then used to detect TR3 by Western blotting. IgG was used as a negative control.The interaction of TR3 with the TSCs is sufficient to influence the activity of mTORC1. HA-TR3 and its deletion mutants were introduced singly into 293T cells, and the phosphorylation of S6K1 was determined by Western blotting.The effects of TSC1 and TSC2 on TR3-induced mTORC1 activity. HA-TR3 was transfected into TSC1+/+ and TSC1−/− MEF cells (left) or TSC2+/+ and TSC2−/− MEF cells (right), and S6K1 phosphorylation was determined by Western blotting.
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fig04: The interaction of TR3 with TSC1/TSC2 affects mTORC1 activityCytoplasmic TR3 is upregulated after AngII stimulation in H9C2 cells (top), NRCMs (middle) and freshly isolated murine cardiomyocytes (bottom). The cells were treated with 500 nM AngII for 3 h. After the preparation of total (T), nuclear (N) and cytoplasmic (C) extracts, the expression of TR3 was determined by Western blotting. Histone 4 (H4) was used as a nuclear loading control, and tubulin was used as total and cytoplasmic loading controls.TR3 interacts with either TSC1 or TSC2 in the cytoplasmic fraction of mouse hearts (n = 3 per group). Heart cytoplasmic fractions were immunoprecipitated with a TSC1 (top) or TSC2 (bottom) antibody; the precipitates were then used to detect TR3 by Western blotting. IgG was used as a negative control.The interaction of TR3 with the TSCs is sufficient to influence the activity of mTORC1. HA-TR3 and its deletion mutants were introduced singly into 293T cells, and the phosphorylation of S6K1 was determined by Western blotting.The effects of TSC1 and TSC2 on TR3-induced mTORC1 activity. HA-TR3 was transfected into TSC1+/+ and TSC1−/− MEF cells (left) or TSC2+/+ and TSC2−/− MEF cells (right), and S6K1 phosphorylation was determined by Western blotting.

Mentions: Because the stimulation of mTOR signalling occurs mainly in the cytoplasm and because our study shows that the regulation of mTORC1 activity by AngII is not associated with transcriptional activation by TR3, we postulated that cytoplasmic rather than nuclear TR3 may mediate AngII-induced mTORC1 activity. We analysed the distribution of TR3 in the nuclei and cytoplasms of H9C2 cells, NRCMs isolated from WT rats and fresh cardiomyocytes isolated from adult WT mice. Although TR3 was present in the nuclei and the cytoplasms, the AngII-induced expression of TR3 occurred only in the cytoplasms of these three cell types (Fig 4A). Immunohistochemical analysis verified the presence of cytoplasmic TR3 in normal and hypertrophied human heart tissue (Supporting Information Fig S4A), and AngII clearly induced cytoplasmic TR3 expression in the hearts of the WT mice (Supporting Information Fig S1B). These results suggest a possible function for TR3 in the cytoplasm.


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)

The interaction of TR3 with TSC1/TSC2 affects mTORC1 activityCytoplasmic TR3 is upregulated after AngII stimulation in H9C2 cells (top), NRCMs (middle) and freshly isolated murine cardiomyocytes (bottom). The cells were treated with 500 nM AngII for 3 h. After the preparation of total (T), nuclear (N) and cytoplasmic (C) extracts, the expression of TR3 was determined by Western blotting. Histone 4 (H4) was used as a nuclear loading control, and tubulin was used as total and cytoplasmic loading controls.TR3 interacts with either TSC1 or TSC2 in the cytoplasmic fraction of mouse hearts (n = 3 per group). Heart cytoplasmic fractions were immunoprecipitated with a TSC1 (top) or TSC2 (bottom) antibody; the precipitates were then used to detect TR3 by Western blotting. IgG was used as a negative control.The interaction of TR3 with the TSCs is sufficient to influence the activity of mTORC1. HA-TR3 and its deletion mutants were introduced singly into 293T cells, and the phosphorylation of S6K1 was determined by Western blotting.The effects of TSC1 and TSC2 on TR3-induced mTORC1 activity. HA-TR3 was transfected into TSC1+/+ and TSC1−/− MEF cells (left) or TSC2+/+ and TSC2−/− MEF cells (right), and S6K1 phosphorylation was determined by Western blotting.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig04: The interaction of TR3 with TSC1/TSC2 affects mTORC1 activityCytoplasmic TR3 is upregulated after AngII stimulation in H9C2 cells (top), NRCMs (middle) and freshly isolated murine cardiomyocytes (bottom). The cells were treated with 500 nM AngII for 3 h. After the preparation of total (T), nuclear (N) and cytoplasmic (C) extracts, the expression of TR3 was determined by Western blotting. Histone 4 (H4) was used as a nuclear loading control, and tubulin was used as total and cytoplasmic loading controls.TR3 interacts with either TSC1 or TSC2 in the cytoplasmic fraction of mouse hearts (n = 3 per group). Heart cytoplasmic fractions were immunoprecipitated with a TSC1 (top) or TSC2 (bottom) antibody; the precipitates were then used to detect TR3 by Western blotting. IgG was used as a negative control.The interaction of TR3 with the TSCs is sufficient to influence the activity of mTORC1. HA-TR3 and its deletion mutants were introduced singly into 293T cells, and the phosphorylation of S6K1 was determined by Western blotting.The effects of TSC1 and TSC2 on TR3-induced mTORC1 activity. HA-TR3 was transfected into TSC1+/+ and TSC1−/− MEF cells (left) or TSC2+/+ and TSC2−/− MEF cells (right), and S6K1 phosphorylation was determined by Western blotting.
Mentions: Because the stimulation of mTOR signalling occurs mainly in the cytoplasm and because our study shows that the regulation of mTORC1 activity by AngII is not associated with transcriptional activation by TR3, we postulated that cytoplasmic rather than nuclear TR3 may mediate AngII-induced mTORC1 activity. We analysed the distribution of TR3 in the nuclei and cytoplasms of H9C2 cells, NRCMs isolated from WT rats and fresh cardiomyocytes isolated from adult WT mice. Although TR3 was present in the nuclei and the cytoplasms, the AngII-induced expression of TR3 occurred only in the cytoplasms of these three cell types (Fig 4A). Immunohistochemical analysis verified the presence of cytoplasmic TR3 in normal and hypertrophied human heart tissue (Supporting Information Fig S4A), and AngII clearly induced cytoplasmic TR3 expression in the hearts of the WT mice (Supporting Information Fig S1B). These results suggest a possible function for TR3 in the cytoplasm.

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