Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth muscle cell survival patterns to promote pulmonary arterial hypertension.

Activation of the mammalian target of rapamycin complex 1 (mTORC1) subunit Raptor induces cell growth and is a downstream target of Akt. Elevated levels of aldosterone activate Akt, and, in pulmonary arterial hypertension (PAH), correlate with pulmonary arteriole thickening, which suggests that mTORC1 regulation by aldosterone may mediate adverse pulmonary vascular remodeling. We hypothesized that aldosterone-Raptor signaling induces abnormal pulmonary artery smooth muscle cell (PASMC) survival patterns to promote PAH. Remodeled pulmonary arterioles from SU-5416/hypoxia-PAH rats and monocrotaline-PAH rats with hyperaldosteronism expressed increased levels of the Raptor target, p70S6K, which provided a basis for investigating aldosterone-Raptor signaling in human PASMCs. Aldosterone (10(-9) to 10(-7) M) increased Akt/mTOR/Raptor to activate p70S6K and increase proliferation, viability, and apoptosis resistance in PASMCs. In PASMCs transfected with Raptor-small interfering RNA or treated with spironolactone/eplerenone, aldosterone or pulmonary arterial plasma from patients with PAH failed to increase p70S6K activation or to induce cell survival in vitro Optimal inhibition of pulmonary arteriole Raptor was achieved by treatment with Staramine-monomethoxy polyethylene glycol that was formulated with Raptor-small interfering RNA plus spironolactone in vivo, which decreased arteriole muscularization and pulmonary hypertension in 2 experimental animal models of PAH in vivo Up-regulation of mTORC1 by aldosterone is a critical pathobiologic mechanism that controls PASMC survival to promote hypertrophic vascular remodeling and PAH.-Aghamohammadzadeh, R., Zhang, Y.-Y., Stephens, T. E., Arons, E., Zaman, P., Polach, K. J., Matar, M., Yung, L.-M., Yu, P. B., Bowman, F. P., Opotowsky, A. R., Waxman, A. B., Loscalzo, J., Leopold, J. A., Maron, B. A. Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth muscle cell survival patterns to promote pulmonary arterial hypertension.

Aghamohammadzadeh R ，Zhang YY ，Stephens TE ，Arons E ，Zaman P ，Polach KJ ，Matar M ，Yung LM ，Yu PB ，Bowman FP ，Opotowsky AR ，Waxman AB ，Loscalzo J ，Leopold JA ，Maron BA ... -  《-》

Mammalian target of rapamycin complex 2 (mTORC2) coordinates pulmonary artery smooth muscle cell metabolism, proliferation, and survival in pulmonary arterial hypertension.

Goncharov DA ，Kudryashova TV ，Ziai H ，Ihida-Stansbury K ，DeLisser H ，Krymskaya VP ，Tuder RM ，Kawut SM ，Goncharova EA ... -  《-》

Rapamycin attenuates BAFF-extended proliferation and survival via disruption of mTORC1/2 signaling in normal and neoplastic B-lymphoid cells.

B cell activating factor from the TNF family (BAFF) stimulates B-cell proliferation and survival, but excessive BAFF promotes the development of aggressive B cells leading to malignant and autoimmune diseases. Recently, we have reported that rapamycin, a macrocyclic lactone, attenuates human soluble BAFF (hsBAFF)-stimulated B-cell proliferation/survival by suppressing mTOR-mediated PP2A-Erk1/2 signaling pathway. Here, we show that the inhibitory effect of rapamycin on hsBAFF-promoted B cell proliferation/survival is also related to blocking hsBAFF-stimulated phosphorylation of Akt, S6K1, and 4E-BP1, as well as expression of survivin in normal and B-lymphoid (Raji and Daudi) cells. It appeared that both mTORC1 and mTORC2 were involved in the inhibitory activity of rapamycin, as silencing raptor or rictor enhanced rapamycin's suppression of hsBAFF-induced survivin expression and proliferation/viability in B cells. Also, PP242, an mTORC1/2 kinase inhibitor, repressed survivin expression, and cell proliferation/viability more potently than rapamycin (mTORC1 inhibitor) in B cells in response to hsBAFF. Of interest, ectopic expression of constitutively active Akt (myr-Akt) or constitutively active S6K1 (S6K1-ca), or downregulation of 4E-BP1 conferred resistance to rapamycin's attenuation of hsBAFF-induced survivin expression and B-cell proliferation/viability, whereas overexpression of dominant negative Akt (dn-Akt) or constitutively hypophosphorylated 4E-BP1 (4EBP1-5A), or downregulation of S6K1, or co-treatment with Akt inhibitor potentiated the inhibitory effects of rapamycin. The findings indicate that rapamycin attenuates excessive hsBAFF-induced cell proliferation/survival via blocking mTORC1/2 signaling in normal and neoplastic B-lymphoid cells. Our data underscore that rapamycin may be a potential agent for preventing excessive BAFF-evoked aggressive B-cell malignancies and autoimmune diseases.

Zeng Q ，Qin S ，Zhang H ，Liu B ，Qin J ，Wang X ，Zhang R ，Liu C ，Dong X ，Zhang S ，Huang S ，Chen L ... -  《-》

Intestinal cell kinase (ICK) promotes activation of mTOR complex 1 (mTORC1) through phosphorylation of Raptor Thr-908.

Wu D ，Chapman JR ，Wang L ，Harris TE ，Shabanowitz J ，Hunt DF ，Fu Z ... -  《-》

Involvement of the bone morphogenetic protein system in endothelin- and aldosterone-induced cell proliferation of pulmonary arterial smooth muscle cells isolated from human patients with pulmonary arterial hypertension.

Yamanaka R ，Otsuka F ，Nakamura K ，Yamashita M ，Otani H ，Takeda M ，Matsumoto Y ，Kusano KF ，Ito H ，Makino H ... -  《-》