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Exp Cell Res ; 389(1): 111890, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32035132


Fibrosis is a key pathological event during muscle aging that accelerates the development of sarcopenia. We show that sarcolipin (SLN) is highly expressed during aging, promotes intracellular calcium overload and participates in impaired myogenic differentiation. d-Galactose (D-gal) was used to induce senescence in C2C12 myoblasts. Conventional AAV-mediated SLN knockdown cells were used to study the role of SLN in muscle physiology and pathophysiology. C2C12 cells were treated with D-gal, which promoted fibrosis and SLN upregulation. The expression of TGF-ß1 and α-SMA, which participate in myogenic transdifferentiation, were also elevated. C2C12 cells with reduced sarcolipin expression produced decreased amounts of collagen. Our study identified an unrecognized role of SLN in regulating myogenic transdifferentiation during aging-associated skeletal muscle cell fibrosis. Targeting SLN may be a novel therapeutic strategy to relieve sarcopenia-associated muscle fibrosis.

Circulation ; 141(8): 655-666, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31893939


BACKGROUND: Blood pressure often rises with aging, but exact mechanisms are still not completely understood. With aging, the level of proinflammatory cytokines increases in T lymphocytes. Prostaglandin D2, a proresolution mediator, suppresses Type 1 T helper (Th1) cytokines through D-prostanoid receptor 1 (DP1). In this study, we aimed to investigate the role of the prostaglandin D2/DP1 axis in T cells on age-related hypertension. METHODS: To clarify the physiological and pathophysiological roles of DP1 in T cells with aging, peripheral blood samples were collected from young and older male participants, and CD4+ T cells were sorted for gene expression, prostaglandin production, and Western blot assays. Mice blood pressure was quantified by invasive telemetric monitor. RESULTS: The prostaglandin D2/DP1 axis was downregulated in CD4+ T cells from older humans and aged mice. DP1 deletion in CD4+ T cells augmented age-related hypertension in aged male mice by enhancing Th1 cytokine secretion, vascular remodeling, CD4+ T cells infiltration, and superoxide production in vasculature and kidneys. Conversely, forced expression of exogenous DP1 in T cells retarded age-associated hypertension in mice by reducing Th1 cytokine secretion. Tumor necrosis factor α neutralization or interferon γ deletion ameliorated the age-related hypertension in DP1 deletion in CD4+ T cells mice. Mechanistically, DP1 inhibited Th1 activity via the PKA (protein kinase A)/p-Sp1 (phosphorylated specificity protein 1)/neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) pathway-mediated T-box-expressed-in-T-cells (T-bet) ubiquitination. T-bet deletion or forced NEDD4L expression in CD4+ T cells attenuated age-related hypertension in CD4+ T cell-specific DP1-deficient mice. DP1 receptor activation by BW245C prevented age-associated blood pressure elevation and reduced vascular/renal superoxide production in male mice. CONCLUSIONS: The prostaglandin D2/DP1 axis suppresses age-related Th1 activation and subsequent hypertensive response in male mice through increase of NEDD4L-mediated T-bet degradation by ubiquitination. Therefore, the T cell DP1 receptor may be an attractive therapeutic target for age-related hypertension.

Artigo em Inglês | MEDLINE | ID: mdl-31917615


RATIONALE: Vascular remodeling, including smooth muscle cell hypertrophy and proliferation, is the key pathological feature of pulmonary arterial hypertension (PAH). Prostaglandin (PG) I2 analogs (baraprost, iloprost, and treprostinil) are effective in the treatment of PAH. Of note, the clinically favorable effects of treprostinil in severe PAH may be attributable to concomitant activation of PGD2 receptor subtype 1 (DP1). OBJECTIVES: To study the role of DP1 in the progression of PAH and its underlying mechanism. METHODS AND RESULTS: DP1 expression was downregulated in hypoxia-treated PASMCs and in pulmonary arteries (PAs) from rodent PAH models and idiopathic PAH patients. DP1 deletion exacerbated PA remodeling in hypoxia-induced PAH, whereas pharmacological activation or forced expression of DP1 receptor had the opposite effect in different rodent models. DP1 deficiency promoted PASMC hypertrophy and proliferation in response to hypoxia via induction of mammalian target of rapamycin complex (mTORC) 1 activity. Rapamycin, an inhibitor of mTORC1, alleviated the hypoxia-induced exacerbation of PAH in DP1-/- mice. DP1 activation facilitated raptor dissociation from mTORC1 complex and suppressed mTORC1 activity through protein kinase A (PKA)-dependent phosphorylation of raptor at Ser791. Moreover, treprostinil treatment blocked the progression of hypoxia-induced PAH in mice in part by targeting DP1 receptor. CONCLUSION: DP1 activation attenuates hypoxia-induced PA remodeling and PAH through PKA-mediated dissociation of raptor from the mTORC1 complex. These results suggest that DP1 receptor may serve as a therapeutic target for the management of PAH.

Exp Gerontol ; 122: 25-33, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31003004


Sarcopenia is an age-related syndrome characterized by a gradual loss of muscle mass and function, but its pathophysiological mechanism remains unclear. Skeletal muscle extracellular matrix (ECM) remodeling is an important pathological change in sarcopenia, and fibrosis is the most obvious manifestation of this change. We found that the expression of the immunoreceptor Toll-like receptor 9 (TLR9) is significantly increased in skeletal muscle in aged mice and is positively related to muscle fibrosis. Moreover, in previous reports, the longevity gene Sirt1 was reported to attenuate ECM deposition and improve muscle function. In this study, we hypothesized that TLR9 modulated skeletal muscle fibrosis via Sirt1. We used TLR9 knockout (TLR9 KO) mice and C57 mice, and grip strength and body composition were compared at different ages. We found that TLR9 knockout significantly attenuated skeletal muscle fibrosis and improved muscle function in aged mice. Furthermore, silent information regulator 1 (Sirt1) activity in mice was inhibited by Ex527, which is a specific inhibitor of Sirt1. Negative Sirt1 regulation via the activation of TLR9-related signaling pathways participated in skeletal muscle fibrosis in the sarcopenic mice, and this process might mediated by the Sirt1/Smad signaling pathway. Our findings revealed that fibrosis changes in the gastrocnemius muscle in sarcopenic mice are closely related to TLR9 activation, and TLR9 modulation could be a therapeutic strategy for combating sarcopenia during aging.

Arterioscler Thromb Vasc Biol ; 39(4): e130-e145, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30676070


Objective- Macrophages participate in the pathogenesis of pulmonary arterial hypertension (PAH). Lgmn (Legumain), a newly discovered cysteine proteinase belonging to the C13 peptidase family, is primarily expressed in macrophages; however, its roles in PAH remain unknown. Approach and Results- Herein, Lgmn was upregulated in lung tissues of PAH mice subjected to hypoxia plus SU5416 and PAH rats challenged with monocrotaline. Global Lgmn ablation and macrophage-specific ablation alleviated PAH compared with wild-type mice, evident from a reduction in right ventricular systolic pressure, the ratio of the right ventricular wall to the left ventricular wall plus the septum, the pulmonary vascular media thickness, and pulmonary vascular muscularization. Increased expression of ECM (extracellular matrix) proteins was correlated with MMP (matrix metalloproteinase)-2 activation and TGF (transforming growth factor)-ß1 signaling in the PAs. Although Lgmn did not affect inflammatory cell infiltration and PA smooth muscle cell proliferation, it drove increased the synthesis of ECM proteins via MMP-2 activation. MMP-2 hydrolyzed the TGF-ß1 precursor to the active form. An Lgmn-specific inhibitor markedly ameliorated PAH. Clinically, serum Lgmn levels were closely associated with the severity of idiopathic PAH. Conclusions- Our results indicate that Lgmn inhibition could be an effective strategy for preventing or delaying PAH.

Cisteína Endopeptidases/fisiologia , Hipertensão Pulmonar/enzimologia , Macrófagos/enzimologia , Metaloproteinase 2 da Matriz/fisiologia , Fator de Crescimento Transformador beta1/fisiologia , Animais , Inibidores de Caspase/farmacologia , Cisteína Endopeptidases/deficiência , Proteínas da Matriz Extracelular/metabolismo , Feminino , Seguimentos , Humanos , Hipertensão Pulmonar/sangue , Hipertensão Pulmonar/patologia , Hipertensão Pulmonar/prevenção & controle , Hipóxia/enzimologia , Indóis/toxicidade , Inflamação , Pulmão/metabolismo , Masculino , Camundongos , Pessoa de Meia-Idade , Monocrotalina/toxicidade , Pirróis/toxicidade , Ratos , Índice de Gravidade de Doença , Transdução de Sinais , Remodelação Vascular/fisiologia