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1.
Acta Pharmacol Sin ; 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31165783

RESUMO

Obesity induces accumulation of adipose tissue macrophages (ATMs) and ATM-driven inflammatory responses that promote the development of glucose and lipid metabolism disorders. ClC-3 chloride channel/antiporter, encoded by the Clcn3, is critical for some basic cellular functions. Our previous work has shown significant alleviation of type 2 diabetes in Clcn3 knockout (Clcn3-/-) mice. In the present study we investigated the role of Clcn3 in high-fat diet (HFD)-induced obesity and ATM inflammation. To establish the mouse obesity model, both Clcn3-/- mice and wild-type mice were fed a HFD for 4 or 16 weeks. The metabolic parameters were assessed and the abdominal total adipose tissue was scanned using computed tomography. Their epididymal fat pad tissue and adipose tissue stromal vascular fraction (SVF) cells were isolated for analyses. We found that the HFD-fed Clcn3-/- mice displayed a significant decrease in obesity-induced body weight gain and abdominal visceral fat accumulation as well as an improvement of glucose and lipid metabolism as compared with HFD-fed wild-type mice. Furthermore, the Clcn3 deficiency significantly attenuated HFD-induced ATM accumulation, HFD-increased F4/80+ CD11c+ CD206- SVF cells as well as HFD-activated TLR-4/NF-κB signaling in epididymal fat tissue. In cultured human THP-1 macrophages, adenovirus-mediated transfer of Clcn3 specific shRNA inhibited, whereas adenovirus-mediated cDNA overexpression of Clcn3 enhanced lipopolysaccharide-induced activation of NF-κB and TLR-4. These results demonstrate a novel role for Clcn3 in HFD-induced obesity and ATM inflammation.

2.
Biochem Biophys Res Commun ; 490(2): 91-97, 2017 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-28526415

RESUMO

LNK (SH2B3) is an intracellular adaptor protein that negatively regulates cellular proliferation or self-renewal of hematopoietic stem cells and some other progenitor cells. LNK is also recognized as a key regulator of insulin resistance and inflammatory responses in several tissues and organs. The function of LNK in adipose tissue is unknown. We previously demonstrated that type 2 diabetes mellitus (T2DM) mouse model had elevated serum free fatty acids (FFAs) levels and increased preadipocyte apoptosis in visceral fat tissue, showing the occurrence of lipotoxicity. Herein, when compared to control mice, the protein expression of LNK decreased in epididymal fat tissue from the high-sucrose/fat diet, low-dose streptozotocin induced T2DM mouse model. We thus investigated whether LNK could regulate palmitate-induced preadipocyte apoptosis in an in vitro apoptotic model in 3T3-L1 preadipocytes. LNK specific siRNA exacerbated palmitate-induced apoptosis and increased pro-apoptotic protein levels of cleaved caspase-3, Bax and cytochrome C; while overexpression of LNK cDNA exhibited significant anti-apoptotic effects. Consistently, LNK specific siRNA further decreased the Akt Ser-473 phosphorylation reduced by palmitate and located on upstream of Bax and cytochrome C. The siRNA-mediated LNK knockdown exacerbated mitochondrial membrane depolarization and mitochondrial-derived reactive oxygen species production induced by palmitate, whereas overexpression of LNK attenuated that. These results indicated that LNK plays a regulatory role in the palmitate-related preadipocyte apoptosis and might be involved in adipose tissue dysfunction.


Assuntos
Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Palmitatos/farmacologia , Adipócitos/metabolismo , Animais , Diabetes Mellitus Tipo 2/induzido quimicamente , Dieta Hiperlipídica , Sacarose na Dieta , Modelos Animais de Doenças , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estreptozocina
3.
Life Sci ; 168: 28-37, 2017 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26764232

RESUMO

AIMS: Palmitate, a common saturated free fatty acid, induces endothelial apoptosis in vitro in culture endothelial cells and in vivo in type 2 diabetes mellitus (T2DM) patients. The present study aimed to investigate whether Kv1.5 regulates palmitate-induced endothelial apoptosis and endothelial dysfunction in T2DM. MAIN METHODS: In vitro experiments were carried out in primary human HUVECs. Apoptosis was analyzed by flow cytometry. Cell viability was determined by Cell Counting Assay Kit-8. The siRNA transfection was employed to knockdown Kv1.5 protein expression. Intracellular and mitochondrial ROS, and mitochondrial membrane potential were detected using fluorescent probes. Male C57BL/6 mice fed with high-sucrose/fat diet were injected with streptozotocin (35mg/kg body weight) to establish T2DM animal model. KEY FINDINGS: We found that palmitate-induced endothelial apoptosis was parallel to a significant increase in endogenous Kv1.5 protein expression in endothelial cells. Silencing of Kv1.5 with siRNA reduced palmitate-induced endothelial apoptosis, intracellular ROS generation, mitochondrial ROS generation and membrane potential (Δψm) alteration and cleaved caspase-3 protein expression; while increased cell viability and ratio of Bcl-2/Bax. Furthermore, we observed that Kv1.5 protein expression increased in endothelial cells of thoracic aorta of T2DM mice. Silencing of Kv1.5 significantly improved the endothelium-dependent vasodilation in thoracic aortic rings of T2DM mice. SIGNIFICANCE: These results demonstrate that suppression of Kv1.5 protects endothelial cells against palmitate-induced apoptosis via inhibiting mitochondria-mediated excessive ROS generation and apoptotic signaling pathway, suggesting that Kv1.5 may serve as a therapeutic target of treatment for endothelial dysfunction induced by palmitate and lipid metabolism in T2DM patients.


Assuntos
Apoptose , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Canal de Potássio Kv1.5/metabolismo , Palmitatos/metabolismo , Animais , Aorta/metabolismo , Aorta/fisiopatologia , Sobrevivência Celular , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/fisiopatologia , Células Endoteliais/citologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Canal de Potássio Kv1.5/genética , Masculino , Potencial da Membrana Mitocondrial , Camundongos Endogâmicos C57BL , Interferência de RNA , RNA Interferente Pequeno/genética , Espécies Reativas de Oxigênio/metabolismo , Vasodilatação
4.
Apoptosis ; 19(11): 1559-70, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25218423

RESUMO

Palmitate, a common saturated free fatty acid (FFA), has been demonstrated to induce preadipocyte apoptosis in the absence of adipogenic stimuli, suggesting that preadipocytes may be prone to apoptosis under adipogenic insufficient conditions, like type 2 diabetes mellitus (T2DM). ClC-3, encoding Cl(-) channel or Cl(-)/H(+) antiporter, is critical for cell fate choices of proliferation versus apoptosis under diseased conditions. However, it is unknown whether ClC-3 is related with preadipocyte apoptosis induced by palmitate or T2DM. Palmitate, but not oleate, induced apoptosis and increase in ClC-3 protein expression and endoplasmic reticulum (ER) stress in 3T3-L1 preadipocyte. ClC-3 specific siRNA attenuated palmitate-induced apoptosis and increased protein levels of Grp78, ATF4, CHOP and phosphorylation of JNK1/2, whereas had no effects on increased phospho-PERK and phospho-eIF2α protein expression. Moreover, the enhanced apoptosis was shown in preadipocytes from high-sucrose/fat, low-dose STZ induced T2DM mouse model with hyperglycemia, hyperlipidemia (elevated serum TG and FFA levels) and insulin resistance. ClC-3 knockout significantly attenuated preadipocyte apoptosis and the above metabolic disorders in T2DM mice. These data demonstrated that ClC-3 deficiency prevent preadipocytes against palmitate-induced apoptosis via suppressing ER stress, and also suggested that ClC-3 may play a role in regulating cellular apoptosis and disorders of glucose and lipid metabolism during T2DM.


Assuntos
Adipócitos/metabolismo , Apoptose , Canais de Cloreto/metabolismo , Diabetes Mellitus Experimental/metabolismo , Palmitatos/farmacologia , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipócitos/patologia , Animais , Canais de Cloreto/genética , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/patologia , Estresse do Retículo Endoplasmático , Camundongos , Camundongos Knockout , Ácido Oleico/farmacologia , RNA Interferente Pequeno/genética , Células-Tronco , Estreptozocina
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