ABSTRACT
Th1 cell activation is considered a key mediator of the pathogenesis of type 1 diabetes. Targeting IL-12-induced Th1 cell differentiation seems to be an effective way to block the development of type 1 diabetes. However, given the critical function of Th1 in the immune system, the potential side effects hinder the application of anti-Th1 therapy in the treatment of type 1 diabetes. To identify safe anti-Th1 treatment(s), we screened the FDA-approved tyrosine kinase inhibitor (TKI) drug library using an IL-12-induced Th1 differentiation cell model. We found that among the TKIs with little effect on T cell viability, sorafenib is the top contender for the inhibition of Th1 differentiation. Treatment of NOD mice with sorafenib significantly impeded the development of type 1 diabetes and ameliorated insulitis, which coincided with a specifically decreased accumulation of Th1 cell population in the pancreas but not in peripheral immune organs. Mechanistically, sorafenib indirectly inhibited janus kinase 2 (JAK2) activity and blocked IL-12-induced phosphorylations of JAK2 and signal transducer and activator of transcription 4 (STAT4). Since sorafenib is classified as an FDA-approved drug, it serves as a preliminary lead point for additional experimentation and may be a promising therapy for type 1 diabetes in humans.
Subject(s)
Diabetes Mellitus, Type 1 , Sorafenib , Animals , Diabetes Mellitus, Type 1/drug therapy , Interleukin-12 , Mice , Mice, Inbred NOD , Sorafenib/pharmacology , Sorafenib/therapeutic use , Th1 CellsABSTRACT
Accumulation and activation of immunocytes in adipose tissues are essential to obesity-induced inflammation and insulin resistance. Chemokines are pivotal for the recruitment of immunocytes in adipose tissue during obesity. Chemokine (C-C motif) ligand 5 (CCL5) plays a vital role in the recruitment of immunocytes to sites of inflammation. CCL5 expression level is increased in obese adipose tissue from humans and mice. However, the role of CCL5 in obesity-induced adipose inflammation remains unclear. Our study found that the CCL5 expression level was increased in the epididymal white adipose tissue (eWAT) of obese mice, particularly in CD8+ T cells. CCL5 knockout (KO) mice exhibited better glucose tolerance than wild-type (WT) mice under lean conditions. In contrast, CCL5 KO mice were more insulin resistant and had severe hepatic steatosis than WT mice under obese conditions. Increased T cells in adipose tissue heaven adipose inflammation in obese CCL5 KO mice. The compensatory increased T cell-associated chemokines may account for increased T cell content in the eWAT of obese CCL5 KO mice. These findings imply that CCL5 deficiency exacerbates adipose inflammation and impairs insulin sensitivity in the metabolic tissues of obese mice.
Subject(s)
CD8-Positive T-Lymphocytes , Chemokine CCL5 , Insulin Resistance , Animals , Mice , CD8-Positive T-Lymphocytes/metabolism , Chemokine CCL5/genetics , Chemokines , Inflammation/metabolism , Mice, Obese , Obesity/metabolismABSTRACT
miRNAs are important regulators of differentiation, development, and function of brown and beige fat cells. In this study, we identify the role of the miR-199a/214 cluster in the regulation of brown and beige adipocyte development and thermogenesis in vitro and in vivo. We show that expression of the miR-199a/214 cluster is dramatically decreased during brown and beige adipocyte differentiation and in response to cold exposure or ß-adrenergic receptor activation. The cluster levels are significantly upregulated in the adipose tissues of obese mice and human subjects. Overexpression of the miR-199a/214 cluster suppresses brown adipocyte differentiation and inhibits thermogenic gene expression and mitochondrial respiration, whereas knockdown of the cluster increases thermogenic gene expression and mitochondrial function in beige adipocytes. In addition, inhibition of the miR-199a/214 cluster promotes beiging effects in vivo. We further show that miR-199a/214 suppresses brown adipocyte differentiation and beige fat development by directly targeting PRDM16 and peroxisome PGC-1α, two key transcriptional regulators of adipose browning. Together, these observations reveal that the miR-199a/214 cluster is a key negative regulator of brown and beige fat development and thermogenesis.
Subject(s)
Adipocytes, Beige/metabolism , Adipocytes, Brown/metabolism , DNA-Binding Proteins/metabolism , MicroRNAs/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Thermogenesis/genetics , Transcription Factors/metabolism , Adipose Tissue, Brown/metabolism , Adipose Tissue, White/metabolism , Animals , DNA-Binding Proteins/genetics , Female , Gene Expression , Gene Expression Regulation , Gene Knockdown Techniques , Gene Regulatory Networks , Humans , Male , Mice , MicroRNAs/genetics , Middle Aged , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , Transcription Factors/geneticsABSTRACT
OBJECTIVES: To clone and characterize the squalene synthase from Siraitia grosvenorii (SgSQS). RESULTS: The gene encoding SgSQS was cloned. SgSQS has 417 amino acid residues with an pI of 7.3. There are 32 phosphorylation sites in its sequence: S48 as well as S196 play important roles in regulation of enzyme activity. The enzyme is a monomeric protein with a cave-like active center formed by α helixes and has two transmembrane domains at its C-terminus. SgSQS mRNA expression in stem and root were about twice as much as that in leaf and peel. Full-length SgSQS with measurable catalytic activity was expressed in Escherichia coli. SgSQS activity was optimal at 37 °C and pH 7.5 respectively. CONCLUSION: SgSQS gene was cloned, and the molecular structure and biochemical function of SgSQS were characterized.
