Mucosal bromodomain-containing protein 4 mediates aeroallergen-induced inflammation and remodeling

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Role of NF-κB in epithelial biology

Since its discovery, nuclear factor-κB (NF-κB) has been recognized as a critical regulator of immune responses. While early studies focused on studying the role of NF-κB in the development and function of immune cells, more recently the function of the inhibitor of NF-κB kinase (IKK)/NF-κB pathway in non-immune cells has gained increased attention. Studies in genetic mouse models were instrumental in dissecting the cell-specific functions of NF-κB and provided experimental evidence that NF-κB signaling in epithelial cells is important for the maintenance of immune homeostasis in barrier tissues such as the skin and the intestine. Increased activation of IKK/NF-κB triggered cytokine expression by the epithelial cells, resulting in exacerbated tissue inflammatory responses. NF-κB inhibition in keratinocytes triggered severe tumor necrosis factor-dependent skin inflammation and epidermal hyperplasia, while inhibition of IKK/NF-κB signaling in intestinal epithelial cells disturbed the intestinal barrier and triggered severe chronic colon inflammation. Therefore, epithelial NF-κB signaling performs critical 'peace keeping' functions in barrier tissues at the interface with the environment by regulating cell survival, barrier integrity, and the immunological and anti-microbial responses of epithelial cells. Improved understanding of epithelial NF-κB functions may hold the key for elucidating the etiology and pathophysiology of chronic inflammatory diseases in epithelial tissues.     

Shedding new light on neurodegenerative diseases through the mammalian target of rapamycin

Neurodegenerative disorders affect a significant portion of the world's population leading to either disability or death for almost 30 million individuals worldwide. One novel therapeutic target that may offer promise for multiple disease entities that involve Alzheimer's disease, Parkinson's disease, epilepsy, trauma, stroke, and tumors of the nervous system is the mammalian target of rapamycin (mTOR). mTOR signaling is dependent upon the mTORC1 and mTORC2 complexes that are composed of mTOR and several regulatory proteins including the tuberous sclerosis complex (TSC1, hamartin/TSC2, tuberin). Through a number of integrated cell signaling pathways that involve those of mTORC1 and mTORC2 as well as more novel signaling tied to cytokines, Wnt, and forkhead, mTOR can foster stem cellular proliferation, tissue repair and longevity, and synaptic growth by modulating mechanisms that foster both apoptosis and autophagy. Yet, mTOR through its proliferative capacity may sometimes be detrimental to central nervous system recovery and even promote tumorigenesis. Further knowledge of mTOR and the critical pathways governed by this serine/threonine protein kinase can bring new light for neurodegeneration and other related diseases that currently require new and robust treatments.     

Apoptotic signal transduction pathways in diabetes

Failure of insulin producing pancreatic beta-cells is a common characteristic of type 1 (insulin-dependent) and type 2 (insulin non-dependent) diabetes mellitus. Accumulating evidence suggests that programmed cell death (apoptosis) is the main form of beta-cell death in these disorders. The beta-cell is particularly sensitive to apoptotic stimuli due to the inherent features of the specialized beta-cell phenotype. In type 1 diabetes anti-beta-cell autoimmune reactivity delivers the apoptotic signals in the form of inflammatory mediators or T-cell effectors. In type 2 diabetes, the metabolic derangement is associated with production of inflammatory mediators in insulin-sensitive tissues leading elevated levels of circulating inflammatory mediators such as IL-6 and TNF. Further glucose has been suggested to induce beta-cell apoptosis via the induction of beta-cell synthesis of IL-1 which via autocrine action may elicit signalling cascades analogous to those seen in beta-cell destruction in type 1 diabetes. Considering the apparent importance of IL-1-beta signalling in beta-cell failure in both type 1 and type 2 diabetes, we here review the modulatory effect exerted on IL-1signalling by cellular characteristics related to the specialized beta-cell phenotype. We conclude that beta-cell differentiation signals (Pdx-1), glucose metabolism, calcium handling as well as regulation of naturally occurring inhibitors of cytokine signalling contribute to sensitize the beta-cell to apoptotic stimuli. We hypothesize that immunological stimuli in type 1 diabetes and metabolic/inflammatory signals in type 2 diabetes converge on common signalling pathways leading to beta-cell failure and destruction in these two diseases.     

Anti-inflammatory activity of bark of Dioscorea batatas DECNE through the inhibition of iNOS and COX-2 expressions in RAW264.7 cells via NF-κB and ERK1/2 inactivation

We identified a bioactive herbal medicine with anti-inflammatory activity from an ethanol extract derived from the bark of Dioscorea batatas DECNE (BDB) in RAW264.7 cells. We examined the effects of BDB on nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in LPS-induced RAW264.7 cells. BDB consistently inhibited both NO and PGE₂ production in a dose-dependent manner, with an IC₅₀ of 87–71 μg/ml, respectively. The reduction of NO and PGE₂ production were accompanied by a reduction in iNOS and COX-2 protein expression, as evaluated by Western blotting. To evaluate the action mode of BDB and its ability to inhibit iNOS and COX-2 protein expression, we assessed the effects of BDB on nuclear factor-κB (NF-κB) DNA-binding activity, NF-κB-dependent reporter gene activity, inhibitory factor-κB (IκB) phosphorylation and degradation, and p65 nuclear translocation. BDB suppressed DNA-binding activity and reporter gene activity as well as translocation of the NF-κB p65 subunit. BDB also down-regulated IκB kinase (IKK), thus inhibiting LPS-induced both phosphorylation and the degradation of IκBα. In addition, BDB also inhibited the LPS-induced activation of ERK1/2.     

MiR‐503 targets PI3K p85 and IKK‐β and suppresses progression of non‐small cell lung cancer

A microRNA usually has the ability to coordinately repress multiple target genes and therefore are associated with many pathological conditions such as human cancer. Our understanding of the biological roles of microRNAs in lung cancer, however, remains incomplete. In this study, we identified miR‐503 as a tumor‐suppressive microRNA in human non‐small cell lung carcinoma (NSCLC), whose expression level correlates inversely with overall survival in NSCLC patients. Ectopic expression of miR‐503 suppressed tumor cell proliferation and metastasis‐related traits in vitro as well as in vivo, supporting a anti‐cancer role of the microRNA in NSCLC progression. Mechanistic study revealed that oncogenic PI3K p85 and IKK‐β were direct targets of miR‐503. Overexpression of either PI3K p85 or IKK‐β partially restored the malignant properties of NSCLC cells in the presence of miR‐503. Taken together, our data demonstrate miR‐503 inhibits the malignant phenotype of NSCLC by targeting PI3K p85 and IKK‐β and might play a suppressive role in the pathogenesis of NSCLC, thus providing new insights in developing novel diagnostic and therapeutic approaches.     

Heregulin通过Her2激活SKBR3细胞内IKK／NF－κB信号通路

目的：初探Her2激动剂Heregulin（HRG）对人乳腺癌SKBR3细胞内IKK／NF－κB信号通路的激活机制。方法：Western blotting法检测 HRG对 SKBR3细胞中 PI3K／Akt／IKK信号通路的影响。以 TNF －α／RIP1／IKK这条经典信号通路为对照,引入各通路中关键蛋白（PI3K、RIP1及IKK）的抑制剂,对比各抑制剂对两条通路的影响。实时无标记细胞分析技术监测HRG对SKBR3细胞增殖的促进作用及IKK抑制剂TPCA1对HRG的拮抗作用。结果：HRG与TNF－α均能激活IKK引起 NF－κB入核,RIP1的抑制剂Necrostatin－1能阻断由TNF－α引起的IKK活化,但不能阻断由HRG引起的IKK活化,表明HRG并非通过传统的途径激活IKK。PI3K抑制剂LY294002能阻断由HRG引起的IKK激活,PI3K是Her2信号通路的关键蛋白之一,因此推测HRG是经由PI3K／Akt信号通路,完成对IKK／NF－κB通路的激活。细胞生长曲线反映,HRG能促进SKBR3细胞的增殖,TPCA1对HRG具有拮抗作用,对数期细胞经100nmol／L的TPCA1处理后,细胞增殖受到抑制,数量迅速下降。结论：HRG可以通过Her2／PI3K／Akt途径激活SKBR3细胞内IKK／NF－κB信号通路。