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1.
Connecdenn 1/2 are DENN (differentially expressed in normal and neoplastic cells) domain-bearing proteins that function as GEFs (guanine nucleotide exchange factors) for the small GTPase Rab35. Disruption of connecdenn/Rab35 function leads to defects in the recycling of multiple cargo proteins from endosomes with altered cell function, yet the regulation of connecdenn GEF activity is unexplored. We now demonstrate that connecdenn 1/2 are autoinhibited such that the purified, full-length proteins have significantly less Rab35 binding and GEF activity than the isolated DENN domain. Both proteins are phosphorylated with prominent phosphorylation sites between residues 500 and 600 of connecdenn 1. A large scale proteomics screen revealed that connecdenn 1 is phosphorylated at residues Ser-536 and Ser-538 in an Akt-dependent manner in response to insulin stimulation of adipocytes. Interestingly, we find that an Akt inhibitor reduces connecdenn 1 interaction with Rab35 after insulin treatment of adipocytes. Remarkably, a peptide flanking Ser-536/Ser-538 binds the DENN domain of connecdenn 1, whereas a phosphomimetic peptide does not. Moreover, connecdenn 1 interacts with 14-3-3 proteins, and this interaction is also disrupted by Akt inhibition and by mutation of Ser-536/Ser-538. We propose that Akt phosphorylation of connecdenn 1 downstream of insulin activation regulates connecdenn 1 function through an intramolecular interaction.  相似文献   
2.
Recent studies have emphasized the important role of microRNA (miRNA) clusters and common target genes in disease progression. Despite the known involvement of the miR‐192/215 family in many human diseases, its biological role in Hirschsprung disease (HSCR) remains undefined. In this study, we explored the role of the miR‐192/215 family in the pathogenesis of HSCR. Quantitative real‐time PCR and western blotting measured relative expression levels of miRNAs, mRNAs, and proteins in 80 HSCR patients and 77 normal colon tissues. Targets were evaluated by dual‐luciferase reporter assays, and the functional effects of miR‐192/215 on human 293T and SH‐SY5Y cells were detected by the Transwell assay, CCK8 assay and flow cytometry. MiR‐192/215 was significantly down‐regulated in HSCR tissue samples, and their knockdown inhibited cell migration and proliferation in the human 293T and SH‐SY5Y cell lines. Nidogen 1 (NID1) was confirmed as a common target gene of miR‐192/215 by dual‐luciferase reporter gene assay and its expression was inversely correlated with that of miR‐192/215 in tissue samples and cell lines. Silencing of NID1 could rescue the extent of the suppressing effects by miR‐192/215 inhibitor. The down‐regulation of miR‐192/215 may contribute to HSCR development by targeting NID1.

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3.
Exposure of endothelial cells (ECs) to agents such as oxidized glycerophospholipids (oxGPs) and cytokines, known to accumulate in atherosclerotic lesions, perturbs the expression of hundreds of genes in ECs involved in inflammatory and other biological processes. We hypothesized that microRNAs (miRNAs) are involved in regulating the inflammatory response in human aortic endothelial cells (HAECs) in response to oxGPs and interleukin 1β (IL-1β). Using next-generation sequencing and RT-quantitative PCR, we characterized the profile of expressed miRNAs in HAECs pre- and postexposure to oxGPs. Using this data, we identified miR-21-3p and miR-27a-5p to be induced 3- to 4-fold in response to oxGP and IL-1β treatment compared with control treatment. Transient overexpression of miR-21-3p and miR-27a-5p resulted in the downregulation of 1,253 genes with 922 genes overlapping between the two miRNAs. Gene Ontology functional enrichment analysis predicted that the two miRNAs were involved in the regulation of nuclear factor κB (NF-κB) signaling. Overexpression of these two miRNAs leads to changes in p65 nuclear translocation. Using 3′ untranslated region luciferase assay, we identified 20 genes within the NF-κB signaling cascade as putative targets of miRs-21-3p and -27a-5p, implicating these two miRNAs as modulators of NF-κB signaling in ECs.  相似文献   
4.
Natural killer (NK) cells are a sub-population of cytotoxic lymphocytes that can kill tumor or infected cells without prior exposure, by secreting the contents of preformed cytotoxic vesicles, containing perforin and granzymes, at the immune synapse. Cytohesin-associated scaffolding protein (CASP) is an adaptor molecule uniquely expressed in lymphocytes that forms complexes with both vesicle-initiating and sorting proteins, and has roles in NK cell migration, cytotoxicity, and cytokine secretion. In this study, we show that CASP contains a conserved granzyme B cleavage site that could modify its intracellular localization and interaction with sorting nexin 27. We also provide evidence that CASP is modified by ubiquitination. Both of these post-translational modifications could rapidly modify CASP function and highlight the dynamic regulatory mechanisms that direct its role in NK cell functions.  相似文献   
5.
Chronic hepatitis is a major cause of liver cancer, so earlier treatment of hepatitis might be reducing liver cancer incidence. Hepatitis can be induced in mice by treatment with Concanavalin A (Con A); the resulting liver injury causes significant CD4+ T cell activation and infiltration. In these T cells, Roquin, a ring-type E3 ubiquitin ligase, is activated. To investigate the role of Roquin, we examined Con A-induced liver injury and T cell infiltration in transgenic (Tg) mice overexpressing Roquin specifically in T cells. In Roquin Tg mice, Con A treatment caused greater increases in both the levels of liver injury enzymes and liver tissue apoptosis, as revealed by TUNEL and H&E staining, than wild type (WT) mice. Further, Roquin Tg mice respond to Con A treatment with greater increases in the T cell population, particularly Th17 cells, though Treg cell counts are lower. Roquin overexpression also enhances increases in pro-inflammatory cytokines, including IFN-γ, TNF-α and IL-6, upon liver injury. Furthermore, Roquin regulates the immune response and apoptosis in Con A induced hepatitis via STATs, Bax and Bcl2. These findings suggest that over-expression of Roquin exacerbates T-cell mediated hepatitis.  相似文献   
6.
7.
Transforming growth factor-β (TGF-β) signaling has been prominently implicated in the pathogenesis of vascular remodeling, especially the initiation and progression of flow-induced vascular remodeling. Smooth muscle cells (SMCs) are the principal resident cells in arterial wall and are critical for arterial remodeling. However, the role of TGF-β signaling in SMC for flow-induced vascular remodeling remains unknown. Therefore, the goal of our study was to determine the effect of TGF-β pathway in SMC for vascular remodeling, by using a genetical smooth muscle-specific (SM-specific) TGF-β type II receptor (Tgfbr2) deletion mice model. Mice deficient in the expression of Tgfbr2 (MyhCre.Tgfbr2f/f) and their corresponding wild-type background mice (MyhCre.Tgfbr2WT/WT) underwent partial ligation of left common carotid artery for 1, 2, or 4 weeks. Then the carotid arteries were harvested and indicated that the disruption of Tgfbr2 in SMC provided prominent inhibition of vascular remodeling. And the thickening of carotid media, proliferation of SMC, infiltration of macrophage, and expression of matrix metalloproteinase (MMP) were all significantly attenuated in Tgfbr2 disruption mice. Our study demonstrated, for the first time, that the TGF-β signaling in SMC plays an essential role in flow-induced vascular remodeling and disruption can prevent this process.  相似文献   
8.
Here we explored the impact of hydrogen sulfide (H2S) on biophysical properties of the primary human airway smooth muscle (ASM)–the end effector of acute airway narrowing in asthma. Using magnetic twisting cytometry (MTC), we measured dynamic changes in the stiffness of isolated ASM, at the single-cell level, in response to varying doses of GYY4137 (1–10 mM). GYY4137 slowly released appreciable levels of H2S in the range of 10–275 μM, and H2S released was long lived. In isolated human ASM cells, GYY4137 acutely decreased stiffness (i.e. an indicator of the single-cell relaxation) in a dose-dependent fashion, and stiffness decreases were sustained in culture for 24 h. Human ASM cells showed protein expressions of cystathionine-γ-lyase (CSE; a H2S synthesizing enzyme) and ATP-sensitive potassium (KATP) channels. The KATP channel opener pinacidil effectively relaxed isolated ASM cells. In addition, pinacidil-induced ASM relaxation was completely inhibited by the treatment of cells with the KATP channel blocker glibenclamide. Glibenclamide also markedly attenuated GYY4137-mediated relaxation of isolated human ASM cells. Taken together, our findings demonstrate that H2S causes the relaxation of human ASM and implicate as well the role for sarcolemmal KATP channels. Finally, given that ASM cells express intrinsic enzymatic machinery of generating H2S, we suggest thereby this class of gasotransmitter can be further exploited for potential therapy against obstructive lung disease.  相似文献   
9.
The present study aims to identify the modulatory effects of kahweol, an antioxidant diterpene present in coffee beans, on a panel of human tumor cell lines. Kahweol inhibits tumor cell proliferation and clonogenicity and induces apoptosis in several kinds of human tumor cells. In the estrogen receptor-negative MDA-MB231 human breast cancer, the mentioned effects are accompanied by caspases 3/7 and 9 activation and cytochrome c release. On the other hand, kahweol increases the production of reactive oxygen species and their cytotoxicity in human breast cancer cells but not in normal cells. Taken together, our data suggest that kahweol is an antitumor compound with inhibitory effects on tumor cell growth and survival, especially against MDA-MB231 breast cancer cells.  相似文献   
10.
Zonula Occludens (ZO) proteins are ubiquitous scaffolding proteins providing the structural basis for the assembly of multiprotein complexes at the cytoplasmic surface of the plasma membrane and linking transmembrane proteins to the filamentous cytoskeleton. They belong to the large family of membrane-associated guanylate kinase (MAGUK)-like proteins comprising a number of subfamilies based on domain content and sequence similarity. ZO proteins were originally described to localize specifically to tight junctions, or Zonulae Occludentes, but this notion was rapidly reconsidered since ZO proteins were found to associate with adherens junctions as well as with gap junctions, particularly with connexin-made intercellular channels, and also with a few other membrane channels. Accumulating evidence reveals that in addition to having passive scaffolding functions in organizing gap junction complexes, including connexins and cytoskeletals, ZO proteins (particularly ZO-1) also actively take part in the dynamic function as well as in the remodeling of junctional complexes in a number of cellular systems. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.  相似文献   
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