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The bZIP repressor proteins, c-Jun Dimerization Protein 2 and Activating Transcription Factor 3, recruit multiple HDAC members to the ATF3 promoter

Darlyuk-Saadon, Ilona; Weidenfeld-Baranboim, Keren; Yokoyama, Kazunari K.; Hai, Tsonwin; Aronheim, Ami
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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JDP2, is a basic leucine zipper (bZIP) protein displaying a high degree of homology with the stress inducible transcription factor, ATF3. Both proteins bind to cAMP and TPA response elements and repress transcription by multiple mechanisms. Histone deacetylases (HDACs) play a key role in gene inactivation by deacetylating lysine residues on histones. Here we describe the association of JDP2 and ATF3 with HDACs 1, 2–6 and 10. Association of HDAC3 and HDAC6 with JDP2 and ATF3 occurs via direct protein-protein interactions. The N-terminal bZIP motif of JDP2 and ATF3 basic domain are necessary and sufficient for the interaction with HDACs in a manner that is independent of coiled-coil dimerization. Class I HDACs associate with the bZIP repressors via the DAC conserved domain whereas the Class IIb HDAC6 associates through its C-terminal unique binder of ubiquitin Zn finger domain. Both JDP2 and ATF3 are known to bind and repress the ATF3 promoter. MEF cells treated with histone deacetylase inhibitor, trichostatin A (TSA) display enhanced ATF3 transcription. ATF3 enhanced transcription is significantly reduced in MEF cells lacking both ATF3 and JDP2. Collectively, we propose that the recruitment of multiple HDAC members to JDP2 and ATF3 is part of their transcription repression mechanism.

Clarithromycin enhances bortezomib-induced cytotoxicity via endoplasmic reticulum stress-mediated CHOP (GADD153) induction and autophagy in breast cancer cells

KOMATSU, SEIICHIRO; MIYAZAWA, KEISUKE; MORIYA, SHOTA; TAKASE, AKIKO; NAITO, MUNEKAZU; INAZU, MASATO; KOHNO, NORIO; ITOH, MASAHIRO; TOMODA, AKIO
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Publicado em 23/12/2011 Português
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The specific 26S proteasome inhibitor, bortezomib (BZ) potently induces apoptosis as well as autophagy in metastatic breast cancer cell lines such as MDA-MB-231 and MDA-MB-468. The combined treatment of clarithromycin (CAM) and BZ significantly enhances cytotoxicity in these cell lines. Although treatment with up to 100 μg/ml CAM alone had little effect on cell growth inhibition, the accumulation of autophagosomes and p62 was observed after treatment with 25 μg/ml CAM. This result indicated that CAM blocked autophagy flux. However, the combined treatment of BZ and CAM resulted in more pronounced autophagy induction, as assessed by increased expression ratios of LC3B-II to LC3B-I and clearance of intracellular p62, than treatment with BZ alone. This combination further enhanced induction of the pro-apoptotic transcription factor CHOP (CADD153) and the chaperone protein GRP78. Knockdown of CHOP by siRNA attenuated the death-promoting effect of BZ in MDA-MB-231 cells. A wild-type murine embryonic fibroblast (MEF) cell line also exhibited enhanced BZ-induced cytotoxicity with the addition of CAM, whereas a Chop knockout MEF cell line completely abolished this enhancement and exhibited resistance to BZ treatment. These data suggest that endoplasmic reticulum (ER)-stress mediated CHOP induction is involved in pronounced cytotoxicity by combining these reagents. Simultaneously targeting two major intracellular protein degradation pathways such as the ubiquitin-proteasome system by BZ and the autophagy-lysosome pathway by CAM may improve the therapeutic outcome in breast cancer patients via ER-stress mediated apoptosis.

A Manganese Superoxide Dismutase (SOD2)-Mediated Adaptive Response

Grdina, David J.; Murley, Jeffrey S.; Miller, Richard C.; Mauceri, Helena J.; Sutton, Harold G.; Thirman, Michael J.; Li, Jian Jian; Woloschak, Gayle E.; Weichselbaum, Ralph R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Very low doses of ionizing radiation, 5 to 100 mGy, can induce adaptive responses characterized by elevation in cell survival and reduction in micronuclei formation. Utilizing these end points, RKO human colon carcinoma and transformed mouse embryo fibroblasts (MEF), wild-type or knockout cells missing TNF receptors 1 and 2 (TNFR1−R2−), and C57BL/6 and TNFR1−R2− knockout mice, we demonstrate that intact TNF signaling is required for induction of elevated manganese superoxide dismutase (SOD2) activity (P < 0.001) and the subsequent expression of these SOD2-mediated adaptive responses when cells are challenged at a later time with 2 Gy. In contrast, amifostine’s free thiol form WR1065 can directly activate NF-κB giving rise to elevated SOD2 activity 24 h later and induce an adaptive response in both MEF wild-type and TNF signaling defective TNFR1−R2− cells. Transfection of cells with SOD2 siRNA completely abolishes both the elevation in SOD2 activity and expression of the adaptive responses. These results were confirmed in vivo using a micronucleus assay in splenocytes derived from C57BL/6 and TNFR1−R2− knockout mice that were exposed to 100 mGy or 400 mg/kg amifostine 24 h prior to exposure to a 2 Gy whole-body dose. A dose of 100 mGy also conferred enhanced protection to C57BL/6 mice exposed 24 h later to 100 mg/kg of N-Ethyl-N-nitrosourea (ENU). While very low radiation doses require an intact TNF signaling process to induce a SOD2-mediated adaptive response...

Changes in Enterococcal Populations and Related Antibiotic Resistance along a Medical Center-Wastewater Treatment Plant-River Continuum

Leclercq, Roland; Oberlé, Kenny; Galopin, Sébastien; Cattoir, Vincent; Budzinski, Hélène; Petit, Fabienne
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/2013 Português
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To determine if hospital effluent input has an ecological impact on downstream aquatic environment, antibiotic resistance in Enterococcus spp. along a medical center-retirement home-wastewater treatment plant-river continuum in France was determined using a culture-based method. Data on antibiotic consumption among hospitalized and general populations and levels of water contamination by antibiotics were collected. All isolated enterococci were genotypically identified to the species level, tested for in vitro antibiotic susceptibility, and typed by multilocus sequence typing. The erm(B) and mef(A) (macrolide resistance) and tet(M) (tetracycline resistance) genes were detected by PCR. Along the continuum, from 89 to 98% of enterococci, according to the sampled site, were identified as Enterococcus faecium. All E. faecium isolates from hospital and retirement home effluents were multiply resistant to antibiotics, contained erm(B) and mef(A) genes, and belonged to hospital-adapted clonal complex 17 (CC17). Even though this species remained dominant in the downstream continuum, the relative proportion of CC17 isolates progressively decreased in favor of other subpopulations of E. faecium that were more diverse, less resistant to antibiotics...

Role of SUMO-Specific Protease 2 in Reprogramming Cellular Glucose Metabolism

Tang, Shuang; Huang, Gang; Tong, Xuemei; Xu, Lian; Cai, Rong; Li, Jie; Zhou, Xiang; Song, Shaoli; Huang, Chen; Cheng, Jinke
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/05/2013 Português
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Most cancer cells exhibit a shift in glucose metabolic strategy, displaying increased glycolysis even with adequate oxygen supply. SUMO-specific proteases (SENPs) de-SUMOylate substrates including HIF1α and p53,two key regulators in cancer glucose metabolism, to regulate their activity, stability and subcellular localization. However, the role of SENPs in tumor glucose metabolism remains unclear. Here we report that SUMO-specific protease 2 (SENP2) negatively regulates aerobic glycolysis in MCF7 and MEF cells. Over-expression of SENP2 reduces the glucose uptake and lactate production, increasing the cellular ATP levels in MCF7 cells, while SENP2 knockout MEF cells show increased glucose uptake and lactate production along with the decreased ATP levels. Consistently, the MCF7 cells over-expressing SENP2 exhibit decreased expression levels of key glycolytic enzymes and an increased rate of glucose oxidation compared with control MCF7 cells, indicating inhibited glycolysis but enhanced oxidative mitochondrial respiration. Moreover, SENP2 over-expressing MCF7 cells demonstrated a reduced amount of phosphorylated AKT, whereas SENP2 knockout MEFs exhibit increased levels of phosphorylated AKT. Furthermore, inhibiting AKT phosphorylation by LY294002 rescued the phenotype induced by SENP2 deficiency in MEFs. In conclusion...

Macrolide antibiotics block autophagy flux and sensitize to bortezomib via endoplasmic reticulum stress-mediated CHOP induction in myeloma cells

MORIYA, SHOTA; CHE, XIAO-FANG; KOMATSU, SEIICHIRO; ABE, AKIHISA; KAWAGUCHI, TOMOHIRO; GOTOH, AKIHIKO; INAZU, MASATO; TOMODA, AKIO; MIYAZAWA, KEISUKE
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Publicado em 28/03/2013 Português
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The specific 26S proteasome inhibitor bortezomib (BZ) potently induces autophagy, endoplasmic reticulum (ER) stress and apoptosis in multiple myeloma (MM) cell lines (U266, IM-9 and RPMI8226). The macrolide antibiotics including concanamycin A, erythromycin (EM), clarithromycin (CAM) and azithromycin (AZM) all blocked autophagy flux, as assessed by intracellular accumulation of LC3B-II and p62. Combined treatment of BZ and CAM or AZM enhanced cytotoxicity in MM cell lines, although treatment with either CAM or AZM alone exhibited almost no cytotoxicity. This combination also substantially enhanced aggresome formation, intracellular ubiquitinated proteins and induced the proapoptotic transcription factor CHOP (CADD153). Expression levels of the proapoptotic genes transcriptionally regulated by CHOP (BIM, BAX, DR5 and TRB3) were all enhanced by combined treatment with BZ plus CAM, compared with treatment with each reagent alone. Like the MM cell lines, the CHOP+/+ murine embryonic fibroblast (MEF) cell line exhibited enhanced cytotoxicity and upregulation of CHOP and its transcriptional targets with a combination of BZ and one of the macrolides. In contrast, CHOP−/− MEF cells exhibited resistance against BZ and almost completely canceled enhanced cytotoxicity with a combination of BZ and a macrolide. These data suggest that ER stress-mediated CHOP induction is involved in pronounced cytotoxicity. Simultaneously targeting two major intracellular protein degradation systems such as the ubiquitin-proteasome system by BZ and the autophagy-lysosome system by a macrolide antibiotic enhances ER stress-mediated apoptosis in MM cells. This result suggests the therapeutic possibility of using a macrolide antibiotic with a proteasome inhibitor for MM therapy.

Extended JAK Activation and Delayed STAT1 Dephosphorylation Contribute to the Distinct Signaling Profile of CNS Neurons Exposed to Interferon-Gamma

Podolsky, Michael A.; Solomos, Andreas C.; Durso, Lisa C.; Evans, Stephanie M.; Rall, Glenn F.; Rose, R. Wesley
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Although interferon-gamma (IFN-γ) plays a critical role in the noncytolytic elimination of many neurotropic viral infections, the signaling response to this cytokine has not been extensively characterized in primary CNS neurons. We previously demonstrated that the IFN-γ response at the signaling and gene expression levels is temporally extended in primary mouse hippocampal neurons, as compared to the transient response of primary mouse embryonic fibroblasts (MEF). We hypothesize that the protracted kinetics of STAT1 phosphorylation in IFN-γ-treated neurons are due to extended receptor activation and/or delayed STAT1 dephosphorylation in the nucleus. Here, we show that in response to IFN-γ, the Janus kinases (JAK1/JAK2) associated with the neuronal IFN-γ receptor complex remain active for an extended period as compared to MEF. Experimental inactivation of JAK1/JAK2 in neurons after IFN-γ treatment did not reverse the extended STAT1 phosphorylation phenotype. These results suggest that the extended kinetics of neuronal IFN-γ signaling are a product of distinct negative feedback mechanisms operating at both the receptor and within the nucleus.

Direct reprogramming of mouse fibroblasts to cardiomyocyte-like cells using Yamanaka factors on engineered poly(ethylene glycol) (PEG) hydrogels

Smith, Amanda W.; Hoyne, Jake D.; Nguyen, Peter K.; McCreedy, Dylan A.; Aly, Haytham; Efimov, Igor R.; Rentschler, Stacey; Elbert, Donald L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Direct reprogramming strategies enable rapid conversion of somatic cells to cardiomyocytes or cardiomyocyte-like cells without going through the pluripotent state. A recently described protocol couples Yamanaka factor induction with pluripotency inhibition followed by BMP4 treatment to achieve rapid reprogramming of mouse fibroblasts to beating cardiomyocyte-like cells. The original study was performed using Matrigel-coated tissue culture polystyrene (TCPS), a stiff material that also non-specifically adsorbs serum proteins. Protein adsorption-resistant poly(ethylene glycol) (PEG) materials can be covalently modified to present precise concentrations of adhesion proteins or peptides without the unintended effects of non-specifically adsorbed proteins. Here, we describe an improved protocol that incorporates custom-engineered materials. We first reproduced the Efe et al. protocol on Matrigel-coated TCPS (the original material), reprogramming adult mouse tail tip mouse fibroblasts (TTF) and mouse embryonic fibroblasts (MEF) to cardiomyocyte-like cells that demonstrated striated sarcomeric α-actinin staining, spontaneous calcium transients, and visible beating. We then designed poly(ethylene glycol) culture substrates to promote MEF adhesion via laminin and RGD-binding integrins. PEG hydrogels improved proliferation and reprogramming efficiency (evidenced by beating patch number and area...

RE-EXAMINATION OF CD91 FUNCTION IN GRP94 (gp96) SURFACE BINDING, UPTAKE AND PEPTIDE CROSS-PRESENTATION1

Jockheck-Clark, Angela R.; Bowers, Edith V.; Totonchy, Mariam B.; Neubauer, Julie; Pizzo, Salvatore V.; Nicchitta, Christopher V.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Extracellular GRP94 (gp96) can initiate both innate and adaptive immune responses through interactions with antigen presenting cell surface receptors. Following the identification of CD91 as a receptor functioning in the cross-presentation of GRP94-associated peptides, scavenger receptors SR-A and SREC-I were demonstrated to function in GRP94 cell surface binding and endocytosis, lending controversy to the assignment of CD91 as the unique GRP94 endocytic receptor. To assess CD91 function in GRP94 surface binding and endocytosis, these parameters were examined in murine embyronic fibroblast (MEF) cell lines whose expression of CD91 was either reduced via RNAi or eliminated by genetic disruption of the CD91 locus. Reduction or loss of CD91 expression abrogated the binding and uptake of the CD91 ligand receptor-associated protein (RAP); surface binding and uptake of an N-terminal domain of GRP94 (GRP94.NTD) was unaffected. GRP94.NTD surface binding was markedly suppressed following treatment of MEF cell lines with heparin, the sulfation inhibitor sodium chlorate, or heparinase II, demonstrating that heparin sulfate proteoglycans can function in GRP94.NTD surface binding. The role of CD91 in the cross-presentaton of GRP94-associated peptides was examined in the DC2.4 dendritic cell line. In DC2.4 cells...

Inhibition of intracellular bacterial replication in fibroblasts is dependent on the perforin-like protein (Perforin-2) encoded by macrophage expressed gene 1

McCormack, Ryan; de Armas, Lesley R.; Shiratsuchi, Motoaki; Ramos, Jay; Podack, Eckhard R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Fibroblasts are known to eliminate intracellular bacteria, but the lethal hit of the bactericidal mechanism has not been defined. We show that primary embryonic and established fibroblasts can be induced by interferons or by intracellular bacterial infection to express a perforin-like mRNA previously described as macrophage expressed gene 1 (mpeg1). The presence and level of the perforin-like mRNA correlate with the ability of primary mouse embryonic fibroblasts (MEF) to eliminate intracellular bacteria. In addition, siRNA knock-down of the perforin-like molecule abolishes bactericidal activity and allows intracellular bacterial replication. Complementation of MEF in which the endogenous perforin-like molecule has been knocked down with an RFP-tagged version restores bactericidal activity. The perforin-like molecule has broad bactericidal specificity for pathogenic and non-pathogenic bacteria including Gram positive, Gram negative and acid fast bacteria. The perforin-like molecule renders previously lysozyme-resistant bacteria sensitive to lysis by lysozyme suggesting physical damage of the outer cell wall by the perforin-like protein. MEFs damage cell walls of intracellular bacteria by insertion, polymerization and pore-formation of the perforin-like protein...

Genetic deletion of caspase-2 accelerates MMTV/c-neu-driven mammary carcinogenesis in mice

Parsons, M J; McCormick, L; Janke, L; Howard, A; Bouchier-Hayes, L; Green, D R
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
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Despite being the most evolutionarily conserved of the mammalian caspases, little is understood about the cellular function of caspase-2 in normal tissues or what role caspase-2 may have in the progression of human disease. It has been reported that deletion of the caspase-2 gene (Casp2), accelerates Eμ-myc lymphomagenesis in mice, and thus caspase-2 may act as a tumor suppressor in hematological malignancies. Here, we sought to extend these findings to epithelial cancers by examining the potential role of caspase-2 as a tumor suppressor in the mouse mammary carcinogenesis model; MMTV/c-neu. The rate of tumor acquisition was significantly higher in multiparous Casp2−/−/MMTV mice compared with Casp2+/+/MMTV and Casp2+/−/MMTV mice. Cells from Casp2−/−/MMTV tumors were often multinucleated and displayed bizarre mitoses and karyomegaly, while cells from Casp2+/+/MMTV and Casp2+/−/MMTV tumors never displayed this phenotype. Tumors from Casp2−/−/MMTV animals had a significantly higher mitotic index than tumors from Casp2+/+/MMTV and Casp2+/−/MMTV animals. Cell cycle analysis of Casp2−/− E1A/Ras-transformed mouse embryonic fibroblasts (MEF) also indicated a higher proliferative rate in the absence of caspase-2. In vitro assays further illustrated that MEF had increased genomic instability in the absence of caspase-2. This appears to be due to disruption of the p53 pathway because we observed a concomitant decrease in the induction of the p53 target genes...

Supplemented αMEM/F12-based medium enables the survival and growth of primary ovarian follicles encapsulated in alginate hydrogels

Tagler, David; Makanji, Yogeshwar; Anderson, Nicholas R.; Woodruff, Teresa K.; Shea, Lonnie D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Hydrogel-encapsulating culture systems for ovarian follicles support the in vitro growth of secondary follicles from various species including mouse, non-primate human, and human; however, the growth of early stage follicles (primary and primordial) has been limited. While encapsulation maintains the structure of early stage follicles, feeder cell populations, such as mouse embryonic fibroblasts (MEFs), are required to stimulate growth and development. Hence, in this report, we investigated feeder-free culture environments for early stage follicle development. Mouse ovarian follicles were encapsulated within alginate hydrogels and cultured in various growth medium formulations. Initial studies employed embryonic stem cell medium formulations as a tool to identify factors that influence the survival, growth, and meiotic competence of early stage follicles. The medium formulation that maximized survival and growth was identified as αMEM/F12 supplemented with fetuin, insulin, transferrin, selenium, and follicle stimulating hormone (FSH). This medium stimulated the growth of late primary (average initial diameter of 80 µm) and early secondary (average initial diameter of 90 µm) follicles, which developed antral cavities and increased to terminal diameters exceeding 300 µm in 14 days. Survival ranged from 18% for 80 µm follicles to 36% for 90 µm follicles. Furthermore...

Role of mitofusin 2 (Mfn2) in controlling cellular proliferation

Chen, Kuang-Hueih; Dasgupta, Asish; Ding, Jinhui; Indig, Fred E.; Ghosh, Paritosh; Longo, Dan L.
Fonte: Federation of American Societies for Experimental Biology Publicador: Federation of American Societies for Experimental Biology
Tipo: Artigo de Revista Científica
Publicado em /01/2014 Português
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It has been reported that Mitofusin2 (Mfn2) inhibits cell proliferation when overexpressed. We wanted to study the role of endogenous Mfn2 in cell proliferation, along with the structural features of Mfn2 that influence its mitochondrial localization and control of cell proliferation. Mfn2-knockdown clones of a B-cell lymphoma cell line BJAB exhibited an increased rate of cell proliferation. A 2-fold increase in cell proliferation was also observed in Mfn2-knockout mouse embryonic fibroblast (MEF) cells as compared with the control wild-type cells, and the proliferative advantage of the knockout MEF cells was blocked on reintroduction of the Mfn2 gene. Mfn2 exerts its antiproliferative effect by acting as an effector molecule of Ras, resulting in the inhibition of the Ras-Raf-ERK signaling pathway. Furthermore, both the N-terminal (aa 1–264) and the C-terminal (aa 265–757) fragments of Mfn2 blocked cell proliferation through distinct mechanisms: the N-terminal-mediated inhibition was due to its interaction with Raf-1, whereas the C-terminal fragment of Mfn2 inhibited cell proliferation by interacting with Ras. The inhibition of proliferation by the N-terminal fragment was independent of its mitochondrial localization. Collectively...

SH2-B Promotes Insulin Receptor Substrate 1 (IRS1)- and IRS2-mediated Activation of the Phosphatidylinositol 3-Kinase Pathway in Response to Leptin*

Duan, Chaojun; Li, Minghua; Rui, Liangyou
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Leptin regulates energy homeostasis primarily by binding and activating its long form receptor (LRb). Deficiency of either leptin or LRb causes morbid obesity. Leptin stimulates LRb-associated JAK2, thus initiating multiple pathways including the Stat3 and phosphatidylinositol (PI) 3-kinase pathways that mediate leptin biological actions. Here we report that SH2-B, a JAK2-interacting protein, promotes activation of the PI 3-kinase pathway by recruiting insulin receptor substrate 1 (IRS1) and IRS2 in response to leptin. SH2-B directly bound, via its PH and SH2 domain, to both IRS1 and IRS2 both in vitro and in intact cells and mediated formation of a JAK2/SH2-B/IRS1 or IRS2 tertiary complex. Consequently, SH2-B dramatically enhanced leptin-stimulated tyrosine phosphorylation of IRS1 and IRS2 in HEK293 cells stably expressing LRb, thus promoting association of IRS1 and IRS2 with the p85 regulatory subunit of PI 3-kinase and phosphorylation and activation of Akt. SH2-B mutants with lower affinity for IRS1 and IRS2 exhibited reduced ability to promote association of JAK2 with IRS1, tyrosine phosphorylation of IRS1, and association of IRS1 with p85 in response to leptin. Moreover, deletion of the SH2-B gene impaired leptin-stimulated tyrosine phosphorylation of endogenous IRS1 in mouse embryonic fibroblasts (MEF)...

Extracellular p53 fragment re-enters K-Ras mutated cells through the caveolin-1 dependent early endosomal system

Lee, Sun-Hye; Woo, Tae-Gyun; Lee, Su-Jin; Kim, Jin-Sik; Ha, Nam-Chul; Park, Bum-Joon
Fonte: Impact Journals LLC Publicador: Impact Journals LLC
Tipo: Artigo de Revista Científica
Publicado em 02/12/2013 Português
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K-Ras mutation is detected in over 30% of human malignancies. In particular, 90% of human pancreatic cancers are initiated by K-Ras mutation. Thus, selective elimination of K-Ras mutated cells would be a plausible strategy to prevent or cure the malignancies. In our previous reports, it has been revealed that oncogenic K-Ras promotes the exocytosis of p53 with Snail. In this study, we have followed the final destination of extracellular p53, which is secreted by the Snail complex. Here we provide evidences that p53, exported from K-Ras-mutated cells, is specifically re-endocytosed by oncogenic K-Ras-containing cancer cells. The p53 DNA-binding domain directly associates with caveolin-1 and enters K-Ras mutated cells through early endosome-mediated endocytosis. Using a serial deletion approach, we revealed that a fragment of human p53 extending from 93-143 amino acids (AA) is responsible for binding with caveolin-1 and for endocytosis. In contrast, p53-Snail binding occurs at the 143-193 aa region. Finally, through in vivo study, we confirmed that injected recombinant p53 could be up-taken by tumor tissues, constructed by oncogenic K-Ras transformed MEF cells. In contrast, the tumors formed by H-Ras mutated MEF cells did not accumulate the injected p53 protein. These results indicate that the p53 fragment might be useful as a specific delivery tool into K- Ras mutated cells as well as a diagnostic method.

Anti-anxiety Activity of Methanolic Extracts of Different Parts of Angelica archangelica Linn.

Kumar, Dinesh; Bhat, Zulfiqar Ali
Fonte: Medknow Publications & Media Pvt Ltd Publicador: Medknow Publications & Media Pvt Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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Angelica archangelica Linn.is a herb distributed in tropical and subtropical regions of the world. In Indian and Chinese system of medicine, it is used for nervous disorders and cerebral diseases. Previously the aqueous extract of the A. archangelica was evaluated for anxiolytic activity and was found to have significant potential for the same. The present study is aimed to evaluate the anxiolytic activity of methanol extract of root (MER), stem (MES), leaf (MEL), fruit (MEF) and whole plant (MEW) of Angelica archangelica Linn. All the extracts (MER, MES, MEL, MEF and MEW) were evaluated for anxiolytic effects using elevated plus maze test (EPM) model in rats. Methanol extracts of different parts of A.archangelica had increased number of entries and time spent in open arms while they decreased the number of entries and duration of time spent in closed arm of the EPM. In a similar fashion, the diazepam increased the percentage of time spent and percentage of arm entries in the open arms (*P <0.05, **P <0.01). Whole plant and the root had the maximum, leaf and fruits showed intermediate, while stem had the least anxiolytic activity (*P <0.05, **P <0.01) in EPM (Figure 1-5). The head dip count in DZ, SMR400, SML400, SMF400 and SMW400 in open arm are significantly shown in Table 1. The DZ...

Roles of Atox1 and p53 in the trafficking of copper-64 to tumor cell nuclei: implications for cancer therapy

Beaino, Wissam; Guo, Yunjun; Chang, Albert J.; Anderson, Carolyn J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Due to its cytotoxicity, free copper is chelated by protein side chains and does not exist in vivo. Several chaperones transport copper to various cell compartments, but none has been identified that traffic copper to the nucleus. Copper-64 decays by β+ and β- allowing for PET imaging and targeted radionuclide therapy of cancer. Because the delivery of 64Cu to the cell nucleus may enhance the therapeutic effect of copper radiopharmaceuticals, elucidation of the pathway(s) involved in transporting copper to the tumor cell nucleus is important for optimizing treatment. We identified Atox1 as one of the proteins that binds copper in the nucleus. Mouse embryonic fibroblast (MEF) cell lines, positive and negative for Atox1, were used to determine the role of Atox1 in 64Cu transport to the nucleus. MEF Atox1+/+ accumulated more 64Cu in the nucleus compared to Atox1-/- cells. HCT116 colorectal cancer cell lines expressing p53 (+/+) and non-expressing (-/-) were used to evaluate the role of this tumor suppressor protein in 64Cu transport. In cells treated with cisplatin (cisPt), the uptake of 64Cu in the nucleus of HCT116 p53+/+ was greater compared to p53-/- cells. Atox1 expression increased in p53 positive and negative HCT116 cells treated with cisPt; however...

Large Enhancement of Quantum Dot Fluorescence by Highly Scalable Nanoporous Gold

Zhang, Ling; Song, Yunke; Fujita, Takeshi; Zhang, Ye; Chen, Mingwei; Wang, Tza-Huei
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Nanoengineered metallic materials have been shown to have a number of exclusive physicochemical properties not available at neither larger (micro- and macroscopic) nor smaller (molecular) scales. Recently, these materials in particular have drawn significant attention due to their capability to enhance fluorescent signals of nearby fluorescent species through a phenomenon known as metal enhanced fluorescence (MEF). MEF originates from the localized surface plasmon resonance (LSPR), a collective oscillation of conduction-band electrons that can modify both the extinction coefficient and quantum yield of adjacent fluorescent molecules/species. [1] The extinction coefficient is a function of the electromagnetic field intensity experienced by the fluorescent molecules, and under an enhanced electromagnetic field, fluorescent molecules absorb photons and promote electrons into excited states at accelerated rates. LSPR of metallic nanostructures can also modify the quantum yield of fluorescent species by increasing their radioactive decay rate. The combined enhancement of extinction coefficient and quantum yield can result in significantly strengthened fluorescence from fluorescent species.

Composite Scaffolds Containing Silk Fibroin, Gelatin, and Hydroxyapatite for Bone Tissue Regeneration and 3D Cell Culturing

Moisenovich, M. M.; Arkhipova, A. Yu.; Orlova, A. A.; Drutskaya, M. S; Volkova, S. V.; Zacharov, S. E.; Agapov, I. I.; Kirpichnikov, M. P.
Fonte: A.I. Gordeyev Publicador: A.I. Gordeyev
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Three-dimensional (3D) silk fibroin scaffolds were modified with one of the major bone tissue derivatives (nano-hydroxyapatite) and/or a collagen derivative (gelatin). Adhesion and proliferation of mouse embryonic fibroblasts (MEF) within the scaffold were increased after modification with either nano-hydroxyapatite or gelatin. However, a significant increase in MEF adhesion and proliferation was observed when both additives were introduced into the scaffold. Such modified composite scaffolds provide a new and better platform to study wound healing, bone and other tissue regeneration, as well as artificial organ bioengineering. This system can further be applied to establish experimental models to study cell-substrate interactions, cell migration and other complex processes, which may be difficult to address using the conventional two-dimensional culture systems.

Contribution of hepatic lineage stage-specific donor memory to the differential potential of induced mouse pluripotent stem cells (iPSC)

Lee, Seung Bum; Seo, Daekwan; Choi, Dongho; Park, Kye-Yoon; Holczbauer, Agnes; Marquardt, Jens U.; Conner, Elizabeth A.; Factor, Valentina M.; Thorgeirsson, Snorri S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/2012 Português
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Recent studies suggested that induced pluripotent stem cells (iPSCs) retain a residual donor cell gene expression which may impact their capacity to differentiate into cell of origin. Here we addressed a contribution of a lineage stage-specific donor cell memory in modulating the functional properties of iPSCs. iPSCs were generated from hepatic lineage cells at an early (hepatoblast-derived, HB-iPSCs) and end stage (adult hepatocyte, AH-iPSCs) of hepatocyte differentiation as well as from mouse fetal fibroblasts (MEF-iPSCs) using a lentiviral vector encoding four pluripotency-inducing factors Oct4, Sox2, Klf4, and c-Myc. All resulting iPS cell lines acquired iPSCs phenotype as judged by the accepted criteria including morphology, expression of pluripotency markers, silencing of transducing factors, capacity of multilineage differentiation in teratoma assay and normal diploid karyotype. However, HB-iPSCs were more efficient in directed differentiation towards hepatocytic lineage as compared to AH-iPSCs, MEF-iPSCs or mESCs. Extensive comparative transcriptome analyses of the early passage iPSCs, donor cells and mESCs revealed that despite global similarities in gene expression patterns between generated iPSCs and mESCs, HB-iPSCs retained a transcriptional memory (7 up- and 17 down-regulated genes) typical of the original cells. Continuous passaging of HB-iPSCs erased most of these differences including a superior capacity for hepatic re-differentiation. These results suggest that retention of lineage stage-specific donor memory in iPSCs may facilitate differentiation into donor cell type. The identified gene set help to improve hepatic differentiation for therapeutic applications and contribute to the better understanding of liver development.