共查询到20条相似文献,搜索用时 15 毫秒
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JoAnne Julian Neeraja Dharmaraj Daniel D. Carson 《Journal of cellular biochemistry》2009,108(4):802-815
Understanding the underlying mechanisms by which a normal cell avoids the oncogenic potential of MUC1 signaling requires further definition of the pathways by which the MUC1 cytoplasmic tail is processed in both normal and tumor‐derived cells. In the present study we describe the processing pathway initiated by TACE/ADAM17 cleavage of MUC1. Utilizing the human uterine epithelial cell line, HES, derived from normal endometrium, we show that endogenous full length MUC1 undergoes regulated intramembranous proteolysis mediated by presenillin‐dependent γ‐secretase. Cytokine‐stimulated HES cells exposed to γ‐secretase inhibitors accumulated a membrane‐associated 15 kDa fragment of the MUC1 C‐terminal subunit (CTF15). Inhibitors of TACE/ADAM17‐mediated shedding inhibited accumulation of MUC1‐CTF15 and MUC1 ectodomain release to a similar extent consistent with MUC1‐CTF15 being a product of TACE/ADAM17 action. Reduction of catalytically active γ‐secretase complex by nicastrin siRNA treatment also resulted in CTF15 accumulation. Furthermore, mature nicastrin, the substrate receptor for γ‐secretase, co‐immunoprecipitated with CTF15 in the presence of γ‐secretase inhibitors indicating the formation of CTF15: nicastrin complexes. MUC1‐CTF15 accumulation in response to γ‐secretase inhibition was demonstrated in both normal and tumor‐derived cells from humans and mice indicating that this processing pathway exists in many cell contexts. We did not detect products of MUC1 cleavage by γ‐secretase in the presence of various proteasomal inhibitors indicating that subsequent degradation is either non‐proteasomal or extremely efficient. We suggest that this efficient pathway attenuates potential signaling mediated by cytoplasmic tail fragments. J. Cell. Biochem. 108: 802–815, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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β‐strand interactions at the domain interface critical for the stability of human lens γD‐crystallin
Payel Das Jonathan A. King Ruhong Zhou 《Protein science : a publication of the Protein Society》2010,19(1):131-140
Human age‐onset cataracts are believed to be caused by the aggregation of partially unfolded or covalently damaged lens crystallin proteins; however, the exact molecular mechanism remains largely unknown. We have used microseconds of molecular dynamics simulations with explicit solvent to investigate the unfolding process of human lens γD‐crystallin protein and its isolated domains. A partially unfolded folding intermediate of γD‐crystallin is detected in simulations with its C‐terminal domain (C‐td) folded and N‐terminal domain (N‐td) unstructured, in excellent agreement with biochemical experiments. Our simulations strongly indicate that the stability and the folding mechanism of the N‐td are regulated by the interdomain interactions, consistent with experimental observations. A hydrophobic folding core was identified within the C‐td that is comprised of a and b strands from the Greek key motif 4, the one near the domain interface. Detailed analyses reveal a surprising non‐native surface salt‐bridge between Glu135 and Arg142 located at the end of the ab folded hairpin turn playing a critical role in stabilizing the folding core. On the other hand, an in silico single E135A substitution that disrupts this non‐native Glu135‐Arg142 salt‐bridge causes significant destabilization to the folding core of the isolated C‐td, which, in turn, induces unfolding of the N‐td interface. These findings indicate that certain highly conserved charged residues, that is, Glu135 and Arg142, of γD‐crystallin are crucial for stabilizing its hydrophobic domain interface in native conformation, and disruption of charges on the γD‐crystallin surface might lead to unfolding and subsequent aggregation. 相似文献
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Kang‐Young Choi Hyun‐Jung Kim Byung‐Chae Cho In‐San Kim Hyun‐Jung Kim Hyun‐Mo Ryoo 《Journal of cellular biochemistry》2009,107(4):818-825
TGF‐β3, TβR‐I, and TGF‐β‐activated Smad2 has been suggested to be a series of signaling molecules for secondary palate fusion. In this article, we show that a gene induced by TGF‐β, βig‐h3, is coincidentally expressed with TGF‐β3 in medial edge epithelial (MEE) cells undergoing apoptosis during normal palatal fusion. βig‐h3 was also highly expressed in the areas of post‐weaning mammary gland cells and developing phalangeal joints in which TGF‐β3 or BMP‐4‐induced apoptosis occurs, respectively. Blocking of βig‐h3 expression in E12.5 embryos with antisense oligodeoxynucleotides (ODN) resulted in cleft of the secondary palate in 84% of the treated mice that were born. Moreover, the antisense ODN treatment resulted in a failure of apoptosis in the MEE between palatal shelves in physical contact in organ culture. We conclude that βig‐h3 expression in the MEE is stimulated by TGF‐β3, causes cell death, and consequently results in complete fusion of the apposed palatal shelves. J. Cell. Biochem. 107: 818–825, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Fatty acids stored as triglycerides, an important source of cellular energy, are catabolized through β‐oxidation pathways predicted to occur both in peroxisomes and mitochondria in filamentous fungi. Here, we characterize the function of Enoyl‐CoA hydratase Ech1, a mitochondrial β‐oxidation enzyme, in the model phytopathogen Magnaporthe oryzae. Ech1 was found to be essential for conidial germination and viability of older hyphae. Unlike wild‐type Magnaporthe, the ech1Δ failed to utilize C14 fatty acid and was partially impeded in growth on C16 and C18 fatty acids. Surprisingly, loss of β‐oxidation led to significantly altered mitochondrial morphology and integrity with ech1Δ showing predominantly vesicular/punctate mitochondria in contrast to the fused tubular network in wild‐type Magnaporthe. The ech1Δ appressoria were aberrant and displayed reduced melanization. Importantly, we show that the significantly reduced ability of ech1Δ to penetrate the host and establish therein is a direct consequence of enhanced sensitivity of the mutant to oxidative stress, as the defects could be remarkably reversed through exogenous antioxidants. Overall, our comparative analyses reveal that peroxisomal lipid catabolism is essential for appressorial function of host penetration, whereas mitochondrial β‐oxidation primarily contributes to conidial viability and maintenance of redox homeostasis during host colonization by Magnaporthe. 相似文献
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Huiguang Yang Meijuan Yan Chun Cheng Jing Jiang Lili Zhang Jie Liu Zhengming Zhou Aiguo Shen 《Journal of cellular biochemistry》2009,108(1):75-86
Glycosylation is one of the most important post‐translational modifications. It is clear that the single step of β‐1,4‐galactosylation is performed by a family of β‐1,4‐galactosyltransferases (β‐1,4‐GalTs), and that each member of this family may play a distinct role in different tissues and cells. In the present study, real‐time PCR revealed that the β‐1,4‐GalT I mRNA reached peaks at 2 weeks after sciatic nerve crush and 3 days after sciatic nerve transection. Combined in situ hybridization for β‐1,4‐GalT I mRNA and immunohistochemistry for S100 showed that β‐1,4‐GalT I mRNAs were mainly located in Schwann cells after sciatic nerve injury. In conclusion, β‐1,4‐GalT I might play important roles in Schwann cells during the regeneration and degeneration of the injured sciatic nerve. In other pathology, such as inflammation, we found that LPS administration affected β‐1,4‐GalT I mRNA expression in sciatic nerve in a time‐ and dose‐dependent manner, and β‐1,4‐GalT I mRNA is expressed mainly in Schwann cells. These results indicated that β‐1,4‐GalT I plays an important role in the inflammation reaction induced by intraperitoneal injection of LPS. Similarly, we found that β‐1,4‐GalT I in Schwann cells in vitro was affected in a time‐ and concentration‐dependent manner in response to LPS stimulation. All these results suggest that β‐1,4‐GalT I play an important role in Schwann cells in vivo and vitro during pathology. In addition, β‐1,4‐GalT I production was drastically suppressed by U0126 (ERK inhibitor), SB203580 (p38 inhibitor), or SP600125 (SAPK/JNK inhibitor), which indicated that Schwann cells which regulated β‐1,4‐GalT I expression after LPS stimulation were via ERK, SAPK/JNK, and P38 MAP kinase signal pathways. J. Cell. Biochem. 108: 75–86, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Alexey S. Gorovoy Olga Gozhina John‐Sigurd Svendsen George V. Tetz Anna Domorad Victor V. Tetz Tore Lejon 《Journal of peptide science》2013,19(10):613-618
Tuberculosis is still affecting millions of people worldwide, and new resistant strains of Mycobacterium tuberculosis are being found. It is therefore necessary to find new compounds for treatment. In this paper, we report the synthesis and in vitro testing of peptidyl β‐aminoboronic acids and β‐aminoboronates with anti‐tubercular activity. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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Amyloid β‐induced astrogliosis is mediated by β1‐integrin via NADPH oxidase 2 in Alzheimer's disease 下载免费PDF全文
Ane Wyssenbach Tania Quintela Francisco Llavero Jose L. Zugaza Carlos Matute Elena Alberdi 《Aging cell》2016,15(6):1140-1152
Astrogliosis is a hallmark of Alzheimer′s disease (AD) and may constitute a primary pathogenic component of that disorder. Elucidation of signaling cascades inducing astrogliosis should help characterizing the function of astrocytes and identifying novel molecular targets to modulate AD progression. Here, we describe a novel mechanism by which soluble amyloid‐β modulates β1‐integrin activity and triggers NADPH oxidase (NOX)‐dependent astrogliosis in vitro and in vivo. Amyloid‐β oligomers activate a PI3K/classical PKC/Rac1/NOX pathway which is initiated by β1‐integrin in cultured astrocytes. This mechanism promotes β1‐integrin maturation, upregulation of NOX2 and of the glial fibrillary acidic protein (GFAP) in astrocytes in vitro and in hippocampal astrocytes in vivo. Notably, immunochemical analysis of the hippocampi of a triple‐transgenic AD mouse model shows increased levels of GFAP, NOX2, and β1‐integrin in reactive astrocytes which correlates with the amyloid β‐oligomer load. Finally, analysis of these proteins in postmortem frontal cortex from different stages of AD (II to V/VI) and matched controls confirmed elevated expression of NOX2 and β1‐integrin in that cortical region and specifically in reactive astrocytes, which was most prominent at advanced AD stages. Importantly, protein levels of NOX2 and β1‐integrin were significantly associated with increased amyloid‐β load in human samples. These data strongly suggest that astrogliosis in AD is caused by direct interaction of amyloid β oligomers with β1‐integrin which in turn leads to enhancing β1‐integrin and NOX2 activity via NOX‐dependent mechanisms. These observations may be relevant to AD pathophysiology. 相似文献
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Dominick L. Auci Clarence N. Ahlem Michael R. Kennedy Theodore M. Page Christopher L. Reading James M. Frincke 《Obesity (Silver Spring, Md.)》2011,19(4):806-811
Metabolic syndrome is marked by perturbed glucocorticoid (GC) signaling, systemic inflammation, and altered immune status. Dehydroepiandrosterone (DHEA), a major circulating adrenal steroid and dietary supplement, demonstrates antiobesity, anti‐inflammatory, GC‐opposing and immune‐modulating activity when administered to rodents. However, plasma DHEA levels failed to correlate with metabolic syndrome and oral replacement therapy provided only mild benefits to patients. Androstene‐3β,7β,17β‐triol (β‐AET) an anti‐inflammatory metabolite of DHEA, also exhibits GC‐opposing and immune‐modulating activity when administered to rodents. We hypothesized a role for β‐AET in obesity. We now report that plasma levels of β‐AET positively correlate with BMI in healthy men and women. Together with previous studies, the observations reported here may suggest a compensatory role for β‐AET in preventing the development of metabolic syndrome. The β‐AET structural core may provide the basis for novel pharmaceuticals to treat this disease. 相似文献
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Activation of Wnt/β‐catenin signalling is required for TGF‐β/Smad2/3 signalling during myofibroblast proliferation 下载免费PDF全文
Liang Xu Wen‐Hui Cui Wen‐Cheng Zhou De‐Lin Li Liu‐Cheng Li Ping Zhao Xiao‐Ting Mo Zhihui Zhang Jian Gao 《Journal of cellular and molecular medicine》2017,21(8):1545-1554
Fibrosis in animal models and human diseases is associated with aberrant activation of the Wnt/β‐catenin pathway. Despite extensive research efforts, effective therapies are still not available. Myofibroblasts are major effectors, responsible for extracellular matrix deposition. Inhibiting the proliferation of the myofibroblast is crucial for treatment of fibrosis. Proliferation of myofibroblasts can have many triggering effects that result in fibrosis. In recent years, the Wnt pathway has been studied as an underlying factor as a primary contributor to fibrotic diseases. These efforts notwithstanding, the specific mechanisms by which Wnt‐mediated promotes fibrosis reaction remain obscure. The central role of the transforming growth factor‐β (TGF‐β) and myofibroblast activity in the pathogenesis of fibrosis has become generally accepted. The details of interaction between these two processes are not obvious. The present investigation was conducted to evaluate the level of sustained expression of fibrosis iconic proteins (vimentin, α‐SMA and collagen I) and the TGF‐β signalling pathway that include smad2/3 and its phosphorylated form p‐smad2/3. Detailed analysis of the possible molecular mechanisms mediated by β‐catenin revealed epithelial–mesenchymal transition and additionally demonstrated transitions of fibroblasts to myofibroblast cell forms, along with increased activity of β‐catenin in regulation of the signalling network, which acts to counteract autocrine TGF‐β/smad2/3 signalling. A major outcome of this study is improved insight into the mechanisms by which epithelial and mesenchymal cells activated by TGFβ1‐smad2/3 signalling through Wnt/β‐catenin contribute to lung fibrosis. 相似文献
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The performance of a resazurin chromogenic agar plate with a combined disc method for rapid screening of extended‐spectrum‐β‐lactamases,AmpC β‐lactamases and co‐β‐lactamases in Enterobacteriaceae 下载免费PDF全文
Yothin Teethaisong Katie Evans Ismini Nakouti Kanokwan Tiamyom James R. Ketudat‐Cairns Glyn Hobbs Griangsak Eumkeb 《Microbiology and immunology》2017,61(8):297-304
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Bárbara Lara‐Chacón Mario Bermúdez de León Daniel Leocadio Pablo Gómez Lizeth Fuentes‐Mera Ivette Martínez‐Vieyra Arturo Ortega David A. Jans Bulmaro Cisneros 《Journal of cellular biochemistry》2010,110(3):706-717
β‐dystroglycan (β‐DG) is a widely expressed transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton, and thereby contributing to plasma membrane integrity and signal transduction. We previously observed nuclear localization of β‐DG in cultured cell lines, implying the existence of a nuclear targeting mechanism that directs it to the nucleus instead of the plasma membrane. In this study, we delineate the nuclear import pathway of β‐DG, characterizing a functional nuclear localization signal (NLS) in the β‐DG cytoplasmic domain, within amino acids 776–782. The NLS either alone or in the context of the whole β‐DG protein was able to target the heterologous GFP protein to the nucleus, with site‐directed mutagenesis indicating that amino acids R779 and K780 are critical for NLS functionality. The nuclear transport molecules Importin (Imp)α and Impβ bound with high affinity to the NLS of β‐DG and were found to be essential for NLS‐dependent nuclear import in an in vitro reconstituted nuclear transport assay; cotransfection experiments confirmed the dependence on Ran for nuclear accumulation. Intriguingly, experiments suggested that tyrosine phosphorylation of β‐DG may result in cytoplasmic retention, with Y892 playing a key role. β‐DG thus follows a conventional Impα/β‐dependent nuclear import pathway, with important implications for its potential function in the nucleus. J. Cell. Biochem. 110: 706–717, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
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Evaluation of tubulin β‐3 as a novel senescence‐associated gene in melanocytic malignant transformation 下载免费PDF全文
Kyriakos Orfanidis Petra Wäster Katarzyna Lundmark Inger Rosdahl Karin Öllinger 《Pigment cell & melanoma research》2017,30(2):243-254
Malignant melanoma might develop from melanocytic nevi in which the growth‐arrested state has been broken. We analyzed the gene expression of young and senescent human melanocytes in culture and compared the gene expression data with a dataset from nevi and melanomas. A concordant altered gene expression was identified in 84 genes when comparing the growth‐arrested samples with proliferating samples. TUBB3, which encodes the microtubule protein tubulin β‐3, showed a decreased expression in senescent melanocytes and nevi and was selected for further studies. Depletion of tubulin β‐3 caused accumulation of cells in the G2/M phase and decreased proliferation and migration. Immunohistochemical assessment of tubulin β‐3 in benign lesions revealed strong staining in the superficial part of the intradermal components, which faded with depth. In contrast, primary melanomas exhibited staining without gradient in a disordered pattern and strong staining of the invasive front. Our results describe an approach to find clinically useful diagnostic biomarkers to more precisely identify cutaneous malignant melanoma and present tubulin β‐3 as a candidate marker. 相似文献
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Małgorzata A. Broda Aneta Buczek Dawid Siodłak Barbara Rzeszotarska 《Journal of peptide science》2009,15(7):465-473
Dehydroamino acids are non‐coded amino acids that offer unique conformational properties. Dehydrophenylalanine (ΔPhe) is most commonly used to modify bioactive peptides to constrain the topography of the phenyl ring in the side chain, which commonly serves as a pharmacophore. The Ramachandran maps (in the gas phase and in CHCl3 mimicking environments) of ΔPhe analogues with methyl groups at the β position of the side chain as well as at the C‐terminal amide were calculated using the B3LYP/6‐31 + G** method. Unexpectedly, β‐methylation alone results in an increase of conformational freedom of the affected ΔPhe residue. However, further modification by introducing an additional methyl group at C‐terminal methyl amide results in a steric crowding that fixes the torsion angle ψ of all conformers to the value 123°, regardless of the Z or E position of the phenyl ring. The number of conformers is reduced and the accessible conformational space of the residues is very limited. In particular, (Z)‐Δ(βMe)Phe with the tertiary C‐terminal amide can be classified as the amino acid derivative that has a single conformational state as it seems to adopt only the β conformation. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. 相似文献