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1.
Article in Korean | WPRIM | ID: wpr-811256

ABSTRACT

PURPOSE: Diabetic nephropathy is one of the most important diabetic complications prompted by chronic hyperglycemia, characterized by glomerulosclerosis, tubular fibrosis, and it eventually causes kidney failure. Nobiletin is a polymethoxyflavone present in tangerine and other citrus peels, and has anti-cancer and anti-inflammatory effects. This study investigated the effects of nobiletin on glomerular fibrosis through inhibition of the transforming growth factor (TGF)-β1-Src-caveolin-1 pathway.METHODS: Human renal mesangial cells (HRMC) were incubated in media containing 33 mM glucose with or without 1–20 uM nobiletin for 3 day. The cellular expression levels of fibrogenic collagen IV, fibronectin, connective tissue growth factor (CTGF), TGF-β1, Src and caveolin-1 were all examined. In addition, TGF-β1, Src and caveolin-1 proteins were screened to reveal the relationship among TGF-β1-Src-caveolin-1 signaling in glomerular fibrosis.RESULTS: High glucose promoted the production of collagen IV, fibronectin and CTGF in HRMC, which was inhibited in a dose dependent manner by 1–20 uM nobiletin. The Western blot data showed that high glucose elevated the expression of TGF-β1, Src, caveolin-1 and Rho GTPase. When nobiletin was treated to the HRMC exposed to high glucose, the expression of TGF-β1-Src-caveolin-1 was dampened. Finally, TGF-β1-Src-caveolin-1 signaling pathway was activated in high glucose-exposed HRMC, and such activation was encumbered by nobiletin.CONCLUSION: These result demonstrated that nobiletin blunted high glucose-induced extracellular matrix accumulation via inhibition of the TGF-β1-Src-caveolin-1 related intracellular signaling pathway. Nobiletin may be a potent renoprotective agent to counteract diabetes-associated glomerular fibrosis that leads to kidney failure.


Subject(s)
Blotting, Western , Caveolin 1 , Citrus , Collagen , Connective Tissue Growth Factor , Diabetes Complications , Diabetic Nephropathies , Extracellular Matrix , Fibronectins , Fibrosis , Glucose , GTP Phosphohydrolases , Humans , Hyperglycemia , Mesangial Cells , Renal Insufficiency , Transforming Growth Factors
2.
Acta Physiologica Sinica ; (6): 249-254, 2020.
Article in Chinese | WPRIM | ID: wpr-827062

ABSTRACT

The aim of this study was to investigate the effect of edaravone (Eda) on the balance of mitochondrial fusion and fission in Parkinson's disease (PD) cell model. A cell model of PD was established by treating PC12 cells with 500 μmol/L 1-methyl-4-phenylpyridinium (MPP). Thiazole blue colorimetry (MTT) was used to detect the effect of different concentrations of Eda on the survival rate of PC12 cells exposed to MPP. The mitochondrial morphology was determined by laser confocal microscope. Western blot was used to measure the protein expression levels of mitochondrial fusion- and fission-related proteins, including OPA1, MFN2, DRP1 and Fis1. The results showed that pretreatment with different concentrations of Eda antagonized MPP-induced PC12 cell damage in a dose-dependent manner. The PC12 cells treated with MPP showed mitochondrial fragmentation, up-regulated DRP1 and Fis1 protein expression levels, and down-regulated MFN2 and OPA1 protein expression levels. Eda could reverse the above changes in the MPP-treated PC12 cells, but did not affect Fis1 protein expression. These results suggest that Eda has a protective effect on the mitochondrial fusion disruption induced by MPP in PC12 cells. The mechanism may be related to the up-regulation of OPA1/MFN2 and down-regulation of DRP1.


Subject(s)
1-Methyl-4-phenylpyridinium , Animals , Dynamins , Edaravone , Pharmacology , GTP Phosphohydrolases , Mitochondria , Mitochondrial Dynamics , Mitochondrial Proteins , PC12 Cells , Parkinson Disease , Rats , Up-Regulation
3.
Immune Network ; : e33-2019.
Article in English | WPRIM | ID: wpr-764027

ABSTRACT

Viperin is an IFN-stimulated gene (ISG)-encoded protein that was identified in human primary macrophages treated with IFN-γ and in human primary fibroblasts infected with cytomegalovirus (CMV). This protein plays multiple roles in various cell types. It inhibits viral replication, mediates signaling pathways, and regulates cellular metabolism. Recent studies have shown that viperin inhibits IFN expression in macrophages, while it enhances TLR7 and TLR9-mediated IFN production in plasmacytoid dendritic cells, suggesting that viperin can play different roles in activation of the same pathway in different cell types. Viperin also controls induction of ISGs in macrophages. However, the effect of viperin on induction of ISGs in cell types other than macrophages is unknown. Here, we show that viperin differentially induces ISGs in 2 distinct cell types, macrophages and fibroblasts isolated from wild type and viperin knockout mice. Unlike in bone marrow-derived macrophages (BMDMs), viperin downregulates the expression levels of ISGs such as bone marrow stromal cell antigen-2, Isg15, Isg54, myxovirus resistance dynamin like GTPase 2, and guanylate binding protein 2 in murine embryonic fibroblasts (MEFs) treated with type I or II IFN. However, viperin upregulates expression of these ISGs in both BMDMs and MEFs stimulated with polyinosinic-polycytidylic acid or CpG DNA and infected with murine CMV. The efficiency of viral entry is inversely proportional to the expression levels of ISGs in both cell types. The data indicate that viperin differentially regulates induction of ISGs in a cell type-dependent manner, which might provide different innate immune responses in distinct cell types against infections.


Subject(s)
Animals , Carrier Proteins , Cytomegalovirus , Dendritic Cells , DNA , Dynamins , Fibroblasts , GTP Phosphohydrolases , Humans , Immunity, Innate , Interferons , Macrophages , Mesenchymal Stem Cells , Metabolism , Mice , Mice, Knockout , Orthomyxoviridae , Poly I-C
4.
Article in English | WPRIM | ID: wpr-759014

ABSTRACT

The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.


Subject(s)
Acute Kidney Injury , Animals , Cell Membrane , Ear , Exocytosis , Extracellular Vesicles , GTP Phosphohydrolases , GTPase-Activating Proteins , Guanine Nucleotide Exchange Factors , Heart , Humans , Kidney , Mice , Monomeric GTP-Binding Proteins , Sensitivity and Specificity , trans-Golgi Network
5.
Article in English | WPRIM | ID: wpr-764233

ABSTRACT

The dynamics of the actin cytoskeleton plays a pivotal role in the process of cell division, the transportation of organelles, vesicle trafficking and cell movement. Human immunodeficiency virus type 1 (HIV-1) hijacks the actin dynamics network during the viral entry and migration of the pre-integration complex (PIC) into the nucleus. Actin dynamics linked to HIV-1 has emerged as a potent therapeutic target against HIV infection. Although some inhibitors have been intensely analyzed with regard to HIV-1 infection, their effects are sometimes disputed and the exact mechanisms for actin dynamics in HIV infection have not been well elucidated. In this study, the small molecules regulating HIV-1 infection from diverse inhibitors of the actin dynamic network were screened. Two compounds, including Chaetoglobosin A and CK-548, were observed to specifically bar the viral infection, while the cytochalasin family, 187-1, N-WASP inhibitor, Rho GTPase family inhibitors (EHop-016, CID44216842, and ML-141) and LIMK inhibitor (LIM domain kinase inhibitor) increased the viral infection without cytotoxicity within a range of ~ µM. However, previously known inhibitory compounds of HIV-1 infection, such as Latrunculin A, Jasplakinolide, Wiskostatin and Swinholide A, exhibited either an inhibitory effect on HIV-1 infection combined with severe cytotoxicity or showed no effects. Our data indicate that Chaetoglobosin A and CK-548 have considerable potential for development as new therapeutic drugs for the treatment of HIV infection. In addition, the newly identified roles of Cytochalasins and some inhibitors of Rho GTPase and LIMK may provide fundamental knowledge for understanding the complicated actin dynamic pathway when infected by HIV-1. Remarkably, the newly defined action modes of the inhibitors may be helpful in developing potent anti-HIV drugs that target the actin network, which are required for HIV infection.


Subject(s)
Actin Cytoskeleton , Actins , Anti-HIV Agents , Cell Division , Cell Movement , Cytochalasins , GTP Phosphohydrolases , HIV Infections , HIV-1 , Humans , Organelles , Phosphotransferases , Transportation
6.
Article in English | WPRIM | ID: wpr-763046

ABSTRACT

Rab25, a member of the Rab11 small GTPase family, is central to achieving cellular polarity in epithelial tissues. Rab25 is highly expressed in epithelial cells of various tissues including breast, vagina, cervix, the gastrointestinal tract, and skin. Rab25 plays key roles in tumorigenesis, mainly by regulating epithelial differentiation and proliferation. However, its role in skin physiology is relatively unknown. In this study, we demonstrated that Rab25 knock-out (KO) mice show a skin barrier dysfunction with high trans-epidermal water loss and low cutaneous hydration. To examine this observation, we investigated the histology and epidermal differentiation markers of the skin in Rab25 KO mice. Rab25 KO increased cell proliferation at the basal layer of epidermis, whereas the supra-basal layer remained unaffected. Ceramide, which is a critical lipid component for skin barrier function, was not altered by Rab25 KO in its distribution or amount, as determined by immunohistochemistry. Notably, levels of epidermal differentiation markers, including loricrin, involucrin, and keratins (5, 14, 1, and 10) increased prominently in Rab25 KO mice. In line with this, depletion of Rab25 with single hairpin RNA increased the expression of differentiation markers in a human keratinocyte cell line, HaCaT. Transcriptomic analysis of the skin revealed increased expression of genes associated with skin development, epidermal development, and keratinocyte differentiation in Rab25 KO mice. Collectively, these results suggested that Rab25 is involved in the regulation of epidermal differentiation and proliferation.


Subject(s)
Animals , Antigens, Differentiation , Breast , Carcinogenesis , Cell Line , Cell Proliferation , Cervix Uteri , Epidermis , Epithelial Cells , Female , Gastrointestinal Tract , GTP Phosphohydrolases , Humans , Immunohistochemistry , Keratinocytes , Mice , RNA , Skin Physiological Phenomena , Skin , Vagina , Water
7.
Frontiers of Medicine ; (4): 229-237, 2019.
Article in English | WPRIM | ID: wpr-771312

ABSTRACT

This retrospective analysis aimed to investigate the mutation profile of 16 common mutated genes in de novo acute myeloid leukemia (AML) patients. A total of 259 patients who were diagnosed of de novo AML were enrolled in this study. Mutation profiling of 16 candidate genes were performed in bone marrow samples by using Sanger sequencing.We identified at least 1 mutation in 199 of the 259 samples (76.8%), and 2 or more mutations in 31.7% of samples. FLT3-ITD was the most common mutated gene (16.2%, 42/259), followed by CEBPA (15.1%, 39/259), NRAS (14.7%, 38/259), and NPM1 (13.5%, 35/259). Concurrence was observed in 97.1% of the NPM1 mutated cases and in 29.6% of the double mutated CEBPA cases. Distinct patterns of co-occurrence were observed for different hotspot mutations within the IDH2 gene: R140 mutations were associated with NPM1 and/or FLT3-ITD mutations, whereas R172 mutations co-occurred with DNMT3A mutations only. Concurrence was also observed in 86.6% of epigenetic regulation genes, most of which co-occurred with NPM1 mutations. The results showed certain rules in the mutation profiling and concurrence of AML patients, which was related to the function classification of genes. Defining the mutation spectrum and mutation pattern of AML will contribute to the comprehensive assessment of patients and identification of new therapeutic targets.


Subject(s)
Adolescent , Adult , Aged , CCAAT-Enhancer-Binding Proteins , Genetics , Child , Child, Preschool , China , DNA Mutational Analysis , Female , GTP Phosphohydrolases , Genetics , Gene Expression Profiling , Gene Frequency , Genetic Predisposition to Disease , Humans , Kaplan-Meier Estimate , Leukemia, Myeloid, Acute , Genetics , Male , Membrane Proteins , Genetics , Middle Aged , Mutation , Nuclear Proteins , Genetics , Phenotype , Retrospective Studies , Young Adult , fms-Like Tyrosine Kinase 3 , Genetics
8.
Experimental Neurobiology ; : 172-182, 2019.
Article in English | WPRIM | ID: wpr-739545

ABSTRACT

Rheb (Ras homolog enriched in the brain) is a small GTPase protein that plays an important role in cell signaling for development of the neocortex through modulation of mTORC1 (mammalian-target-of-rapamycin-complex-1) activity. mTORC1 is known to control various biological processes including axonal growth in forming complexes at the lysosomal membrane compartment. As such, anchoring of Rheb on the lysosomal membrane via the farnesylation of Rheb at its cysteine residue (C180) is required for its promotion of mTOR activity. To test the significance of Rheb farnesylation, we overexpressed a farnesylation mutant form of Rheb, Rheb C180S, in primary rat hippocampal neurons and also in mouse embryonic neurons using in utero electroporation. Interestingly, we found that Rheb C180S maintained promotional effect of axonal elongation similar to the wild-type Rheb in both test systems. On the other hand, Rheb C180S failed to exhibit the multiple axon-promoting effect which is found in wild-type Rheb. The levels of phospho-4EBP1, a downstream target of mTORC1, were surprisingly increased in Rheb C180S transfected neurons, despite the levels of phosphorylated mTOR being significantly decreased compared to control vector transfectants. A specific mTORC1 inhibitor, rapamycin, also could not completely abolish axon elongation characteristics of Rheb C180S in transfected cells. Our data suggests that Rheb in a non-membrane compartment can promote the axonal elongation via phosphorylation of 4EBP1 and through an mTORC1-independent pathway.


Subject(s)
Animals , Axons , Biological Phenomena , Cysteine , Electroporation , GTP Phosphohydrolases , Hand , Membranes , Mice , Neocortex , Neurons , Phosphorylation , Prenylation , Protein Prenylation , Rats , Sirolimus , TOR Serine-Threonine Kinases
9.
Middle East Journal of Digestive Diseases. 2018; 10 (1): 18-23
in English | IMEMR | ID: emr-192420

ABSTRACT

Background: Incidence of colorectal cancer is increasing in countries such as Iran. Molecular biomarkers play very important role in the diagnosis, treatment, and prognosis of this cancer. Mutation in the RAS family [including KRAS and NRAS] is one of these important molecular biomarkers, which should be tested before starting treatment with anti-EGRF [Epidermal growth factor] drugs


Objectives: There has been very few reports about the frequency of NRAS mutation from Iran and no study from south of the country. In this article we will describe our experience about the frequency of NRAS mutation in colorectal cancers from the largest referral center in the south of Iran


Methods: During 5 years [2011-2015], we had 52 cases of colorectal cancers with wild type KRAS and BRAF in the hospitals affiliated to Shiraz University of Medical Sciences with enough tissue for molecular studies. NRAS mutation analysis was performed on paraffin embedded formalin fixed tissue of these cases by polymerase chain reaction [PCR]-sequencing method


Results: Among these 52 cases of colorectal cancer with wild type KRAS and BRAF, there has been 3 [5.7%] cases with mutant NRAS. One of the mutations has been in codon 12 and two in codon 61. No mutation in codon 13 was found. All the three cases were women with stage IV and well differentiated histomorphology


Conclusion: Our results showed that frequency of NRAS mutation in colorectal cancer is rare, which is very close to other studies from different geographic areas of the world


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Aged, 80 and over , Mutation , Polymerase Chain Reaction , Biomarkers , Biomarkers, Tumor , Membrane Proteins , GTP Phosphohydrolases , Proto-Oncogene Proteins p21(ras) , Proto-Oncogene Proteins B-raf
10.
Mycobiology ; : 114-121, 2018.
Article in English | WPRIM | ID: wpr-729789

ABSTRACT

Mon1 is a guanine nucleotide exchange factor subunit that activates the Ypt7 Rab GTPase and is essential for vacuole trafficking and autophagy in eukaryotic organisms. Here, we identified and characterized the function of Mon1, an ortholog of Saccharomyces cerevisiae Mon1, in a human fungal pathogen, Cryptococcus neoformans. Mutation in mon1 resulted in hypersensitivity to thermal stress. The mon1 deletion mutant exhibited increased sensitivity to cell wall and endoplasmic reticulum stress. However, the mon1 deletion mutant showed more resistance to the antifungal agent fluconazole. In vivo studies demonstrated that compared to the wild-type strain, the mon1 deletion mutant attenuated virulence in the Galleria mellonella insect model. Moreover, the mon1 deletion mutant was avirulent in the murine inhalation model. These results demonstrate that Mon1 plays a crucial role in stress survival and pathogenicity in C. neoformans.


Subject(s)
Autophagy , Cell Wall , Cryptococcus neoformans , Cryptococcus , Endoplasmic Reticulum Stress , Fluconazole , GTP Phosphohydrolases , Guanine Nucleotide Exchange Factors , Humans , Hypersensitivity , Inhalation , Insecta , Saccharomyces cerevisiae , Vacuoles , Virulence
11.
Journal of Stroke ; : 110-121, 2018.
Article in English | WPRIM | ID: wpr-740604

ABSTRACT

BACKGROUND AND PURPOSE: MicroRNA (miRNA) expression has been examined in multiple conditions, including various cancers, neurological diseases, and cerebrovascular diseases, particularly stroke. Existing evidence indicates that miRNA biosynthesis and function play crucial roles in ischemic stroke physiology and pathology. In this study, we selected six known polymorphisms in miRNA-biogenesis genes; DICER rs13078A>T, rs3742330A>G; DROSHA rs10719T>C, rs6877842G>C; Ran GTPase (RAN) rs14035C>T; exportin 5 (XPO5) rs11077A>C. METHODS: We analyzed the associations between these polymorphisms and disease status and clinical factors in 585 ischemic stroke patients and 403 controls. Genotyping was performed with the polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: The DICER rs3742330A>G (AA vs. AG+GG: adjusted odds ratio [AOR], 1.360; 95% confidence interval [CI], 1.024 to 1.807; P=0.034) and DROSHA rs10719T>C polymorphisms (TT vs. CC: AOR, 2.038; 95% CI, 1.113 to 3.730; P=0.021) were associated with ischemic stroke prevalence. During a mean follow-up of 4.80±2.11 years, 99 (5.91%) of the stroke patients died. In multivariate Cox proportional hazard regression models, a significant association was found between RAN rs14035 and survival of large artery disease patients with ischemic stroke (CC vs. TT: adjusted hazard ratio, 5.978; P=0.015). CONCLUSIONS: An association was identified between the DICER and DROSHA polymorphisms and ischemic stroke. Specifically, polymorphisms (rs3742330 and rs10719) were more common in stroke patients, suggesting that they may be associated with an increased risk of ischemic stroke.


Subject(s)
Arteries , Cerebrovascular Disorders , Follow-Up Studies , GTP Phosphohydrolases , Humans , Methods , MicroRNAs , Mortality , Odds Ratio , Pathology , Physiology , Polymorphism, Genetic , Prevalence , Stroke
12.
Article in English | WPRIM | ID: wpr-716963

ABSTRACT

BACKGROUND: Emerging evidence suggests that sphingolipids may be involved in type 2 diabetes. However, the exact signaling defect through which disordered sphingolipid metabolism induces β-cell dysfunction remains unknown. The current study demonstrated that sphingosine-1-phosphate (S1P), the product of sphingosine kinase (SphK), is an essential factor for maintaining β-cell function and survival via regulation of mitochondrial action, as mediated by prohibitin (PHB). METHODS: We examined β-cell function and viability, as measured by mitochondrial function, in mouse insulinoma 6 (MIN6) cells in response to manipulation of cellular S1P and PHB levels. RESULTS: Lack of S1P induced by sphingosine kinase inhibitor (SphKi) treatment caused β-cell dysfunction and apoptosis, with repression of mitochondrial function shown by decreases in cellular adenosine triphosphate content, the oxygen consumption rate, the expression of oxidative phosphorylation complexes, the mitochondrial membrane potential, and the expression of key regulators of mitochondrial dynamics (mitochondrial dynamin-like GTPase [OPA1] and mitofusin 1 [MFN1]). Supplementation of S1P led to the recovery of mitochondrial function and greatly improved β-cell function and viability. Knockdown of SphK2 using small interfering RNA induced mitochondrial dysfunction, decreased glucose-stimulated insulin secretion (GSIS), and reduced the expression of PHB, an essential regulator of mitochondrial metabolism. PHB deficiency significantly reduced GSIS and induced mitochondrial dysfunction, and co-treatment with S1P did not reverse these trends. CONCLUSION: Altogether, these data suggest that S1P is an essential factor in the maintenance of β-cell function and survival through its regulation of mitochondrial action and PHB expression.


Subject(s)
Adenosine Triphosphate , Animals , Apoptosis , GTP Phosphohydrolases , Insulin , Insulin-Secreting Cells , Insulinoma , Membrane Potential, Mitochondrial , Metabolism , Mice , Mitochondria , Mitochondrial Dynamics , Oxidative Phosphorylation , Oxygen Consumption , Phosphotransferases , Repression, Psychology , RNA, Small Interfering , Sphingolipids , Sphingosine
13.
Braz. j. med. biol. res ; 50(6): e5758, 2017. tab, graf
Article in English | LILACS | ID: biblio-839304

ABSTRACT

This study aimed to determine the role of mitofusin 2 (MFN2) gene polymorphisms in the risk and prognosis of acute liver failure (ALF). A total of 298 blood samples were collected from 138 ALF patients (case group) and 160 healthy participants (control group). Coagulation function, glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), total bilirubin (TB), blood ammonia and lactic acid (LA) were measured. The predictive evaluation of MFN2 gene polymorphisms in the risk and prognosis of ALF patients was estimated using Kaplan-Meier survival analysis, haplotype analysis, binary logistic regression analysis and Cox regression analysis. Higher levels of GPT, GOT, TB, blood ammonia and LA were observed in ALF patients with the GG genotype of rs873457 or the TT genotype of rs4846085 than in those with the CC genotype of these two SNPs. The GTACAGC and GTGTGGC haplotypes were a protective factor and a risk factor for ALF, respectively. Blood ammonia and LA levels were independent risk factors and the CC genotype of rs873457 and the CC genotype of rs4846085 were protective factors for ALF. ALF patients with the GG genotype of rs873457 or the TT genotype of rs4846085 had a lower survival rate than those with other genotypes of these two SNPs. The rs4846085 and rs873457 polymorphisms were both independent factors affecting the prognosis of ALF patients. MFN2 gene polymorphisms (rs873457, rs2336384, rs1474868, rs4846085 and rs2236055) may be associated with ALF and the rs873457 and rs4846085 polymorphisms are correlated with the risk and prognosis of ALF.


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Young Adult , GTP Phosphohydrolases/genetics , Liver Failure, Acute/genetics , Mitochondrial Proteins/genetics , Polymorphism, Single Nucleotide , Ammonia/blood , Asian Continental Ancestry Group/genetics , Case-Control Studies , China , Gene Frequency/genetics , Genetic Predisposition to Disease/genetics , Genotype , Hepatitis A/genetics , Kaplan-Meier Estimate , Lactic Acid/blood , Liver Failure, Acute/blood , Risk Factors , Survival Analysis
14.
Article in English | WPRIM | ID: wpr-161484

ABSTRACT

Aging-dependent cellular behaviors toward extrinsic stress are characterized by the confined localization of certain molecules to either nuclear or perinuclear regions. Although most growth factors can activate downstream signaling in aging cells, they do not in fact have any impact on the cells because the signals cannot reach their genetic targets in the nucleus. For the same reason, varying apoptotic stress factors cannot stimulate the apoptotic pathway in senescent cells. Thus, the operation of a functional nuclear barrier in an aging-dependent manner has been investigated. To elucidate the mechanism for this process, the housekeeping transcription factor Sp1 was identified as a general regulator of nucleocytoplasmic trafficking (NCT) genes, including various nucleoporins, importins, exportins and Ran GTPase cycle-related genes. Interestingly, the posttranslational modification of Sp1 is readily influenced by extrinsic stress, including oxidative and metabolic stress. The decrease in SP1 O-GlcNAcylation under oxidative stress or during replicative senescence makes it susceptible to proteosomal degradation, resulting in defective NCT functions and leading to nuclear barrier formation. The operation of the nuclear barrier in aging provides a fundamental mechanism for cellular protection against stress and promotes survival at the expense of growth via stress-sensitive transcriptional control.


Subject(s)
Aging , Cellular Senescence , GTP Phosphohydrolases , Housekeeping , Intercellular Signaling Peptides and Proteins , Karyopherins , Nuclear Pore Complex Proteins , Oxidative Stress , Protein Processing, Post-Translational , Stress, Physiological , Transcription Factors
15.
Protein & Cell ; (12): 187-200, 2016.
Article in English | WPRIM | ID: wpr-757153

ABSTRACT

The human Shwachman-Diamond syndrome (SDS) is an autosomal recessive disease caused by mutations in a highly conserved ribosome assembly factor SBDS. The functional role of SBDS is to cooperate with another assembly factor, elongation factor 1-like (Efl1), to promote the release of eukaryotic initiation factor 6 (eIF6) from the late-stage cytoplasmic 60S precursors. In the present work, we characterized, both biochemically and structurally, the interaction between the 60S subunit and SBDS protein (Sdo1p) from yeast. Our data show that Sdo1p interacts tightly with the mature 60S subunit in vitro through its domain I and II, and is capable of bridging two 60S subunits to form a stable 2:2 dimer. Structural analysis indicates that Sdo1p bind to the ribosomal P-site, in the proximity of uL16 and uL5, and with direct contact to H69 and H38. The dynamic nature of Sdo1p on the 60S subunit, together with its strategic binding position, suggests a surveillance role of Sdo1p in monitoring the conformational maturation of the ribosomal P-site. Altogether, our data support a conformational signal-relay cascade during late-stage 60S maturation, involving uL16, Sdo1p, and Efl1p, which interrogates the functional P-site to control the departure of the anti-association factor eIF6.


Subject(s)
Crystallography, X-Ray , GTP Phosphohydrolases , Chemistry , Metabolism , Humans , Protein Domains , Ribosome Subunits, Large, Eukaryotic , Chemistry , Metabolism , Saccharomyces cerevisiae , Chemistry , Metabolism , Saccharomyces cerevisiae Proteins , Chemistry , Metabolism
16.
São Paulo; s.n; s.n; 2015. 157 p. tab, graf, ilus.
Thesis in Portuguese | LILACS | ID: biblio-847447

ABSTRACT

O mecanismo pelo qual uma célula responde a algum dano no seu material genético é extremamente importante. Isto ocorre pela rápida ativação da maquinaria de reparo de danos no DNA, a qual é composta por uma rede intrincada de sinalização proteica, culminando no reparo do DNA; porém se o dano for irreparável ocorre ativação de mecanismos de morte celular. RhoA,e Rac1 pertencem a família das pequenas proteínas sinalizadoras Rho GTPases, as quais atuam como interruptores moleculares ciclando entre estado ativo (ligada a GTP) e inativo (ligada a GDP). Os componentes desta família estão relacionados ao controle dos mais diversos processos celulares como, por exemplo, remodelamento do citoesqueleto, migração, adesão, endocitose, progressão do ciclo celular e oncogênese. No entanto, apesar das proteínas Rho GTPases estarem envolvidas em um amplo espectro de atividades biológicas, há poucas informações sobre seu papel na manutenção da integridade genômica quando células são submetidas a algum agente genotóxico. Para investigar o envolvimento das GTPases RhoA e Rac1 nas respostas de células submetidas a radiação gama, foram gerados, a partir de células de carcinoma de cervix humano - HeLa, sublinhagens clonais mutantes de RhoA e Rac1 expressando exogenamente RhoA constitutivamente ativa (HeLa-RhoA V14), RhoA dominante negativa (HeLa-RhoA N19), Rac1 constitutivamente ativa (HeLa-Rac1 V12) e Rac1 dominante negativa (HeLa-Rac N17). Após estas linhagens celulares serem expostas a diferentes doses de radiação gama, observamos que ambas GTPases, RhoA e Rac1, são ativadas em resposta aos efeitos da radiação. Além disso, a modulação da atividade destas enzimas, através das mutações, levou a uma alteração das respostas celulares frente aos danos no DNA, como uma redução da capacidade de reparar quebras simples e duplas nas fitas do DNA. Por outro lado, a deficiência de RhoA ou Rac1 GTPase levou a uma redução da ativação de Chk1 e Chk2 ou da fosforilação da histona H2AX, respectivamente, prejudicando os mecanismos de detecção de danos no DNA e levando as células a permanecerem mais tempo nos pontos de checagem G1/S e/ou G2/M do ciclo celular. Esses fatores contribuíram de modo expressivo para a redução da proliferação e sobrevivência celular levando as células à morte. Por fim, ensaios celulares de reparo de danos de um DNA exógeno através de mecanismos de Recombinação Homóloga (HR) e Recombinação Não-Homóloga de extremidades (NHEJ), demonstraram que a inibição da atividade de RhoA reduz significativamente a eficiência de ambas vias de reparo. Desta maneira, este trabalho demonstra e reforça a existência de mais um viés de atuação das pequenas GTPases RhoA e Rac1, agora em células HeLa, nas respostas celulares aos danos induzidos por exposição a radiação gama, modulando a sobrevivência, proliferação e indiretamente modulando resposta ao reparo do DNA através da via de Recombinação Homóloga e Não-Homóloga


The mechanism by which a cell responds to DNA damage is extremely important. This occurs by a quick activation of the DNA damage repair machinery, which consists of an intricate protein signaling network culminating in DNA repair. But if the damages are irreparable occurs there is activation of cell death mechanisms. RhoA and Rac1 belong to family of small Rho GTPases, signaling proteins that act as molecular switches cycling between the active state (GTP-bound) and inactive state (GDP-bound). Members of this family are implicated in the control of diverse cellular process such as cytoskeletal remodeling, migration, adhesion, endocytosis, cell cycle progression, and oncogenesis. However, despite Rho proteins are involved in a broad spectrum of biological activities, there is just a few information about their roles in the maintenance of genomic integrity, that is, when the cells are subjected to some kinf of genotoxic agent. To investigate the involvement of the GTPases RhoA and Rac1 in cellular responses to gamma radiation, we generated from human cervix carcinoma cells - HeLa, clonal sublines of RhoA and Rac1 mutants, exogenous and stably expressing the constitutively active RhoA (HeLa-RhoA V14), the dominant negative RhoA (HeLa-RhoA N19), the constitutively active Rac1 (HeLa-Rac1 V12) and the dominant negative Rac1 (HeLa-Rac1 N17). After all these cell lines have been exposed to different doses of gamma radiation, we found that both GTPases, RhoA and Rac1, are activated in response to the radiation effects. Furthermore, the modulation of two enzymes activity, by using the mutant clones, led to a change in cellular responses to the DNA damage, as the reduction in the capacity of repairing DNA single and double strand breaksr. On the other hand, the deficiency of RhoA or Rac1 GTPase led to a reduction of Chk1 and Chk2 activation, or on the phosphorylation of histone H2AX, respectively, hindering the mechanisms of DNA damage detection and arresting cells in the G1/S and/or G2/M checkpoints of cell cycle. These factors significantly contributed to the reduction of cell proliferation and survival, leading cells to death. Finally, cellular assays of DNA damage repair of exogenous DNA by Homologous Recombination (HR) and Non-Homologous End Joining (NHEJ), demonstrated that RhoA inhibition significantly reduced the repair efficiency of both pathways. Thus, this work demonstrates and reinforces the existence of other biological functions of small GTPases RhoA and Rac1 in HeLa cells, by regulating cellular responses to DNA damage induced by exposure to gamma radiation, modulating the survival, proliferation and indirectly modulating the response to DNA damage repair pathway through the Homologous Recombination and Non-Homologous Recombination


Subject(s)
GTP Phosphohydrolases/analysis , rac1 GTP-Binding Protein/analysis , rhoA GTP-Binding Protein/analysis , DNA End-Joining Repair/genetics , HeLa Cells , Homologous Recombination/genetics , Radiation
17.
Acta Pharmaceutica Sinica ; (12): 1186-1191, 2015.
Article in Chinese | WPRIM | ID: wpr-257008

ABSTRACT

Four small GTPase genes which may be relative to sclerotial development were firstly cloned from medicinal fungus Polyporus umbellatus using rapid amplification of cDNA end PCR (RACE) method. The results showed that full-length cDNA of PuRhoA was 698 bp contained 585 bp ORF, which was predicted to encode a 194 amino acid protein with a molecular weight of 21.75 kD with an isoelectric point (pI) of 6.44; the full length cDNA of PuRhoA2 was 837 bp in length and encoded a 194 amino acid protein with a molecular weight of 21.75 kD and an isoelectric point (pI) of 6.33; the full length cDNA of Puypt1 was 896 bp in length and encoded a 204-aa protein with a molecular weight of 22.556 kD and an isoelectric point (pI) of 5.75; the full length cDNA of PuRas was 803 bp in length and encoded a 212-aa protein with a molecular weight of 23.821 kD and an isoelectric point (pI) of 5.2. There are fani acyl transferase enzyme catalytic site and myrcene-transferase enzyme catalytic site in PuRhoA1 while the PuRhoA2 only possess myrcene-transferase enzyme catalytic site. Puypt1 contains the Rab1-Ypt1 conserved domain of small GTPase family and PuRas contains the fani acyl transferase enzyme catalytic site. According to the phylogenetic analysis all these four small GTPase clustered with basidiomycete group. Quantitative real-time PCR analysis revealed that Puypt1, PuRas and PuRhoA1 transcripts were significantly higher in the beginning of sclerotial formation than that in the mycelia, whereas the transcripts levels of PuRhoA2 gene were particularly lower in sclerotia than that in mycelia, suggesting that these four genes might be involved in P umbellatus selerotial development.


Subject(s)
Amino Acid Sequence , Cloning, Molecular , DNA, Complementary , Fungal Proteins , Genetics , GTP Phosphohydrolases , Genetics , Genes, Fungal , Mycelium , Phylogeny , Polyporus , Genetics , Real-Time Polymerase Chain Reaction
18.
Article in Chinese | WPRIM | ID: wpr-351227

ABSTRACT

To observe the protective effect and mechanism of Sailuotong capsule in focal cerebral ischemia/reperfusion. The 90 min middle cerebral artery occlusion (MCAO) reperfusion model was established. The expressions of dynamin-related protein 1 ( Drp1) and optic atrophy 1 (Opa1) were tested by Western blot. The transmission electron microscope was used to observe the changes in the mitochondrial ultra-structure. The pathological morphological changes were observed through the HE staining. The immunohistochemical method was used to test Drp1 and Opa1 expressions. Sailuotong capsule (33, 16.5 mg x kg(-1), ig) can inhibit the abnormal mitochondrial fission and fusion in the cortical area on the ischemia side and the mitochondrial fission gene expression and promote the mitochondrial fusion gene Opa1 expression, so as to alleviate the energy metabolism disorder caused by ischemia/reperfusion. Sailuotong capsule can inhibit the abnormal mitochondrial dynamics in peri-ischemic regions and maintain the normal morphology of mitochondria, which may be the mechanism of Sailuotong capsule in promoting the self-recovery function in the ischemic brain region.


Subject(s)
Animals , Brain , Metabolism , Brain Ischemia , Drug Therapy , Genetics , Metabolism , General Surgery , Drugs, Chinese Herbal , Dynamins , Genetics , Metabolism , GTP Phosphohydrolases , Genetics , Metabolism , Humans , Male , Mitochondria , Metabolism , Rats
19.
Protein & Cell ; (12): 139-146, 2015.
Article in English | WPRIM | ID: wpr-757621

ABSTRACT

Formation of the endoplasmic reticulum (ER) network requires homotypic membrane fusion, which involves a class of atlastin (ATL) GTPases. Purified Drosophila ATL is capable of mediating vesicle fusion in vitro, but such activity has not been reported for any other ATLs. Here, we determined the preliminary crystal structure of the cytosolic segment of Drosophila ATL in a GDP-bound state. The structure reveals a GTPase domain dimer with the subsequent three-helix bundles associating with their own GTPase domains and pointing in opposite directions. This conformation is similar to that of human ATL1, to which GDP and high concentrations of inorganic phosphate, but not GDP only, were included. Drosophila ATL restored ER morphology defects in mammalian cells lacking ATLs, and measurements of nucleotide-dependent dimerization and GTPase activity were comparable for Drosophila ATL and human ATL1. However, purified and reconstituted human ATL1 exhibited no in vitro fusion activity. When the cytosolic segment of human ATL1 was connected to the transmembrane (TM) region and C-terminal tail (CT) of Drosophila ATL, the chimera still exhibited no fusion activity, though its GTPase activity was normal. These results suggest that GDP-bound ATLs may adopt multiple conformations and the in vitro fusion activity of ATL cannot be achieved by a simple collection of functional domains.


Subject(s)
Animals , Dimerization , Drosophila , Drosophila Proteins , Chemistry , Genetics , Endoplasmic Reticulum , Chemistry , GTP Phosphohydrolases , Chemistry , Genetics , GTP-Binding Proteins , Chemistry , Genetics , Guanosine Diphosphate , Chemistry , Metabolism , Humans , Membrane Proteins , Chemistry , Genetics , Mutation , Protein Conformation , Protein Structure, Secondary
20.
Korean Journal of Radiology ; : 1349-1352, 2015.
Article in English | WPRIM | ID: wpr-172969

ABSTRACT

Thyroid cancer may have small adipose structures detected by microscopy. However, there are no reports of thyroid cancer with gross fat evaluated by radiological methods. We reported a case of a 58-year-old woman with a fat containing thyroid mass. The mass was hyperechoic and ovoid in shape with a smooth margin on ultrasonography. On computed tomography, the mass had markedly low attenuation suggestive of fat, and fine reticular and thick septa-like structures. The patient underwent a right lobectomy. The mass was finally diagnosed as a follicular variant of papillary thyroid cancer with massive stromal fat.


Subject(s)
Carcinoma/diagnosis , Exons , Female , GTP Phosphohydrolases/genetics , Humans , Immunohistochemistry , Membrane Proteins/genetics , Middle Aged , Mutation , Thyroid Neoplasms/diagnosis , Tomography, X-Ray Computed
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