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1.
Toxicol Ind Health ; 38(7): 417-434, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35592919

RESUMO

Today, tattooing has become very popular among people all over the world. Tattooists, with the help of tiny needles, place tattoo ink inside the skin surface and unintentionally introduce a large number of unknown ingredients. These ingredients include polycyclic aromatic hydrocarbons (PAHs), heavy metals, and primary aromatic amines (PAAs), which are either unintentionally introduced along with the ink or produced inside the skin by different types of processes for example cleavage, metabolism and photodecomposition. These could pose toxicological risks to human health, if present beyond permissible limits. PAH such as Benzo(a)pyrene is present in carbon black ink. PAAs could be formed inside the skin as a result of reductive cleavage of organic azo dyes. They are reported to be highly carcinogenic by environmental protection agencies. Heavy metals, namely, cadmium, lead, mercury, antimony, beryllium, and arsenic are responsible for cancer, neurodegenerative diseases, cardiovascular, gastrointestinal, lungs, kidneys, liver, endocrine, and bone diseases. Mercury, cobalt sulphate, other soluble cobalt salts, and carbon black are in Group 2B, which means they may cause cancer in humans. Cadmium and compounds of cadmium, on the other hand, are in Group 1 (carcinogenic to humans). The present article addresses the various ingredients of tattoo inks, their metabolic fate inside human skin and unintentionally added impurities that could pose toxicological risk to human health. Public awareness and regulations that are warranted to be implemented globally for improving the safety of tattooing.


Assuntos
Mercúrio , Hidrocarbonetos Policíclicos Aromáticos , Tatuagem , Aminas/toxicidade , Cádmio , Carcinógenos/toxicidade , Humanos , Tinta , Metais , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Fuligem , Tatuagem/efeitos adversos
2.
Asian Cardiovasc Thorac Ann ; 30(2): 156-163, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33853386

RESUMO

BACKGROUND: Pulmonary complications after cardiac surgery are very common and lead to an increased incidence of post-operative morbidity and mortality. Several factors, either modifiable or non-modifiable, may contribute to the associated unfavorable consequences related to pulmonary function. This study was aimed to investigate the degree of alteration and factors influencing pulmonary function (forced expiratory volume in one second (FEV1) and forced vital capacity), on third, fifth, and seventh post-operative days following cardiac surgery. METHODS: This study was executed in 71 patients who underwent on-pump cardiac surgery. Pulmonary function was assessed before surgery and on the third, fifth, and seventh post-operative days. Data including surgical details, information about risk factors, and assessment of pulmonary function were obtained. RESULTS: The FEV1 and forced vital capacity were significantly impaired on post-operative days 3, 5, and 7 compared to pre-operative values. The reduction in FEV1 was 41%, 29%, and 16% and in forced vital capacity was 42%, 29%, and 19% consecutively on post-operative days 3, 5, and 7. Multivariate analysis was done to detect the factors influencing post-operative FEV1 and forced vital capacity. DISCUSSION: This study observed a significant impairment in FEV1 and forced vital capacity, which did not completely recover by the seventh post-operative day. Different factors affecting post-operative FEV1 and forced vital capacity were pre-operative FEV1, age ≥60, less body surface area, lower pre-operative chest expansion at the axillary level, and having more duration of cardiopulmonary bypass during surgery. Presence of these factors enhances the chance of developing post-operative pulmonary complications.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Pulmão , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Volume Expiratório Forçado , Humanos , Pulmão/cirurgia , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/etiologia , Resultado do Tratamento , Capacidade Vital
3.
Artigo em Inglês | MEDLINE | ID: mdl-33599434

RESUMO

INTRODUCTION: Homozygous familial hypercholesterolaemia (HoFH) carries a grave prognosis but is often underdiagnosed and undertreated. Confirmation of molecular diagnosis helps in planning effective management and determining prognosis accurately. Aim of the study: To determine the spectrum of mutations in the LDLR gene in a cohort of children with a clinical diagnosis of HoFH. MATERIAL AND METHODS: Genomic DNA was extracted from peripheral blood samples of 8 patients, who were children of either sex, aged under 16 years, and diagnosed clinically with HoFH using the Simon Broome criteria. The potential variants in the LDLR gene were analysed by Sanger sequencing. RESULTS: Fifty variations were found in the 8 patients; 39 (78%) were single nucleotide variations while 8 (16%) and 3 (6%) were deletions and insertions, respectively. The pathogenic variants in the LDLR gene were detected in four patients; three showed duplication in exon 17 (c.2416dupG) creating an amino acid change at position 806 (p.Val806GlyfsTer11) while one had a missense variant in the exon 9 at position c.1285G>A resulting in a change in amino acid at position 429 (p.Val429Met). The variants were found in heterozygous state in the parents or siblings of probands who showed pathogenic variants. CONCLUSIONS: The frequency of disease-causing variants in the LDLR gene in our patients with HoFH was 50%. Further studies to characterise mutations in genes for apolipoprotein B, proprotein convertase subtilisin/kexin type 9, or LDL adaptor protein are suggested in all children with a clinical diagnosis of HoFH.


Assuntos
Hiperlipoproteinemia Tipo II , Receptores de LDL , Idoso , Criança , Homozigoto , Humanos , Hiperlipoproteinemia Tipo II/genética , Mutação , Fenótipo , Receptores de LDL/genética
4.
J Cell Biochem ; 121(2): 1273-1282, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31709634

RESUMO

Prolonged exposure of the earth's surface to the sun's ultraviolet radiation may result in various skin diseases and cataract. Carbazole (CBZ), as a polycyclic-aromatic hydrocarbon (PAH), is blended with a five-member nitrogen-containing ring. It is found in cigarette smoke, coal, eye kohl, tattoo ink, and wood combustion and affects various types of flora and fauna. Our findings suggest that CBZ generates reactive oxygen species (ROS) like O2•- through type-I photodynamic reaction and causes phototoxicity in the human keratinocyte cell line (HaCaT), which has been proved by mitochondrial dehydrogenase and neutral red uptake assays. CBZ induces single strand DNA damage. We have investigated the involvement of the apoptotic pattern of cell death and confirmed it by cytochrome C release from mitochondria and caspase-9 activation. Similarly, photo-micronuclei formation was associated to CBZ-induced phototoxicity. The results of this study strongly support that the upregulation of bax, cyto-C, apaf-1, casp-9 and down regulation of bcl2, keap-1, nrf-2, and hmox-1 genes cause apoptopic cell death. Downregulation of antioxidant genes showed a significant amount of ROS generation by photosensitized CBZ. Therefore, the current study will be a step forward to safeguard human beings from sunlight-induced photosensitive CBZ prolonged exposure.


Assuntos
Carbazóis/farmacologia , Regulação da Expressão Gênica , Queratinócitos/patologia , Mitocôndrias/patologia , Estresse Oxidativo/efeitos dos fármacos , Pele/patologia , Raios Ultravioleta , Apoptose , Células Cultivadas , Citocromos c/metabolismo , Dano ao DNA , Humanos , Queratinócitos/efeitos dos fármacos , Queratinócitos/efeitos da radiação , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/efeitos da radiação , Estresse Oxidativo/efeitos da radiação , Espécies Reativas de Oxigênio , Pele/efeitos dos fármacos , Pele/efeitos da radiação
5.
Oncotarget ; 6(33): 34846-58, 2015 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-26472108

RESUMO

Enhanced rRNA synthesis is a downstream effect of many of the signaling pathways that are aberrantly activated in cancer, such as the PI3K/mTOR and MAP kinase pathways. Recently, two new rRNA synthesis inhibitors have demonstrated therapeutic effects on cancer cells while sparing normal cells. One of them, CX-5461, is currently in phase 1 clinical trials for hematological malignancies. Here, we investigate the effectiveness of transient treatment with this drug on acute lymphoblastic leukemia cells. Our results show that short exposure to CX-5461 followed by drug washout is sufficient to induce persistent G2 cell-cycle arrest and irreversible commitment to cell death, in spite of rRNA synthesis returning to normal within 24 hours of drug washout. The magnitude of cell death after transient exposure is similar to continuous exposure, but the time to cell death is relatively delayed with transient exposure. In this report, we also investigate rational drug combinations that can potentiate the effect of continuous CX-5461 treatment. We show that the checkpoint abrogator UCN-01 can relieve CX-5461-induced G2 arrest and potentiate the cytotoxic effects of CX-5461. Finally, we show that ERK1/2 is activated upon CX-5461 treatment, and that pharmacological inhibition of MEK1/2 leads to enhanced cell death in combination with CX-5461. In summary, our results provide evidence for the effectiveness of CX-5461 pulse treatment, which may minimize drug related toxicity, and evidence for enhanced effectiveness of CX-5461 in combination with other targeted agents.


Assuntos
Benzotiazóis/farmacologia , Naftiridinas/farmacologia , Inibidores da Síntese de Ácido Nucleico/farmacologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , RNA Ribossômico/efeitos dos fármacos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Western Blotting , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sinergismo Farmacológico , Citometria de Fluxo , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Humanos , Reação em Cadeia da Polimerase em Tempo Real , Células Tumorais Cultivadas
6.
Oncotarget ; 6(20): 18094-104, 2015 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-26061708

RESUMO

Ribosome biogenesis is a fundamental cellular process and is elevated in cancer cells. As one of the most energy consuming cellular processes, it is highly regulated by signaling pathways in response to changing cellular conditions. Many of the regulators of this process are aberrantly activated in various cancers. Recently two novel rRNA synthesis inhibitors, CX-5461 and BMH-21, have been shown to selectively kill cancer cells while sparing normal cells. Here, we tested the effectiveness of pre-rRNA synthesis inhibitor CX-5461 on acute lymphoblastic leukemia cells with different cytogenetic abnormalities. Acute lymphoblastic leukemia cells are more sensitive to rRNA synthesis inhibition compared to normal bone marrow cells. CX-5461 treated cells undergo caspase-dependent apoptosis independent of their p53 status. More-over, CX5461, activates checkpoint kinases and arrests cells in G2 phase of cell cycle. Finally, overcoming this G2 arrest by inhibiting ATR kinase leads to robust cell killing. These results show that CX-5461 can be even more potent in combination with ATR inhibitors.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Benzotiazóis/farmacologia , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Naftiridinas/farmacologia , Inibidores da Síntese de Ácido Nucleico/farmacologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , RNA Polimerase I/antagonistas & inibidores , RNA Ribossômico/biossíntese , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Proteínas Mutadas de Ataxia Telangiectasia/antagonistas & inibidores , Proteínas Mutadas de Ataxia Telangiectasia/genética , Caspases/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/enzimologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Inibidores de Proteínas Quinases/farmacologia , RNA Polimerase I/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
7.
Oncol Rep ; 28(4): 1498-502, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22842486

RESUMO

Cancer testis antigens (CTAs) are proteins that are normally expressed only in male germ cells and are aberrantly upregulated in a variety of cancers such as melanomas and lung cancer. MAGEA proteins belong to Class I CTAs and are being utilized as targets for cancer immunotherapy. Despite the discovery of the first CTA (MAGEA1) 20 years ago, the functions of these proteins remain poorly understood and evidence suggests both oncogenic as well as tumor suppressive roles for these proteins. Herein, we investigated the role of MAGEA4 in promoting cell growth. When overexpressed, MAGEA4 promotes growth of spontaneously transformed normal oral keratinocytes (NOK-SI). To understand the mechanism of growth stimulation by MAGEA4, we explored the effect of overexpressing MAGEA4 on cell cycle and apoptosis. MAGEA4 inhibits growth arrest of cells in the G1 phase of the cell cycle. We also found that overexpression of MAGEA4 inhibits G418-induced apoptosis of NOK-SI cells. Interestingly, this inhibition was accompanied by repression of two p53 downstream genes, BAX and CDKN1A. Our results indicate that MAGEA4 promotes growth by preventing cell cycle arrest and by inhibiting apoptosis mediated by the p53 transcriptional targets.


Assuntos
Antígenos de Neoplasias/genética , Apoptose/genética , Queratinócitos/citologia , Proteínas de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Pontos de Checagem do Ciclo Celular/genética , Células Cultivadas , Inibidor de Quinase Dependente de Ciclina p21/genética , Regulação da Expressão Gênica , Genes p53 , Neoplasias de Cabeça e Pescoço/genética , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Queratinócitos/fisiologia , Boca/citologia , Proteínas de Neoplasias/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço , Proteína X Associada a bcl-2/genética
8.
Clin Cancer Res ; 17(13): 4267-76, 2011 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21558405

RESUMO

PURPOSE: Aim of this study was to determine whether BORIS (Brother of the Regulator of Imprinted Sites) is a regulator of MAGEA2, MAGEA3, and MAGEA4 genes in lung cancer. EXPERIMENTAL DESIGN: Changes in expression of MAGEA genes upon BORIS induction/knockdown were studied. Recruitment of BORIS and changes in histone modifications at their promoters upon BORIS induction were analyzed. Luciferase assays were used to study their activation by BORIS. Changes in methylation at these promoters upon BORIS induction were evaluated. RESULTS: Alteration of BORIS expression by induction/knockdown directly correlated with expression of MAGEA genes. BORIS was enriched at their promoters in H1299 cells, which show high expression of these cancer testis antigens (CTA), compared with normal human bronchial epithelial (NHBE) cells which show low expression of the target CTAs. BORIS induction in A549 cells resulted in increased amounts of BORIS and activating histone modifications at their promoters along with a corresponding increase in their expression. Similarly, BORIS binding at these promoters in H1299 correlates with enrichment of activating modifications, whereas absence of BORIS binding in NHBE is associated with enrichment of repressive marks. BORIS induction of MAGEA3 was associated with promoter demethylation, but no methylation changes were noted with activation of MAGEA2 and MAGEA4. CONCLUSIONS: These data suggest that BORIS positively regulates these CTAs by binding and inducing a shift to a more open chromatin conformation with promoter demethylation for MAGEA3 or independent of promoter demethylation in case of MAGEA2 and MAGEA4 and may be a key effector involved in their derepression in lung cancer.


Assuntos
Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação Neoplásica da Expressão Gênica , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Regiões Promotoras Genéticas/genética , Sequência de Bases , Linhagem Celular , Linhagem Celular Tumoral , Metilação de DNA/genética , Proteínas de Ligação a DNA/genética , Histonas/metabolismo , Humanos , Masculino , Ligação Proteica
9.
Blood ; 115(23): 4798-809, 2010 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-20215641

RESUMO

Cooperating leukemogenic events in MLL-rearranged (MLL-r) infant acute lymphoblastic leukemia (ALL) are largely unknown. We explored the role of promoter CpG island hypermethylation in the biology and therapeutic targeting of MLL-r infant ALL. The HELP (HpaII tiny fragment enrichment by ligation-mediated polymerase chain reaction [PCR]) assay was used to examine genome-wide methylation of a cohort of MLL-r infant leukemia samples (n = 5), other common childhood ALLs (n = 5), and normals (n = 5). Unsupervised analysis showed tight clustering of samples into their known biologic groups, indicating large differences in methylation patterns. Global hypermethylation was seen in the MLL-r cohort compared with both the normals and the others, with ratios of significantly (P < .001) hypermethylated to hypomethylated CpGs of 1.7 and 2.9, respectively. A subset of 7 differentially hypermethylated genes was assayed by quantitative reverse-transcription (qRT)-PCR, confirming relative silencing in 5 of 7. In cell line treatment assays with the DNA methyltransferase inhibitor (DNMTi) decitabine, MLL-r (but not MLL wild-type cell lines) showed dose- and time-dependent cytotoxicity and re-expression of 4 of the 5 silenced genes. Methylation-specific PCR (MSP) confirmed promoter hypermethylation at baseline, and a relative decrease in methylation after treatment. DNMTi may represent a novel molecularly targeted therapy for MLL-r infant ALL.


Assuntos
Azacitidina/análogos & derivados , Ilhas de CpG , Metilação de DNA/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Proteína de Leucina Linfoide-Mieloide/biossíntese , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Regiões Promotoras Genéticas , Azacitidina/farmacologia , Azacitidina/uso terapêutico , Linhagem Celular Tumoral , Criança , Pré-Escolar , Estudos de Coortes , Metilação de DNA/genética , Metilases de Modificação do DNA/antagonistas & inibidores , Metilases de Modificação do DNA/metabolismo , Decitabina , Inibidores Enzimáticos/uso terapêutico , Feminino , Rearranjo Gênico/efeitos dos fármacos , Rearranjo Gênico/genética , Inativação Gênica/efeitos dos fármacos , Estudo de Associação Genômica Ampla , Histona-Lisina N-Metiltransferase , Humanos , Lactente , Masculino , Proteína de Leucina Linfoide-Mieloide/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/enzimologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética
10.
J Cell Sci ; 122(Pt 11): 1872-81, 2009 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-19435804

RESUMO

Cajal bodies (CBs) are nuclear structures that are thought to have diverse functions, including small nuclear ribonucleoprotein (snRNP) biogenesis. The phosphorylation status of coilin, the CB marker protein, might impact CB formation. We hypothesize that primary cells, which lack CBs, contain different phosphoisoforms of coilin compared with that found in transformed cells, which have CBs. Localization, self-association and fluorescence recovery after photobleaching (FRAP) studies on coilin phosphomutants all suggest this modification impacts the function of coilin and may thus contribute towards CB formation. Two-dimensional gel electrophoresis demonstrates that coilin is hyperphosphorylated in primary cells compared with transformed cells. mRNA levels of the nuclear phosphatase PPM1G are significantly reduced in primary cells and expression of PPM1G in primary cells induces CBs. Additionally, PPM1G can dephosphorylate coilin in vitro. Surprisingly, however, expression of green fluorescent protein alone is sufficient to form CBs in primary cells. Taken together, our data support a model whereby coilin is the target of an uncharacterized signal transduction cascade that responds to the increased transcription and snRNP demands found in transformed cells.


Assuntos
Linhagem Celular Tumoral , Células Cultivadas , Corpos Enovelados/metabolismo , Proteínas Nucleares/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular Tumoral/citologia , Linhagem Celular Tumoral/metabolismo , Células Cultivadas/citologia , Células Cultivadas/metabolismo , Humanos , Dados de Sequência Molecular , Proteínas Nucleares/química , Proteínas Nucleares/genética , Fosfoproteínas Fosfatases/metabolismo , Fosforilação , Proteína Fosfatase 2C , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais/fisiologia , Proteína 1 de Sobrevivência do Neurônio Motor/genética , Proteína 1 de Sobrevivência do Neurônio Motor/metabolismo
11.
J Neurosci Res ; 85(11): 2306-17, 2007 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-17526020

RESUMO

Nuclear inclusions formed by proteins with expanded polyglutamine tracts are found in several neurodegenerative diseases. The effect of nuclear inclusions formed by these disease proteins on the functional organization of the nucleus is only partially understood. In particular, it is not known whether polyglutamine disease proteins disrupt the function of Cajal bodies, which are subnuclear domains that play a role in the biogenesis of small nuclear ribonucleoproteins (snRNPs). snRNPs are an integral part of the pre-mRNA splicing machinery, so it is possible that mutant proteins that alter Cajal body activity indirectly affect pre-mRNA splicing. Here, we evaluate three different polyglutamine disease proteins--ataxin-1, ataxin-3, and huntingtin--for their ability to disrupt Cajal body localization and reduce the splicing of an artificial reporter in HeLa cells. Consistent with previous observations, ataxin-1 inclusions do not drastically alter the localization of Cajal bodies. In contrast, ataxin-3 inclusions associate with this structure. Inclusions formed by a fragment of the huntingtin protein do not associate with Cajal bodies or PML bodies, another subnuclear domain. Among the three disease proteins, only ataxin-3 significantly decreases the splicing of an artificial reporter. These results support the hypothesis that different mutant proteins vary in their ability to disrupt nuclear organization and function.


Assuntos
Núcleo Celular/metabolismo , Corpos Enovelados/metabolismo , Doenças Neurodegenerativas/metabolismo , Peptídeos/metabolismo , Splicing de RNA/fisiologia , Ataxina-1 , Ataxina-3 , Ataxinas , Núcleo Celular/patologia , Imunofluorescência , Genes Reporter , Células HeLa , Humanos , Proteína Huntingtina , Hibridização in Situ Fluorescente , Corpos de Inclusão Intranuclear/metabolismo , Corpos de Inclusão Intranuclear/patologia , Proteínas do Tecido Nervoso/metabolismo , Doenças Neurodegenerativas/patologia , Proteínas Nucleares/metabolismo , Proteínas/metabolismo , Proteínas Repressoras/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Transfecção
12.
J Biol Chem ; 278(11): 9107-15, 2003 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-12511551

RESUMO

Protein B23 is a multifunctional nucleolar protein whose molecular chaperone activity is proposed to play role in ribosome assembly. Previous studies (Szebeni, A., and Olson, M. O. J. (1999) Protein Sci. 8, 905-912) showed that protein B23 has several characteristics typical of molecular chaperones, including anti-aggregation activity, promoting the renaturation of denatured proteins, and preferential binding to denatured substrates. However, until now there has been no proposed mechanism for release of a bound substrate. Protein B23 can be phosphorylated by protein kinase CK2 (CK2) in a segment required for chaperone activity. The presence of bound substrate enhanced the rate of CK2 phosphorylation of protein B23 by 2-3-fold, and this enhancement was dependent on a nonpolar region in its N-terminal end. Formation of a complex between B23 and chaperone test substrates (rhodanese or citrate synthase) was inhibited by CK2 phosphorylation. Furthermore, CK2 phosphorylation of a previously formed B23-substrate complex promoted its dissociation. The dissociation of complexes between B23 and the human immunodeficiency virus-Rev protein required both CK2 phosphorylation and competition with a Rev nuclear localization signal peptide, suggesting that Rev binds B23 at two separate sites. These studies suggest that unlike many molecular chaperones, which directly hydrolyze ATP, substrate release by protein B23 is dependent on its phosphorylation by CK2.


Assuntos
Núcleo Celular/metabolismo , Proteínas Nucleares/química , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Caseína Quinase II , Escherichia coli/metabolismo , Produtos do Gene rev/metabolismo , Humanos , Hidrólise , Modelos Biológicos , Mutação , Nucleofosmina , Peptídeos/química , Fosfopeptídeos/química , Ligação Proteica , Desnaturação Proteica , Estrutura Terciária de Proteína , Ratos , Proteínas Recombinantes/química , Fatores de Tempo
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