RESUMO
Chemical investigation of the marine hydroid Dentitheca habereri led to the identification of eight new diacylated zoanthoxanthin alkaloids, named dentithecamides A-H (1-8), along with three previously reported analogues, zoamides B-D (9-11). The structures of compounds 1-11 were elucidated by spectroscopic and spectrometric analyses, including IR, HRESIMS, and NMR experiments, and by comparison with literature data. Compounds 1-11 are the first zoanthoxanthin alkaloids to be reported from a hydroid. Dentithecamides A (1) and B (2) along with zoamides B-D (9-11), which all share a conformationally mobile cycloheptadiene core, inhibited PAX3-FOXO1 regulated transcriptional activity and thus provided a structural framework for the potential development of more potent PAX3-FOXO1 inhibitors.
Assuntos
Alcaloides , Imidazóis , Alcaloides/químicaRESUMO
Seven new arylpyrrole alkaloids (1-7), along with four known compounds, were isolated from an extract of a Dactylia sp. nov. marine sponge, and their structures were elucidated by interpretation of NMR and MS spectroscopic data. Denigrins D-G (1-4) have highly substituted pyrrole or pyrrolone rings in their core structures, while dactylpyrroles A-C (5-7) have tricyclic phenanthrene cores. Due to the proton-deficient nature of these scaffolds, key heteronuclear correlations from 1H-15N HMBC and LR-HSQMBC NMR experiments were used in the structure assignment of denigrin D (1). Dictyodendrin F (8), a previously described co-metabolite, inhibited transcription driven by the oncogenic PAX3-FOXO1 fusion gene with an IC50 value of 13 µM.
Assuntos
Alcaloides/química , Poríferos/química , Pirróis/química , Animais , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13/métodos , Estrutura Molecular , Espectroscopia de Prótons por Ressonância Magnética/métodosRESUMO
A cell-based high-throughput screen that assessed the cellular stability of a tumor suppressor protein PDCD4 (Programmed cell death 4) was used to identify a new guanidine-containing marine alkaloid mirabilin K (3), as well as the known compounds mirabilin G (1) and netamine M (2). The structures of these tricyclic guanidine alkaloids were established from extensive spectroscopic analyses. Compounds 1 and 2 inhibited cellular degradation of PDCD4 with EC50 values of 1.8 µg/mL and 2.8 µg/mL, respectively. Mirabilin G (1) and netamine M (2) are the first marine natural products reported to stabilize PDCD4 under tumor promoting conditions.
Assuntos
Alcaloides/química , Alcaloides/farmacologia , Proteínas Reguladoras de Apoptose/metabolismo , Guanidina/química , Guanidina/farmacologia , Poríferos/química , Proteínas de Ligação a RNA/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Células HEK293 , Humanos , Ácido Oleanólico/análogos & derivados , Ácido Oleanólico/química , Saponinas/químicaRESUMO
INTRODUCTION: Year-round training is standard for elite gymnasts in the United States, but the coronavirus disease 2019 (COVID-19) pandemic led to unprecedented training interruptions. The effect of these training disruptions is unknown. OBJECTIVE: This study aimed to describe and compare training interruptions in elite gymnasts before and during the pandemic, the time it took to return to the prior level of gymnastics training, the development of injuries during return to gymnastics training, and gymnast-reported difficulty in and nervousness about returning to prior level of gymnastics training. DESIGN: Retrospective study. SETTING: Anonymous online surveys distributed to elite gymnasts in the United States. PARTICIPANTS: A total of 184 current elite gymnasts who completed the surveys were included. This represented an overall response rate of 52.3% (184/352). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Information was collected about training interruptions and time, nervousness, difficulty, and injury during return to gymnastics. RESULTS: Gymnasts reported significantly longer training interruptions due to COVID-19 than before the pandemic (8.7 ± 4.4 vs. 4.4 ± 7.9 weeks, p < .001), but duration of return to prior gymnastics level was similar (4.6 ± 2.7 vs. 3.7 ± 4.8 weeks, p = .106). Of the 137 gymnasts who had returned to training by the time of the survey, 46 (33.6%) reported an injury during their return to gymnastics. A high degree of nervousness to return to gymnastics was significantly associated with greater risks of injury upon return (risk ratio [RR] 2.7, 95% confidence interval [CI]: 1.6-4.7; p < .001) and difficulty returning to prior level (RR 3.4, 95% CI: 1.7-6.6; p < .001). CONCLUSION: Pandemic-related training interruption was significantly greater in duration than prior interruptions, but time required for return to gymnastics was similar. Gymnasts may be at increased risk of injury during return to gymnastics if experiencing nervousness about returning following a break in training. These findings provide guidance for gymnasts' return from training interruptions and may refute the long-held belief that gymnasts should not take time away from training due to fear of injury or difficulty regaining skills.
Assuntos
COVID-19 , Ginástica , Humanos , Ginástica/lesões , Volta ao Esporte , Estudos Retrospectivos , COVID-19/epidemiologiaRESUMO
Introduction: Community-based participatory research and animated video offer promising approaches to attenuate disparities in access to kidney transplant information. Project Aims: We refined an evidence-based animated video curriculum (Kidney Transplant and Donation Information Made Easy) designed for diverse individuals, that is currently being trialed to advance kidney transplant access among referred patients at a single transplant center, to further accommodate information needs in earlier stages of the path to transplant (pre-referral) and to enhance fit for Black and Hispanic people. Design: We describe formation of an academic-community partnership and the application of qualitative research methods and partnership discussions to refine the Kidney Transplant and Donation Information Made Easy videos. A simple content analysis was undertaken of intervention refinement transcriptions, minutes, and meeting notes. Results: We formed a community steering committee and advisory board of local members predominantly of minoritized race or ethnicity. Full engagement with community members is evident in the program's adaptation process. Essential refinement elements were adaptation of 17 original videos and iterative development of 8 new videos with the community, conducting parallel cognitive interviews of an expanded sample of stakeholders, maintaining the theoretical grounding of Elaboration Theory, communication/multimedia learning best practices, and self-efficacy framework, and doing Spanish-language translation. Conclusions: Applying community-based participatory research principles and qualitative methods, we produced a culturally grounded adaptation of the Kidney Transplant and Donation Information Made Easy videos that provides information about kidney transplantation from primary care to transplantation. This approach is likely to strengthen our community partnership and eventual community acceptance of the intervention during the implementation phase. Challenges were achieving consensus and adding Spanish-language translation.
Assuntos
Pesquisa Participativa Baseada na Comunidade , Disparidades em Assistência à Saúde , Transplante de Rim , Humanos , Pesquisa Participativa Baseada na Comunidade/métodos , Hispânico ou Latino , Projetos de Pesquisa , População Negra , Acessibilidade aos Serviços de Saúde , Educação de Pacientes como AssuntoRESUMO
Cucurbitacins B and D were among the compounds identified as sensitizers of cancer cells to TRAIL-mediated apoptosis in a high-throughput screen. Therefore a series of cucurbitacins was further investigated for TRAIL sensitization and possible mechanisms of action. A total of six cucurbitacins promoted TRAIL-induced apoptosis (B, I, E, C, D, and K) and one (P) was inactive. Sensitization of renal adenocarcinoma cells to TRAIL was apparent after as little as 1-4 h pretreatment and did not require continued presence of cucurbitacin. Active cucurbitacins induced caspase-8 activation only after subsequent TRAIL addition and caspase activation was required for apoptosis suggesting amplified proximal signaling from TRAIL death receptors. Cucurbitacin-sensitized TRAIL-induced cytotoxicity was inhibited by N-acetyl cysteine. Structure-activity relationship analysis in comparison to published studies suggests that TRAIL-sensitizing and general cytotoxic activities of cucurbitacins may be decoupled. Cucurbitacins are reported to be inhibitors of STAT3 activation. However, their TRAIL-sensitizing activity is STAT3-independent. Treatment of renal carcinoma cells with active cucurbitacins produced rapid and dramatic changes in cell morphology and cytoskeletal organization (also prevented by NAC). Therefore, cucurbitacins may be useful as tools for investigating the molecular mechanism(s) of action of TRAIL sensitizers, particularly with regard to temporal aspects of sensitization and modulation of TRAIL signaling by cell morphology, and could form the basis for future therapeutic development in combination with TRAIL death receptor agonists.
Assuntos
Apoptose/efeitos dos fármacos , Carcinoma de Células Renais/fisiopatologia , Cucurbitacinas/farmacologia , Neoplasias Renais/fisiopatologia , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/metabolismo , Caspase 8/genética , Caspase 8/metabolismo , Linhagem Celular Tumoral , Forma Celular/efeitos dos fármacos , Humanos , Neoplasias Renais/genética , Neoplasias Renais/metabolismo , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/genética , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/metabolismoRESUMO
Barleria alluaudii and Diospyros maritima were both investigated as part of an ongoing search for synergistic TRAIL (tumor necrosis factor-α-related apoptosis-inducing ligand) sensitizers. As a result of this study, two naphthoquinone epoxides, 2,3-epoxy-2,3-dihydrolapachol (1) and 2,3-epoxy-2,3-dihydro-8-hydroxylapachol (2), both not previously isolated from natural sources, and the known 2-methylanthraquinone (3) were identified from B. alluaudii. Time-dependent density functional theory (TD-DFT) calculations of electronic circular dichroism (ECD) spectra were utilized to establish the absolute configuration of 1 and 2. Additionally, five known naphthoquinone derivatives, maritinone (4), elliptinone (5), plumbagin (6), (+)-cis-isoshinanolone (7), and ethylidene-6,6'-biplumbagin (8), were isolated from D. maritima. Compounds 1, 2, and 4-6 showed varying levels of synergy with TRAIL. Maritinone (4) and elliptinone (5) showed the highest synergistic effect, with more than a 3-fold increase in activity observed with TRAIL than with compound alone.
Assuntos
Acanthaceae/química , Antraquinonas/isolamento & purificação , Diospyros/química , Naftoquinonas/isolamento & purificação , Ligante Indutor de Apoptose Relacionado a TNF/efeitos dos fármacos , Antraquinonas/química , Antraquinonas/farmacologia , Madagáscar , Estrutura Molecular , Naftoquinonas/química , Naftoquinonas/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Fator de Necrose Tumoral alfaRESUMO
A high-throughput cell-based reporter assay designed to identify small-molecule stabilizers of the tumor suppressor Pdcd4 was used to screen extracts in the NCI Natural Products Repository. Bioassay-guided fractionation of an extract from a Papua New Guinea collection of the tropical tree Cryptocarya sp. provided a series of new 5,6-dihydro-α-pyrone-containing 1,3-polyols (1-8), named cryptocaryols A-H. Their structures were assigned from a combination of NMR, MS, and CD studies in conjunction with NMR database comparisons. Compounds 1-8 were found to rescue Pdcd4 from TPA-induced degradation with EC50 concentrations that ranged from 1.3 to 4.9 µM.
Assuntos
Proteínas Reguladoras de Apoptose/efeitos dos fármacos , Cryptocarya/química , Polímeros/química , Pironas/isolamento & purificação , Pironas/farmacologia , Proteínas de Ligação a RNA/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/metabolismo , Genes Supressores de Tumor , Estrutura Molecular , National Cancer Institute (U.S.) , Ressonância Magnética Nuclear Biomolecular , Papua Nova Guiné , Pironas/química , Proteínas de Ligação a RNA/metabolismo , Estados UnidosRESUMO
Medium-chain acyl-coA dehydrogenase (MCAD) deficiency is a commonly detected fatty acid oxidation disorder and its diagnosis relies on both biochemical and molecular analyses. Over a 5-year period, sequencing all 12 exons of the MCAD gene (ACADM) in our laboratory revealed a total of 54 variants in 549 subjects analyzed. As most molecular ACADM testing is referred for the follow-up of an abnormal newborn screening result obtained from an asymptomatic newborn, the identification of a novel DNA variant, or "variant of unknown significance (VUS)," presents clinicians with a dilemma. Frequently, the results of molecular analyses are correlated to biochemical findings, such as the concentration of octanoylcarnitine (C8) in plasma and the excretion of hexanoylglycine (HG) in urine. Here, we describe the classification of genotypes harboring at least one VUS through the comparison of C8 and HG values measured in individuals who are carriers of, or affected with, MCAD deficiency on the basis of the following genotypes: c.985A>G/wildtype, c.199T>C/c.985A>G and c.985A>G/c.985A>G. Our findings emphasize the importance of obtaining both plasma and urine when following up positive newborn screening results and may influence the way physicians counsel their asymptomatic patients about MCAD deficiency after genetic analysis.
Assuntos
Acil-CoA Desidrogenase/deficiência , Acil-CoA Desidrogenase/genética , Variação Genética , Erros Inatos do Metabolismo Lipídico/enzimologia , Erros Inatos do Metabolismo Lipídico/genética , Mutação , Adolescente , Adulto , Alelos , Carnitina/análogos & derivados , Carnitina/sangue , Criança , Pré-Escolar , Análise Mutacional de DNA , Éxons , Estudos de Associação Genética , Triagem de Portadores Genéticos , Genótipo , Glicina/análogos & derivados , Glicina/urina , Humanos , Recém-Nascido , Erros Inatos do Metabolismo Lipídico/sangue , Erros Inatos do Metabolismo Lipídico/urina , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Triagem Neonatal , Polimorfismo de Nucleotídeo Único , Adulto JovemRESUMO
Casearia arguta was investigated as part of the ongoing search for synergistic TRAIL (tumor necrosis factor-α-related apoptosis-inducing ligand) sensitizers. As a result of this study, argutins A-H, eight new highly oxygenated clerodane diterpenes, were isolated from the plant Casearia arguta collected in Guatemala. The modified Mosher ester method was utilized to establish the absolute configuration of argutins A and F. Each of the argutins showed varying levels of synergy with TRAIL. Argutin B showed the highest TRAIL sensitization; the synergistic effect of argutin B and TRAIL together was 3-fold greater than argutin B alone.
Assuntos
Casearia/química , Diterpenos Clerodânicos/isolamento & purificação , Diterpenos Clerodânicos/farmacologia , Plantas Medicinais/química , Ligante Indutor de Apoptose Relacionado a TNF/efeitos dos fármacos , Diterpenos Clerodânicos/química , Guatemala , Estrutura Molecular , Folhas de Planta/químicaRESUMO
Background: Poison control centers (PCCs) manage millions of information and exposure cases a year. Exposure cases are almost always managed on-site (i.e., at "home") or at a health care facility (HCF). Over the last 10 years, there have been significant changes in the composition of cases managed by PCCs with an overall decrease in total cases but an increase in exposures managed at an HCF. The management and documentation of HCF cases may require more time than cases managed on-site or information cases. Time-work data are needed to accurately gauge the staff resources needed to address these changes.Methods: One poison center with an annual case volume of 74,000 conducted a time-work study of total case management time for a subset of cases: exposures Managed on-site and Managed at an HCF as well as information Drug identification cases. Specialists tracked the time spent communicating, managing, researching, consulting, and documenting. Additionally, the PCC medical records and phone call database were audited to ensure all calls and documented efforts related to a case were included.Results: Cases Managed at an HCF (n = 140) took more time (mean 45.8 min, median 29.3 min) than those Managed on-site (n = 430; mean 7.4 min, median 5.9 min) or Drug identification case (n = 392; mean 2.7 min, median 2.2 min); this difference was significant (p<.0001). There were 32 cases (23%) Managed at an HCF that required more than 1 h for total management; no Managed On-site or Drug identification cases required more than 33 min.Conclusions: The time required for one PCC to manage cases at an HCF was approximately six times longer than cases that were managed on-site. With PCC case volume and composition changing, previous staffing assumptions may no longer hold true. It would be incorrect to base staffing requirements on case volume alone without scrutiny of case types.
Assuntos
Exposição Ambiental/estatística & dados numéricos , Instalações de Saúde/estatística & dados numéricos , Centros de Controle de Intoxicações/estatística & dados numéricos , Intoxicação/epidemiologia , Bases de Dados Factuais , Humanos , Serviços de Informação/organização & administração , Serviços de Informação/estatística & dados numéricos , Centros de Controle de Intoxicações/organização & administração , Fatores de TempoRESUMO
We have developed a high-throughput screen (HTS) to search for novel molecules that can synergize with TRAIL, thus promoting apoptosis of ACHN renal tumor cells in a combinatorial fashion. The HTS detects synthetic compounds and pure natural products that can pre-sensitize the cancer cells to TRAIL-mediated apoptosis, yet have limited toxicity on their own. We have taken into account the individual effects of the single agents, versus the combination, and have identified hits that are synergistic, synergistic-toxic, or additive when combined with TRAIL in promoting tumor cell death. Preliminary mechanistic studies indicate that a subset of the synergistic TRAIL sensitizers act very rapidly to promote cleavage and activation of caspase-8 following TRAIL binding. Caspase-8 is an apical enzyme that initiates programmed cell death via the extrinsic apoptotic pathway. Thus, these TRAIL sensitizers may potentially reduce resistance of tumor cells to TRAIL-mediated apoptosis. Two representative sensitizers were found to increase levels of p53 but did not inhibit the proteasome, suggesting that early DNA damage-sensing pathways may be involved in their mechanisms of action.
Assuntos
Adenocarcinoma/metabolismo , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Caspase 8/metabolismo , Neoplasias Renais/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Apoptose , Caspase 8/efeitos dos fármacos , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Sinergismo Farmacológico , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/fisiologia , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteína Supressora de Tumor p53/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismoRESUMO
Here we describe a novel strategy using multiplexes of synthetic small interfering RNAs (siRNAs) corresponding to multiple gene targets in order to compress RNA interference (RNAi) screen size. Before investigating the practical use of this strategy, we first characterized the gene-specific RNAi induced by a large subset (258 siRNAs, 129 genes) of the entire siRNA library used in this study ( approximately 800 siRNAs, approximately 400 genes). We next demonstrated that multiplexed siRNAs could silence at least six genes to the same degree as when the genes were targeted individually. The entire library was then used in a screen in which randomly multiplexed siRNAs were assayed for their affect on cell viability. Using this strategy, several gene targets that influenced the viability of a breast cancer cell line were identified. This study suggests that the screening of randomly multiplexed siRNAs may provide an important avenue towards the identification of candidate gene targets for downstream functional analyses and may also be useful for the rapid identification of positive controls for use in novel assay systems. This approach is likely to be especially applicable where assay costs or platform limitations are prohibitive.
Assuntos
Interferência de RNA , RNA Interferente Pequeno/química , Linhagem Celular Tumoral , Sobrevivência Celular , Biblioteca Gênica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , RNA Interferente Pequeno/síntese químicaRESUMO
Identification of RNA-interacting pharmacophores could provide chemical probes and, potentially, small molecules for RNA-based therapeutics. Using a high-throughput differential scanning fluorimetry assay, we identified small-molecule natural products with the capacity to bind the discrete stem-looped structure of pre-miR-21. The most potent compound identified was a prodiginine-type compound, butylcycloheptyl prodiginine (bPGN), with the ability to inhibit Dicer-mediated processing of pre-miR-21 in vitro and in cells. Time-dependent RT-qPCR, western blot, and transcriptomic analyses showed modulation of miR-21 expression and its target genes such as PDCD4 and PTEN upon treatment with bPGN, supporting on-target inhibition. Consequently, inhibition of cellular proliferation in HCT-116 colorectal cancer cells was also observed when treated with bPGN. The discovery that bPGN can bind and modulate the expression of regulatory RNAs such as miR-21 helps set the stage for further development of this class of natural product as a molecular probe or therapeutic agent against miRNA-dependent diseases.
Assuntos
Produtos Biológicos/farmacologia , MicroRNAs/antagonistas & inibidores , Prodigiosina/análogos & derivados , Sítios de Ligação/efeitos dos fármacos , Produtos Biológicos/química , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Células HCT116 , Humanos , MicroRNAs/metabolismo , Estrutura Molecular , Imagem Óptica , Prodigiosina/química , Prodigiosina/farmacologia , Relação Estrutura-Atividade , Células Tumorais CultivadasRESUMO
Rocaglamide has been reported to sensitize several cell types to TRAIL-induced apoptosis. In recent years, advances in synthetic techniques have led to generation of novel rocaglamide analogs. However, these have not been extensively analyzed as TRAIL sensitizers, particularly in TRAIL-resistant renal cell carcinoma cells. Evaluation of rocaglamide and analogs identified 29 compounds that are able to sensitize TRAIL-resistant ACHN cells to TRAIL-induced, caspase-dependent apoptosis with sub-µM potency which correlated with their potency as protein synthesis inhibitors and with loss of cFLIP protein in the same cells. Rocaglamide alone induced cell cycle arrest, but not apoptosis. Rocaglates averaged 4-5-fold higher potency as TRAIL sensitizers than as protein synthesis inhibitors suggesting a potential window for maximizing TRAIL sensitization while minimizing effects of general protein synthesis inhibition. A wide range of other rocaglate effects (e.g. on JNK or RAF-MEK-ERK signaling, death receptor levels, ROS, ER stress, eIF4E phosphorylation) were assessed, but did not contribute to TRAIL sensitization. Other than a rapid loss of MCL-1, rocaglates had minimal effects on mitochondrial apoptotic pathway proteins. The identification of structurally diverse/mechanistically similar TRAIL sensitizing rocaglates provides insights into both rocaglate structure and function and potential further development for use in RCC-directed combination therapy.
Assuntos
Apoptose/efeitos dos fármacos , Benzofuranos/farmacologia , Carcinoma de Células Renais/patologia , Neoplasias Renais/patologia , Ligante Indutor de Apoptose Relacionado a TNF/fisiologia , Benzofuranos/administração & dosagem , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/genética , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/metabolismo , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Humanos , RNA Mensageiro/genética , Transdução de Sinais , Ligante Indutor de Apoptose Relacionado a TNF/metabolismoRESUMO
Inactivating APC mutations cause familial adenomatous polyposis, classically characterized by hundreds to thousands of adenomatous colorectal polyps and cancer. Historically, 98% of pathogenic alterations in APC are nonsense or frameshift mutations; however, few reported series have used techniques that test for large deletions or duplications. Splice site mutations are only rarely documented. Consecutive cases (n = 1591) submitted for complete APC gene analysis during a 4-year period were reviewed. Testing included mutation screening (Sanger sequencing or conformation sensitive gel electrophoresis and protein truncation testing) with reflex confirmation sequencing. Gene deletion or duplication analysis was performed in 1421 cases by multiplex ligation-dependent probe amplification. Testing yielded 411 pathogenic, 20 likely pathogenic, 15 variant of uncertain significance, 140 likely benign, and 1005 negative reports. Identified were 168 novel variants (103 pathogenic, 5 likely pathogenic, 12 variant of uncertain significance, and 48 likely benign). Of the 431 pathogenic or likely pathogenic mutations, frameshift, nonsense, splice site, and large deletion or duplication mutations represented 43%, 42%, 9%, and 6% of cases, respectively. This is the largest report of clinical APC testing experience with concurrent multiplex ligation-dependent probe amplification. In addition to nonsense and frameshift mutations, large deletions or duplications and canonical splice site mutations are a significant cause of familial adenomatous polyposis. Despite technological advances, broad allelic, locus, and phenotypic heterogeneity continue to pose challenges for genetic testing of patients with colorectal adenomatous polyposis.
Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/genética , Mutação em Linhagem Germinativa , Polipose Adenomatosa do Colo/patologia , Neoplasias Colorretais/genética , DNA/genética , DNA/isolamento & purificação , Análise Mutacional de DNA , Éxons , Mutação da Fase de Leitura , Deleção de Genes , Genoma Humano , Genômica , Humanos , Polimorfismo GenéticoRESUMO
Mutations were introduced to the domain-swapped homodimer of the antiviral lectin griffithsin (GRFT). Whereas several single and double mutants remained dimeric, insertion of either two or four amino acids at the dimerization interface resulted in a monomeric form of the protein (mGRFT). Monomeric character of the modified proteins was confirmed by sedimentation equilibrium ultracentrifugation and by their high resolution X-ray crystal structures, whereas their binding to carbohydrates was assessed by isothermal titration calorimetry. Cell-based antiviral activity assays utilizing different variants of mGRFT indicated that the monomeric form of the lectin had greatly reduced activity against HIV-1, suggesting that the antiviral activity of GRFT stems from crosslinking and aggregation of viral particles via multivalent interactions between GRFT and oligosaccharides present on HIV envelope glycoproteins. Atomic resolution crystal structure of a complex between mGRFT and nonamannoside revealed that a single mGRFT molecule binds to two different nonamannoside molecules through all three carbohydrate-binding sites present on the monomer.
Assuntos
Proteínas de Algas/química , Fármacos Anti-HIV/química , Lectinas/química , Proteínas de Algas/metabolismo , Fármacos Anti-HIV/metabolismo , Sítios de Ligação , Carboidratos/química , Cristalografia por Raios X , Dimerização , HIV-1/efeitos dos fármacos , Lectinas/metabolismo , Modelos Moleculares , Lectinas de PlantasRESUMO
The novel tumor suppressor Pdcd4 affects tumorigenesis by inhibiting translation. Pdcd4 is phosphorylated and subsequently lost by proteasomal degradation in response to tumor-promoting conditions. Here, the authors describe the development of a reporter cell system to monitor the stability of Pdcd4. The phosphorylation-dependent degradation domain ("target") or an adjacent ("off-target") region of Pdcd4 was cloned into a luciferase expression system. The target constructs were responsive to Pdcd4 degrading conditions (e.g., TPA, p70(S6K1) overactivation), whereas the off-target constructs remained stable. The system was optimized for and shown to be reliable in a high-throughput compatible 384-well format. Screening of 15,275 pure compounds resulted in a hit rate of 0.30% (>50% inhibition of TPA-induced loss of signal, confirmed by reassay). Among the hits were inhibitors of previously identified critical signaling events for TPA-induced Pdcd4 degradation. One compound was identified to be nonspecific using the off-target control cell line. Screening of 135,678 natural product extracts yielded 42 confirmed, specific hits. Z' averaged 0.58 across 446 plates. Further characterization of active natural products and synthetic compounds is expected to identify novel Pdcd4 stabilizers that may be useful in targeting translation to prevent or treat cancers.