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This study investigates the impact of Body Mass Index (BMI) on Quality of Life (QoL) and treatment outcomes in breast cancer (BC) patients, particularly focusing on underweight individuals with compromised nutritional status. A nonrandomized prospective study comprising 121 newly diagnosed patients across various BMI categories utilized FACT-B & FACIT-Sp-12 questionnaires. Follow-ups occurred at baseline, during (3rd and 6th), and after (12th month) anthracycline-taxane chemotherapy, either sequentially or concomitantly. Patients with low BMI (<18.5 kg/m2; 53.7%) exhibited significantly poorer QoL, marked by compromised nutritional indicators (low MUAC and SFT). Repeated measures ANOVA identified significant correlations between BMI groups in functional, social, and emotional QoL aspects (p < 0.05), with no notable differences in other domains. A Chi-square (ê2) test underscored a significant link between BMI and treatment response (p < 0.0001), showing higher rates of non-responders among underweight patients (p = 4.259e-14). The study advocates pretreatment consultation with a dietitian as standard care for Indian BC patients, offering complimentary nutritional support for improved QoL outcomes and treatment responses.
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Índice de Massa Corporal , Neoplasias da Mama , Estado Nutricional , Qualidade de Vida , Centros de Atenção Terciária , Magreza , Humanos , Neoplasias da Mama/complicações , Neoplasias da Mama/psicologia , Feminino , Índia/epidemiologia , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto , Resultado do Tratamento , Antraciclinas , Idoso , Inquéritos e Questionários , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Hidrocarbonetos Aromáticos com Pontes , TaxoidesRESUMO
Loss of mitosis regulation is a common feature of malignant cells that leads to aberrant cell division with inaccurate chromosome segregation. The mitotic checkpoint is responsible for faithful transmission of genetic material to the progeny. Defects in this checkpoint, such as mutations and changes in gene expression, lead to abnormal chromosome content or aneuploidy that may facilitate cancer development. Furthermore, a defective checkpoint response is indicated in the development of drug resistance to microtubule poisons that are used in treatment of various blood and solid cancers for several decades. Mitotic slippage and senescence are important cell fates that occur even with an active mitotic checkpoint and are held responsible for the resistance. However, contradictory findings in both the scenarios of carcinogenesis and drug resistance have aroused questions on whether mitotic checkpoint defects are truly responsible for these dismal outcomes. Here, we discuss the possible contribution of the faulty checkpoint signaling in cancer development and drug resistance, followed by the latest research on this pathway for better outcomes in cancer treatment.
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Pontos de Checagem da Fase M do Ciclo Celular , Neoplasias , Segregação de Cromossomos , Resistência a Medicamentos , Humanos , Mitose , Neoplasias/tratamento farmacológico , Neoplasias/genética , Fuso AcromáticoRESUMO
In the absence of adequate diagnosis and treatment, leishmaniasis remains a major public health concern on a global scale. Drug resistance remains a key obstacle in controlling and eliminating visceral leishmaniasis. The therapeutic gap due to lack of target-specific medicine and vaccine can be minimized by obtaining parasite's genomic information. This study compared whole-genome sequence of paromomycin-resistant parasite (K133PMM) developed through in vitro adaptation and selection with sensitive Leishmania clinical isolate (K133WT). We found a large number of upstream and intergenic gene variations in K133PMM. There were 259 single nucleotide polymorphisms (SNPs), 187 insertion-deletion (InDels), and 546 copy number variations (CNVs) identified. Most of the genomic variations were found in the gene's upstream and non-coding regions. Ploidy estimation revealed chromosome 5 in tetrasomy and 6, 9, and 12 in trisomy, uniquely in K133PMM. These contain the genes for protein degradation, parasite motility, autophagy, cell cycle maintenance, and drug efflux membrane transporters. Furthermore, we also observed reduction in ploidy of chromosomes 15, 20, and 23, in the resistant parasite containing mostly the genes for hypothetical proteins and membrane transporters. We chronicled correlated genomic conversion and aneuploidy in parasites and hypothesize that this led to rapid evolutionary changes in response to drug induced pressure, which causes them to become resistant.
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Variações do Número de Cópias de DNA , Leishmania donovani , Cromossomos/genética , Resistência a Medicamentos , Leishmania donovani/genética , Proteínas de Membrana Transportadoras/genética , Paromomicina/farmacologiaRESUMO
Artemisinin, extracted from a medicinal herb Artemisia annua, is widely used to treat malaria and has shown potent anticancer activity. Artemisinin has been found to be effective against experimental visceral and cutaneous leishmaniasis. Despite extensive research to understand the complex mechanism of resistance to artemisinin, several questions remain unanswered. The artesunate (ART)-resistant line of Leishmania donovani was selected and cellular mechanisms associated with resistance to artemisinin were investigated. ART-resistant (AS-R) parasites showed reduced susceptibility towards ART both at promastigote and amastigote stage compared with ART sensitive (WT) parasites. WT and AS-R parasites were both more susceptible to ART at the early log phase of growth compared with late log phase. AS-R parasites were more infective to the host macrophages (p < 0.05). Evaluation of parasites' tolerance towards host microbicidal mechanisms revealed that AS-R parasites were more tolerant to complement-mediated lysis and nitrosative stress. ROS levels were modulated in presence of ART in AS-R parasites infected macrophages. Interestingly, infection of macrophages by AS-R parasites led to modulated levels of host interleukins, IL-2 and IL-10, in addition to nitric oxide. Additionally, AS-R parasites showed upregulated expression of genes of unfolded protein response pathway including methyltransferase domain-containing protein (HSP40) and flagellar attachment zone protein (prefoldin), that are reported to be associated with ART resistance in Plasmodium falciparum malaria. This study presents in vitro model of artemisinin-resistant Leishmania parasite and cellular mechanisms associated with ART resistance in Leishmania.
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Antiprotozoários/administração & dosagem , Artemisininas/administração & dosagem , Leishmania donovani/efeitos dos fármacos , Leishmaniose Visceral/genética , Leishmaniose Visceral/imunologia , Extratos Vegetais/administração & dosagem , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Animais , Artemisia annua/química , Artesunato/administração & dosagem , Feminino , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/imunologia , Interações Hospedeiro-Parasita , Humanos , Interleucina-10/genética , Interleucina-10/imunologia , Leishmania donovani/crescimento & desenvolvimento , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/fisiopatologia , Macrófagos/imunologia , Camundongos Endogâmicos BALB CRESUMO
Post-kala-azar dermal leishmaniasis (PKDL) patients are a key source of Leishmania donovani parasites, hindering the goal of eliminating visceral leishmaniasis (VL). Monitoring treatment response and parasite susceptibility is essential due to increasing drug resistance. We assessed the drug susceptibility of PKDL isolates (n = 18) from pre-miltefosine (MIL) era (1997-2004) with isolates (n = 16) from the post-miltefosine era (2010-2019) and post-miltefosine treatment relapse isolates (n = 5) towards miltefosine and amphotericin B (AmB) at promastigote stage and towards sodium antimony gluconate (SAG) at amastigote stage. PKDL isolates were examined for mutation in gene-encoding AQP1 transporter, C26882T mutation on chromosome 24, and miltefosine-transporter (MT). PKDL isolates from the post-miltefosine era were significantly more susceptible to SAG than SAG-resistant isolates from the pre-miltefosine era (P = 0.0002). There was no significant difference in the susceptibility of parasites to miltefosine between pre- and post-miltefosine era isolates. The susceptibility of PKDL isolates towards AmB remained unchanged between the pre- and post-miltefosine era. However, the post-miltefosine era isolates had a higher IC50 value towards AmB compared with PKDL relapse isolates. We did not find any association between AQP1 gene sequence variation and susceptibility to SAG, or between miltefosine susceptibility and single nucleotide polymorphisms (SNPs in the MT gene. This study demonstrates that recent isolates of Leishmania have resumed susceptibility to antimonials in vitro. The study also offers significant insights into the intrinsic drug susceptibility of Leishmania parasites over the past two decades, covering the period before the introduction of miltefosine and after its extensive use. IMPORTANCE: Post-kala-azar dermal leishmaniasis (PKDL) patients, a key source of Leishmania donovani parasites, hinder eliminating visceral-leishmaniasis. Assessment of the susceptibility of PKDL isolates to antimony, miltefosine (MIL), and amphotericin-B indicated that recent isolates remain susceptible to antimony, enabling its use with other drugs for treating PKDL.
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Anfotericina B , Antimônio , Antiprotozoários , Resistência a Medicamentos , Leishmania donovani , Leishmaniose Cutânea , Leishmaniose Visceral , Fosforilcolina , Humanos , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/genética , Leishmania donovani/isolamento & purificação , Fosforilcolina/análogos & derivados , Fosforilcolina/farmacologia , Fosforilcolina/uso terapêutico , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/tratamento farmacológico , Antiprotozoários/farmacologia , Antimônio/farmacologia , Antimônio/uso terapêutico , Leishmaniose Cutânea/parasitologia , Leishmaniose Cutânea/tratamento farmacológico , Resistência a Medicamentos/genética , Anfotericina B/farmacologia , Testes de Sensibilidade Parasitária , Gluconato de Antimônio e Sódio/farmacologia , Gluconato de Antimônio e Sódio/uso terapêutico , MutaçãoRESUMO
Triple-negative breast cancer is characterized by high lethality attributed to factors such as chemoresistance, transcriptomic, and genomic heterogeneity, leading to a poor prognosis and limiting available targeted treatment options. While the identification of molecular targets remains pivotal for therapy involving chemo drugs, the current challenge lies in the poor response rates, low survival rates, and frequent relapses. Despite various clinical investigations exploring molecular targeted therapies in conjunction with conventional chemo treatment, the outcomes have been less than optimal. The critical need for more effective therapies underscores the urgency to discover potent novel treatments, including molecular and immune targets, as well as emerging strategies. This review provides a comprehensive analysis of conventional treatment approaches and explores emerging molecular and immune-targeted therapeutics, elucidating their mechanisms to address the existing obstacles for a more effective management of triple-negative breast cancer.
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Antineoplásicos , Neoplasias de Mama Triplo Negativas , Humanos , Antineoplásicos/uso terapêutico , Perfilação da Expressão Gênica , Terapia de Alvo Molecular , Recidiva Local de Neoplasia/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/genética , FemininoRESUMO
The present study involves the design, synthesis, and biological evaluation of a series of thirty-three, pyrazole-based and N,N-diethylcarbamate functionalized, novel aurone analogs, against AGS cancer cell line. These novel aurone analogs are obtained from the reaction of pyrazole-based 6-hydroxyaurones with diethyl carbamoyl chloride using mild basic reagent. The cytotoxic activities of these compounds were evaluated against a human gastric adenocarcinoma cell line (AGS) and disclosed some potential outcomes as several analogs were found to have cytotoxicity better than the reference drugs Oxaliplatin and Leucovorin. The structure-activity relationship (SAR) study further unveiled the critical role of replacing the hydroxyl group in ring A with a carbamoyl group for cytotoxic activity. Among these aurone analogs, 8e and 8f, with IC50 values of 6.5 ± 0.024 µM and 6.6 ± 0.035 µM, respectively, are identified as the most active compounds. Molecular docking studies were conducted against HER2, a human epidermal growth factor involved in gastric and ovarian cancer, to investigate the binding interactions between the compounds and the protein HER2, where7e and 8e exhibited maximum interactions.
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OBJECTIVE: Our study aims to analyse and compare the efficacy, adverse effect profile and survival among the Paclitaxel/Cisplatin/5-Flurouracil (TPF) induction chemotherapy and Paclitaxel/carboplatin (PC) first line or cisplatin chemotherapy in a high-volume tertiary care cancer centre. MATERIALS AND METHODS: 215 patients with oral cavity cancer were recruited in this study. Patients with stages I-IIc underwent surgical resection or radiation therapy 66-74 GY/fraction. Patients of Stages III-IV were administered with either induction chemotherapy TPF or PC or cisplatin regimen. Treatment responses were assessed by CT and MRI. Response rates, survival and adverse effects data were tabulated and analysed. RESULTS: The mean age was 49.2 ± 11.68 years. Symptoms were ulceration (33.5%), growth (20.5%), pain (13%), ulcer-proliferative growth (8.4%) and swelling (13, 6%). The tumour site was found at the base of the tongue, C01 (42.2%) followed by C06 (35.8%), C08 (6.5%), C07 (5.2%) and C05 (4.6%). There were no significant differences ( P > 0.05) in efficacy and survival outcomes between the different groups of treatment. Median survival was achieved within 36 months. The major side effect observed were anaemia (15.81%), diarrhoea (36.2%), dyspepsia (28.8%), fever (33.95%), mucositis (28.85%), myalgia (33.95%) and nausea (7.9%). Survival among the responder categories (CR, PR and NR) was significantly different as per Log-rank analysis ( P = 0.015). CONCLUSIONS: TPF induction therapy and PC first line chemotherapy showed similar efficacy, safety profile and survival whereas cisplatin shows poor efficacy and safety and survival in Indian oral cancer patients.
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Protocolos de Quimioterapia Combinada Antineoplásica , Cisplatino , Quimioterapia de Indução , Neoplasias Bucais , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Neoplasias Bucais/tratamento farmacológico , Neoplasias Bucais/patologia , Neoplasias Bucais/mortalidade , Quimioterapia de Indução/métodos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Seguimentos , Adulto , Resultado do Tratamento , Cisplatino/administração & dosagem , Cisplatino/uso terapêutico , Cisplatino/efeitos adversos , Paclitaxel/administração & dosagem , Paclitaxel/uso terapêutico , Paclitaxel/efeitos adversos , Idoso , Estadiamento de Neoplasias , Carboplatina/administração & dosagem , Carboplatina/uso terapêutico , Fluoruracila/administração & dosagem , Fluoruracila/uso terapêutico , Fluoruracila/efeitos adversosRESUMO
Triple-negative breast cancer lacks an expression of ER, PR, and Her-2, has a poor prognosis, and there are no target therapies available. Therapeutic options to treat TNBC are limited and urgently needed. Strong evidence indicates that molecular signaling pathways have a significant function to regulate biological mechanisms and their abnormal expression endows with the development of cancer. PIM kinase is overexpressed in various human cancers including TNBC which is regulated by various signaling pathways that are crucial for cancer cell proliferation and survival and also make PIM kinase as an attractive drug target. One of the targets of the STAT3 signaling pathway is PIM1 that plays a key role in tumor progression and transformation. In this review, we accumulate the current scenario of the PIM-STAT3 axis that provides insights into the PIM1 and STAT3 inhibitors which can be developed as potential co-inhibitors as prospective anticancer agents.
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Antineoplásicos , Neoplasias de Mama Triplo Negativas , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Estudos Prospectivos , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Neoplasias de Mama Triplo Negativas/metabolismoRESUMO
BACKGROUND AND AIM: Advanced epithelial ovarian cancer (OC) has a high disease manifestation with difficult-to-manage symptoms that limit the patients' functionality. Abdominal pain, persistent back pain, and neuropathic pain are among the common discomforts associated with OC and its treatment. Our study aims to determine pain scores in advanced OC patients undergoing surgery and chemotherapeutic treatment with carboplatin and paclitaxel. METHODS: One hundred and ten patients with advanced epithelial OC were enrolled and treated with surgery and an adjuvant/neoadjuvant chemotherapy regimen of carboplatin-paclitaxel for six cycles (triweekly). Pain intensity was analyzed using the validated numerical rating scale for resting, movement, sleep interference-associated pain, and neuropathic pain scores were evaluated using the neuropathic pain symptom inventory scale. Pain was correlated with Qol according to Fact-O questionnaires. Chemo-response was evaluated using the CA125 blood biomarker and CT scan of the abdomen and thorax. Data were recorded at baseline, 2, 4, and 6 months of the six chemotherapy cycles. RESULTS: Of the 110 patients, no statistically significant differences were found in pain at baseline and after treatment (P > 0.05) and between the responder and non-responder categories (P > 0.05). However, movement-associated pain had a significant correlation with chemo-response and a strong positive correlation with the patients' physical and functional wellbeing. There were more chemo-induced neuropathy occurrences (P = 0.001) in the neoadjuvant chemotherapy group. CONCLUSION: Patients in the neoadjuvant chemotherapy arm experienced more chemo-induced neuropathy that was persistent and did not improve with the treatment. RELEVANCE FOR PATIENTS: Peripheral neuropathy is a common adverse effect of platinum and taxane chemotherapeutic drugs that persists throughout cancer treatment and in survivorship. This research provides evidence that chemotherapy-associated neuropathy affects Qol of patients and it will be helpful to improve pain and palliative care management policies.
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BACKGROUND: Oral carcinoma and precancers are major public health challenges in India and other developing countries. OBJECTIVES: Aim of the study was to assess the associations of demographic characteristics, addictions, chief complaints of mouth/oral and clinical diagnosis by cytology smear and punch biopsy in early detection of oral premalignant and malignant lesions. Methods Study was designed on retrospective data of case files of CDC, CNCI, Kolkata, from patients attended from January 1996 to September 2016. History was taken, histopathology and Pap smear were performed. Descriptive statistical analysis, cross-tabulation and Pearson's Chi-square test were done. RESULTS: Total participants (n = 692); 110 (15.9%) having history of swallowing betel leaf, nut lime, dokta, jarda, catecheu with an average of 11 years. Three hundred twenty-five (46.9%) had multiple addiction (cigarette/bidi/tobacco/all). Ninety-eight (12.1%), 99 (12.2%) and 68 (8.4%) were addicted to cigarette, bidi and chewing tobacco, respectively. Twenty-nine participants were addicted to alcohol; 18 (2.6%) and 11 (1.5%) took country and foreign alcohol correspondingly. Clinicians thoroughly examined lips (4.1%), buccal mucosa (27.3%), gingival (2.8%), tongue (23.1%), hard and soft palate (4.9%), mouth loor (5.2%) and other parts (32.3%); diagnosed participants as normal (22.8%)/benign (23.1%)/premalignant (39.1%)/malignant (14.8%). Smears confirmed 60, 131, 42, 9 and 8 cases as carcinoma, mild, moderate, severe dysplasia and inflammation, respectively. The punch biopsy identified 11 carcinomas, two severe, two moderate and seveeen mild dysplasia's. Chi-square test showed significant association between smear and examination (P = 0.022), diagnosis and examinations of the oral cancer patients (P = 0.0001). CONCLUSION: The study provided strong evidence that betel leaf, chewing tobacco, smoking and alcohol are independent risk factors for oral cancer. Cytological smear and biopsy are cost-effective approaches for early detection.
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Carcinoma , Neoplasias Bucais , Lesões Pré-Cancerosas , Feminino , Hospitais , Humanos , Hiperplasia , Índia/epidemiologia , Neoplasias Bucais/diagnóstico , Neoplasias Bucais/epidemiologia , Neoplasias Bucais/etiologia , Teste de Papanicolaou , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/epidemiologia , Estudos RetrospectivosRESUMO
Current therapy for visceral leishmaniasis (VL), compromised by drug resistance, toxicity, and high cost, demands for more effective, safer, and low-cost drugs. Artemisinin has been found to be an effectual drug alternative in experimental models of leishmaniasis. Comparative genome and transcriptome analysis of in vitro-adapted artesunate-resistant (K133AS-R) and -sensitive wild-type (K133WT) Leishmania donovani parasites was carried out using next-generation sequencing and single-color DNA microarray technology, respectively, to identify genes and interlinked pathways contributing to drug resistance. Whole-genome sequence analysis of K133WT vs. K133AS-R parasites revealed substantial variation among the two and identified 240 single nucleotide polymorphisms (SNPs), 237 insertion deletions (InDels), 616 copy number variations (CNVs) (377 deletions and 239 duplications), and trisomy of chromosome 12 in K133AS-R parasites. Transcriptome analysis revealed differential expression of 208 genes (fold change ≥ 2) in K133AS-R parasites. Functional categorization and analysis of modulated genes of interlinked pathways pointed out plausible adaptations in K133AS-R parasites, such as (i) a dependency on lipid and amino acid metabolism for generating energy, (ii) reduced DNA and protein synthesis leading to parasites in the quiescence state, and (iii) active drug efflux. The upregulated expression of cathepsin-L like protease, amastin-like surface protein, and amino acid transporter and downregulated expression of the gene encoding ABCG2, pteridine receptor, adenylatecyclase-type receptor, phosphoaceylglucosamine mutase, and certain hypothetical proteins are concordant with genomic alterations suggesting their potential role in drug resistance. The study provided an understanding of the molecular basis linked to artemisinin resistance in Leishmania parasites, which may be advantageous for safeguarding this drug for future use.
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Antiprotozoários/farmacologia , Resistência a Medicamentos/genética , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/genética , Animais , Aquagliceroporinas/genética , Aquagliceroporinas/metabolismo , Artemisininas/farmacologia , Artesunato/farmacologia , Cromossomos , Resistência a Medicamentos/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Frequência do Gene , Genoma de Protozoário , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Leishmaniose Visceral/parasitologia , Camundongos , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Reprodutibilidade dos Testes , Sequenciamento Completo do GenomaRESUMO
The rnp-4f gene in Drosophila melanogaster encodes nuclear protein RNP-4F. This encoded protein is represented by homologs in other eukaryotic species, where it has been shown to function as an intron splicing assembly factor. Here, RNP-4F is believed to initially bind to a recognition sequence on U6-snRNA, serving as a chaperone to facilitate its association with U4-snRNA by intermolecular hydrogen bonding. RNA conformations are a key factor in spliceosome function, so that elucidation of changing secondary structures for interacting snRNAs is a subject of considerable interest and importance. Among the five snRNAs which participate in removal of spliceosomal introns, there is a growing consensus that U6-snRNA is the most structurally dynamic and may constitute the catalytic core. Previous studies by others have generated potential secondary structures for free U4- and U6-snRNAs, including the Y-shaped U4-/U6-snRNA model. These models were based on study of RNAs from relatively few species, and the popular Y-shaped model remains to be systematically re-examined with reference to the many new sequences generated by recent genomic sequencing projects. We have utilized a comparative phylogenetic approach on 60 diverse eukaryotic species, which resulted in a revised and improved U4-/U6-snRNA secondary structure. This general model is supported by observation of abundant compensatory base mutations in every stem, and incorporates more of the nucleotides into base-paired associations than in previous models, thus being more energetically stable. We have extensively sampled the eukaryotic phylogenetic tree to its deepest roots, but did not find genes potentially encoding either U4- or U6-snRNA in the Giardia and Trichomonas data-bases. Our results support the hypothesis that nuclear introns in these most deeply rooted eukaryotes may represent evolutionary intermediates, sharing characteristics of both group II and spliceosomal introns. An unexpected result of this study was discovery of a potential competitive binding site for Drosophila splicing assembly factor RNP-4F to a 5'-UTR regulatory region within its own premRNA, which may play a role in negative feedback control.
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Adenosine Deaminases Acting on RNA (ADARs) have been studied in many animal phyla, where they have been shown to deaminate specific adenosines into inosines in duplex mRNA regions. In Drosophila, two isoform classes are encoded, designated full-length (contains the editase domain) and truncated (lacks this domain). Much is known about the full-length isoform, which plays a major role in regulating functions of voltage-gated ion channel proteins in the adult brain. In contrast, almost nothing is known about the functional significance of the truncated isoform. In situ hybridization shows that both isoform mRNA classes are maternally derived and transcripts for both localize primarily to the developing central nervous system. Quantitative RT-PCR shows that about 35% of all dADAR mRNA transcripts belong to the truncated class in embryos. 3'-RACE results show that abundance of the truncated isoform class is developmentally regulated, with a longer transcript appearing after the mid-blastula transition. 3'-UTR sequences for the truncated isoform have been determined from diverse Drosophila species and important regulatory regions including stop codons have been mapped. Western analysis shows that both mRNA isoform classes are translated into protein during embryonic development, as full-length variant levels gradually diminish. The truncated protein isoform is present in every Drosophila species studied, extending over a period spanning about 40 × 106 years, implying a conserved function. Previous work has shown that a dADAR protein isoform binds to the evolutionarily conserved rnp-4f pre-mRNA stem-loop located in the 5'-UTR to regulate splicing, while no RNA editing was observed, suggesting the hypothesis that it is the non-catalytic truncated isoform which regulates splicing. To test this hypothesis, we have utilized RNAi technology, the results of which support the hypothesis. These results demonstrate a novel, non-catalytic function for the truncated dADAR protein isoform in Drosophila embryonic development, which is very likely evolutionarily conserved.
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Alternative splicing greatly enhances the diversity of proteins encoded by eukaryotic genomes, and is also important in gene expression control. In contrast to the great depth of knowledge as to molecular mechanisms in the splicing pathway itself, relatively little is known about the regulatory events behind this process. The 5'-UTR and 3'-UTR in pre-mRNAs play a variety of roles in controlling eukaryotic gene expression, including translational modulation, and nearly 4000 of the roughly 14,000 protein coding genes in Drosophila contain introns of unknown functional significance in their 5'-UTR. Here we report the results of an RNA electrophoretic mobility shift analysis of Drosophila rnp-4f 5'-UTR intron 0 splicing regulatory proteins. The pre-mRNA potential regulatory element consists of an evolutionarily-conserved 177-nt stem-loop arising from pairing of intron 0 with part of adjacent exon 2. Incubation of in vitro transcribed probe with embryo protein extract is shown to result in two shifted RNA-protein bands, and protein extract from a dADAR null mutant fly line results in only one shifted band. A mutated stem-loop in which the conserved exon 2 primary sequence is changed but secondary structure maintained by introducing compensatory base changes results in diminished band shifts. To test the hypothesis that dADAR plays a role in intron splicing regulation in vivo, levels of unspliced rnp-4f mRNA in dADAR mutant were compared to wild-type via real-time qRT-PCR. The results show that during embryogenesis unspliced rnp-4f mRNA levels fall by up to 85% in the mutant, in support of the hypothesis. Taken together, these results demonstrate a novel role for dADAR protein in rnp-4f 5'-UTR alternative intron splicing regulation which is consistent with a previously proposed model.
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Regiões 5' não Traduzidas , Adenosina Desaminase/fisiologia , Proteínas de Drosophila/fisiologia , Drosophila melanogaster/genética , Ensaio de Desvio de Mobilidade Eletroforética/métodos , Íntrons , Isoformas de Proteínas/fisiologia , Splicing de RNA , Animais , Sequência de Bases , Dados de Sequência Molecular , Conformação de Ácido Nucleico , RNA/química , RNA/genética , Reação em Cadeia da Polimerase em Tempo Real , Homologia de Sequência do Ácido NucleicoRESUMO
The chemotherapeutic drug bleomycin causes DNA damage and apoptosis in the lungs of mice within hours of endotracheal instillation followed by inflammation and fibrosis weeks later. The p53 tumor suppressor protein mediates cellular responses to DNA damage, including induction of apoptosis, but the effects of p53 activation in the various cell types of the lung during bleomycin-induced pulmonary fibrosis remain unclear. We show here that a transgene with a dominant-negative mutant form of human p53 expressed from the surfactant protein C promoter sensitizes mice to bleomycin-induced lung injury. The bleomycin-exposed transgenic animals display more severe lung pathology with associated collagen deposition and more pronounced lung eosinophilia than simultaneously exposed nontransgenic littermates. These observations suggest that compromising p53 function in the alveolar epithelium impairs recovery of the lung from bleomycin-induced injury.