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1.
Proc Natl Acad Sci U S A ; 119(50): e2217542119, 2022 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-36490315

RESUMEN

R-loops, or RNA:DNA hybrids, can induce DNA damage, which requires DNA repair factors including breast cancer type 1 susceptibility protein (BRCA1) to restore genomic integrity. To date, several pathogenic mutations have been found within the tandem BRCA1 carboxyl-terminal (BRCT) domains that mediate BRCA1 interactions with proteins and DNA in response to DNA damage. Here, we describe a nonrepair role of BRCA1 BRCT in suppressing ribosomal R-loops via two mechanisms. Through its RNA binding and annealing activities, BRCA1 BRCT facilitates the formation of double-stranded RNA between ribosomal RNA (rRNA) and antisense-rRNA (as-rRNA), hereby minimizing rRNA hybridization to ribosomal DNA to form R-loops. BRCA1 BRCT also promotes RNA polymerase I-dependent transcription of as-rRNA to enhance double-stranded rRNA (ds-rRNA) formation. In addition, BRCA1 BRCT-mediated as-rRNA production restricts rRNA maturation in unperturbed cells. Hence, impairing as-rRNA transcription and ds-rRNA formation due to BRCA1 BRCT deficiency deregulates rRNA processing and increases ribosomal R-loops and DNA breaks. Our results link ribosomal biogenesis dysfunction to BRCA1-associated genomic instability.


Asunto(s)
Proteína BRCA1 , ARN Bicatenario , Proteína BRCA1/metabolismo , ARN sin Sentido , Reparación del ADN , Daño del ADN , ADN
2.
Microb Cell Fact ; 22(1): 201, 2023 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-37803395

RESUMEN

BACKGROUND: Xylitol has a wide range of applications in the pharmaceuticals, cosmetic, food and beverage industry. Microbial xylitol production reduces the risk of contamination and is considered as environment friendly and sustainable compared to the chemical method. In this study, random mutagenesis and genetic engineering approaches were employed to develop Candida tropicalis strains with reduced xylitol dehydrogenase (XDH) activity to eliminate co-substrate requirement for corn cob-based xylitol-ethanol biorefinery. RESULTS: The results suggest that when pure xylose (10% w/v) was fermented in bioreactor, the Ethyl methane sulfonate (EMS) mutated strain (C. tropicalis K2M) showed 9.2% and XYL2 heterozygous (XYL2/xyl2Δ::FRT) strain (C. tropicalis K21D) showed 16% improvement in xylitol production compared to parental strain (C. tropicalis K2). Furthermore, 1.5-fold improvement (88.62 g/L to 132 g/L) in xylitol production was achieved by C. tropicalis K21D after Response Surface Methodology (RSM) and one factor at a time (OFAT) applied for media component optimization. Finally, corncob hydrolysate was tested for xylitol production in biorefinery mode, which leads to the production of 32.6 g/L xylitol from hemicellulosic fraction, 32.0 g/L ethanol from cellulosic fraction and 13.0 g/L animal feed. CONCLUSIONS: This work, for the first time, illustrates the potential of C. tropicalis K21D as a microbial cell factory for efficient production of xylitol and ethanol via an integrated biorefinery framework by utilising lignocellulosic biomass with minimum waste generation.


Asunto(s)
Candida tropicalis , Xilitol , Candida tropicalis/genética , Zea mays , Fermentación , Etanol , Hidrólisis , Xilosa
3.
Proc Natl Acad Sci U S A ; 117(7): 3621-3626, 2020 02 18.
Artículo en Inglés | MEDLINE | ID: mdl-32024762

RESUMEN

Ten-eleven translocation (TET) family enzymes (TET1, TET2, and TET3) oxidize 5-methylcytosine (5mC) and generate 5-hydroxymethylcytosine (5hmC) marks on the genome. Each TET protein also interacts with specific binding partners and partly plays their role independent of catalytic activity. Although the basic role of TET enzymes is well established now, the molecular mechanism and specific contribution of their catalytic and noncatalytic domains remain elusive. Here, by combining in silico and biochemical screening strategy, we have identified a small molecule compound, C35, as a first-in-class TET inhibitor that specifically blocks their catalytic activities. Using this inhibitor, we explored the enzymatic function of TET proteins during somatic cell reprogramming. Interestingly, we found that C35-mediated TET inactivation increased the efficiency of somatic cell programming without affecting TET complexes. Using high-throughput mRNA sequencing, we found that by targeting 5hmC repressive marks in the promoter regions, C35-mediated TET inhibition activates the transcription of the BMP-SMAD-ID signaling pathway, which may be responsible for promoting somatic cell reprogramming. These results suggest that C35 is an important tool for inducing somatic cell reprogramming, as well as for dissecting the other biological functions of TET enzymatic activities without affecting their other nonenzymatic roles.


Asunto(s)
Reprogramación Celular , Proteínas de Unión al ADN/antagonistas & inhibidores , Dioxigenasas/antagonistas & inhibidores , Inhibidores Enzimáticos/química , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , 5-Metilcitosina/análogos & derivados , 5-Metilcitosina/metabolismo , Dominio Catalítico , Línea Celular , Reprogramación Celular/efectos de los fármacos , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Dioxigenasas/química , Dioxigenasas/genética , Dioxigenasas/metabolismo , Humanos , Oxigenasas de Función Mixta/antagonistas & inhibidores , Oxigenasas de Función Mixta/química , Oxigenasas de Función Mixta/genética , Oxigenasas de Función Mixta/metabolismo , Proteínas Proto-Oncogénicas/química , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo
4.
J Craniofac Surg ; 34(1): e46-e52, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36008879

RESUMEN

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has posed another serious threat, mucormycosis infection, affecting the maxilla and orbitocerebral region. This condition has not spared world population from its merciless claws. This article addresses the challenges faced by the maxillofacial surgeons in setting the protocols from preoperative diagnosis, surgical management to postoperative care, including short-term and long-term rehabilitation. To manage this relentlessly progressing condition, a multispecialty team approach is to be activated in diagnosing, managing, and rehabilitating the patients. PURPOSE: The purpose of this clinical study is to document and analyze the clinical and demographic data, presentation of the lesion, the diagnostic methods followed for early clinical detection, and management of post COVID-19 midface mucormycosis. The article also discusses postoperative medical management and prosthetic rehabilitation. RESULTS: Most of the mucormycosis cases reporting to our center were treated and recovered patients of Severe Acute Respiratory Syndrome Coronavirus 2 infection. Thirty-four (n=34) case were operated for post COVID-19 midface mucormycosis between October 2020 and December 2021. Male to Female ratio is 1:42. The average age of the patients was 57.5 years. Maximum patients were in fifth and sixth decade of life. Maxilla was the involved bone. Treatment was primarily surgical debridement to extended or radical maxillectomy. All patients were treated with Liposomal Amphotericin B and tab posaconazole for 3 to 4 weeks depending upon the age, weight, and physiological state of the patients to attain an optimal cumulative load. Three patients succumbed to illness postoperatively (n=3, 1.02%). Average duration of hospital stay was 47 days. The average review period was 5.1 months.


Asunto(s)
COVID-19 , Mucormicosis , Humanos , Femenino , Masculino , Persona de Mediana Edad , Mucormicosis/diagnóstico , Mucormicosis/cirugía , Cara , Cuidados Posoperatorios , Antifúngicos/uso terapéutico
5.
Nucleic Acids Res ; 48(6): 3001-3013, 2020 04 06.
Artículo en Inglés | MEDLINE | ID: mdl-31965183

RESUMEN

Nucleosomal histones are barriers to the DNA repair process particularly at DNA double-strand breaks (DSBs). However, the molecular mechanism by which these histone barriers are removed from the sites of DNA damage remains elusive. Here, we have generated a single specific inducible DSB in the cells and systematically examined the histone removal process at the DNA lesion. We found that histone removal occurred immediately following DNA damage and could extend up to a range of few kilobases from the lesion. To examine the molecular mechanism underlying DNA damage-induced histone removal, we screened histone modifications and found that histone ADP-ribosylation was associated with histone removal at DNA lesions. PARP inhibitor treatment suppressed the immediate histone eviction at DNA lesions. Moreover, we examined histone chaperones and found that the FACT complex recognized ADP-ribosylated histones and mediated the removal of histones in response to DNA damage. Taken together, our results reveal a pathway that regulates early histone barrier removal at DNA lesions. It may also explain the mechanism by which PARP inhibitor regulates early DNA damage repair.


Asunto(s)
Daño del ADN/genética , Reparación del ADN/genética , Histonas/genética , Poli ADP Ribosilación/genética , ADP-Ribosilación/genética , Núcleo Celular/genética , Cromatina/genética , Cromosomas Humanos X/genética , Roturas del ADN de Doble Cadena/efectos de los fármacos , Reparación del ADN/efectos de los fármacos , Células HCT116 , Humanos , Chaperonas Moleculares/genética , Nucleosomas/genética , Inhibidores de Poli(ADP-Ribosa) Polimerasas/farmacología
6.
Med J Armed Forces India ; 78(3): 360-364, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35368449

RESUMEN

COVID-19 (Coronavirus Disease 2019), illness with associated comorbidities and corticosteroid therapy makes the host immunocompromised and prone to opportunistic microbial infections. As the world continues to struggle with the pandemic of COVID-19, an increase in cases of opportunistic fungal infections have been reported from all over the world during the second wave of COVID-19 like aspergillosis, mucormycosis, and candidiasis. Scedosporium apiospermum is an emerging pathogen that is usually associated with mycetoma, pulmonary infection, and central nervous infections. It has been rarely associated with fungal rhinosinusitis (FRS). In this study, a rare case of FRS caused by S.apiospermum in an immunocompromised post-Covid-19 diabetic woman is reported.

7.
Curr Microbiol ; 78(8): 3258-3267, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34230990

RESUMEN

Rapid industrialization and intensive agriculture activities have led to a rise in heavy metal contamination all over the world. Chhattisgarh (India) being an industrial state, the soil and water are thickly contaminated with heavy metals, especially from arsenic (As). In the present study, we isolated 108 arsenic-resistant bacteria (both from soil and water) from different arsenic-contaminated industrial and mining sites of Chhattisgarh to explore the bacterial gene pool. Further, we screened 24 potential isolates out of 108 for their ability to tolerate a high level of arsenic. The sequencing of the 16S rRNA gene of bacterial isolates revealed that all these samples belong to different diverse genera including Bacillus, Enterobacter, Klebsiella, Pantoea, Acinetobacter, Cronobacter, Pseudomonas and Agrobacterium. The metal tolerance ability was determined by amplification of arsB (arsenite efflux gene) and arsC (arsenate reductase gene) from chromosomal DNA of isolated RnASA11, which was identified as Klebsiella pneumoniae through in silico analysis. The bacterial strains RpSWA2 and RnASA11 were found to tolerate 600 mM As (V) and 30 mM As (III) but the growth of strain RpSWA2 was slower than RnASA11. Furthermore, atomic absorption spectroscopy (AAS) of the sample obtained from bioremediation assay revealed that Klebsiella pneumoniae RnASA11 was able to reduce the arsenic concentration significantly in the presence of arsenate (44%) and arsenite (38.8%) as compared to control.


Asunto(s)
Arsénico , Contaminantes del Suelo , Biodegradación Ambiental , Farmacorresistencia Bacteriana , India , Klebsiella pneumoniae/genética , Filogenia , ARN Ribosómico 16S/genética , Suelo , Agua
8.
J Biol Chem ; 293(33): 12770-12780, 2018 08 17.
Artículo en Inglés | MEDLINE | ID: mdl-29959229

RESUMEN

Set7/9 (also known as Set7, Set9, Setd7, and Kmt7) is a lysine methyltransferase that catalyzes the methylation of multiple substrates, including histone H3 and non-histone proteins. Although not essential for normal development and physiology, Set7/9-mediated methylation events play important roles in regulating cellular pathways involved in various human diseases, making Set7/9 a promising therapeutic target. Multiple Set7/9 inhibitors have been developed, which exhibit varying degrees of potency and selectivity in vitro However, validation of these compounds in vivo has been hampered by the lack of a reliable cellular biomarker for Set7/9 activity. Here, we report the identification of Rpl29, a ribosomal protein abundantly expressed in all cell types, as a major substrate of Set7/9. We show that Rpl29 lysine 5 (Rpl29K5) is methylated exclusively by Set7/9 and can be demethylated by Lsd1 (also known as Kdm1a). Rpl29 is not a core component of the ribosome translational machinery and plays a regulatory role in translation efficiency. Our results indicate that Rpl29 methylation has no effect on global protein synthesis but affects Rpl29 subcellular localization. Using an Rpl29 methylation-specific antibody, we demonstrate that Rpl29K5 methylation is present ubiquitously and validate that (R)-PFI-2, a Set7/9 inhibitor, efficiently reduces Rpl29K5 methylation in cell lines. Thus, Rpl29 methylation can serve as a specific cellular biomarker for measuring Set7/9 activity.


Asunto(s)
Factores de Coagulación Sanguínea/genética , Metilación de ADN , Regulación de la Expresión Génica , N-Metiltransferasa de Histona-Lisina/metabolismo , Histonas/metabolismo , Lisina/química , Proteínas Ribosómicas/fisiología , Animales , Factores de Coagulación Sanguínea/metabolismo , Células Cultivadas , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Fibroblastos/citología , Fibroblastos/metabolismo , N-Metiltransferasa de Histona-Lisina/genética , Humanos , Masculino , Ratones Noqueados , Procesamiento Proteico-Postraduccional , Proteínas de Unión al ARN , Transcripción Genética
9.
New Phytol ; 215(3): 1115-1131, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-28649699

RESUMEN

Withania somnifera produces pharmacologically important triterpenoid withanolides that are derived via phytosterol pathway; however, their biosynthesis and regulation remain to be elucidated. A jasmonate- and salicin-inducible WRKY transcription factor from W. somnifera (WsWRKY1) exhibiting correlation with withaferin A accumulation was functionally characterized employing virus-induced gene silencing and overexpression studies combined with transcript and metabolite analyses, and chromatin immunoprecipitation assay. WsWRKY1 silencing resulted in stunted plant growth, reduced transcripts of phytosterol pathway genes with corresponding reduction in phytosterols and withanolides in W. somnifera. Its overexpression elevated the biosynthesis of triterpenoids in W. somnifera (phytosterols and withanolides), as well as tobacco and tomato (phytosterols). Moreover, WsWRKY1 binds to W-box sequences in promoters of W. somnifera genes encoding squalene synthase and squalene epoxidase, indicating its direct regulation of triterpenoid pathway. Furthermore, while WsWRKY1 silencing in W. somnifera compromised the tolerance to bacterial growth, fungal infection, and insect feeding, its overexpression in tobacco led to improved biotic stress tolerance. Together these findings demonstrate that WsWRKY1 has a positive regulatory role on phytosterol and withanolides biosynthesis, and defense against biotic stress, highlighting its importance as a metabolic engineering tool for simultaneous improvement of triterpenoid biosynthesis and plant defense.


Asunto(s)
Adaptación Fisiológica , Fitosteroles/metabolismo , Proteínas de Plantas/metabolismo , Estrés Fisiológico , Factores de Transcripción/metabolismo , Withania/metabolismo , Witanólidos/metabolismo , Acetatos/farmacología , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/genética , Secuencia de Aminoácidos , Alcoholes Bencílicos/farmacología , Vías Biosintéticas/efectos de los fármacos , Vías Biosintéticas/genética , Ciclopentanos/farmacología , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Silenciador del Gen/efectos de los fármacos , Genes de Plantas , Glucósidos/farmacología , Oxilipinas/farmacología , Proteínas de Plantas/química , Proteínas de Plantas/genética , Regiones Promotoras Genéticas/genética , Unión Proteica/efectos de los fármacos , Análisis de Secuencia de Proteína , Estrés Fisiológico/efectos de los fármacos , Estrés Fisiológico/genética , Fracciones Subcelulares/metabolismo , Factores de Transcripción/química , Factores de Transcripción/genética , Regulación hacia Arriba/efectos de los fármacos , Withania/genética
10.
Langmuir ; 33(46): 13401-13406, 2017 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-29087204

RESUMEN

Rylene imides (RIs) self-assemble into various nanostructures. Often, the synthesis of unsymmetrical RIs (URIs) is required to achieve nanostructures. However, the synthesis of URIs is nontrivial. Thus, a structurally similar alternative is desirable. iso-Indigo (i-indigo) has a π core and lactam rings that are structurally similar to the RIs. Unsymmetrical iso-indigo (i-indigo) can be easily synthesized by condensing oxindole and isatin. We have synthesized a series of unsymmetrical i-indigo molecules. In these molecules, the π-π interaction, hydrogen bonding, and van der Waals interactions are in operation. Because of these, the molecules self-assemble into spheres, fibers, and dahlia flower morphologies. If the hydrogen bonding interaction is disrupted, then all of them form fibers. Control experiments indicate that the complete absence of hydrogen bonding is deleterious to self-assembly. We also show that the lower analogs of i-indigo are not sufficient to form self-assembled nanostructures.

11.
Carcinogenesis ; 37(11): 1027-1040, 2016 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-27543608

RESUMEN

Mouse double minute 2 (MDM2) protein functionally inactivates the tumor suppressor p53 in human cancer. Conventional MDM2 inhibitors provide limited clinical application as they interfere only with the MDM2-p53 interaction to release p53 from MDM2 sequestration but do not prevent activated p53 from transcriptionally inducing MDM2 expression. Here, we report a rationally synthesized chalcone-based pyrido[ b ]indole, CPI-7c, as a unique small-molecule inhibitor of MDM2, which not only inhibited MDM2-p53 interaction but also promoted MDM2 degradation. CPI-7c bound to both RING and N-terminal domains of MDM2 to promote its ubiquitin-mediated degradation and p53 stabilization. CPI-7c-induced p53 directly recruited to the promoters of DR4 and DR5 genes and enhanced their expression, resulting in sensitization of TNF-related apoptosis-inducing ligand (TRAIL)-resistant cancer cells toward TRAIL-induced apoptosis. Collectively, we identified CPI-7c as a novel small-molecule inhibitor of MDM2 with a unique two-prong mechanism of action that sensitized TRAIL-resistant cancer cells to apoptosis by modulating the MDM2-p53-DR4/DR5 pathway.


Asunto(s)
Antineoplásicos/farmacología , Carbolinas/farmacología , Resistencia a Antineoplásicos , Propiofenonas/farmacología , Proteínas Proto-Oncogénicas c-mdm2/antagonistas & inhibidores , Ligando Inductor de Apoptosis Relacionado con TNF/farmacología , Antineoplásicos/química , Apoptosis/efectos de los fármacos , Carbolinas/química , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Modelos Moleculares , Terapia Molecular Dirigida , Regiones Promotoras Genéticas , Propiofenonas/química , Unión Proteica , Estabilidad Proteica , Proteolisis , Proteínas Proto-Oncogénicas c-mdm2/química , Proteínas Proto-Oncogénicas c-mdm2/metabolismo , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/genética , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/metabolismo , Transcripción Genética/efectos de los fármacos , Proteína p53 Supresora de Tumor/metabolismo , Ubiquitinación/efectos de los fármacos , Regulación hacia Arriba
12.
Int J Cancer ; 136(9): 1991-2000, 2015 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-24615680

RESUMEN

Although tumor heterogeneity is widely accepted, the existence of cancer stem cells (CSCs) and their proposed role in tumor maintenance has always been challenged and remains a matter of debate. Recently, a path-breaking chapter was added to this saga when three independent groups reported the in vivo existence of CSCs in brain, skin and intestinal tumors using lineage-tracing and thus strengthens the CSC concept; even though certain fundamental caveats are always associated with lineage-tracing approach. In principle, the CSC hypothesis proposes that similar to normal stem cells, CSCs maintain self renewal and multilineage differentiation property and are found at the central echelon of cellular hierarchy present within tumors. However, these cells differ from their normal counterpart by maintaining their malignant potential, alteration of genomic integrity, epigenetic identity and the expression of specific surface protein profiles. As CSCs are highly resistant to chemotherapeutics, they are thought to be a crucial factor involved in tumor relapse and superficially appear as the ultimate therapeutic target. However, even that is not the end; further complication is attributed by reports of bidirectional regeneration mechanism for CSCs, one from their self-renewal capability and another from the recently proposed concept of dynamic equilibrium between CSCs and non-CSCs via their interconversion. This phenomenon has currently added a new layer of complexity in understanding the biology of tumor heterogeneity. In-spite of its associated controversies, this area has rapidly emerged as the center of attention for researchers and clinicians, because of the conceptual framework it provides towards devising new therapies.


Asunto(s)
Neoplasias/patología , Células Madre Neoplásicas/patología , Animales , Diferenciación Celular/fisiología , Humanos
13.
J Cell Sci ; 126(Pt 20): 4636-46, 2013 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-23868976

RESUMEN

The E2F family of transcription factors are considered versatile modulators, poised at biological crossroads to execute diverse cellular functions. Despite extensive studies on E2F, the molecular mechanisms that control specific biological functions of the E2F1 transcription factor are still not fully understood. Here we have addressed the molecular underpinnings of paradoxical functions of E2F1 in a tumour microenvironment using the 'X15-myc' oncomouse model of hepatocellular carcinoma. We observed that the HBx oncoprotein of hepatitis B virus regulates E2F1 functions by interfering with its binding to Skp2 E3 ubiquitin ligase. The HBx-Skp2 interaction led to the accumulation of transcriptionally active E2F1 and histone methyltransferase mixed lineage leukemia 1 (MLL1) protein. During early stages of hepatocarcinogenesis, the increased E2F1 activity promoted cellular proliferation by stimulating the genes involved in cell cycle control and replication. However, during the late stages, E2F1 triggered replication-stress-induced DNA damage and sensitized cells to apoptotic death in a p53-independent manner. Interestingly, the different promoter occupancy of MLL1 during the early and late stages of tumour development seemed to specify the proliferative and apoptotic functions of E2F1, through its dynamic interaction with the co-activator CBP or co-repressor Brg1. Thus, the temporally regulated promoter occupancy of histone methyltransferase could be a regulatory mechanism associated with the diverse cellular functions of the E2F family of transcription factors.


Asunto(s)
Factor de Transcripción E2F1/metabolismo , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Animales , Apoptosis/fisiología , Procesos de Crecimiento Celular/fisiología , Línea Celular Tumoral , Daño del ADN , Factor de Transcripción E2F1/genética , Células Hep G2 , Hepatoblastoma/genética , Hepatoblastoma/metabolismo , Hepatoblastoma/patología , Histona Metiltransferasas , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Ratones , Ratones Transgénicos , Proteína de la Leucemia Mieloide-Linfoide/genética , Regiones Promotoras Genéticas , Microambiente Tumoral/fisiología , Ubiquitinación
14.
Plant Biotechnol J ; 13(9): 1287-99, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25809293

RESUMEN

Withania somnifera (L.) Dunal is an important Indian medicinal plant that produces withanolides, which are triterpenoid steroidal lactones having diverse biological activities. To enable fast and efficient functional characterization of genes in this slow-growing and difficult-to-transform plant, a virus-induced gene silencing (VIGS) was established by silencing phytoene desaturase (PDS) and squalene synthase (SQS). VIGS of the gene encoding SQS, which provides precursors for triterpenoids, resulted in significant reduction of squalene and withanolides, demonstrating its application in studying withanolides biosynthesis in W. somnifera leaves. A comprehensive analysis of gene expression and sterol pathway intermediates in WsSQS-vigs plants revealed transcriptional modulation with positive feedback regulation of mevalonate pathway genes, and negative feed-forward regulation of downstream sterol pathway genes including DWF1 (delta-24-sterol reductase) and CYP710A1 (C-22-sterol desaturase), resulting in significant reduction of sitosterol, campesterol and stigmasterol. However, there was little effect of SQS silencing on cholesterol, indicating the contribution of sitosterol, campesterol and stigmasterol, but not of cholesterol, towards withanolides formation. Branch-point oxidosqualene synthases in WsSQS-vigs plants exhibited differential regulation with reduced CAS (cycloartenol synthase) and cycloartenol, and induced BAS (ß-amyrin synthase) and ß-amyrin. Moreover, SQS silencing also led to the down-regulation of brassinosteroid-6-oxidase-2 (BR6OX2), pathogenesis-related (PR) and nonexpressor of PR (NPR) genes, resulting in reduced tolerance to bacterial and fungal infection as well as to insect feeding. Taken together, SQS silencing negatively regulated sterol and defence-related genes leading to reduced phytosterols, withanolides and biotic stress tolerance, thus implicating the application of VIGS for functional analysis of genes related to withanolides formation in W. somnifera leaves.


Asunto(s)
Farnesil Difosfato Farnesil Transferasa/fisiología , Estrés Fisiológico/genética , Withania/genética , Witanólidos/metabolismo , Farnesil Difosfato Farnesil Transferasa/genética , Silenciador del Gen , Genes de Plantas/genética , Genes de Plantas/fisiología , Redes y Vías Metabólicas/genética , Redes y Vías Metabólicas/fisiología , Oxidorreductasas/genética , Oxidorreductasas/fisiología , Hojas de la Planta/metabolismo , Estrés Fisiológico/fisiología , Withania/enzimología , Withania/metabolismo , Withania/fisiología
15.
Blood ; 122(25): 4086-9, 2013 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-24167195

RESUMEN

Somatic heterozygous mutations of the DNA methyltransferase gene DNMT3A occur frequently in acute myeloid leukemia and other hematological malignancies, with the majority (∼60%) of mutations affecting a single amino acid, Arg882 (R882), in the catalytic domain. Although the mutations impair DNMT3A catalytic activity in vitro, their effects on DNA methylation in cells have not been explored. Here, we show that exogenously expressed mouse Dnmt3a proteins harboring the corresponding R878 mutations largely fail to mediate DNA methylation in murine embryonic stem (ES) cells but are capable of interacting with wild-type Dnmt3a and Dnmt3b. Coexpression of the Dnmt3a R878H (histidine) mutant protein results in inhibition of the ability of wild-type Dnmt3a and Dnmt3b to methylate DNA in murine ES cells. Furthermore, expression of Dnmt3a R878H in ES cells containing endogenous Dnmt3a or Dnmt3b induces hypomethylation. These results suggest that the DNMT3A R882 mutations, in addition to being hypomorphic, have dominant-negative effects.


Asunto(s)
ADN (Citosina-5-)-Metiltransferasas/genética , Metilación de ADN/genética , Células Madre Embrionarias/enzimología , Genes Dominantes , Mutación Missense , Sustitución de Aminoácidos , Animales , Células COS , Chlorocebus aethiops , ADN (Citosina-5-)-Metiltransferasas/biosíntesis , ADN Metiltransferasa 3A , Células Madre Embrionarias/patología , Regulación Enzimológica de la Expresión Génica/genética , Regulación Leucémica de la Expresión Génica/genética , Leucemia Mieloide Aguda/enzimología , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patología , Ratones , Ratones Mutantes , ADN Metiltransferasa 3B
16.
Nucleic Acids Res ; 40(18): 9021-35, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22772991

RESUMEN

Recent genome-wide mapping of the mammalian replication origins has suggested the role of transcriptional regulatory elements in origin activation. However, the nature of chromatin modifications associated with such trans-factors or epigenetic marks imprinted on cis-elements during the spatio-temporal regulation of replication initiation remains enigmatic. To unveil the molecular underpinnings, we studied the human lamin B2 origin that spatially overlaps with TIMM 13 promoter. We observed an early G(1)-specific occupancy of c-Myc that facilitated the loading of mini chromosome maintenance protein (MCM) complex during subsequent mid-G(1) phase rather stimulating TIMM 13 gene expression. Investigations on the Myc-induced downstream events suggested a direct interaction between c-Myc and histone methyltransferase mixed-lineage leukemia 1 that imparted histone H3K4me3 mark essential for both recruitment of acetylase complex HBO1 and hyperacetylation of histone H4. Contemporaneously, the nucleosome remodeling promoted the loading of MCM proteins at the origin. These chromatin modifications were under the tight control of active demethylation of E-box as evident from methylation profiling. The active demethylation was mediated by the Ten-eleven translocation (TET)-thymine DNA glycosylase-base excision repair (BER) pathway, which facilitated spatio-temporal occupancy of Myc. Intriguingly, the genome-wide 43% occurrence of E-box among the human origins could support our hypothesis that epigenetic control of E-box could be a molecular switch for the licensing of early replicating origins.


Asunto(s)
Ensamble y Desensamble de Cromatina , Elementos E-Box , Epigénesis Genética , Fase G1/genética , Lamina Tipo B/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Origen de Réplica , Acetilación , Proteínas de Unión al ADN/metabolismo , Células HEK293 , Células HL-60 , Células HeLa , Histona Metiltransferasas , N-Metiltransferasa de Histona-Lisina/metabolismo , Histonas/metabolismo , Humanos , Proteínas de Transporte de Membrana Mitocondrial/biosíntesis , Proteínas de Transporte de Membrana Mitocondrial/genética , Proteínas del Complejo de Importación de Proteínas Precursoras Mitocondriales , Proteína de la Leucemia Mieloide-Linfoide/metabolismo , Nucleosomas/metabolismo , Regiones Promotoras Genéticas
17.
J Maxillofac Oral Surg ; 23(3): 688-691, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38911413

RESUMEN

Primary hyperparathyroidism is an endocrine disorder occurring due to increased secretion of parathormone resulting in clinical, anatomical, and biochemical alterations. On the other hand, excision of a parathyroid adenoma can normalize the metabolic status. Brown tumors represent the terminal stage of the remodeling processes during primary or secondary hyperparathyroidism. They are erosive bony lesions caused by rapid osteolysis and peritrabecular fibrosis, resulting in a local destructive phenomenon. Facial skeleton is involved in about 2% of all cases of which the mandible is frequently affected. We report a case series of four patients who presented with brown tumor of both maxilla and mandible. A complete assessment of the medical history, blood investigations and radiological findings combined with biopsy results is necessary for a correct diagnosis. The standard treatment of the Brown tumors is not a surgical resection, but the treatment of the cause of the tumor, which in this case is hyperparathyroidism. However in our case, the extent of the lesion and the non resolution after the parathyroidectomy necessitated a surgical approach in two of our patients however two responded well to medical management alone.

18.
Indian J Chest Dis Allied Sci ; 55(2): 85-95, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24046998

RESUMEN

Children with congenital heart disease (CHD) are more frequently living into adulthood as their survival has improved due to availability of better medical and surgical management in recent times. Management of adults with CHD is emerging as new challenge in the field of medical science. Adults surviving with CHD for longer duration have been observed to develop more complications as compared to children. It is important to recognise and treat these complications early to reduce the morbidity. Pulmonary diseases are the most common systemic complications associated with adults having CHD. These individuals are presenting to clinics or emergency for pulmonary complaints, hence, pulmonologist must be aware about the pulmonary manifestations of CHD and their management.


Asunto(s)
Cardiopatías Congénitas/fisiopatología , Enfermedades Pulmonares/fisiopatología , Adulto , Humanos
19.
Philos Trans R Soc Lond B Biol Sci ; 378(1890): 20220236, 2023 11 20.
Artículo en Inglés | MEDLINE | ID: mdl-37778387

RESUMEN

During mammalian embryo development, pluripotent epiblast cells diversify into the three primary germ layers, which will later give rise to all fetal and adult tissues. These processes involve profound transcriptional and epigenetic changes that require precise coordination. Peptidylarginine deiminase IV (PADI4) is a transcriptional regulator that is strongly associated with inflammation and carcinogenesis but whose physiological roles are less well understood. We previously found that Padi4 expression is associated with pluripotency. Here, we examined the role of PADI4 in maintaining the multi-lineage differentiation potential of mouse embryonic stem (ES) cells. Using bulk and single-cell transcriptomic analyses of embryoid bodies (EBs) derived from Padi4 knock-out (Padi4-KO) mouse ES cells, we find that PADI4 loss impairs mesoderm diversification and differentiation of cardimyocytes and endothelial cells. Additionally, Padi4 deletion leads to concerted downregulation of genes associated with polarized growth, sterol metabolism and the extracellular matrix (ECM). This study indicates a requirement for Padi4 in the specification of the mesodermal lineage and reports the Padi4 associated transcriptome, providing a platform for understanding the physiological functions of Padi4 in development and homeostasis. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.


Asunto(s)
Células Endoteliales , Arginina Deiminasa Proteína-Tipo 4 , Transcriptoma , Animales , Ratones , Diferenciación Celular , Células Madre Embrionarias , Arginina Deiminasa Proteína-Tipo 4/genética
20.
Ann Maxillofac Surg ; 13(2): 240-243, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38405571

RESUMEN

Rationale: Congenital orofacial swellings in neonates are mainly limited to vascular malformations and neuroectodermal benign tumours. Congenital granular cell tumour (CGCT) is a rare condition affecting neonates with a prevalence rate of 6 in 1 million. Our report provides a brief review of diagnosis and management. Patient Concern: A 4-day-old female neonate was brought in with the chief complaint of a single, lobulated mass protruding from the right side of the oral cavity. The inability to achieve lip seal and suckling resulting in feeding problems was the primary concern. Diagnosis and Treatment: Surgical excision of the lesion was carried out under general anaesthesia. Resected mass was confirmed to be a CGCT upon histopathological evaluation. Outcome: One-year follow-up showed satisfactory healing with no evidence of recurrence. Take-away Lesson: Ultrasonography and other imaging modalities help in differentiating it from vascular malformations. Simple surgical excision suffices to treat the condition.

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