RESUMO
Radicular cysts are the most common cystic lesions which affect the jaw. Traumatic dental injuries cause injury to the periodontal ligament and dental pulp often leads to pulpal necrosis. The necrosed pulp eventually becomes the nidus of infection and irritates the periapical epithelial cell remnants, which in turn develops into a cyst eventually. This case report presents the successful conservative surgical management of a large infected radicular cyst which was associated with traumatised, necrotic, permanent maxillary lateral incisor with open apex by Partsch II surgical procedure followed by a combination of retrograde and orthograde root canal obturation. This report will guide the clinicians in the arena of surgical endodontics in a conservative approach.
Assuntos
Cisto Radicular , Humanos , IncisivoRESUMO
Mammalian cells immediately inhibit transcription upon exposure to genotoxic stress to avoid fatal collision between ongoing transcription and newly recruited DNA repair machineries to protect genomic integrity. However, mechanisms of this early transcriptional inhibition are poorly understood. In this study, we decipher a novel role of human EAF1, a positive regulator of ELL-dependent RNA Polymerase II-mediated transcription in vitro, in regulation of temporal inhibition of transcription during genotoxic stress. Our results show that, besides Super Elongation Complex (SEC) and Little Elongation Complex (LEC), human ELL (aka ELL1) also forms a complex with EAF1 alone. Interestingly, contrary to the in vitro studies, EAF1 inhibits ELL-dependent RNA polymerase II-mediated transcription of diverse target genes. Mechanistically, we show that intrinsic self-association property of ELL leads to its reduced interaction with other SEC components. EAF1 enhances ELL self-association and thus reduces its interaction with other SEC components leading to transcriptional inhibition. Physiologically, we show that upon exposure to genotoxic stress, ATM-mediated ELL phosphorylation-dependent enhanced EAF1 association results in reduced ELL interaction with other SEC components that lead to global transcriptional inhibition. Thus, we describe an important mechanism of dynamic transcriptional regulation during genotoxic stress involving post-translational modification of a key elongation factor.
Assuntos
Proteínas Mutadas de Ataxia Telangiectasia , Fatores de Transcrição , Fatores de Elongação da Transcrição , Humanos , Proteínas Mutadas de Ataxia Telangiectasia/genética , Dano ao DNA , Fosforilação , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica , Fatores de Elongação da Transcrição/metabolismo , Processamento de Proteína Pós-TraducionalRESUMO
Among all of the Super Elongation Complex (SEC) components, ELL1 (also known as ELL) is the only bona fide elongation factor that directly stimulates transcription elongation by RNA polymerase II. However, the mechanism(s) of functional regulation of ELL1 (referred to as ELL hereafter), through its stabilization, is completely unknown. Here, we report a function of human DBC1 in regulating ELL stability involving HDAC3, p300, and Siah1. Mechanistically, we show that p300-mediated site-specific acetylation increases, whereas HDAC3-mediated deacetylation decreases, ELL stability through polyubiquitylation by the E3 ubiquitin ligase Siah1. DBC1 competes with HDAC3 for the same binding sites on ELL and thus increases its acetylation and stability. Knockdown of DBC1 reduces ELL levels and expression of a significant number of genes, including those involved in glucose metabolism. Consistently, Type 2 diabetes patient-derived peripheral blood mononuclear cells show reduced expression of DBC1 and ELL and associated key target genes required for glucose homeostasis. Thus, we describe a pathway of regulating stability and functions of key elongation factor ELL for expression of diverse sets of genes, including ones that are linked to Type 2 diabetes pathogenesis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína p300 Associada a E1A/metabolismo , Regulação da Expressão Gênica , Histona Desacetilases/metabolismo , Proteínas Nucleares/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Acetilação , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Sítios de Ligação , Linhagem Celular , Diabetes Mellitus Tipo 2/patologia , Proteína p300 Associada a E1A/genética , Técnicas de Silenciamento de Genes , Glucose/metabolismo , Histona Desacetilases/genética , Humanos , Leucócitos Mononucleares/metabolismo , Mutação , Ligação Proteica , Estabilidade Proteica , Transcrição Gênica , Fatores de Elongação da Transcrição/química , Fatores de Elongação da Transcrição/genética , UbiquitinaçãoRESUMO
Despite substantial progress in our understanding of the players involved and the regulatory mechanisms controlling the initiation and elongation steps of transcription, little is known about the recruitment of elongation factors at promoter-proximal regions for the initiation-to-elongation transition. Here, we show evidence that human TFIID, which initiates pre-initiation complex (PIC) assembly, contributes to regulating the recruitment of super-elongation complex (SEC) components at the promoter-proximal region through interactions among selective TAF and SEC components. In vitro direct interactions, coupled with cell-based assays, identified an important poly-Ser domain within SEC components that are involved in their interaction with TFIID. DNA template-based recruitment assays, using purified components, further show a direct role for poly-Ser domain-dependent TFIID interaction in recruiting SEC components on target DNA. Consistently, ChIP and RNA analyses have shown the importance of this mechanism in TFIID-dependent SEC recruitment and target gene expression within mammalian cells.
