RESUMEN
BACKGROUND/AIM: Activation-induced cytidine deaminase (AID) is a DNA modifying enzyme which has an essential function in promoting antibody diversification. Its overexpression is strongly associated with B-cell derived malignancies including Burkitt lymphoma, where AID is required for the characteristic c-MYC/IGH translocation. This study aimed at defining AID's oncopathogenic role which is still poorly understood. MATERIALS AND METHODS: We created over-expressing and knock-down cell culture models of AID, and used cellular assays to provide insight into its contribution to lymphomagenesis. RESULTS: We showed that AID expression is highly specific to, and abundantly expressed in B-cell-derived cancers and that ectopic overexpression of AID leads to rapid cell death. Using a knock-down model, we revealed that AID expression significantly impacts genomic stability, proliferation, migration and drug resistance. CONCLUSION: AID is an important driver of lymphoma, impacting multiple cellular events, and is potentially a strong candidate for targeted therapy in lymphoma.
Asunto(s)
Citidina Desaminasa/metabolismo , Resistencia a Antineoplásicos , Linfoma de Células B/metabolismo , Animales , Antineoplásicos/farmacología , Linfoma de Burkitt/tratamiento farmacológico , Linfoma de Burkitt/genética , Linfoma de Burkitt/metabolismo , Linfoma de Burkitt/patología , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular , Citidina Desaminasa/genética , Daño del ADN , Doxorrubicina/farmacología , Expresión Génica Ectópica , Activación Enzimática , Expresión Génica , Técnicas de Silenciamiento del Gen , Humanos , Linfoma de Células B/tratamiento farmacológico , Linfoma de Células B/genética , Linfoma de Células B/patologíaRESUMEN
Hearing impairment (HI) is a sensory disorder with a prevalence of 0.0055 live births in South Africa. DNA samples from a South African family presenting with progressive, autosomal dominant non-syndromic HI were subjected to whole-exome sequencing, and a novel monoallelic variant in REST [c.1244GC; p.(C415S)], was identified as the putative causative variant. The co-segregation of the variant was confirmed with Sanger Sequencing. The variant is absent from databases, 103 healthy South African controls, and 52 South African probands with isolated HI. In silico analysis indicates that the p.C415S variant in REST substitutes a conserved cysteine and results in changes to the surrounding secondary structure and the disulphide bonds, culminating in alteration of the tertiary structure of REST. Localization studies using ectopically expressed GFP-tagged Wild type (WT) and mutant REST in HEK-293 cells show that WT REST localizes exclusively to the nucleus; however, the mutant protein localizes throughout the cell. Additionally, mutant REST has an impaired ability to repress its known target AF1q. The data demonstrates that the identified mutation compromises the function of REST and support its implication in HI. This study is the second report, worldwide, to implicate REST in HI and suggests that it should be included in diagnostic HI panels.