RESUMO
Topoisomerase IIß is a type II DNA topoisomerase that was reported to be expressed in all mammalian cells but abundantly expressed in cells that have undergone terminal differentiation to attain a post mitotic state. Enzymatically it catalyzes ATP-dependent topological changes of double stranded DNA, while as a protein it was reported to be associated with several factors in promoting cell growth, migration, DNA repair and transcription regulation. The cellular roles of topoisomerase IIß are very less understood compared to its counterpart topoisomerase IIα. This review discusses origin of Topoisomerase II beta, its structure, activities reported in vitro and in vivo along with implications in cellular processes namely transcription, DNA repair, neuronal development, aging, HIV-infection and cancer.
Assuntos
Envelhecimento/genética , Reparo do DNA , DNA Topoisomerases Tipo II/genética , Proteínas de Ligação a DNA/genética , DNA/genética , Neurogênese/genética , Transcrição Gênica , Envelhecimento/metabolismo , Animais , Ciclo Celular/genética , Diferenciação Celular , Movimento Celular , DNA/química , DNA/metabolismo , DNA Topoisomerases Tipo II/química , DNA Topoisomerases Tipo II/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Infecções por HIV/enzimologia , Infecções por HIV/genética , Infecções por HIV/patologia , Infecções por HIV/virologia , Humanos , Modelos Moleculares , Neoplasias/enzimologia , Neoplasias/genética , Neoplasias/patologia , Neurônios/citologia , Neurônios/enzimologia , Estrutura Terciária de ProteínaRESUMO
TopoisomeraseIIß, an isoform of type II topoisomerase, was found to be functional in various viral infections. Its plausible role in HIV life cycle was also suggested earlier, but not clearly established. In the present study, we have investigated the role of TopoIIß in HIV-1 infection by its gain and loss of function. Overexpression of TopoIIß lead to an increase in viral replication, resulting in enhanced virion production. HIV-1 replication was impaired when TopoIIß was down regulated by siRNA and inhibited by ICRF-193 and merbarone. The role of TopoIIß in HIV-1 transcription was shown through its interaction with Tat and recruitement to long terminal repeat (LTR) region by co-immunoprecipitation and ChIP assays. Involvement of TopoIIß in transactivation of HIV-1 LTR was confirmed by luciferase assay in reporter cell line, TZM bl and also by transfection of reporter exogenously. It was also observed that LTR transactivation commensurated with the expression of TopoIIß in the presence of Tat. In addition, a decreased viral gene expression on treatment with merbarone exemplifies the importance of catalytic activity of TopoIIß in viral replication. These observations indicate that TopoIIß is involved in the cascade of coactivator complexes that are recruited to LTR for regulation of HIV-1 transcription.
Assuntos
DNA Topoisomerases Tipo II/metabolismo , Proteínas de Ligação a DNA/metabolismo , HIV-1/genética , Antígenos Nucleares/metabolismo , Linhagem Celular Tumoral , Células HEK293 , Repetição Terminal Longa de HIV , HIV-1/metabolismo , Humanos , Autoantígeno Ku , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases/metabolismo , Ativação Transcricional , Replicação Viral , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismoRESUMO
Curcumin is known to have neuroprotective role and possess antioxidant, anti-inflammatory activities. Rotenone, a flavonoid induced neurotoxicity in dopaminergic cells is being widely studied in Parkinson's Disease (PD) research. In the present study, curcumin loaded lactoferrin nano particles prepared by sol-oil chemistry were used to protect dopaminergic cell line SK-N-SH against rotenone induced neurotoxicity. These curcumin loaded nano particles were of 43-60 nm diameter size and around 100 nm hydrodynamic size as assessed by transmission electron microscopy, atomic force microscopy and dynamic light scattering analysis respectively. The encapsulation efficiency was 61.3% ± 2.4%. Cellular uptake of curcumin through these nano particles was confirmed by confocal imaging and spectrofluorimetric analysis. The curcumin loaded lactoferrin nanoparticles showed greater intracellular drug uptake, sustained retention and greater neuroprotection than soluble counterpart. Neuroprotective activity was characterized through viability assays and by estimating ROS levels. Furthermore rotenone induced PD like features were characterized by decrease in tyrosine hydroxylase expression and increase in α-synuclein expression. Taken together curcumin loaded lactoferrin nanoparticles could be a promising drug delivery strategy against neurotoxicity in dopaminergic neurons.