Regulation of GADD45 alpha in cellular response to arsenic

Regulation of GADD45 Alpha in Cellular Response to Arsenic

In a study tackling the relationship of arsenic and how GADD45 ? reacts to it specifically the nucleolin links to arsenic-induced stabilization of GADD45 ? mRNA , the study asserts that GADD45 , a growth arrest and DNA damage inducible gene 45 , is induced by arsenic mainly through post-transcriptional mechanism . The study utilizes arsenic (III chloride (As3 ) as the experimental base . The treatment of the human bronchial epithelial cell line , BEAS-2B , with As3 had induced a considerably high increase in GADD45 ? protein and mRNA but As3 only

br showed an effect on the transcription of the GADD45 ? gene that can be considered generally as minor . The accumulation of GADD45 ? mRNA is mainly attributed to the stabilization of GADD45 ? mRNA at the cellular level , particularly its reaction to As3 . Lastly , As3 is able to stimulate the synthesis of mRNA stabilizing proteins , nucleolin and less potently , HuR , with GADD45 ? mRNA . Even though As3 was not successful in affecting the expression of nucleolin , the treatment of the cells with As3 gave way to the re-distribution of nucleolin from nucleoli to nucleoplasm . Silencing of the nucleolin mRNA by RNA interference reversed As3 -induced stabilization of the GADD45 ? mRNA and accretion of the GADD45 ? protein . It can be asserted that the stabilization of GADD45 ? mRNA , symbolizes a novel method of contributing to the construction of GADD45 ? and cell cycle arrest in reaction to As3 (Zhang , 485-495

GADD45 as a cell cycle check point protein

In studies considering GADD45 's function as a cell cycle checkpoint protein , a study was conducted to determine how a G2 /M cell cycle checkpoint can be induced by GADD45 . G1 /S and G2 /M cell cycle checkpoints maintain genomic stability in eukaryotes as a reactive action to genotoxic stress . In the study conducted there is evidence in both genetic and functional sections of a Gadd45-mediated G2 /M checkpoint within human and murine cells . Increased appearance of Gadd45 via inserting in a microscopic level an expression vector into primary human fibroblasts arrests the cells at the G2 /M boundary with a phenotype of MPM2 immunopositivity , 4n DNA content and , in 15 of the cells , centrosome separation . The Gadd45-mediated G2 /M arrest rests on wild-type p53 , because no arrest was observed either in p53-null Li-Fraumeni fibroblasts or in normal fibroblasts coexpressed with p53 mutants . Amplified expression of cyclin B1 and Cdc25C reserved the Gadd45-mediated G2 /M arrest in human fibroblasts , which implies that the mechanism of Gadd45-mediated G2 /M checkpoint is at least in part throughout the modulation of the activity of the G2-specific kinase cyclin B1 /p34cdc2 . There was also evidence that was acquired in genetic and physiological aspects of a Gadd45-mediated G2 /M checkpoint by using GADD45-deficient human /murine cells . Human cells with endogenous Gadd45 expression reduced by antisense GADD45 expression have an impaired G2 /M checkpoint after exposure to either ultraviolet radiation or methyl methanesulfonate but are still capable to undergo G2 arrest following ionizing radiation . Lastly , Lymphocytes from gadd45-knockout mice also retained a G2...