DNA-Damage Protein

GADD45GIP1 is a nuclear protein which takes part in apoptosis control. GADD45GIP1 is expressed in several tissues, such as heart, thyroid, trachea, kidney, ovary, pancreas, testis and stomach and acts as a negative regulator of G1 to S phase cell cycle production by collaborating with GADD45 proteins to inhibit the activity of cyclin-dependent kinases.

GADD45G is part of the nuclear proteins to interact with various proteins whose transcript levels are raised after stressful growth arrest conditions and treatment with DNA-damaging agents. GADD45G reacts to environmental stresses by mediating activation of the p38/JNK pathway which is mediated through their protein binding and activating MTK1/MEKK4 kinase, which is an upstream activator of both p38 and JNK MAPKs. GADD45G acts as a new-age tumor suppressor however is being frequently inactivated epigenetically in multiple tumors. GADD45G mRNA expression is down-regulated in hepatocellular carcinoma. GADD45G causes cell cycle arrest at G2/M transition when transfected into Hep-G2 cells. GADD45 Gamma induction by androgens involves new protein synthesis. Overexpression of GADD45 Gamma inhibits cell growth and causes morphological modifications in prostate cell lines thus GADD45 gamma takes part in differentiation induction by androgens.

GADD45B is part of the nuclear proteins to interact with various proteins whose transcript levels are raised after stressful growth arrest conditions and treatment with DNA-damaging agents. GADD45B reacts to environmental stresses by mediating activation of the p38/JNK pathway which is mediated through their protein binding and activating MTK1/MEKK4 kinase, which is an upstream activator of both p38 and JNK MAPKs. GADD45B is involved in the regulation of growth and apoptosis. GADD45b takes part during chondrocyte terminal differentiation and mediates MMP-13 gene expression. GADD45 in B cells is induced by CD40 via a mechanism that involves NF-kappa B and that induction suppresses Fas-mediated killing. GADD45b is down-regulated in most cases of hepatocellular carcinoma (HCC), and is a molecular marker in the diagnosis of HCC and as a possible therapeutic target.

Growth arrest and DNA Damage-Inducible Protein (GADD45A) binds both Cdks and PCNA. GADD45A is involved in DNA replication and repair. GADD45A stimulates DNA excision repair in vitro and inhibits entry of cells into S phase. GADD45A may serve as a link between p53-dependent cell cycle checkpoint and DNA repair. The GADD45A gene belongs to a group of genes whose transcript levels are increased following stressful growth arrest conditions and treatment with DNA-damaging agents. GADD45A responds to environmental stresses by mediating activation of the p38/JNK pathway via MTK1/MEKK4 kinase. GADD45A binds to proliferating cell nuclear antigen.

PDRG1 is a 133 amino acid protein that localizes to the cytoplasm and belongs to the prefoldin subunit beta family. PDRG1 is expressed primarily in normal testicular tissue, it is functionally induced by ultraviolet light and is thought to have a role in chaperone-mediated protein folding, possibly having a role in cellular degradation. PDRG1 is linked to Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, spinal muscular atrophy, ring chromosome 20 epilepsy syndrome and Alagille syndrome.

DDIT4 has a role in the regulation of reactive oxygen species. DDIT4 is upregulated at the transcriptional level as a reaction to stress due to DNA damage and glucocorticoid treatment. DDIT4 negatively regulates the mammalian target of Rapamycin, a serine/threonine kinase frequently referred to as mTOR. DDIT4 is vital in the coupling of extra- and intracellular cues to mTOR regulation.

DDIT3 reduces DNA-binding activity of C/EBP and lap by forming heterodimers which don’t bind DNA. DDIT3, also known as GADD153, is a basic domain-leucine zipper(bZIP) transcription factor of C/EBP family. DDIT3 protein is up-regulated by several stresses, such as amino acid or glucose starvation, endoplasmic reticulum (ER) stress, osmotic stress and hypoxia. DDIT3 protein is invloved in ER stress-mediated apoptosis and in disease including diabetes, brain ischemia and neurodegenerative disease. DDIT3 plays a role in asoprisnil-induced apoptosis. Hypoglycaemia-induced necrotic cell death of neuroblastoma cells is an active process mediated via the induction of the transcription factor DDIT3. DDIT3 plays an important role in melanoma progression. HRG stimulation of mammary epithelial cells induces the expression of DDIT3 mRNA and protein and transcription of DDIT3 promoter.