Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mildly affected individuals from xeroderma pigmentosum complementation group G (XP-G) possess single amino acid substitutions in the XPG protein that adversely affects its 3' endonuclease function in nucleotide excision repair. More serious mutations in the XPG gene generate truncated or unstable XPG proteins and result in a particularly early and severe form of the combined XP/CS complex. Following UV irradiation, cells from such XP-G/CS patients enter apoptosis more readily than other DNA repair-deficient cells. Here, we explore the mechanisms by which UV triggers the apoptotic cell death program in XP-G and XP-G/CS primary fibroblasts. Activation of the CD95 signalling pathway occurs within minutes and it is the earliest detectable post-UV event in such cells. This is rapidly followed by activation of caspase-8 then caspase-3. Several hours later caspase-9 becomes activated and the mitochondrial membrane potential drops, but without any obvious prior release of cytochrome c. Although p53 accumulates in XPG-deficient cells after UV irradiation, use of RNA interference demonstrates that p53 is not required for their UV-induced apoptotic response. p53 ablation of wild-type fibroblasts reduces MDM2 mRNA levels, inhibits accumulation of the 90kDa/92kDa Mdm2 isoforms, and prevents the nuclear relocalisation of Mdm2 after UV treatment. The same post-UV effects occur in XPG-deficient cells that express normal p53 levels. These results emphasise the importance of the extrinsic apoptotic pathway and aberrant Mdm2 events for the severe UV-induced apoptosis of XPG-deficient primary fibroblasts. XP-G/CS cells constitutively overexpress the pro-apoptotic Bax protein and a long isoform of the E2F1 transcription factor that controls S phase entry, which may prime them to enter apoptosis very readily after UV irradiation.
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PMID:UV-induced apoptosis in XPG-deficient fibroblasts involves activation of CD95 and caspases but not p53. 1720 56

Apurinic/apyrimidinic endonuclease-1 (APE1) is a multifunctional DNA repair/gene regulatory protein in mammalian cells, and was recently reported to be phosphorylated at Thr233 by CDK5. We here report that ubiquitination of T233E APE1, a mimicry of phospho-T233 APE1, was markedly increased in multiple cell lines. Expression of CDK5 enhanced monoubiquitination of endogenous APE1. Polyubiquitinated APE1 was decreased when K48R ubiquitin was expressed, suggesting that polyubiquitination was mediated mainly through Lys48 of ubiquitin. The ubiquitination activity of MDM2, consistent in its role for APE1 ubiquitination, was increased for T233E APE1 compared to the wild-type APE1. In mouse embryonic fibroblasts lacking the MDM2 gene, ubiquitination of T233E APE1 was still observed probably because of the decreased degradation activity for monoubiquitinated APE1 and because of backup E3 ligases in the cells. Monoubiquitinated APE1 was present in the nucleus, and analyzing global gene expression profiles with or without induction of a ubiquitin-APE1 fusion gene suggested that monoubiquitination enhanced the gene suppression activity of APE1. These data reveal a delicate balance of ubiquitination and phosphorylation activities that alter the gene regulatory function of APE1.
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PMID:Ubiquitination of human AP-endonuclease 1 (APE1) enhanced by T233E substitution and by CDK5. 2172 86

The G309 allele of SNPs in the mouse double minute (MDM2) promoter locus is associated with a higher risk of cancer and proliferative vitreoretinopathy (PVR), but whether SNP G309 contributes to the pathogenesis of PVR is to date unknown. The clustered regularly interspaced short palindromic repeats (CRISPR)-associated endonuclease (Cas) 9 from Streptococcus pyogenes (SpCas9) can be harnessed to manipulate a single or multiple nucleotides in mammalian cells. Here we delivered SpCas9 and guide RNAs using dual adeno-associated virus-derived vectors to target the MDM2 genomic locus together with a homologous repair template for creating the mutation of MDM2 T309G in human primary retinal pigment epithelial (hPRPE) cells whose genotype is MDM2 T309T. The next-generation sequencing results indicated that there was 42.51% MDM2 G309 in the edited hPRPE cells using adeno-associated viral CRISPR/Cas9. Our data showed that vitreous induced an increase in MDM2 and subsequent attenuation of p53 expression in MDM2 T309G hPRPE cells. Furthermore, our experimental results demonstrated that MDM2 T309G in hPRPE cells enhanced vitreous-induced cell proliferation and survival, suggesting that this SNP contributes to the pathogenesis of PVR.
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PMID:The Clustered, Regularly Interspaced, Short Palindromic Repeats-associated Endonuclease 9 (CRISPR/Cas9)-created MDM2 T309G Mutation Enhances Vitreous-induced Expression of MDM2 and Proliferation and Survival of Cells. 2724 50