Sequence 516 (si 111)

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Sequence si_111
Target ERCC2 ( Homo sapiens )
Description Excision repair cross-complementing rodent repair deficiency, complementation group 2 (xeroderma pigmentosum D)

Ensembl: ENSG00000013441 UniGene: Hs.487294 EntrezGene: 2068 Ensembl Chr2: 201416164 - 201437667 Strand: -1 GO terms: 0000074 0000166 0004672 0004674 0004713 0004715 0005524 0005634 0006468 0008283 0016740

Design siRNA
Chemistry RNA
Sequence siRNA sense (21b) CCAGGAGCACCTCACAGATGC / siRNA antisense (21b) ATCTGTGAGGTGCTCCTGGAT
Application gene silencing
Name si_111

References

DSIR: assessing the design of highly potent siRNA by testing a set of cancer-relevant target genes. Filhol O, Ciais D, Lajaunie C, Charbonnier P, Foveau N, Vert JP, Vandenbrouck Y. PLoS One. 2012;7(10):e48057.

Intrathecal Injections in Children With Spinal Muscular Atrophy: Nusinersen Clinical Trial Experience. Hache M, Swoboda KJ, Sethna N, Farrow-Gillespie A, Khandji A, Xia S, Bishop KM. J Child Neurol. 2016 Jun;31(7):899-906. PubMed:26823478

Comments

Background

Gene Function. Flejter et al. (1992) demonstrated that the ERCC2 gene corrected the sensitivity to ultraviolet (UV) radiation and defective nucleotide excision repair in xeroderma pigmentosum cells of complementation group D (XPD; 278730). The XPD cell line used in these studies was GM08207. They first demonstrated correction by the transfer of a rearranged human chromosome by the method of microcell-mediated chromosome transfer (MMCT). Then, having demonstrated that the rearranged chromosome involved human chromosomes 16 and 19, including the region of the latter chromosome containing the ERCC2 gene, they directly transferred a cosmid containing the ERCC2 gene into XPD cells and showed that UV resistance was conferred thereby. Flejter et al. (1992) further demonstrated a single rearranged human chromosome, designated Tneo, which corrected the UV sensitivity and excision repair defect of XPD cells in culture. They went on to analyze the complex rearrangement involving material from chromosomes 16, 17, and 19 and showed that the 19q13.2-q13.3 region was included. The ERCC2 gene is homologous to the RAD3 gene of the budding yeast Saccharomyces cerevisiae and the Rad15+ of the fission yeast Schizosaccharomyces pombe (Friedberg, 1992). Sung et al. (1993) purified the XPD protein to near homogeneity and showed that it possesses single-stranded DNA-dependent ATPase and DNA helicase activities. Expression of the human XPD gene in Saccharomyces cerevisiae complemented the lethal defect of a mutation in the RAD3 gene. In most cases, XPD and trichothiodystrophy (TTD; 601675) patients carry mutations in the carboxy-terminal domain of the XPD helicase, which is one of the subunits of the transcription/repair factor TFIIH (189972). Coin et al. (1998) demonstrated that XPD (ERCC2) interacts specifically with p44 (601748), another subunit of TFIIH, and that this interaction results in the stimulation of 5-prime-to-3-prime helicase activity. Mutations in the XPD C-terminal domain, as found in most patients, prevent the interaction with p44, thus explaining the decrease in XPD helicase activity and the nucleotide excision repair (NER) defect. Inherited mutations of the TFIIH helicase subunits XPB (ERCC3; 133510) or XPD yield overlapping DNA repair and transcription syndromes. The high risk of cancer in these patients is not fully explained by the repair defect. The transcription defect, however, is subtle and more difficult to evaluate. Liu et al. (2001) showed that XPB and XPD mutations block transcription activation by the FUSE-binding protein (FBP; 603444), a regulator of MYC (190080) expression, and block repression by the FBP-interacting repressor (FIR; 604819). Through TFIIH, FBP facilitates transcription until promoter escape, whereas after initiation, FIR uses TFIIH to delay promoter escape. Mutations in TFIIH that impair regulation by FBP and FIR affect proper regulation of MYC expression and have implications in the development of malignancy. The CDK-activating kinase, or CAK complex, consists of CDK7 (601955), cyclin H (601953) and MAT1 (602659). As the kinase subunit of TFIIH, CDK7 participates in basal transcription by phosphorylating the carboxy-terminal domain of the largest subunit of RNA polymerase II. As part of CAK, CDK7 also phosphorylates other CDKs, an essential step for their activation. Chen et al. (2003) showed that the Drosophila TFIIH component Xpd, whose human homolog is ERCC2, negatively regulates the cell cycle function of Cdk7, the CAK activity. Excess Xpd titrated CAK activity, resulting in decreased Cdk T-loop phosphorylation, mitotic defects, and lethality, whereas a decrease in Xpd resulted in increased CAK activity and cell proliferation. Moreover, Chen et al. (2003) showed that Xpd is downregulated at the beginning of mitosis when Cdk1 (116940), a cell cycle target of Cdk7, is most active. Downregulation of Xpd thus seems to contribute to the upregulation of mitotic CAK activity and to regulate mitotic progression positively. Chen et al. (2003) concluded that the downregulation of Xpd might be a major mechanism of mitotic silencing of basal transcription. Yoder et al. (2006) showed that transduction by human immunodeficiency virus (HIV) or Moloney murine leukemia virus was substantially greater in XPB or XPD mutant cells than in isogenic complemented cells or XPA (611153) mutant cells. The difference in transduction efficiency was not due to apoptosis. Yoder et al. (2006) concluded that XPB and XPD reduce retroviral integration efficiency by enhancing degradation of retroviral cDNA, thereby reducing the available pool of cDNA molecules for integration. Rudolf et al. (2006) identified a conserved domain that includes an iron-sulfur (Fe-S) cluster near the N termini of XPD and FANCJ (BRIP1; 605882). Three absolutely conserved cysteines provide ligands for the Fe-S cluster, and Rudolf et al. (2006) showed that the cluster is essential for XPD helicase activity. Yeast strains harboring mutations in the Fe-S domain of Rad3 retained their overall fold and stability and could hydrolyze ATP in a single-stranded DNA-dependent manner, but they were defective in excision repair of UV-induced damage.

Animal Model De Boer et al. (1998) generated a mouse model for trichothiodystrophy by gene-cDNA fusion targeting and introduction of the ERCC2/XPD arg722-to-trp mutation in the mouse. They therefore had mimicked the causative XPD point mutation of a TTD patient in the mouse. TTD R722W/R722W mice reflect to a remarkable extent the human disorder, including brittle hair, developmental abnormalities, reduced life span, UV sensitivity, and skin abnormalities. The cutaneous symptoms are associated with reduced transcription of a skin-specific gene, SPRR2 (see 182265), strongly supporting the concept of TTD as a human disease due to inborn defects in basal transcription and DNA repair. De Boer et al. (2002) found that mice with the ERCC2 mutation arg722-to-trp (126340.0014) had many symptoms of premature aging, including osteoporosis and kyphosis, osteosclerosis, early graying, cachexia, infertility, and reduced life span. TTD mice carrying an additional mutation in XPA, which enhances the DNA repair defect, showed a greatly accelerated aging phenotype, which correlated with an increased cellular sensitivity to oxidative DNA damage. De Boer et al. (2002) hypothesized that aging in TTD mice is caused by unrepaired DNA damage that compromises transcription, leading to functional inactivation of critical genes and enhanced apoptosis.

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