1. XPF Nucleotide Excision Repair

2. Xerderma Pigmentosum (XP) UV Light Sensitivity Early Age Freckling Severe Sunburning Keratosis Neurological defects Non-melonoma skin cancer ~10 yrs basal and squamous cell carcinomas and melanomas 1000x increase in risk of cancer autosomal recessive inheritance tumor suppressor Image from: institut national de recherche pédagogique http://www.inrp.fr/Acces/biotic/gpe/dossiers/xeroderma/html/phenomacr.htm

3. XP: Complementation Groups 8 subtypes identified by Cell-Fusion Complementation Tests XPA-G : Nucleotide Excision Repair XPV: DNA polymerase Sugasawa 2008

4. UV Light and DNA Damage cyclobutane pyrimidinedimer (CPD) (A) pyrimidine -pyrimidone photoproduct (B) bulky base adducts Sinha and H ӓ der, 2002

5. Nucleotide Excision Repair Sugasawa 2008

6. ERCC1-XPF Complex XPF: 5’ endonuclease ERCC1: interacts with DNA through helix– hairpin–helix (HhH) motif at C-terminus Only one recorded instance of human deficiency XPF Homologs: –S. cerevisiae: Rad1 –Schizosaccharomyces pombe: rad16 –Drosophila melanogaster: MEI-9 –Mouse: ERCC4

7. Identification of cDNA of XPF Cloned using rt- PCR fragment of Rad1 in a human testis cDNA library Encodes 115 kD protein Chromosome 16p13.1–13.2 Sijbers et al.1996

8. 5’ Endonuclease Activity Sijbers et al.1996 Chinese Hamster Cell Model Shows ERCC1-XPF is necessary for 5’ incisions that only occur in coupled reactions

9. Mouse Models Reduced Function ERCC1 mice -growth retardation -lack of subcutaneous fat -no similar symptoms of XP -liver and vascular defects Weeda et al 1997 ERCC1 (-/-) Knockout Mice: -died before weening -liver failure -kidney and vascular defects McWhir et al 1993

10. XPF in Humans Majority of cases in Japan Rare complementation group Overall XP(all groups): 1 : 250,000 in US (Cleaver et al 1999)

11. XP Treatments Palliative Care Avoidance of UV with frequent check ups Keratosis treatment with isotrentinoin (prevention) and ctyotherapy and fluorouracil Applied Genetics, Inc.'s –T4N5 endonuclease study (Phase III) –T4 endonuclease V encapsulated in liposome in cream

12. Future Directions XPF role in homologous recombination Its role outside of the NER complex

13. References Cleaver, J. L. Thompson, A Richardson, and J. States. 1999. A Summary of Mutations in the UV-Sensitive Disorders: Xeroderma Pigmentosum, Cockayne Syndrome, and Trichothiodystrophy. Human Mutation. 14:9-22 de Laat W, AM. Sijbers, H. Odijk, Nicolaas GJ. Jaspers and J. Hoeijmakers. 1998. Mapping of interaction domains between human repairproteins ERCC1 and XPF 1. Nuc. Acid Res. 26:4146-52 Sijber, A. A. de Laat, R. Ariza, M. Biggerstaff, YF. Wei, J. Moggs, K. Carter, B. Shell, E. Evans, M. Jong, S. Rademakers, J. de Rooij, N. Jaspers, J. Hoeijmakers, and R. Wooods. 1996. Xeroderma Pigmentosum Group F Caused by a Defect in a Structure-Specific DNA Repair Endonuclease Cell 86:811-22 Sinha, R. and D. Häder. 2002. UV-induced DNA damage and repair: a review. Photochem. Photobiol. Sci. 1: 225-236 Sugasawa, K. 2008. Xeroderma pigmentosum genes: functions inside and outside DNA repair. Carcinogenesis 29: 455-465. Weeda, G. I. Donker, J. de Wit, H. Morreau, R. Janssens, C.J. Vissers, A. Nigg, H. van Steeg, D. Bootsma and J.H.J. Hoeijmakers.1997. Disruption of mouse ERCC1 results in a novel repair syndrome with growth failure, nuclear abnormalities and senescence.Current Biology, 7:427–439 Xeroderma Pigmentosum. Updated 3/16/2008. http://en.wikipedia.org/wiki/Xeroderma_pigmentosum

14. QUESTONS?