XPF

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XPF

• Nucleotide Excision Repair

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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
pédagogiquehttp//www.inrp.fr/Acces/biotic/gpe/do
ssiers/xeroderma/html/phenomacr.htm
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XP Complementation Groups

• 8 subtypes identified by Cell-Fusion
  Complementation Tests
• XPA-G Nucleotide Excision Repair
• XPV DNA polymerase

Sugasawa 2008
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UV Light and DNA Damage

• cyclobutane pyrimidinedimer (CPD) (A)
• pyrimidine -pyrimidone photoproduct (B)
• bulky base adducts

Sinha and H?der, 2002
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Nucleotide Excision Repair
Sugasawa 2008
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ERCC1-XPF Complex

• XPF 5 endonuclease
• ERCC1 interacts with DNA through
  helixhairpinhelix (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

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Identification of cDNA of XPF

• Cloned using rt-PCR fragment of Rad1 in a
  humantestis cDNA library
• Encodes 115 kD protein
• Chromosome 16p13.113.2

Sijbers et al.1996
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5 Endonuclease Activity
Chinese Hamster Cell Model Shows ERCC1-XPF is
necessary for 5 incisions that only occur in
coupled reactions
Sijbers et al.1996
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Mouse Models
ERCC1 (-/-) Knockout Mice -died before
weening -liver failure -kidney and vascular
defects McWhir et al 1993
Reduced Function ERCC1 mice -growth
retardation -lack of subcutaneous fat -no
similar symptoms of XP -liver and vascular
defects Weeda et al 1997
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XPF in Humans

• Majority of cases in Japan
• Rare complementation group
• Overall XP(all groups) 1 250,000 in US
• (Cleaver et al 1999)

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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

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Future Directions

• XPF role in homologous recombination
• Its role outside of the NER complex

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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. 149-22
• 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. 264146-52
• 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
  86811-22
• 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, 7427439
• Xeroderma Pigmentosum. Updated 3/16/2008.
  http//en.wikipedia.org/wiki/Xeroderma_pigmentosum

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QUESTONS?