1. Cellular Responses to DNA Damage Kate Dixon Department of Molecular and Cellular Biology http://www.childrensmuseum.org/teachers/unitsofstudy/biotechnology/lesson3.htm

2. 5  m Light microscope resolving power ~0.2  m Human cell DNA 6 x 10 9 base pairs 2 meters of DNA 4 x 10 5 times the nuclear diameter Organization of DNA in the human cell nucleus http://www.aw-bc.com/mathews/ch28/fi28p12.htm

3. Leffell and Brash, Scientific American, July 1996

4. 2%-10% UVB reaches basal layer of skin Midwest: 20 min sunlight would kill 50% of cells in culture dish

5. UV Sun exposure – ultraviolet radiation http://www.medicalecology.org/images/atmosphere/dimersfromp345.gif

6. Cellular Responses to DNA Damage CANCER

7. http://www.genmapp.org/HTML_MAPPs/Human/Biological_process/response _to_DNA_damage_stimulus/_Support/response_to_DNA_damage_stimulus.jpg Proteins Involved in Responses to DNA Damage

8. Genetic Alterations in Cancer

9. Xeroderma pigmentosum patient showing distribution of skin lesions Cancer DNA damage Repair MutationNormal Xeroderma pigmentosum: Extreme sun sensitivity, high risk of skin cancer http://www.mdconsult.com/das/book/body/160721681-2/0/1492/I4-u1.0-B978-1-4160-2805-5..50467-5--f13.fig?tocnode=54631832 Goldman: Cecil Medicine, 23rd ed. Copyright © 2007 Saunders, An Imprint of Elsevier2007 Saunders, An Imprint of Elsevier

10. Nucleotide Excision Repair Repair of UV-induced DNA damage http://locus.umdnj.edu/nigms/pathways/ner.html Cancer in xeroderma pigmentosum and related disorders of DNA repair James E. Cleaver Nature Reviews Cancer 5, 564-573 (July 2005) doi:10.1038/nrc1652

11. Xermoderma pigmentosum variant: High skin cancer risk, normal NER DNA replication blocking lesions: UV photoproducts, DNA adducts, etc. TT XPV is DNA polymerase  Can insert “A” opposite T in TT dimer – overcome replication block In absence of XPV – other less accurate polymerase replicate past lesion

12. DNA Repair Pathways

13. Replication fork integrity and double strand break repair TT Replication fork “collapse” DNA double strand breaks Ionizing radiation,etc. Chromosome instability syndromes NBS1 MRE11 WRN BLM/RECQL3 BRCA1, BRCA2 ATM Nijmegen breakage syndrome A-T-like disorder Werners syndrome Blooms syndrome Familial breast cancer Ataxia telangiectasia Lymphoma Lymphoma/leukemia Various Leukemia,carcinomas Breast/ovarian cancer Leukemia,lymphoma

14. Ataxia Telangiectasia Increased cancer risk Neurodegeneration Chromosomal instability Abnormal responses to UV and IR IR: Chromosomal aberrations; Cell killing UV: Chromosomal aberrations 350 kDa serine/threonine protein kinase Related to ATR, DNA-PK, Mec1, Tel1 ATM Kinase www.atcp.org

15. Apoptosis DNA repair Cell cycle checkpoints ATM www.biocarta.com/pathfiles/atmPathway.asp

16. Error FreeError Prone RecombinationEnd Joining Dividing Cells Non- Dividing Cells Strand Invasion DSB Resection DNA synthesis Ligation Joint molecular resolution DSB End Binding Ligation A: HRB: NHEJ DSB Resection C: MMEJ pairing Ligation

17. Replication fork integrity and double strand break repair Chromosome instability syndromes NBS1 MRE11 WRN BLM/RECQL3 BRCA1, BRCA2 ATM Nijmegen breakage syndrome A-T-like disorder Werners syndrome Blooms syndrome Familial breast cancer Ataxia telangiectasia Lymphoma Lymphoma/leukemia Various Leukemia,carcinomas Breast/ovarian cancer Leukemia,lymphoma MRN complex: Mre11, Rad50 and Nbs1 Mre11: Nuclease (both endo- and exo-nuclease) Rad50: DNA binding Nbs1: Protein-protein interactions

18. Mre11/Rad50/Nbs1 (MRN) Complex DNA double-strand break repair http://www.eurekalert.org/features/doe/2002-11/dbnl-tsb110702.php

19. What is the function of ATM in non-dividing cells? DSB End Binding Ligation B: NHEJ DSB Resection C: MMEJ pairing Ligation ATM In the absence of ATM (Ataxia Telangiectasia): MMEJ is increased End resection is increased MRN ATM MRN

20. BRCA1 MRN NHEJ: BRCA1 Inhibits MRN Nuclease by Binding to DNA Ends (Paull et al., 2001) ATM Promotion of DNA Binding Inhibition of DNA degradation Mre11 nuclease ? HR: BRCA2 Regulates Homologous Recombination by Binding to Rad51 BRCA2 ATM BRCA2 P Rad51 Free to promote recombination BRCA1 and BRCA2 Promote Recombination Repair and Inhibit End Joining

21. Mitotic somatic cells Post-Mitotic neuronal cells Failure to repair or misrepair CancerNeurodegeneration Cellular responses to DNA damage ATM

22. Defective DNA Repair and Neurological Dysfunction Rass, U. et al. 2007; Cell, 130: 991-1004.

23. http://www.genome.jp/dbget-bin/get_pathway?org_name=bsu&mapno=03430

24. Microsatellite sequences are repeated sequences that can easily misalign during DNA replication – causing changes in the length of the sequence. Normally these mistakes are corrected by MMR Expansion of microsatellite sequences is often observed in tumor tissue from patients with hereditary nonpolyposis colorectal cancer (HNPCC; also called Lynch Syndrome) http://www.bma.org.uk/health_promotion_ethics/ genetics/Cancergenetics.jsp?page=12 http://www.ehponline.org/members/ 1997/Suppl-4/peltomaki-full.html

25. http://asajj.roswellpark.org/huberman/DNA_Repair/MMRproteins.gif