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Fanconi Anemia & FANCD2 http://locus.umdnj.edu/nigms/pathways/fanc_diagram.html
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What is FA? Rare autosomal recessive disorder Characterized by… Progressive bone marrow failure Cancer susceptibility… Congenital malformations… Increased apoptosis in hemopoietic cells Prolonged G2 phase http://www.fanconicanada.org/sys-tmpl/fanconianemia/
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Developmental Results of FA http://www.emedicine.com/rc/rc/pimages/i30/anemia.htm Shorter digits and slightly unattached thumbs of toddler Small stature of 3- year old with FA
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Diagnosis and Treatment The most common test to diagnose FA is the Chromosome Breakage Test There are no real treatments for FA…
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http://www.bloodjournal.org/cgi/content/full/101/3/822
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Expressivity of FA (and penetrance of certain phenotypes) Severity of clinical phenotype is a result of:
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FA is a multigenic disease 9 genes We will discuss one of the FA proteins, FANCD2
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Overview Other FA proteins in nucleus and cytoplasm The nuclear core complex monoubiquitinates FANCD2 Repair mechanisms can come and repair problem DNA can replicate properly
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The Cell Biology of FANCD2 Thompson, et al. Environmental and Molecular Mutagenesis 45:128-142. (2005).
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Details of FANCD2 and how it stabilizes replication forks FANCD2 protein increases during S- phase. FANCD2 is monoubiquitinated at Lys 561 (only if the cell has the full FA complex). Monoubiquitination of FANCD2 is mediated by other FA proteins.
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Details of FANCD2 and how it stabilizes replication forks What does it do? With what does it work?
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FANCD2 pathway http://www.nature.com/nm/journal/v8/n6/images/nm0602-555-F1.gif
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Without proper functioning… In the cell cycle stages: During replication: The results include, but aren’t limited to, non-homologous end joining (NHEJ) in the following ways:
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Possibilities in FA cells Thompson, et al. Environmental and Molecular Mutagenesis 45:128-142. (2005).
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FANCD2 Mouse knockouts Are mice good models? How are mutants made? What was the result? What does this tell us? What about other mutants?
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Mouse knockouts continued… Fancd2 -/- were smaller than the rest of the non-mutant litter Smaller testes and lower sperm and egg count This tell us that FANCD2 is involved in germ cell development and survival
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Mouse knockouts continued… Mouse mutant phenotype similar to humans Was anything different?
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http://www.genesdev.org/cgi/content/full/17/16/2021 Wild-typemutant
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http://www.genesdev.org/cgi/content/full/17/16/2021
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FANCD2 and other cancer genes FA and BRCA2 FA and BRCA1 FANCD2 and common cancers
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Take-home message FA or a mutation in FANCD2 hasn’t been shown to directly cause cancer…
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Text References Published online before print July 31, 2003, 10.1101/gad.1103403 GENES & DEVELOPMENT 17:2021-2035, 2003 Scott Houghtaling, Cynthia Timmers, Meenakshi Noll, Milton J. Finegold3, Stephen N. Jones4, M. Stephen Meyn2 and Markus Grompe1 Epithelial cancer in Fanconi anemia complementation group D2 (Fancd2) knockout mice
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