Fanconi Anemia & FANCD2

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

Developmental Results of FA Shorter digits and slightly unattached thumbs of toddler Small stature of 3- year old with FA

Diagnosis and Treatment  The most common test to diagnose FA is the Chromosome Breakage Test  There are no real treatments for FA…

Expressivity of FA (and penetrance of certain phenotypes)  Severity of clinical phenotype is a result of:

FA is a multigenic disease  9 genes  We will discuss one of the FA proteins, FANCD2

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

The Cell Biology of FANCD2 Thompson, et al. Environmental and Molecular Mutagenesis 45: (2005).

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.

Details of FANCD2 and how it stabilizes replication forks  What does it do?  With what does it work?

FANCD2 pathway

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:

Possibilities in FA cells Thompson, et al. Environmental and Molecular Mutagenesis 45: (2005).

FANCD2 Mouse knockouts  Are mice good models?  How are mutants made?  What was the result?  What does this tell us?  What about other mutants?

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

Mouse knockouts continued…  Mouse mutant phenotype similar to humans  Was anything different?

Wild-typemutant

FANCD2 and other cancer genes  FA and BRCA2  FA and BRCA1  FANCD2 and common cancers

Take-home message FA or a mutation in FANCD2 hasn’t been shown to directly cause cancer…

Text References  Published online before print July 31, 2003, /gad GENES & DEVELOPMENT 17: , 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