Increased genomic instability is a hallmark of aging. Trinucleotide repeat (TNR) expansions are one type of instability;these unstable expansions contribute to over a dozen neurodegenerative diseases. Unfortunately, these diseases are difficult to study in vivo because they are characterized by late onset, long time course and a complex phenotype. While Friedreich's Ataxia (FRDA) has the same underlying mechanism as age-related TNR diseases, it has an accelerated course and can be studied in vitro. The contribution of the DNA mismatch repair (MMR) pathway to age-related TNR expansion is an area of intense focus. Using FRDA as a model, we can determine what role DNA mismatch repair proteins play in age-related TNR diseases. In the MMR pathway DNA mismatches are recognized and repaired in a stepwise fashion by MutS and MutL heterodimers. Our preliminary data suggests that silencing the MutS Homologue 3 (MSH3), a component of the MutS complex, slows the rate of expansion. Therefore, we hypothesize that depleting MSH3 will slow the rate of TNR expansion and that the MutL pathway is a necessary component of that expansion.
Specific Aim 1 : we will determine the role of MSH3 in repeat expansion through overexpression and the use of both lentivirus- mediated and zinc finger nuclease-mediated knockdown of MSH3.
Specific Aim 2 : we will use the same methods to establish the contribution of the MutL complex proteins (MutL Homologue 1 (MLH1) and MLH3) to the rate of repeat expansion. This research is significant because it provides insight into the mechanism of a common type of genomic instability that underlies age-related neurodegeneration. Such insight could provide new targets for the development of more effective treatments.

Public Health Relevance

Genomic instability is a significant part of the aging process. Elucidating the mechanism underlying repeat expansion, a common type of instability, can help identify therapeutic targets that can delay or prevent the onset of this class of age-related diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Individual Predoctoral NRSA for M.D./Ph.D. Fellowships (ADAMHA) (F30)
Project #
5F30AG042263-03
Application #
8607872
Study Section
Special Emphasis Panel (ZRG1-F08-K (20))
Program Officer
Wise, Bradley C
Project Start
2012-04-01
Project End
2015-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
3
Fiscal Year
2014
Total Cost
$47,676
Indirect Cost
Name
Louisiana State Univ Hsc New Orleans
Department
Genetics
Type
Schools of Medicine
DUNS #
197723646
City
New Orleans
State
LA
Country
United States
Zip Code
70112