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Polymorphisms and HNPCC: PMS2-MLH1 protein interactions diminished by single nucleotide polymorphisms.
Zi Qiang Yuan1, Bruce Gottlieb, Lenore K Beitel
1Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
Human Mutation
|January 17, 2002
Summary
Three single nucleotide polymorphisms (SNPs) in PMS2 disrupt MLH1-PMS2 interactions, potentially increasing hereditary nonpolyposis colorectal cancer (HNPCC) risk. This challenges traditional definitions of SNPs and mutations.
Area of Science:
- Molecular Biology
- Genetics
- Oncology
Background:
- Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant inherited disease linked to mutations in mismatch repair (MMR) genes.
- MLH1 and MSH2 proteins interact with PMS1, PMS2, and MSH6 proteins, crucial for DNA repair.
- Previous studies identified MLH1 mutations affecting PMS2 interaction, but PMS2's role in MLH1 interaction was less understood.
Purpose of the Study:
- To investigate the functional impact of three specific PMS2 single nucleotide polymorphisms (SNPs) on MLH1-PMS2 protein-protein interactions.
- To determine if these SNPs, previously considered benign, affect protein function and could be risk factors for HNPCC.
Main Methods:
- Analysis of three missense alterations in PMS2 (P511K, T597S, M622I) identified as SNPs.
- Functional assay to assess the impact of these PMS2 variants on protein-protein interactions with MLH1.
- Comparison of interaction domains between MLH1 and PMS2.
Main Results:
- The three PMS2 SNPs (P511K, T597S, M622I) resulted in defective protein-protein interactions with MLH1.
- These functional defects occurred despite the altered regions not being the previously identified interaction domain.
- This suggests an additional domain in PMS2 is involved in MLH1-PMS2 interaction.
Conclusions:
- Single nucleotide polymorphisms (SNPs) can have significant functional consequences, impacting protein interactions and phenotype.
- The studied PMS2 SNPs may represent variants that increase the risk of tumorgenesis in HNPCC.
- The findings necessitate a reconsideration of the distinction between polymorphisms and mutations based on functional impact.