Abstract
Nearly one-third of the identified MSH6 germline mutations deal with single amino acid substitutions. For an effective genetic counselling it is necessary to clearly elucidate by functional tools the specific sub-processes underlying the mismatch repair (MMR) misfunctioning in MSH6 non-truncating mutants. Since the MMR repair pathway occurs in the nucleus, we suppose the impairment of MutSα nuclear trafficking to be a possible Lynch syndrome susceptibility causative mechanism. In the present study the MMR status of the tumour, the main clinical features of mutation carriers and population data associated to the MSH6 missense variants, were complemented with computational data about tolerability predictions and amino acid substitution conservation. The selected panel of ten potentially pathogenic MSH6 mutations was analyzed in a homologous expression system for possible deleterious effects on nucleo-cytoplasmic shuttling through the assessment of the sub-cellular localization of the corresponding mutated proteins. Localization analysis results do not reveal an apparent role of MSH6 missense mutations in nuclear import impairment and provide the first hint to exclude the MSH6 nuclear translocation sub-process as a possible causative mechanisms of MMR misfunctioning.
References
Lynch HT, de la Chapelle A (2003) Hereditary colorectal cancer. N Engl J Med 348:919–932
Peltomäki P (2005) Lynch syndrome genes. Fam Cancer 4:227–232
Peltomäki P, Vasen H (2004) Mutations associated with HNPCC predisposition—update of ICG-HNPCC/INSiGHT mutation database. Dis Markers 20:269–276
Ou J, Niessen RC, Lützen A et al (2007) Functional analysis helps to clarify the clinical importance of unclassified variants in DNA mismatch repair genes. Hum Mutat 28:1047–1054
Woods MO, Williams P, Careen A et al (2007) A new variant database for mismatch repair genes associated with Lynch syndrome. Hum Mutat 28:669–673
Cravo M, Afonso AJ, Lage P (2002) Pathogenicity of missense and splice site mutations in hMSH2 and hMLH1 mismatch repair genes: implications for genetic testing. Gut 50:405–412
Christensen LL, Kariola R, Korhonen MK et al (2009) Functional characterization of rare missense mutations in MLH1 and MSH2 identified in Danish colorectal cancer patients. Fam Cancer 8:489–500
Trojan J, Zeuzem S, Randolph A et al (2002) Functional analysis of hMLH1 variants and HNPCC-related mutations using a human expression system. Gastroenterology 122:211–219
Barnetson RA, Cartwright N, van Vliet A et al (2008) Classification of ambiguous mutations in DNA mismatch repair genes identified in a population-based study of colorectal cancer. Hum Mutat 29:367–374
Kolodner RD, Tytell JD, Schmeits JL et al (1999) Germ-line msh6 mutations in colorectal cancer families. Cancer Res 59:5068–5074
Kariola R, Raevaara TE, Lönnqvist KE et al (2002) Functional analysis of MSH6 mutations linked to kindreds with putative hereditary non-polyposis colorectal cancer syndrome. Hum Mol Genet 11:1303–1310
Kariola R, Hampel H, Frankel WL et al (2004) MSH6 missense mutations are often associated with no or low cancer susceptibility. Br J Cancer 91:1287–1292
Cyr JL, Heinen CD (2009) Hereditary cancer-associated missense mutations in hMSH6 uncouple ATP hydrolysis from DNA mismatch binding. J Biol Chem 283:31641–31648
Knudsen NØ, Nielsen FC, Vinther L et al (2007) Nuclear localization of human DNA mismatch repair protein exonuclease 1 (hEXO1). Nucleic Acids Res 35:2609–2619
Stewart M (2007) Molecular mechanism of the nuclear protein import cycle. Nat Rev Mol Cell Biol 8:195–208
Wu X, Platt JL, Cascalho M (2003) Dimerization of MLH1 and PMS2 limits nuclear localization of MutLalpha. Mol Cell Biol 23:3320–3328
Brieger A, Plotz G, Raedle J et al (2005) Characterization of the nuclear import of human MutLα. Mol Carcinog 43:51–58
Korhonen MK, Raevaara TE, Lohi H et al (2007) Conditional nuclear localization of hMLH3 suggests a minor activity in mismatch repair and supports its role as a low-risk gene in HNPCC. Oncol Rep 17:351–354
Knudsen NØ, Andersen SD, Lützen A et al (2009) Nuclear translocation contributes to regulation of DNA excision repair activities. DNA Repair 8:682–689
Christmann M, Kaina B (2000) Nuclear translocation of mismatch repair proteins MSH2 and MSH6 as a response of cells to alkylating agents. J Biol Chem 275:36256–36262
Hayes AP, Sevi LA, Feldt MC (2009) Reciprocal regulation of nuclear import of the yeast MutSalpha DNA mismatch repair proteins Msh2 and Msh6. DNA Repair 8:739–751
Lützen A, de Wind N, Georgijevic D et al (2008) Functional analysis of HNPCC-related missense mutations in MSH2. Mutat Res 645:44–55
Kumar P, Henikoff S, Ng PC (2009) Predicting the effects of coding non-synonymous variants on protein function using the SIFT algorithm. Nat Protoc 4:1073–1081
Thompson JD, Higgins DG, Gibson TJ (1994) CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Res 22:4673–4680
Raevaara TE, Korhonen MK, Lohi H et al (2005) Functional significance and clinical phenotype of nontruncating mismatch repair variants of MLH1. Gastroenterology 129:537–549
Horton P, Park KJ, Obayashi T et al (2007) WoLF PSORT: protein localization predictor. Nucleic Acids Res 35:W585–W587
Belvederesi L, Bianchi F, Galizia E et al (2008) MSH2 missense mutations and HNPCC syndrome: pathogenicity assessment in a human expression system. Hum Mutat 29:E296–E309
Heinen CD, Wilson T, Mazurek A et al (2002) HNPCC mutations in hMSH2 result in reduced hMSH2-hMSH6 molecular switch functions. Cancer Cell 1:469–478
Kijas AW, Studamire B, Alani E (2003) Msh2 separation of function mutations confer defects in the initiation steps of mismatch repair. J Mol Biol 331:123–138
Iyer RR, Pluciennik A, Burdett V et al (2006) DNA mismatch repair: functions and mechanisms. Chem Rev 106:302–323
Jun SH, Kim TG, Ban C (2006) DNA mismatch repair system. Classical and fresh roles. FEBS J 273:1609–1619
Niessen RC, Sijmons RH, Ou J et al (2006) MUTYH and the mismatch repair system: partners in crime? Hum Genet 119:206–211
Berends MJ, Wu Y, Sijmons RH et al (2002) Molecular and clinical characteristics of MSH6 variants: an analysis of 25 index carriers of a germline variant. Am J Hum Genet 70:26–37
Woods MO, Hyde AJ, Curtis FK et al (2005) High frequency of hereditary colorectal cancer in Newfoundland likely involves novel susceptibility genes. Clin Cancer Res 11:6853–6861
Chan TL, Yuen ST, Chung LP et al (1999) Frequent microsatellite instability and mismatch repair gene mutations in young Chinese patients with colorectal cancer. J Natl Cancer Inst 91:1221–1226
Kariola R, Otway R, Lönnqvist KE et al (2003) Two mismatch repair gene mutations found in a colon cancer patient—which one is pathogenic? Hum Genet 112:105–109
Acknowledgments
The authors thank Dr. Santarelli and all the Scientists of the Clinic of Occupational Medicine, Polytechnic University of Marche, Ancona, Italy, for providing helpful support and technical assistance in fluorescence microscopy analysis.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Belvederesi, L., Bianchi, F., Loretelli, C. et al. Sub-cellular localization analysis of MSH6 missense mutations does not reveal an overt MSH6 nuclear transport impairment. Familial Cancer 11, 675–680 (2012). https://doi.org/10.1007/s10689-012-9558-y
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10689-012-9558-y