Background Friedreich ataxia (FRDA), the most common autosomal recessive ataxia disorder, is caused by a dynamic GAA repeat expansion mutation within intron 1 of FXN gene, resulting in down-regulation of frataxin expression. Studies of cell and mouse models have revealed a role for the mismatch repair (MMR) MutS-heterodimer complexes and the PMS2 component of the MutLα complex in the dynamics of intergenerational and somatic GAA repeat expansions: MSH2, MSH3 and MSH6 promote GAA repeat expansions, while PMS2 inhibits GAA repeat expansions. Methodology/Principal Findings To determine the potential role of the other component of the MutLα complex, MLH1, in GAA repeat instability in FRDA, we have analyzed intergenerational and somatic GAA repeat expansions from FXN transgenic mice that have been crossed with Mlh1 deficient mice. We find that loss of Mlh1 activity reduces both intergenerational and somatic GAA repeat expansions. However, we also find that loss of either Mlh1 or Pms2 reduces FXN transcription, suggesting different mechanisms of action for Mlh1 and Pms2 on GAA repeat expansion dynamics and regulation of FXN transcription. Conclusions/Significance Both MutLα components, PMS2 and MLH1, have now been shown to modify the molecular phenotype of FRDA. We propose that upregulation of MLH1 or PMS2 could be potential FRDA therapeutic approaches to increase FXN transcription.
References
[1]
Campuzano V, Montermini L, Molto MD, Pianese L, Cossee M, et al. (1996) Friedreich's ataxia: autosomal recessive disease caused by an intronic GAA triplet repeat expansion. Science 271: 1423–1427. doi: 10.1126/science.271.5254.1423
[2]
Saveliev A, Everett C, Sharpe T, Webster Z, Festenstein R (2003) DNA triplet repeats mediate heterochromatin-protein-1-sensitive variegated gene silencing. Nature 422: 909–913. doi: 10.1038/nature01596
[3]
Wells RD (2008) DNA triplexes and Friedreich ataxia. FASEB J 22: 1625–1634. doi: 10.1096/fj.07-097857
[4]
Grabczyk E, Mancuso M, Sammarco MC (2007) A persistent RNA.DNA hybrid formed by transcription of the Friedreich ataxia triplet repeat in live bacteria, and by T7 RNAP in vitro. Nucleic Acids Res 35: 5351–5359. doi: 10.1093/nar/gkm589
[5]
Campuzano V, Montermini L, Lutz Y, Cova L, Hindelang C, et al. (1997) Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes. Hum Mol Genet 6: 1771–1780. doi: 10.1093/hmg/6.11.1771
[6]
Bradley JL, Blake JC, Chamberlain S, Thomas PK, Cooper JM, et al. (2000) Clinical, biochemical and molecular genetic correlations in Friedreich's ataxia. Hum Mol Genet 9: 275–282. doi: 10.1093/hmg/9.2.275
Schulz JB, Boesch S, Burk K, Durr A, Giunti P, et al. (2009) Diagnosis and treatment of Friedreich ataxia: a European perspective. Nat Rev Neurol 5: 222–234. doi: 10.1038/nrneurol.2009.26
[9]
Pandolfo M, Pastore A (2009) The pathogenesis of Friedreich ataxia and the structure and function of frataxin. J Neurol 256 Suppl 1: 9–17. doi: 10.1007/s00415-009-1003-2
[10]
Pandolfo M (2002) The molecular basis of Friedreich ataxia. Adv Exp Med Biol 516: 99–118. doi: 10.1007/978-1-4615-0117-6_5
[11]
Montermini L, Andermann E, Labuda M, Richter A, Pandolfo M, et al. (1997) The Friedreich ataxia GAA triplet repeat: premutation and normal alleles. Hum Mol Genet 6: 1261–1266. doi: 10.1093/hmg/6.8.1261
[12]
De Biase I, Rasmussen A, Endres D, Al-Mahdawi S, Monticelli A, et al. (2007) Progressive GAA expansions in dorsal root ganglia of Friedreich's ataxia patients. Ann Neurol 61: 55–60. doi: 10.1002/ana.21052
[13]
De Biase I, Rasmussen A, Monticelli A, Al-Mahdawi S, Pook M, et al. (2007) Somatic instability of the expanded GAA triplet-repeat sequence in Friedreich ataxia progresses throughout life. Genomics 90: 1–5. doi: 10.1016/j.ygeno.2007.04.001
[14]
De Michele G, Cavalcanti F, Criscuolo C, Pianese L, Monticelli A, et al. (1998) Parental gender, age at birth and expansion length influence GAA repeat intergenerational instability in the X25 gene: pedigree studies and analysis of sperm from patients with Friedreich's ataxia. Hum Mol Genet 7: 1901–1906. doi: 10.1093/hmg/7.12.1901
[15]
Delatycki MB, Paris D, Gardner RJ, Forshaw K, Nicholson GA, et al. (1998) Sperm DNA analysis in a Friedreich ataxia premutation carrier suggests both meiotic and mitotic expansion in the FRDA gene. J Med Genet 35: 713–716. doi: 10.1136/jmg.35.9.713
[16]
Monros E, Molto MD, Martinez F, Canizares J, Blanca J, et al. (1997) Phenotype correlation and intergenerational dynamics of the Friedreich ataxia GAA trinucleotide repeat. Am J Hum Genet 61: 101–110. doi: 10.1086/513887
[17]
Pianese L, Cavalcanti F, De Michele G, Filla A, Campanella G, et al. (1997) The effect of parental gender on the GAA dynamic mutation in the FRDA gene. Am J Hum Genet 60: 460–463.
Al-Mahdawi S, Sandi C, Mouro Pinto R, Pook MA (2013) Friedreich ataxia patient tissues exhibit increased 5-hydroxymethylcytosine modification and decreased CTCF binding at the FXN locus. PLoS One 8: e74956. doi: 10.1371/journal.pone.0074956
[20]
Ezzatizadeh V, Pinto RM, Sandi C, Sandi M, Al-Mahdawi S, et al. (2012) The mismatch repair system protects against intergenerational GAA repeat instability in a Friedreich ataxia mouse model. Neurobiol Dis 46: 165–171. doi: 10.1016/j.nbd.2012.01.002
[21]
Tomassini B, Arcuri G, Fortuni S, Sandi C, Ezzatizadeh V, et al. (2012) Interferon gamma upregulates frataxin and corrects the functional deficits in a Friedreich ataxia model. Hum Mol Genet 21: 2855–2861. doi: 10.1093/hmg/dds110
[22]
Sandi C, Pinto RM, Al-Mahdawi S, Ezzatizadeh V, Barnes G, et al. (2011) Prolonged treatment with pimelic o-aminobenzamide HDAC inhibitors ameliorates the disease phenotype of a Friedreich ataxia mouse model. Neurobiol Dis 42: 496–505. doi: 10.1016/j.nbd.2011.02.016
[23]
Al-Mahdawi S, Pinto RM, Ismail O, Varshney D, Lymperi S, et al. (2008) The Friedreich ataxia GAA repeat expansion mutation induces comparable epigenetic changes in human and transgenic mouse brain and heart tissues. Hum Mol Genet 17: 735–746. doi: 10.1093/hmg/ddm346
[24]
Al-Mahdawi S, Pinto RM, Varshney D, Lawrence L, Lowrie MB, et al. (2006) GAA repeat expansion mutation mouse models of Friedreich ataxia exhibit oxidative stress leading to progressive neuronal and cardiac pathology. Genomics 88: 580–590. doi: 10.1016/j.ygeno.2006.06.015
[25]
Clark RM, De Biase I, Malykhina AP, Al-Mahdawi S, Pook M, et al. (2007) The GAA triplet-repeat is unstable in the context of the human FXN locus and displays age-dependent expansions in cerebellum and DRG in a transgenic mouse model. Hum Genet 120: 633–640. doi: 10.1007/s00439-006-0249-3
[26]
Lopez Castel A, Cleary JD, Pearson CE (2010) Repeat instability as the basis for human diseases and as a potential target for therapy. Nat Rev Mol Cell Biol 11: 165–170. doi: 10.1038/nrm2854
[27]
Bourn RL, De Biase I, Pinto RM, Sandi C, Al-Mahdawi S, et al. (2012) Pms2 suppresses large expansions of the (GAA.TTC)n sequence in neuronal tissues. PLoS One 7: e47085. doi: 10.1371/journal.pone.0047085
[28]
Li GM (2008) Mechanisms and functions of DNA mismatch repair. Cell Res 18: 85–98. doi: 10.1038/cr.2007.115
[29]
Ellison AR, Lofing J, Bitter GA (2004) Human MutL homolog (MLH1) function in DNA mismatch repair: a prospective screen for missense mutations in the ATPase domain. Nucleic Acids Res 32: 5321–5338. doi: 10.1093/nar/gkh855
[30]
Pinto RM, Dragileva E, Kirby A, Lloret A, Lopez E, et al. (2013) Mismatch Repair Genes Mlh1 and Mlh3 Modify CAG Instability in Huntington's Disease Mice: Genome-Wide and Candidate Approaches. PLoS Genet 9: e1003930. doi: 10.1371/journal.pgen.1003930
[31]
Edelmann W, Cohen PE, Kane M, Lau K, Morrow B, et al. (1996) Meiotic pachytene arrest in MLH1-deficient mice. Cell 85: 1125–1134. doi: 10.1016/s0092-8674(00)81312-4
[32]
Baker SM, Bronner CE, Zhang L, Plug AW, Robatzek M, et al. (1995) Male mice defective in the DNA mismatch repair gene PMS2 exhibit abnormal chromosome synapsis in meiosis. Cell 82: 309–319. doi: 10.1016/0092-8674(95)90318-6
[33]
Moyer MP, Manzano LA, Merriman RL, Stauffer JS, Tanzer LR (1996) NCM460, a normal human colon mucosal epithelial cell line. In Vitro Cell Dev Biol Anim 32: 315–317. doi: 10.1007/bf02722955
[34]
Davis TW, Wilson-Van Patten C, Meyers M, Kunugi KA, Cuthill S, et al. (1998) Defective expression of the DNA mismatch repair protein, MLH1, alters G2-M cell cycle checkpoint arrest following ionizing radiation. Cancer Res 58: 767–778.
[35]
Bustin SA, Benes V, Garson JA, Hellemans J, Huggett J, et al. (2009) The MIQE guidelines: minimum information for publication of quantitative real-time PCR experiments. Clin Chem 55: 611–622. doi: 10.1373/clinchem.2008.112797
[36]
Pianese L, Turano M, Lo Casale MS, De Biase I, Giacchetti M, et al. (2004) Real time PCR quantification of frataxin mRNA in the peripheral blood leucocytes of Friedreich ataxia patients and carriers. J Neurol Neurosurg Psychiatry 75: 1061–1063. doi: 10.1136/jnnp.2003.028605
[37]
Belvederesi L, Bianchi F, Loretelli C, Gagliardini D, Galizia E, et al. (2006) Assessing the pathogenicity of MLH1 missense mutations in patients with suspected hereditary nonpolyposis colorectal cancer: correlation with clinical, genetic and functional features. Eur J Hum Genet 14: 853–859. doi: 10.1038/sj.ejhg.5201628
[38]
Chang DK, Ricciardiello L, Goel A, Chang CL, Boland CR (2000) Steady-state regulation of the human DNA mismatch repair system. J Biol Chem 275: 18424–18431. doi: 10.1074/jbc.m001140200
[39]
Chahwan R, van Oers JM, Avdievich E, Zhao C, Edelmann W, et al. (2012) The ATPase activity of MLH1 is required to orchestrate DNA double-strand breaks and end processing during class switch recombination. J Exp Med 209: 671–678. doi: 10.1084/jem.20111531
[40]
Vetcher AA, Napierala M, Iyer RR, Chastain PD, Griffith JD, et al. (2002) Sticky DNA, a long GAA.GAA.TTC triplex that is formed intramolecularly, in the sequence of intron 1 of the frataxin gene. J Biol Chem 277: 39217–39227. doi: 10.1074/jbc.m205209200
[41]
Chandok GS, Patel MP, Mirkin SM, Krasilnikova MM (2012) Effects of Friedreich's ataxia GAA repeats on DNA replication in mammalian cells. Nucleic Acids Res 40: 3964–3974. doi: 10.1093/nar/gks021
[42]
Sakamoto N, Chastain PD, Parniewski P, Ohshima K, Pandolfo M, et al. (1999) Sticky DNA: self-association properties of long GAA.TTC repeats in R.R.Y triplex structures from Friedreich's ataxia. Mol Cell 3: 465–475.
[43]
Martini E, Borde V, Legendre M, Audic S, Regnault B, et al. (2011) Genome-wide analysis of heteroduplex DNA in mismatch repair-deficient yeast cells reveals novel properties of meiotic recombination pathways. PLoS Genet 7: e1002305. doi: 10.1371/journal.pgen.1002305
[44]
Du J, Campau E, Soragni E, Ku S, Puckett JW, et al. (2012) Role of mismatch repair enzymes in GAA.TTC triplet-repeat expansion in Friedreich ataxia induced pluripotent stem cells. J Biol Chem 287: 29861–29872. doi: 10.1074/jbc.m112.391961
[45]
Jun SH, Kim TG, Ban C (2006) DNA mismatch repair system. Classical and fresh roles. FEBS J 273: 1609–1619. doi: 10.1111/j.1742-4658.2006.05190.x
[46]
Frizzell A, Nguyen JH, Petalcorin MI, Turner KD, Boulton SJ, et al. (2014) RTEL1 Inhibits Trinucleotide Repeat Expansions and Fragility. Cell Rep 6: 827–835. doi: 10.1016/j.celrep.2014.01.034
[47]
Hsieh P, Yamane K (2008) DNA mismatch repair: molecular mechanism, cancer, and ageing. Mech Ageing Dev 129: 391–407. doi: 10.1016/j.mad.2008.02.012
[48]
Grabczyk E, Usdin K (2000) The GAA*TTC triplet repeat expanded in Friedreich's ataxia impedes transcription elongation by T7 RNA polymerase in a length and supercoil dependent manner. Nucleic Acids Res 28: 2815–2822. doi: 10.1093/nar/28.14.2815
[49]
Kuehner JN, Pearson EL, Moore C (2011) Unravelling the means to an end: RNA polymerase II transcription termination. Nat Rev Mol Cell Biol 12: 283–294. doi: 10.1038/nrm3098
[50]
Groh M, Lufino MM, Wade-Martins R, Gromak N (2014) R-loops Associated with Triplet Repeat Expansions Promote Gene Silencing in Friedreich Ataxia and Fragile X Syndrome. PLoS Genet 10: e1004318. doi: 10.1371/journal.pgen.1004318
[51]
Lin Y, Wilson JH (2012) Nucleotide excision repair, mismatch repair, and R-loops modulate convergent transcription-induced cell death and repeat instability. PLoS One 7: e46807. doi: 10.1371/journal.pone.0046807
[52]
Zhang Y, Rohde LH, Wu H (2009) Involvement of nucleotide excision and mismatch repair mechanisms in double strand break repair. Curr Genomics 10: 250–258. doi: 10.2174/138920209788488544
[53]
Denver DR, Feinberg S, Steding C, Durbin M, Lynch M (2006) The relative roles of three DNA repair pathways in preventing Caenorhabditis elegans mutation accumulation. Genetics 174: 57–65. doi: 10.1534/genetics.106.059840
[54]
Kobayashi K, Karran P, Oda S, Yanaga K (2005) Involvement of mismatch repair in transcription-coupled nucleotide excision repair. Hum Cell 18: 103–115. doi: 10.1111/j.1749-0774.2005.tb00001.x
[55]
Mellon I, Hanawalt PC (1989) Induction of the Escherichia coli lactose operon selectively increases repair of its transcribed DNA strand. Nature 342: 95–98. doi: 10.1038/342095a0
[56]
Mellon I, Rajpal DK, Koi M, Boland CR, Champe GN (1996) Transcription-coupled repair deficiency and mutations in human mismatch repair genes. Science 272: 557–560. doi: 10.1126/science.272.5261.557
[57]
Michalowski J, Seavey SE, Mendrysa SM, Perry ME (2001) Defects in transcription coupled repair interfere with expression of p90(MDM2) in response to ultraviolet light. Oncogene 20: 5856–5864. doi: 10.1038/sj.onc.1204721
[58]
Gibson SL, Narayanan L, Hegan DC, Buermeyer AB, Liskay RM, et al. (2006) Overexpression of the DNA mismatch repair factor, PMS2, confers hypermutability and DNA damage tolerance. Cancer Lett 244: 195–202. doi: 10.1016/j.canlet.2005.12.009
