OBJECTIVE: To address the relationship between novel mutations in polynucleotide 5'-kinase 3'-phosphatase (PNKP), DNA strand break repair, and neurologic disease. METHODS: We have employed whole-exome sequencing, Sanger sequencing, and molecular/cellular biology. RESULTS: We describe here a patient with microcephaly with early onset seizures (MCSZ) from the Indian sub-continent harboring 2 novel mutations in PNKP, including a pathogenic mutation in the fork-head associated domain. In addition, we confirm that MCSZ is associated with hyperactivation of the single-strand break sensor protein protein poly (ADP-ribose) polymerase 1 (PARP1) following the induction of abortive topoisomerase I activity, a source of DNA strand breakage associated previously with neurologic disease. CONCLUSIONS: These data expand the spectrum of PNKP mutations associated with MCSZ and show that PARP1 hyperactivation at unrepaired topoisomerase-induced DNA breaks is a molecular feature of this disease.

Department of Genome Dynamics Department of Pediatrics All India Institute of Medical Sciences New Delhi India

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Jiang B, Glover JNM, Weinfeld M. Neurological disorders associated with DNA strand-break processing enzymes. Mech Ageing Dev 2017;161(pt A):130–140. PubMed PMC

Yoon G, Caldecott KW. Nonsyndromic cerebellar ataxias associated with disorders of DNA single-strand break repair. Handb Clin Neurol 2018;155:105–115. PubMed

Hoch NC, Hanzlikova H, Rulten SL, et al. . XRCC1 mutation is associated with PARP1 hyperactivation and cerebellar ataxia. Nature 2016;541:87–91. PubMed PMC

Jilani A, Ramotar D, Slack C, et al. . Molecular cloning of the human gene, PNKP, encoding a polynucleotide kinase 3'-phosphatase and evidence for its role in repair of DNA strand breaks caused by oxidative damage. J Biol Chem 1999;274:24176–24186. PubMed

Karimi-Busheri F, Daly G, Robins P, et al. . Molecular characterization of a human DNA kinase. J Biol Chem 1999;274:24187–24194. PubMed

Loizou JI, El-Khamisy SF, Zlatanou A, et al. . The protein kinase CK2 facilitates repair of chromosomal DNA single-strand breaks. Cell 2004;117:17–28. PubMed

Shen J, Gilmore EC, Marshall CA, et al. . Mutations in PNKP cause microcephaly, seizures and defects in DNA repair. Nat Genet 2010;42:245–249. PubMed PMC

Bras J, Alonso I, Barbot C, et al. . Mutations in PNKP cause recessive ataxia with oculomotor apraxia type 4. Am J Hum Genet 2015;96:474–479. PubMed PMC

Leal A, Bogantes-Ledezma S, Ekici AB, et al. . The polynucleotide kinase 3'-phosphatase gene (PNKP) is involved in Charcot-Marie-Tooth disease (CMT2B2) previously related to MED25. Neurogenetics 2018;19:215–225. PubMed PMC

Pedroso JL, Rocha CRR, Macedo-Souza LI, et al. . Mutation in PNKP presenting initially as axonal Charcot-Marie-Tooth disease. Neurol Genet 2015;1:e30. PubMed PMC

Breslin C, Clements PM, El-Khamisy SF, Petermann E, Iles N, Caldecott KW. Measurement of chromosomal DNA single-strand breaks and replication fork progression rates. Meth Enzymol 2006;409:410–425. PubMed

Dobson CJ, Allinson SL. The phosphatase activity of mammalian polynucleotide kinase takes precedence over its kinase activity in repair of single strand breaks. Nucleic Acids Res 2006;34:2230–2237. PubMed PMC

El-Khamisy SF, Saifi GM, Weinfeld M, et al. . Defective DNA single-strand break repair in spinocerebellar ataxia with axonal neuropathy-1. Nature 2005;434:108–113. PubMed

Katyal S, Lee Y, Nitiss KC, et al. . Aberrant topoisomerase-1 DNA lesions are pathogenic in neurodegenerative genome instability syndromes. Nat Neurosci 2014;17:813–821. PubMed PMC

Reynolds JJ, Walker AK, Gilmore EC, Walsh CA, Caldecott KW. Impact of PNKP mutations associated with microcephaly, seizures and developmental delay on enzyme activity and DNA strand break repair. Nucleic Acids Res 2012;40:6608–6619. PubMed PMC

O'Driscoll M, Ruiz-Perez VL, Woods CG, Jeggo PA, Goodship JA. A splicing mutation affecting expression of ataxia-telangiectasia and Rad3-related protein (ATR) results in Seckel syndrome. Nat Genet 2003;33:497–501. PubMed

Shimada M, Dumitrache LC, Russell HR, McKinnon PJ. Polynucleotide kinase-phosphatase enables neurogenesis via multiple DNA repair pathways to maintain genome stability. EMBO J 2015;34:2465–2480. PubMed PMC

Pathological mutations in PNKP trigger defects in DNA single-strand break repair but not DNA double-strand break repair