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The novel human gene aprataxin is directly involved in DNA single-strand-break repair

P Mosesso1, M Piane, F Palitti

  • 1Dipartimento di Agrobiologia e Agrochimica, Università degli Studi della Tuscia, Via San Camino de Lellis s.n.c., 01100 Viterbo, Italy. mosesso@unitus.it.

Cellular and Molecular Life Sciences : CMLS
|February 19, 2005
PubMed

Insights

Aprataxin (a protein) is directly involved in repairing DNA single-strand breaks. Cells from ataxia-oculomotor apraxia type 1 patients with aprataxin mutations showed increased DNA damage when exposed to specific agents.

Area of Science:

  • Genetics
  • Molecular Biology
  • DNA Repair Mechanisms

Background:

  • Ataxia-oculomotor apraxia type 1 (AOA1) is a rare neurological disorder.
  • Aprataxin is a protein implicated in DNA repair, but its precise role in single-strand break repair is not fully understood.

Purpose of the Study:

  • To investigate the direct involvement of aprataxin in DNA single-strand break repair.
  • To characterize the DNA repair capabilities of cells with a novel aprataxin mutation.

Main Methods:

  • Cultured cells from an AOA1 patient (homozygous for T739C aprataxin mutation) and her heterozygous mother were treated with camptothecin.
  • DNA damage was assessed using cytogenetic analysis of chromosomal aberrations and the alkaline comet assay.
  • Sensitivity to ionizing radiation (X-rays) was also evaluated.

Main Results:

  • Camptothecin treatment induced a marked, dose-related increase in chromosomal aberrations in AOA1 patient and heterozygous cells compared to wild-type controls.
  • The alkaline comet assay confirmed increased DNA damage in the patient's cells.
  • AOA1 cells did not exhibit hypersensitivity to X-ray-induced DNA damage.

Conclusions:

  • The results strongly suggest that aprataxin plays a direct role in the cellular machinery responsible for repairing DNA single-strand breaks.
  • The novel T739C mutation in aprataxin impairs this DNA repair function, contributing to the AOA1 phenotype.

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