DNA single-strand break repair is impaired in aprataxin-related ataxia.

Abstract

OBJECTIVE:

Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive form of cerebellar ataxia. The causative protein for EAOH/AOA1, aprataxin (APTX), interacts with X-ray repair cross-complementing 1 (XRCC1), a scaffold DNA repair protein for single-strand breaks (SSBs). The goal of this study was to prove the functional involvement of APTX in SSB repair (SSBR).

METHODS:

We visualized the SSBR process with a recently developed laser irradiation system that allows real-time observation of SSBR proteins and with a local ultraviolet-irradiation system using a XPA-UVDE cell line that repairs DNA lesions exclusively via SSBR. APTX was knocked down using small interference RNA in the cells. Oxidative stress-induced DNA damage and cell death were assessed in EAOH fibroblasts and cerebellum.

RESULTS:

Our systems showed the XRCC1-dependent recruitment of APTX to SSBs. SSBR was impaired in APTX-knocked-down cells. Oxidative stress in EAOH fibroblasts readily induced SSBs and cell death, which were blocked by antioxidants. Accumulated oxidative DNA damage was confirmed in EAOH cerebellum.

INTERPRETATION:

This study provides the first direct evidence for the functional involvement of APTX in SSBR and in vivo DNA damage in EAOH/AOA1, and suggests a benefit of antioxidant treatment.

• Authors: Makito Hirano, Aya Yamamoto, Toshio Mori, Li Lan, Taka-aki Iwamoto, Masashi Aoki, Keiji Shimada, Yoshiko Furiya, Shingo Kariya, Hirohide Asai, Akira Yasui, Tomohisa Nishiwaki, Kyoko Imoto, Nobuhiko Kobayashi, Takao Kiriyama, Tetsuya Nagata, Noboru Konishi, Yasuto Itoyama, Satoshi Ueno
• Journal: Annals of neurology (Ann Neurol) Vol. 61 Issue 2 Pg. 162-74 (Feb 2007) ISSN: 0364-5134 [Print] United States
• PMID: 17315206 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• APTX protein, human
• Antibodies, Monoclonal
• DNA-Binding Proteins
• Nuclear Proteins
• Proliferating Cell Nuclear Antigen
• RNA, Small Interfering
• X-ray Repair Cross Complementing Protein 1
• XRCC1 protein, human
• Proteasome Endopeptidase Complex

Topics

• Adult
• Animals
• Antibodies, Monoclonal
• Cell Death
• Cells, Cultured
• Cerebellar Ataxia (genetics, metabolism, physiopathology)
• Cerebellum (metabolism)
• DNA Breaks, Single-Stranded
• DNA Repair
• DNA-Binding Proteins (antagonists & inhibitors, genetics, immunology, metabolism)
• Drug Interactions
• Drug Stability
• Female
• Fibroblasts (metabolism)
• Genes, Recessive
• Humans
• Lasers
• Male
• Mutation
• Nuclear Proteins (antagonists & inhibitors, genetics, immunology, metabolism)
• Oxidative Stress
• Proliferating Cell Nuclear Antigen (metabolism)
• Proteasome Endopeptidase Complex (metabolism)
• RNA, Small Interfering (pharmacology)
• Ultraviolet Rays
• X-ray Repair Cross Complementing Protein 1