Hypomorphic PCNA mutation underlies a human DNA repair disorder

Area of Science:

• Genetics
• Molecular Biology
• Human Disease

Background:

• Nucleotide excision repair (NER) gene mutations cause various human disorders like Cockayne syndrome and xeroderma pigmentosum.
• Proliferating Cell Nuclear Antigen (PCNA) is a crucial protein for DNA replication and repair, acting as a sliding clamp.

Observation:

• A novel syndrome presents with short stature, hearing loss, premature aging, telangiectasia, neurodegeneration, and photosensitivity.
• This syndrome is caused by a homozygous missense alteration (p.Ser228Ile) in the PCNA gene.

Findings:

• The PCNA p.Ser228Ile alteration did not affect protein levels or DNA replication but significantly impaired UV survival and RNA synthesis recovery in patient cells.
• This mutation altered PCNA's interaction with DNA metabolism enzymes Flap endonuclease 1 and DNA Ligase 1.
• The findings indicate a hypomorphic alteration in PCNA leading to a neurodegenerative phenotype with features of DNA repair disorders.

Implications:

• This study identifies a specific PCNA mutation responsible for a distinct human syndrome, expanding the spectrum of DNA repair disorders.
• Understanding the molecular mechanisms of this PCNA alteration can provide insights into DNA repair pathways and neurodegeneration.
• The findings highlight the critical role of PCNA in maintaining genomic stability and preventing disease.