Regulation of global genome nucleotide excision repair by SIRT1 through xeroderma pigmentosum C

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• Mutations in nucleotide excision repair (NER) pathway genes cause xeroderma pigmentosum, increasing skin cancer risk.
• The xeroderma pigmentosum C (XPC) protein initiates global genome NER by detecting DNA damage.
• SIRT1 is a deacetylase and longevity factor implicated in various cellular processes.

Purpose of the Study:

• To investigate the role of SIRT1 in the NER pathway.
• To determine if SIRT1 affects XPC protein expression and function.
• To explore the clinical relevance of SIRT1 in human skin tumors.

Main Methods:

• Inhibition of SIRT1 activity in cellular models.
• Analysis of XPC gene transcription and protein levels.
• Assessment of SIRT1 expression in human skin tumor samples.

Main Results:

• SIRT1 inhibition impairs global genome NER by suppressing XPC transcription in a deacetylase-dependent manner.
• SIRT1 promotes XPC expression by reducing the nuclear localization of an XPC transcription repressor, mediated by AKT.
• Significantly lower SIRT1 levels were observed in skin tumors from Caucasian patients.

Conclusions:

• SIRT1 plays a critical role in initiating global genome NER through regulating XPC expression.
• SIRT1 functions as a tumor suppressor by maintaining DNA repair integrity.
• Reduced SIRT1 levels in skin tumors highlight its potential as a biomarker and therapeutic target.