R-loops and impaired autophagy trigger cGAS-dependent inflammation via micronuclei formation in Senataxin-deficient...

Area of Science:

• Molecular Biology
• Genetics
• Immunology

Background:

• Senataxin (SETX) is a DNA/RNA helicase crucial for removing R-loops, structures that can cause DNA damage and replication stress.
• Dysfunction of Senataxin is implicated in neurodegenerative diseases and cancer.
• R-loops are nucleic acid structures that, if unresolved, can lead to genomic instability.

Purpose of the Study:

• To investigate the consequences of Senataxin deficiency on DNA integrity and cellular responses.
• To elucidate the role of Senataxin in R-loop homeostasis and its impact on innate immunity.
• To identify mechanisms driving inflammation in Senataxin-deficient cells.

Main Methods:

• Cellular assays to assess DNA damage and micronuclei formation in Senataxin-deficient cells.
• Immunofluorescence microscopy to detect cGAS recruitment and R-loop persistence.
• Analysis of autophagy function and gene expression related to innate immunity.
• Correlation analysis between EXO1 levels, Senataxin expression, and patient prognosis.

Main Results:

• Senataxin deficiency leads to the release of damaged DNA into micronuclei with defective membranes.
• These micronuclei trigger a strong innate immune response via cGAS-STING pathway activation, stimulating interferon genes.
• Autophagy, essential for clearing damaged micronuclei, is impaired in Senataxin-deficient cells.
• Persistent nuclear R-loops, DSIF, and EXO1 activity contribute to Senataxin-dependent inflamed micronuclei formation.
• High EXO1 levels correlate with poor prognosis in tumors lacking Senataxin.

Conclusions:

• Impaired R-loop homeostasis and autophagy failure in Senataxin-deficient cells promote the formation of inflamed micronuclei.
• This process activates the innate immune system, potentially contributing to disease pathogenesis.
• Targeting EXO1 activity may offer therapeutic strategies for cancers with low Senataxin expression.