RAD50 missense variants differentially affect the DNA damage response and mitotic progression

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• RAD50 is essential for DNA double-strand break repair via the MRN complex.
• RAD50 deficiency leads to genomic instability, microcephaly, and stunted growth.

Purpose of the Study:

• To investigate if cancer-related RAD50 missense variants can restore DNA damage response and mitotic progression in RAD50-deficient cells.
• To analyze the functional impact of RAD50 variants on epirubicin treatment response and cell division.

Main Methods:

• Utilized lentiviral constructs to introduce RAD50 missense variants into RAD50-deficient fibroblasts.
• Assessed complementation of DNA damage response after epirubicin exposure.
• Evaluated mitotic progression in cells expressing RAD50 variants.

Main Results:

• Eight RAD50 missense variants, capable of forming the MRN complex, partially restored DNA damage response and mitotic features.
• Three variants demonstrated impaired epirubicin response and slowed cell division, falling within the likely pathogenic range.
• Functional analysis revealed separable roles for RAD50 in DNA repair and cell cycle progression.

Conclusions:

• Functional heterogeneity exists among RAD50 missense variants, impacting DNA repair and cell division distinctly.
• Assessing RAD50 variants at multiple functional levels can clarify their roles in diseases like immunodeficiency and cancer.
• Understanding variant-specific functions may inform improved therapeutic strategies for cancer and related disorders.