Cholangiocytes' primary cilia regulate DNA damage response and repair

Area of Science:

• Cell Biology
• Cancer Research
• Genetics

Background:

• Primary cilia are implicated as tumor suppressors in cholangiocarcinoma (CCA).
• The precise mechanisms by which primary cilia influence DNA damage response (DDR) and repair remain incompletely understood.

Purpose of the Study:

• To investigate the role of primary cilia in regulating DNA damage response and repair pathways in cholangiocytes.
• To determine the impact of primary cilia loss on cellular response to genotoxic stress.

Main Methods:

• Utilized human cholangiocyte cell lines with experimental deciliation (shRNA/CRISPR targeting IFT20, IFT88, KIF3A).
• Assessed DNA repair protein localization at cilia and DNA repair pathway function after genotoxic agent exposure (cisplatin, MMS, irradiation).
• Employed an in vivo liver-specific IFT88 knockout mouse model to study cilia loss in the liver.

Main Results:

• DNA repair proteins (RAD51, ATR, PARP1, CHK1, CHK2) were found to localize within primary cilia.
• Deciliated cells exhibited impaired DNA repair, reduced survival, increased S-phase arrest, and elevated DNA damage (γH2AX, comet assays) post-genotoxic challenge.
• Downregulation of key DDR proteins (ATM, p53, p21) was observed in deciliated cells after irradiation; in vivo models confirmed increased DNA damage.

Conclusions:

• Primary cilia play a critical role in maintaining genomic stability by regulating DNA damage response and repair.
• Loss of primary cilia compromises cellular defense mechanisms against genotoxic stress in cholangiocytes.
• Targeting cilia-dependent pathways presents a potential novel therapeutic strategy for cholangiocarcinoma.