A role for Keratin 17 in Rac1-mediated DNA damage response in keratinocytes

Area of Science:

• Cell Biology
• Molecular Biology
• Dermatology

Background:

• Keratin 17 (K17) is a stress-induced protein implicated in skin diseases and cancer.
• K17 influences nuclear architecture and DNA damage response (DDR) in keratinocytes.
• Previous work demonstrated K17's role in keratinocyte survival and tumor promotion.

Purpose of the Study:

• To identify K17-interacting partners involved in the DNA damage response.
• To elucidate the molecular mechanisms by which K17 impacts DDR and cellular proliferation.

Main Methods:

• Mass spectrometry to identify K17-interacting proteins.
• Biochemical assays to confirm K17-Rac1 interaction in vitro and in tumor keratinocytes.
• Analysis of KRT17 deletion effects on Rac1, TOP2A, and proliferation post-irradiation.
• Rescue experiments using constitutively-active and dominant-negative Rac mutants.

Main Results:

• A network of K17-interacting Rho GTPase signaling proteins, including Rac1, was identified.
• K17 and Rac1 directly interact in keratinocytes, with KRT17 deletion reducing Rac1 levels.
• KRT17 deletion decreased Rac1-dependent proliferation after ionizing radiation.
• Constitutively-active Rac1 rescued K17-dependent readouts in KRT17-null cells.

Conclusions:

• A novel K17-Rac1-TOP2A signaling axis promotes DNA damage response and proliferation.
• This pathway has significant implications for understanding and treating cancer and chronic skin diseases.