GSK-3 is an RNA polymerase II phospho-CTD kinase.

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• UV-induced DNA damage triggers hyperphosphorylation of RNA polymerase II (RNAPII) CTD, inhibiting transcription elongation and altering alternative splicing (AS).
• The protein kinases mediating this DNA damage response in AS remain largely uncharacterized.

Purpose of the Study:

• To identify novel protein kinases involved in the alternative splicing response to DNA damage.
• To elucidate the role of glycogen synthase kinase 3 (GSK-3) in UV-induced transcription and splicing alterations.

Main Methods:

• Unbiased screening for protein kinases involved in DNA damage response.
• Inhibition of GSK-3 activity and overexpression of dominant-negative mutants.
• In vitro kinase assays using CTD substrates.
• Analysis of RNAPII elongation, alternative splicing, and apoptosis.

Main Results:

• Glycogen synthase kinase 3 (GSK-3) was identified as a novel participant in the UV-induced AS response.
• GSK-3 inhibition specifically prevents UV-induced CTD hyperphosphorylation, RNAPII elongation inhibition, and AS changes.
• GSK-3 phosphorylates the CTD in vitro, preferentially on pre-phosphorylated substrates.
• GSK-3 inhibition protects against UV-induced apoptosis.

Conclusions:

• GSK-3 plays a critical role in regulating eukaryotic transcription and pre-mRNA processing following DNA damage.
• GSK-3 inhibition offers a potential protective mechanism against UV-induced cellular damage and apoptosis.