RSK1 and RSK2 serine/threonine kinases regulate different transcription programs in cancer

Area of Science:

• Molecular Biology
• Cancer Biology
• Signal Transduction

Background:

• Ribosomal S6 kinases (RSKs) are serine/threonine kinases with four isoforms.
• RSK isoforms (RSK1-4) exhibit overlapping functions in cancer-related processes like migration, proliferation, and gene transcription.
• Specific differences in gene regulation between RSK1 and RSK2 remain largely undefined.

Purpose of the Study:

• To delineate isoform-specific transcriptional gene regulation by RSK1 and RSK2.
• To compare transcription programs between RSK1 and RSK2 knockout cells.
• To identify distinct functions of RSK1 and RSK2 in cellular processes.

Main Methods:

• Microarray analysis of RSK1 and RSK2 knockout cell lines to compare mRNA expression patterns.
• Bioinformatic analysis to identify differentially expressed gene sets.
• Cellular assays to validate the functional significance of identified transcriptional programs.

Main Results:

• Microarray analysis revealed distinct mRNA expression profiles in RSK1 vs. RSK2 knockout cells.
• RSK1 was found to specifically regulate cell adhesion, cell cycle, DNA replication, and repair pathways.
• RSK2 was specifically implicated in immune response and interferon signaling pathways.
• RSK1 modulates Fibronectin1 and CDK2 expression, impacting cell adhesion and cell cycle arrest.
• RSK2 influences ISG15 expression, affecting immune response and cytokine signaling.
• Identified gene sets correlated significantly with cancer patient mRNA datasets.

Conclusions:

• RSK1 and RSK2 exhibit isoform-specific transcriptional regulation.
• RSK1 plays distinct roles in cell adhesion, cell cycle control, and DNA maintenance.
• RSK2 has specific functions in immune system modulation and interferon signaling.
• These findings define separate functional roles for closely related RSK isoforms in cancer biology.