Global phosphoproteomic analysis identifies SRMS-regulated secondary signaling intermediates

Area of Science:

• Cellular signaling and kinase regulation
• Phosphoproteomics and bioinformatics analysis
• Molecular mechanisms of DNA repair and apoptosis

Background:

• SRMS (Src-related kinase lacking C-terminal regulatory tyrosine and N-terminal myristoylation sites) is a non-receptor tyrosine kinase and a member of the BRK family kinases.
• Tyrosine kinases regulate cellular processes through protein phosphorylation and signaling cross-talks.
• Previous work identified SRMS tyrosine kinase substrates, but its broader signaling network remained unknown.

Purpose of the Study:

• To uncover the broader SRMS-regulated phosphoproteome.
• To identify SRMS-regulated indirect signaling intermediates.
• To elucidate the role of SRMS in cellular signaling pathways.

Main Methods:

• Performed label-free global phosphoproteomics analysis on cells expressing wild-type SRMS.
• Utilized computational database searching and bioinformatics analyses to characterize the phosphoproteomics dataset.
• Analyzed motifs derived from upregulated phosphosites to identify contributing kinases.

Main Results:

• Identified 60 hyperphosphorylated proteins from 140 hyperphosphorylated peptides.
• Bioinformatics analyses revealed significantly enriched biological processes, including upregulated DNA repair and downregulated apoptotic pathways.
• Casein kinase 2 alpha (CK2α) was identified as a major potential kinase involved in SRMS-dependent indirect signaling regulation.

Conclusions:

• Phosphoproteomics analysis highlighted the importance of serine/threonine phosphorylation dynamics in the SRMS-regulated phosphoproteome.
• These secondary phosphorylation events have significant implications for regulating cellular and biological processes.
• The study expands the understanding of SRMS kinase's role in cellular signaling networks.