K-Ras Binds Calmodulin-Related Centrin1 with Potential Implications for K-Ras Driven Cancer Cell Stemness

Area of Science:

• Molecular and Cellular Biology
• Oncology
• Signal Transduction

Background:

• K-Ras4B (K-Ras) is implicated in driving cancer cell stemness through calmodulin (CaM)-dependent non-canonical Wnt signaling.
• The role of other calcium-binding proteins, such as centrin1, in mediating K-Ras functions remains largely unexplored.

Purpose of the Study:

• To investigate whether centrin1 binds to K-Ras.
• To determine if centrin1 can mediate K-Ras functions previously attributed to CaM.
• To compare the binding interactions and functional overlap between K-Ras, CaM, and centrin1.

Main Methods:

• Cellular BRET (Bioluminescence Resonance Energy Transfer) assays.
• Immunoprecipitation experiments.
• Analysis of K-Ras binding to CaM and centrin1 under various conditions, including mutations and inhibitor treatments.

Main Results:

• Both CaM and centrin1 bind to K-Ras in cells, with CaM showing stronger engagement, particularly with the K-Ras C-terminal membrane anchor.
• Oncogenic K-RasG12V exhibits increased binding to both CaM and centrin1, dependent on effector interactions.
• CaM inhibitors disrupt the K-RasG12V-centrin1 interaction, indicating functional crosstalk.

Conclusions:

• Centrin1 interacts with K-Ras, suggesting a potential overlap in functions with CaM.
• The G-domain of K-Ras is involved in its complex formation with CaM and centrin1.
• These findings highlight a significant overlap in CaM- and centrin1-dependent functions of K-Ras, with implications for cancer biology.