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Updated: May 9, 2025
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Fully Processed Recombinant KRAS4b: Isolating and Characterizing the Farnesylated and Methylated Protein
Published on: January 16, 2020
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MTMR regulates KRAS function by controlling plasma membrane levels of phospholipids
Taylor E Lange1, Ali Naji2, Ransome van der Hoeven2
1Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA.
The Journal of Cell Biology
|May 2, 2025
Summary
Myotubularin-related proteins (MTMR) 2, 3, 4, and 7 regulate KRAS protein localization by controlling plasma membrane lipid levels. Their depletion disrupts KRAS binding, impacting cancer cell processes.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- KRAS, a key GTPase in cell signaling, requires plasma membrane (PM) binding for its function.
- Phosphatidylserine (PtdSer) on the PM is crucial for KRAS membrane association and activity.
- Activating KRAS mutations are common in human cancers.
Purpose of the Study:
- To identify genes regulating KRAS PM localization.
- To elucidate the role of phosphatidylinositol (PI) 3-phosphatases in KRAS membrane targeting.
Main Methods:
- Genome-wide siRNA screen to identify regulators of KRAS PM localization.
- Analysis of lipid levels (PI4P, PI3P, PtdSer) at the PM.
- Assessment of KRAS PM binding and activity upon gene silencing.
Main Results:
- Silencing myotubularin-related proteins (MTMR) 2, 3, 4, and 7 reduced PM PI 4-phosphate (PI4P) levels.
- MTMR depletion disrupted the ORP5 lipid transfer protein, impairing PM PtdSer enrichment.
- MTMR silencing elevated PM PI 3-phosphate (PI3P) and decreased PM and total PtdSer levels, affecting KRAS PM localization.
Conclusions:
- The PI 3-phosphatase activity of MTMR proteins is essential for maintaining PM PI levels.
- This activity supports PM PI4P synthesis, crucial for ORP5 function and PtdSer localization.
- MTMR proteins are critical regulators of PtdSer and KRAS localization at the plasma membrane.
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