Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Necroptosis is a programmed cell death pathway regulated by RIPK3 and executed by MLKL.
• This inflammatory cell death is implicated in various diseases, including autoimmune disorders, infections, cardiovascular conditions, neurodegeneration, and cancer.

Purpose of the Study:

• To develop and present protocols for characterizing MLKL's role in necroptosis-induced plasma membrane rupture.
• To identify molecular interactions and modulators of MLKL activity during necroptosis.

Main Methods:

• Live-cell imaging (conventional and confocal fluorescence microscopy) to visualize necroptosis dynamics.
• Electron microscopy for detailed analysis of fixed cells.
• In vitro nuclear magnetic resonance (NMR) spectroscopy with lipids to determine MLKL-lipid interactions.

Main Results:

• Visual evidence showed MLKL redistribution from the cytosol to the plasma membrane preceding membrane permeabilization.
• NMR analysis identified specific lipid-binding preferences for MLKL.
• Phosphatidyl-inositol phosphates (PIPs) were identified as critical binders of MLKL, essential for its plasma membrane targeting and subsequent permeabilization.

Conclusions:

• MLKL acts as the executioner of plasma membrane rupture during necroptosis.
• PIPs are critical regulators of MLKL localization and function in necroptosis.
• The developed protocols provide valuable tools for studying necroptosis mechanisms.