Acylation of MLKL Impacts Its Function in Necroptosis

Area of Science:

• Cellular Biology
• Biochemistry
• Molecular Signaling

Background:

• Mixed lineage kinase domain-like (MLKL) is crucial for necroptosis, a form of programmed cell death.
• MLKL activation involves phosphorylation and translocation to the plasma membrane, leading to membrane permeabilization and inflammation.
• Previous studies indicated MLKL and its phosphorylated form (pMLKL) undergo S-acylation during necroptosis.

Purpose of the Study:

• To characterize the specific cysteine residues involved in MLKL S-acylation.
• To investigate the impact of MLKL acylation on its interaction with cell membranes.
• To identify the S-palmitoyltransferases responsible for pMLKL acylation and assess their role in necroptosis.

Main Methods:

• Site-directed mutagenesis to identify MLKL acylation sites.
• All-atom molecular dynamic simulations to analyze protein-membrane interactions.
• Cell-based assays to evaluate the effect of zDHHC21 inhibition on pMLKL levels and cell viability.

Main Results:

• MLKL and pMLKL can be acylated at single cysteine sites, with C184, C269, and C286 identified as potential sites.
• Molecular dynamics simulations revealed distinct effects of acylation on MLKL structure and membrane binding.
• Inhibition of zDHHC21 significantly reduced pMLKL levels, improved membrane integrity, and ameliorated necroptotic activity.

Conclusions:

• S-acylation of MLKL at specific cysteines is a critical regulatory mechanism in necroptosis.
• Targeting MLKL acylation, particularly zDHHC21 activity, offers a potential therapeutic strategy to control necroptosis.
• This study elucidates the role of S-acylation in MLKL function and its membrane interactions during necroptosis.