Mechanisms of MLKL in necroptosis: from intramolecular rearrangements to isoform regulation

• Applicant: Professorin Dr. Ana Jesús Garcia Sáez
• Subject Area: Cell Biology
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418168917

Necroptosis is a newly discovered form of regulated necrosis that is inflammatory and plays a role in a number of diseases associated with chronic inflammation and infection. It results in release of the cellular contents after plasma membrane permeabilization dependent on the pseudokinase mixed lineage kinase domain-like (MLKL) protein, which is the most terminal effector of necroptosis known to date. Additionally, non-deadly roles of MLKL in intracellular vesicle trafficking that seem to counterbalance necroptotic cell death have been recently described. However, the molecular mechanism behind these MLKL functions remains obscure and is a matter of debate. In preliminary work, we have discovered that the different isoforms of mouse and human MLKL identified by transcriptome analysis exhibit distinct death-inducing potency. While lack of the inhibitory pseudokinase domain renders MLKL intrinsically active, insertion of just eight amino acids in the C-terminal helix abolishes its necroptotic activity. The main goal of this project is to shed new light on the molecular mechanism how MLKL executes necroptosis. To this aim, we will uncover the structural elements that regulate MLKL activity and determine the contribution of the different MLKL isoforms to MLKL deadly and non-deadly functions. Based on the effect of small differences in the sequence of the C-terminal helix on MLKL activity, we plan to investigate how MLKL structure regulates function. We will then use this information to discover new small molecules that regulate MLKL activity. Finally, we will examine the role of the different MLKL isoforms on the regulation of necroptosis and of additional non-deadly functions. This multidisciplinary project combines cell biology and advanced microscopy with molecular dynamic simulations to disclose new molecular steps involved in the coordination of necroptosis. The identification of new small molecules and proteins implicated in necroptosis regulation will pave the way for the design of new drugs that modulate MLKL activity for human health.

• DFG Programme: Research Grants