Targeting Necroptosis for Neurodegenerative Disease Therapy

PROJECT SUMMARY/ABSTRACT The long-term objective of the project is to develop therapeutics for Alzheimer’s that inhibit a unique method of cell death known as necroptosis. This cell death pathway has been known to be upregulated in neurodegenerative diseases, highlighting the need to find therapeutics that target the proteins involved. Several kinases are known to be important regulators that include: RIPK1, RIPK3 and MLKL. However, unlike most therapeutic approaches that target the kinase portion of RIPK proteins involved in necroptosis, we are targeting the protein-protein interface between RIPK3 and MLKL. This targeting method should uncover more specific compounds since RIPK kinases are involved in multiple pathways. By targeting an interface that is only shared between two proteins involved in necroptosis (protein-protein interface), we ensure that there are fewer side effects as compared to targeting the kinase function implicated in more than just necroptosis. It was previously shown that an interaction between RIPK3 and MLKL located away from the kinase interface is necessary to promote RIPK3 and MLKL binding. We targeted in silico this pocket that is involved in the interaction of RIPK3 to MLKL using a library of small molecules. The top 13 compounds were tested using flow to assay of cells where apoptosis is inhibited and cells only undergo cell death through necroptosis. Using this assay, we were able to narrow down the list of compounds to two hits that specifically inhibit necroptosis, we showed the compounds are targeting the RIPK3 protein in cells. Follow-up studies with derivatives of these two hit compounds exhibited improvements. We propose to further develop compounds using chemical synthesis and test the compounds using patient-derived stem cells for improvements in cellular assays. These new derivative compounds should create a more extensive SAR and will be the next generation compounds to develop more lead-like compounds for AD therapeutics.PROJECT NARRATIVE Despite many years of research and development, only four cholinesterase inhibitors and memantine have been approved by the FDA for the treatment of Alzheimer’s disease (AD). Recent reports have implicated necroptosis, a form of cell death, to be activated in human (AD) brains and we have developed a novel approach to target the protein-protein interactions involved in necroptosis without affecting their other crucial functions. The purpose of this grant is to develop novel molecules that target proteins involved in necroptosis and to test them in human AD patient derived induced pluripotent stem cells.