PROJECT SUMMARY
Mitochondria serve as a central signaling hub for innate immune responses. Disruption of mitochondrial function
is a hallmark for various infections and chronic inflammatory diseases. The overall objective of this proposal is
to define the molecular mechanisms that regulate mitochondrial membrane homeostasis and determine how
membrane disruption promotes inflammatory cell death. Mutations in leucine-rich repeat kinase 2 (LRRK2) are
associated with disrupted mitochondrial integrity and increased reactive oxygen species. They are also
associated with increased susceptibility to hormonal breast cancer, Crohn's disease, and mycobacterial
infection, strongly suggesting a role in innate immune function. Recently, the Watson lab set out to investigate
LRRK2's role in peripheral innate immunity, focusing on a gain of function mutation, Lrrk2G2019S. Mitochondrial
stress conferred by the Lrrk2G2019S mutation increases demand on the electron transport chain, which leads to
excessive ROS production. This increased ROS triggers a new type of cell death where a protein canonically
associated with pyroptosis, gasdermin D (GSDMD), can associate with mitochondrial membranes and cause
necroptotic cell death. Aim 1 of this proposal will identify the minimal domain within GSDMD that targets
mitochondrial membranes, enabling a better understanding of the molecular mechanisms underlying GSDMD's
newly described role in necroptosis. Aim 2 will investigate the contribution of various aspects of mitochondrial
dysfunction to GSDMD mitochondrial targeting and necroptosis, providing new insights into connections between
the disruption of mitochondrial homeostasis and GSDM relocalization. With the goal of understanding how
mitochondria are impacted by genetic mutations and/or stress, Aim 3 will measure relocalization of the
mitochondrial inner membrane phospholipid cardiolipin in WT and Lrrk2G2019S macrophages and catalog
mitochondrial lipids in WT vs. Lrrk2G2019S macrophages. Defining the molecular mechanisms that drive
inflammation in the face of specific mitochondrial mutations will help enable therapeutic interventions designed
to correct specific aspects of mitochondrial dysfunction associated with a variety of inflammatory, infectious,
cardiac, and neurological disorders.