Proper development of multicellular organisms requires a coordination of conserved developmental pathways involved in proper tissue growth and patterning. Genetic analyses have identified Fat (Ft), an atypical cadherin that functions to regulate planar cell polarity (PCP) tissue organization and the Hippo pathway. Mutations of Ft cadherins have been implicated in polarity defects, tissue overgrowth, and spindle orientation defects.
The intracellular domain (ICD) of Ft has been previously dissected using structure-function analyses, and distinct regions affecting Ft’s function in PCP and Hippo signaling have been identified. We recently have identified a novel signaling role for Ft in regulating mitochondrial function that maps to previously identified regions in the ICD. We showed that Ft is processed intracellularly to generate Ftmito, and is required for regulating the stability and/or ability of Complexes I and/or V. Our analysis of the ICD of Ft identified two predicted mitochondrial targeting sequences (MTS), and a highly conserved region that is necessary for Ndufv2 binding. Subsequent experiments will help understand the mechanism of how Ft regulates mitochondrial function. We are currently conducting CRISPR mutagenesis and genetic analyses to ablate the two MTS sites as well as other conserved regions in the ICD to understand how their loss affects mitochondrial function. I am also deleting a conserved potential cleavage site in the ICD to examine if the intracellular processing of Ft is lost and whether the mitochondrial localization of Ft is affected. I will conduct tissue-specific RNAi knockdown of Ft to determine whether the mitochondrial activity of Ft is ubiquitous throughout the Drosophila larvae. These experiments will allow us to examine the role of Ft in the mitochondria endogenously, and can be applied to understand how endogenous deletions within the ICD affect Ft's other functions in PCP and Hippo signaling.