ABSTRACT We will identify potential new pharmacological therapies targeted to improve mitochondrial function in a class of cerebral cortical neurons thought to be compromised in multiple neurodevelopmental disorders. We have shown that mitochondrial metabolism is disrupted in layer 2/3 Projection Neurons (PNs) in the LgDel mouse model of 22q11.2 Deletion Syndrome, a syndromic neurodevelopmental disorder. We have also demonstrated that this disruption apparently accounts for quantitative differences in association cortical connectivity correlated with cognitive behavioral deficits in LgDel mice. Finally, we showed that a free radical scavenger that influences mitochondrial function, N-acetyl cysteine (NAC), can reverse these molecular, cellular and behavioral deficits. We will now assess the capacity of multiple mitochondrial targeted pharmacological compounds, as well as known mitochondria-targeted drugs, to modulate LgDel Layer 2/3 PN mitochondrial metabolism and its influences on layer 2/3 PN homeostasis. In Specific Aim 1, we will evaluate compound activity in a validated, homogeneous layer 2/3 PN in vitro assay using the Agilent Seahorse Metabolic Analyzer to measure key aspects of mitochondrial function. Candidate compounds that restore LgDel mitochondrial dysfunction toward WT, without disrupting WT mitochondrial function, will be further validated for their capacity to diminish aberrant mitochondrial reactive oxygen species (ROS) levels and restore dendritic and axonal growth in LgDel layer 2/3 PNs. To provide additional interpretative resolution of the mechanistic precision of these compounds, in Specific Aim 2 we will perform a parallel transcriptome comparison of LgDel versus WT Layer 2/3 PNs in vitro to identify pathways whose transcriptional regulation is altered due to mitochondrial dysfunction and diminished growth in developing Layer 2/3 PNs targeted by neurodevelopmental pathology. We will further contrast this data with the transcriptome profile of LgDel layer 2/3 PNs treated with NAC, whose metabolic and growth-restoring activity we have previously demonstrated. Thus, compounds identified in this screen will be validated for specificity, targeted cellular activity, and placed in context of differentially regulated transcriptional pathways sensitive to altered mitochondrial function. These pathways underlie diminished neuron growth that contributes to neurodevelopmental cortical circuit pathology. Thus, our experiments identify potential candidates for further development of mitochondria-based therapies and a molecular mechanistic framework for rational design of precisely targeted new drugs to correct molecular and cellular pathology associated with cortical neuron and circuits compromised in multiple neurodevelopmental disorders.

PROJECT NARRATIVE Mitochondria targeted drugs are thought to relieve behavioral symptoms associated with multiple neurodevelopmental disorders; however, the cellular targets and molecular mechanisms by which these drugs act remain unknown. We will develop a screen for mitochondrial drugs that defines their action on a specific class of neuron that is a target for neurodevelopmental pathology and identify the gene networks underlying therapeutic effects of these compounds. Our results will suggest new diagnostic and therapeutic approaches for a broad range of clinically or genetically diagnosed neurodevelopmental diseases.