Anxiety-associated behaviors following ablation of Miro1 from cortical excitatory neurons

Autism spectrum disorder, schizophrenia, and bipolar disorder are neuropsychiatric conditions that manifest early in life with a wide range of phenotypes, including repetitive behavior, agitation, and anxiety (American Psychological Association, 2013). While the etiology of these disorders is incompletely understood, recent data implicate a role for mitochondrial dysfunction (Norkett et al., 2017; Khaliulin et al., 2025). Mitochondria dynamically translocate to intracellular compartments to support energetics and free-radical buffering; failure to achieve this localization results in cellular dysfunction (Picard et al., 2016). Mitochondrial Rho-GTPase 1 ( Miro1 ) resides on the outer mitochondrial membrane and facilitates microtubule-mediated mitochondrial motility and homeostasis (Fransson et al., 2003). The loss of MIRO1 is reported to contribute to the onset/progression of neurodegenerative diseases, including amyotrophic lateral sclerosis, Alzheimer’s disease, and Parkinson’s disease (Kay et al., 2018). We have hypothesized that MIRO1 also has a role in nervous system development and function (Lin-Hendel et al., 2016). To test this, we ablated Miro1 from cortical excitatory progenitors by crossing floxed Miro1 mice with Emx1-Cre mice and used mice of either sex for experiments. We found that mitochondrial mis-localization in migrating excitatory neurons was associated with reduced brain weight, decreased cortical volume, and subtle cortical disorganization. Adult Miro1 conditional mutants exhibit agitative-like behaviors, including decreased nesting behavior and abnormal home cage activity. The mice exhibited anxiety-like behavior and avoided confined spaces, features that have been linked to several human behavioral disorders. Our data link MIRO1 function with mitochondrial dynamics in the pathogenesis of several neuropsychiatric disorders and implicate intracellular mitochondrial dynamics to some anxiety-like behaviors. Significance Statement Neuropsychological disorders such as autism spectrum disorder, schizophrenia, and bipolar disorder have overlapping endophenotypes. While the mechanisms underlying these disorders are poorly understood, recent evidence implicates mitochondrial dysfunction and cellular mis-localization playing a role. Mitochondria support energy requirements and other physiological functions in cells. Previous research from our lab has shown distinct dynamic localization patterns within migrating excitatory and inhibitory neurons during development. To further examine the importance of mitochondrial localization, we ablated MIRO1, a protein important for coupling mitochondria to motor proteins, in excitatory neurons. The mis-localization of mitochondria in migrating excitatory neurons is associated with diminished motor skills and anxiety-like behavior in post-natal mice.