Meander tail and development of the anterior lobe. - Project Summary The anterior lobe of the cerebellum has unique sensitivities in developmental and degenerative disorders. How anterior and posterior compartments are differentiated developmentally are not adequately understood. The classical mouse mutation meander tail (mea) causes both the kinked tail for which it is named and a compartment-specific disorganization of the anterior cerebellum. Three independent alleles have been reported. Positional cloning efforts more than a decade ago identified a genomic interval but failed to identify causal variants due to technical limitations. Data from that project and from genome-scale mutagenesis projects highly suggest a recurrent regulatory mutation involving one or more structural genes adjacent to the mapped location. This exploratory proposal will identify mutations underlying the two extant mea alleles and test the molecular sequelae of mea mutation on anterior compartment identity and development using cutting-edge genomic tools. The mea locus has been studied for nearly 50 years, but molecular identification eluded efforts with earlier technology. We will resolve this genetic puzzle using de novo long read sequencing, layered onto previously unpublished mapping data. We propose that mea mutations are regulatory in nature and affect compartmentation or compartment-specific identity with respect in the anterior cerebellar lobe. This predicts either discrete or graded changes in expression signatures within or across compartments. We will test this family of hypotheses using single nucleus sequencing of RNA and transposon-accessible chromatin sites from mutant and control littermates in a highly congenic background. Together these aims will resolve a longstanding mystery in the genetics of cerebellum development and point to plausible mechanisms for pleiotropic effects on vertebral development.
