Phenotypic and genetic analysis of the cerebellar mutant tmgc26, a new ENU‐induced ROR‐alpha allele

Abstract

ROR-alpha is an orphan nuclear receptor, the inactivation of which cell-autonomously blocks differentiation of cerebellar Purkinje cells with a secondary loss of granule neurons. As part of our ENU mutagenesis screen we isolated the recessive tmgc26 mouse mutant, characterized by early onset progressive ataxia, cerebellar degeneration and juvenile lethality. Detailed analysis of the tmgc26−/− cerebella revealed Purkinje cell and granule cell abnormalities, and defects in molecular layer interneurons and radial glia. Chimera studies suggested a cell-autonomous effect of the tmgc26 mutation in Purkinje cells and molecular layer interneurons, and a non-cell autonomous effect in granule cells. The mutation was mapped to a 13Mb interval on chromosome 9, a region that contains the ROR-alpha gene. Sequencing of genomic DNA revealed a T-to-A transition in exon 5 of the ROR-alpha gene, resulting in a nonsense mutation C257X and severe truncation of the ROR-alpha protein. Together, our data identify new roles for ROR-alpha in molecular layer interneurons and radial glia development and introduce tmgc26 as a novel RORalpha allele suitable for further delineating molecular mechanisms of ROR-alpha action.

Preterm birth disrupts cerebellar development by affecting granule cell proliferation program and Bergmann glia

“…As controls, we used term pigs that were either naturally born or delivered via c-section. Cell-type specific markers were used to identify and quantify distinct cerebellar populations, including Pax6, which labels both proliferating and differentiating cerebellar granule cell precursors in the EGL, and Calbindin, Pax2 and GFAP, which label Purkinje cells, GABAergic molecular layer (ML) interneurons, and Bergmann glia, respectively (Swanson et al, 2010; Yeung et al, 2016). The number of Pax6+ granule precursors was reduced in preterm pigs relative to both naturally born term controls and term controls delivered via c-section in both anterior and posterior cerebellum (Fig.…”

Melatonin and Melatonergic Influence on Neuronal Transcription Factors: Implications for the Development of Novel Therapies for Neurodegenerative Disorders

“…It was initially believed that melatonin may act through a nuclear signalling pathway that is mediated via a transcription factor (RZR/ROR) to influence neuronal differentiation. Along this line, studies in staggerers (which are natural RZR/RORα “knockout” mice) have reported defects in cerebellar Purkinje cell development [ 148 , 149 ]. However, recent findings cast doubts on the validity of RORs acting as nuclear melatonin receptors [ 150 ].…”

Characterization of Highper, an ENU-induced mouse mutant with abnormal psychostimulant and stress responses

“…ENU mutagenesis is a high-throughput approach for generating random heritable mutations in an unbiased manner, thereby allowing for the identification of phenotypes that have not yet been linked to a given gene. ENU-induced mutations have resulted in the identification of genes underlying complex phenotypes, including ataxia (Sharkey et al 2009; Swanson et al 2010; Xie et al 2010), epilepsy (Frankel et al 2009; Tokuda et al 2011), and deafness (Grillet et al 2009; Mackenzie et al 2009; Parker et al 2010; Schwander et al 2009a, b). Mapping ENU-induced mutations for complex behavioral phenotypes has proven particularly difficult, but genes involved in locomotor activity have been identified (Furuse et al 2010; Keays et al 2004; Speca et al 2010).…”