Biology subjects

Ratner, C.

Publications and source records attributed to Ratner, C..

3 recordsLinked to original sources

bioRxiv2023

Mouse model of atypical DAT deficiency syndrome uncovers dopamine dysfunction associated with parkinsonism and psychiatric disease

The dopamine transporter (DAT) plays a crucial role in regulating the brains dopamine (DA) homeostasis. Atypical DAT deficiency syndrome (DTSD) is a disease characterized by early-onset parkinsonism and comorbid psychiatric symptoms, but the pathobiological processes that link DAT dysfunction to both parkinsonism and psychiatric symptoms are unknown. Here, we present a genetic mouse model of atypical DTDS that expresses two coding DAT variants, DAT-I312F and DAT-D421N, derived from a patient diagnosed with ADHD and parkinsonism. Phenotypic characterization of the mutant mice revealed impaired DAT function and major homeostatic changes including increased ambient extracellular DA levels, decreased evoked DA release, and reduced expression of both tyrosine hydroxylase (TH) and of DA D1/D2 receptors. This was accompanied by diminished striatal dopaminergic axonal density and a psychomotor phenotype characterized by hyperactivity, enhanced exploratory activity, and pronounced clasping. Importantly, both amphetamine and anticholinergic treatment ameliorated aberrant hyperlocomotion in the mice. Summarized, by replicating core aspects of the patients phenotype, the mouse model not only provides insights into the mechanisms underlying atypical DTDS but also underlines the broad relevance of DA deficits for understanding the co-morbidity between neuropsychiatric diseases and parkinsonism. ONE SENTENCE SUMMARYIn a new mouse disease model, we explore the behavioral consequences and dopaminergic dysfunction that arise from patient-derived mutations in the dopamine transporter associated with parkinsonism and co-morbid neuropsychiatric disease

neuroscience↗

bioRxiv2023

Comparison of TRIBE and STAMP for identifying targets of RNA binding proteins in human and Drosophila cells

RNA binding proteins (RBPs) perform a myriad of functions and are implicated in numerous neurological diseases. To identify the targets of RBPs in small numbers of cells, we developed TRIBE, in which the catalytic domain of the RNA editing enzyme ADAR (ADARcd) is fused to a RBP. When the RBP binds to a mRNA, ADAR catalyzes A to G modifications in the target mRNA that can be easily identified in standard RNA-sequencing. In STAMP, the concept is the same except the ADARcd is replaced by the RNA editing enzyme APOBEC. Here we compared the two enzymes fused to the RBP TDP-43 in human cells. Although they both identified TDP-43 target mRNAs, combining the two methods more successfully identified high confidence targets. We also assayed the two enzymes in Drosophila cells: RBP-APOBEC fusions generated only low numbers of editing sites, comparable to the level of control editing. This was true for two different RBPs, Hrp48 and Thor (Drosophila EIF4E-BP), indicating that TRIBE performed better in Drosophila.

molecular biology↗

bioRxiv2018

In vivo epigenetic editing of sema6a promoter reverses impaired transcallosal connectivity caused by C11orf46/ARL14EP neurodevelopmental risk gene

Many neuropsychiatric risk genes contribute to epigenetic regulation of gene expression but very little is known about specific chromatin-associated mechanisms governing the formation and maintenance of neuronal connectivity. Here we show that transcallosal connectivity is critically dependent on C11orf46 (also known as ARL14EP), a small nuclear protein encoded in the chromosome 11p13 Wilms Tumor, Aniridia, Genitourinary Abnormalities, intellectual disability (formerly referred to as Mental Retardation) (WAGR) risk locus. C11orf46 haploinsufficiency in WAGR microdeletion cases was associated with severe hypoplasia of the corpus callosum. In utero short hairpin RNA-mediated C11orf46 knockdown disrupted transcallosal projections of cortical pyramidal neurons, a phenotype that was rescued by wild type C11orf46 but not the C11orf46R236H mutant associated with autosomal recessive intellectual disability. Multiple genes encoding key regulators of axonal growth and differentiation, including Sema6A, were hyperexpressed in C11orf46-knockdown neurons. Importantly, RNA-guided epigenetic editing of neuronal Sema6a gene promoters via a dCas9 protein-conjugated SunTag scaffold with multimeric (10x) C11orf46 binding during early developmental periods, resulted in normalization of expression and rescue of transcallosal dysconnectivity via repressive chromatin remodeling, including up-regulated histone H3K9 methylation by the KAP1-SETDB1 repressor complex. Our study demonstrates that interhemispheric communication is highly sensitive to locus-specific remodeling of neuronal chromatin, revealing the therapeutic potential for shaping the brains connectome via gene-targeted designer activators and repressor proteins.

developmental biology↗