Biology subjects

Nygaard, K. R.

Publications and source records attributed to Nygaard, K. R..

3 recordsLinked to original sources

bioRxiv2023

Extensive characterization of a Williams Syndrome murine model shows Gtf2ird1-mediated rescue of select sensorimotor tasks, but no effect on enhanced social behavior

Williams Syndrome is a rare neurodevelopmental disorder exhibiting cognitive and behavioral abnormalities, including increased social motivation, risk of anxiety and specific phobias along with perturbed motor function. Williams Syndrome is caused by a microdeletion of 26-28 genes on chromosome 7, including GTF2IRD1, which encodes a transcription factor suggested to play a role in the behavioral profile of Williams Syndrome. Duplications of the full region also lead to frequent autism diagnosis, social phobias, and language delay. Thus, genes in the region appear to regulate social motivation in a dose-sensitive manner. A Complete Deletion mouse, heterozygously eliminating the syntenic Williams Syndrome region, has been deeply characterized for cardiac phenotypes, but direct measures of social motivation have not been assessed. Furthermore, the role of Gtf2ird1 in these behaviors has not been addressed in a relevant genetic context. Here, we have generated a mouse overexpressing Gtf2ird1, which can be used both to model duplication of this gene alone and to rescue Gtf2ird1 expression in the Complete Deletion mice. Using a comprehensive behavioral pipeline and direct measures of social motivation, we provide evidence that the Williams Syndrome Critical Region regulates social motivation along with motor and anxiety phenotypes, but that Gtf2ird1 complementation is not sufficient to rescue most of these traits, and duplication does not decrease social motivation. However, Gtf2ird1 complementation does rescue light-aversive behavior and performance on select sensorimotor tasks, perhaps indicating a role for this gene in sensory processing or integration.

animal behavior and cognition↗

bioRxiv2021

Oxytocin receptor activation does not mediate associative fear deficits in a Williams Syndrome model

Williams Syndrome is caused by a deletion of 26-28 genes on chromosome 7q11.23. Patients with this disorder have distinct behavioral phenotypes including learning deficits, anxiety, increased phobias, and hypersociability. Some studies also suggest elevated blood oxytocin and altered oxytocin receptor expression, and this oxytocin dysregulation is hypothesized to be involved in the underlying mechanisms driving a subset of these phenotypes. A Complete Deletion mouse, modeling the hemizygous critical region deletion in Williams Syndrome, recapitulates many of the phenotypes present in humans. These Complete Deletion mice also exhibited impaired fear responses in the conditioned fear task. Here, we address whether oxytocin dysregulation is responsible for this impaired associative fear memory response. We show direct delivery of an oxytocin receptor antagonist to the central nervous system did not rescue the attenuated contextual or cued fear memory responses in Complete Deletion mice. Thus, increased oxytocin signaling is not acutely responsible for this phenotype. We also evaluated oxytocin receptor and serotonin transporter availability in regions related to fear learning, memory, and sociability using autoradiography in wild type and Complete Deletion mice. While we identified trends in lowered oxytocin receptor expression in the lateral septal nucleus, and trends towards lowered serotonin transporter availability in the striatum and orbitofrontal cortex, we found no significant differences after correction. Together, these data suggest the fear conditioning anomalies in the Williams Syndrome mouse model are independent of any alterations in the oxytocinergic system caused by deletion of the Williams locus.

animal behavior and cognition↗

bioRxiv2019

Functions of Gtf2i and Gtf2ird1 in the developing brain: transcription, DNA-binding, and long term behavioral consequences.

Gtf2ird1 and Gtf2i may mediate aspects of the cognitive and behavioral phenotypes of Williams Syndrome (WS) - a microdeletion syndrome encompassing these transcription factors (TFs). Knockout mouse models of each TF show behavioral phenotypes. Here we identify their genomic binding sites in the developing brain, and test for additive effects of their mutation on transcription and behavior. Both TFs target constrained chromatin modifier and synaptic protein genes, including a significant number of ASD genes. They bind promoters, strongly overlap CTCF binding and TAD boundaries, and moderately overlap each other, suggesting epistatic effects. We used single and double mutants to test whether mutating both TFs will modify transcriptional and behavioral phenotypes of single Gtf2ird1 mutants. Despite little difference in DNA-binding and transcriptome-wide expression, Gtf2ird1 mutation caused balance, marble burying, and conditioned fear phenotypes. However, mutating Gtf2i in addition to Gtf2ird1 did not further modify transcriptomic or most behavioral phenotypes, suggesting Gtf2ird1 mutation alone is sufficient.

genetics↗