Leveraging interindividual variability in threat conditioning of inbred mice to model trait anxiety.

Trait anxiety is a major risk factor for stress-induced and anxiety disorders in humans. However, animal models accounting for the interindividual variability in stress vulnerability are largely lacking. Moreover, the pervasive bias of using mostly male animals in preclinical studies poorly reflects the increased prevalence of psychiatric disorders in women. Using the threat imminence continuum theory, we designed and validated an auditory aversive conditioning-based pipeline in both female and male mice. We operationalised trait anxiety by harnessing the naturally occurring variability of defensive freezing responses combined with a model-based clustering strategy. While sustained freezing during prolonged retrieval sessions was identified as an anxiety-endophenotype behavioral marker in both sexes, females were consistently associated with an increased freezing response. RNA-sequencing of CeA, BLA, ACC, and BNST revealed massive differences in phasic and sustained responders' transcriptomes, correlating with transcriptomic signatures of psychiatric disorders, particularly post-traumatic stress disorder (PTSD). Moreover, we detected significant alterations in the excitation/inhibition balance of principal neurons in the lateral amygdala. These findings provide compelling evidence that trait anxiety in inbred mice can be leveraged to develop translationally relevant preclinical models to investigate mechanisms of stress susceptibility in a sex-specific manner.

Motor neuron disease, TDP-43 pathology, and memory deficits in mice expressing ALS-FTD-linked UBQLN2 mutations.

Missense mutations in ubiquilin 2 (UBQLN2) cause ALS with frontotemporal dementia (ALS-FTD). Animal models of ALS are useful for understanding the mechanisms of pathogenesis and for preclinical investigations. However, previous rodent models carrying UBQLN2 mutations failed to manifest any sign of motor neuron disease. Here, we show that lines of mice expressing either the ALS-FTD-linked P497S or P506T UBQLN2 mutations have cognitive deficits, shortened lifespans, and develop motor neuron disease, mimicking the human disease. Neuropathologic analysis of the mice with end-stage disease revealed the accumulation of ubiquitinated inclusions in the brain and spinal cord, astrocytosis, a reduction in the number of hippocampal neurons, and reduced staining of TAR-DNA binding protein 43 in the nucleus, with concomitant formation of ubiquitin+ inclusions in the cytoplasm of spinal motor neurons. Moreover, both lines displayed denervation muscle atrophy and age-dependent loss of motor neurons that correlated with a reduction in the number of large-caliber axons. By contrast, two mouse lines expressing WT UBQLN2 were mostly devoid of clinical and pathological signs of disease. These UBQLN2 mouse models provide valuable tools for identifying the mechanisms underlying ALS-FTD pathogenesis and for investigating therapeutic strategies to halt disease.

beeRapp: an R shiny app for automated high-throughput explorative analysis of multivariate behavioral data.

Summary: Animal behavioral studies typically generate high-dimensional datasets consisting of multiple correlated outcome measures across distinct or related behavioral domains. Here, we introduce the BEhavioral Explorative analysis R shiny APP (beeRapp) that facilitates explorative and inferential analysis of behavioral data in a high-throughput fashion. By employing an intuitive and user-friendly graphical user interface, beeRapp empowers behavioral scientists without programming and data science expertise to perform clustering, dimensionality reduction, correlational and inferential statistics and produce up to thousands of high-quality output plots visualizing results in a standardized and automated way. Availability and implementation: The code and data underlying this article are available at https://github.com/anmabu/beeRapp.

Multi-omic analysis of selectively vulnerable motor neuron subtypes implicates altered lipid metabolism in ALS.

Amyotrophic lateral sclerosis (ALS) is a devastating disorder in which motor neurons degenerate, the causes of which remain unclear. In particular, the basis for selective vulnerability of spinal motor neurons (sMNs) and resistance of ocular motor neurons to degeneration in ALS has yet to be elucidated. Here, we applied comparative multi-omics analysis of human induced pluripotent stem cell-derived sMNs and ocular motor neurons to identify shared metabolic perturbations in inherited and sporadic ALS sMNs, revealing dysregulation in lipid metabolism and its related genes. Targeted metabolomics studies confirmed such findings in sMNs of 17 ALS (SOD1, C9ORF72, TDP43 (TARDBP) and sporadic) human induced pluripotent stem cell lines, identifying elevated levels of arachidonic acid. Pharmacological reduction of arachidonic acid levels was sufficient to reverse ALS-related phenotypes in both human sMNs and in vivo in Drosophila and SOD1G93A mouse models. Collectively, these findings pinpoint a catalytic step of lipid metabolism as a potential therapeutic target for ALS.

Generation of multipotent induced neural crest by direct reprogramming of human postnatal fibroblasts with a single transcription factor.

Neural crest (NC) generates diverse lineages including peripheral neurons, glia, melanocytes, and mesenchymal derivatives. Isolating multipotent human NC has proven challenging, limiting our ability to understand NC development and model NC-associated disorders. Here, we report direct reprogramming of human fibroblasts into induced neural crest (iNC) cells by overexpression of a single transcription factor, SOX10, in combination with environmental cues including WNT activation. iNC cells possess extensive capacity for migration in vivo, and single iNC clones can differentiate into the four main NC lineages. We further identified a cell surface marker for prospective isolation of iNCs, which was used to generate and purify iNCs from familial dysautonomia (FD) patient fibroblasts. FD-iNC cells displayed defects in cellular migration and alternative mRNA splicing, providing insights into FD pathogenesis. Thus, this study provides an accessible platform for studying NC biology and disease through rapid and efficient reprogramming of human postnatal fibroblasts.