Comparing synaptic proteomes across five mouse models for autism reveals converging molecular similarities including deficits in oxidative phosphorylation and Rho GTPase signaling.

Specific and effective treatments for autism spectrum disorder (ASD) are lacking due to a poor understanding of disease mechanisms. Here we test the idea that similarities between diverse ASD mouse models are caused by deficits in common molecular pathways at neuronal synapses. To do this, we leverage the availability of multiple genetic models of ASD that exhibit shared synaptic and behavioral deficits and use quantitative mass spectrometry with isobaric tandem mass tagging (TMT) to compare their hippocampal synaptic proteomes. Comparative analyses of mouse models for Fragile X syndrome (Fmr1 knockout), cortical dysplasia focal epilepsy syndrome (Cntnap2 knockout), PTEN hamartoma tumor syndrome (Pten haploinsufficiency), ANKS1B syndrome (Anks1b haploinsufficiency), and idiopathic autism (BTBR+) revealed several common altered cellular and molecular pathways at the synapse, including changes in oxidative phosphorylation, and Rho family small GTPase signaling. Functional validation of one of these aberrant pathways, Rac1 signaling, confirms that the ANKS1B model displays altered Rac1 activity counter to that observed in other models, as predicted by the bioinformatic analyses. Overall similarity analyses reveal clusters of synaptic profiles, which may form the basis for molecular subtypes that explain genetic heterogeneity in ASD despite a common clinical diagnosis. Our results suggest that ASD-linked susceptibility genes ultimately converge on common signaling pathways regulating synaptic function and propose that these points of convergence are key to understanding the pathogenesis of this disorder.

Common genetic variation impacts stress response in the brain.

To explain why individuals exposed to identical stressors experience divergent clinical outcomes, we determine how molecular encoding of stress modifies genetic risk for brain disorders. Analysis of post-mortem brain (n=304) revealed 8557 stress-interactive expression quantitative trait loci (eQTLs) that dysregulate expression of 915 eGenes in response to stress, and lie in stress-related transcription factor binding sites. Response to stress is robust across experimental paradigms: up to 50% of stress-interactive eGenes validate in glucocorticoid treated hiPSC-derived neurons (n=39 donors). Stress-interactive eGenes show brain region- and cell type-specificity, and, in post-mortem brain, implicate glial and endothelial mechanisms. Stress dysregulates long-term expression of disorder risk genes in a genotype-dependent manner; stress-interactive transcriptomic imputation uncovered 139 novel genes conferring brain disorder risk only in the context of traumatic stress. Molecular stress-encoding explains individualized responses to traumatic stress; incorporating trauma into genomic studies of brain disorders is likely to improve diagnosis, prognosis, and drug discovery.

Viral Determinants in H5N1 Influenza A Virus Enable Productive Infection of HeLa Cells.

Influenza A virus (IAV) is a human respiratory pathogen that causes yearly global epidemics, as well as sporadic pandemics due to human adaptation of pathogenic strains. Efficient replication of IAV in different species is, in part, dictated by its ability to exploit the genetic environment of the host cell. To investigate IAV tropism in human cells, we evaluated the replication of IAV strains in a diverse subset of epithelial cell lines. HeLa cells were refractory to the growth of human H1N1 and H3N2 viruses and low-pathogenic avian influenza (LPAI) viruses. Interestingly, a human isolate of the highly pathogenic avian influenza (HPAI) H5N1 virus successfully propagated in HeLa cells to levels comparable to those in a human lung cell line. Heterokaryon cells generated by fusion of HeLa and permissive cells supported H1N1 virus growth, suggesting the absence of a host factor(s) required for the replication of H1N1, but not H5N1, viruses in HeLa cells. The absence of this factor(s) was mapped to reduced nuclear import, replication, and translation, as well as deficient viral budding. Using reassortant H1N1:H5N1 viruses, we found that the combined introduction of nucleoprotein (NP) and hemagglutinin (HA) from an H5N1 virus was necessary and sufficient to enable H1N1 virus growth. Overall, this study suggests that the absence of one or more cellular factors in HeLa cells results in abortive replication of H1N1, H3N2, and LPAI viruses, which can be circumvented upon the introduction of H5N1 virus NP and HA. Further understanding of the molecular basis of this restriction will provide important insights into the virus-host interactions that underlie IAV pathogenesis and tropism.IMPORTANCE Many zoonotic avian influenza A viruses have successfully crossed the species barrier and caused mild to life-threatening disease in humans. While human-to-human transmission is limited, there is a risk that these zoonotic viruses may acquire adaptive mutations enabling them to propagate efficiently and cause devastating human pandemics. Therefore, it is important to identify viral determinants that provide these viruses with a replicative advantage in human cells. Here, we tested the growth of influenza A virus in a subset of human cell lines and found that abortive replication of H1N1 viruses in HeLa cells can be circumvented upon the introduction of H5N1 virus HA and NP. Overall, this work leverages the genetic diversity of multiple human cell lines to highlight viral determinants that could contribute to H5N1 virus pathogenesis and tropism.