Coordinated evolution at amino acid sites of SARS-CoV-2 spike

SARS-CoV-2 has adapted in a stepwise manner, with multiple beneficial mutations accumulating in a rapid succession at origins of VOCs, and the reasons for this are unclear. Here, we searched for coordinated evolution of amino acid sites in the spike protein of SARS-CoV-2. Specifically, we searched for concordantly evolving site pairs (CSPs) for which changes at one site were rapidly followed by changes at the other site in the same lineage. We detected 46 sites which formed 45 CSP. Sites in CSP were closer to each other in the protein structure than random pairs, indicating that concordant evolution has a functional basis. Notably, site pairs carrying lineage defining mutations of the four VOCs that circulated before May 2021 are enriched in CSPs. For the Alpha VOC, the enrichment is detected even if Alpha sequences are removed from analysis, indicating that VOC origin could have been facilitated by positive epistasis. Additionally, we detected nine discordantly evolving pairs of sites where mutations at one site unexpectedly rarely occurred on the background of a specific allele at another site, for example on the background of wild-type D at site 614 (four pairs) or derived Y at site 501 (three pairs). Our findings hint that positive epistasis between accumulating mutations could have delayed the assembly of advantageous combinations of mutations comprising at least some of the VOCs.

Epigenetic-genetic chromatin footprinting identifies novel and subject-specific genes active in prefrontal cortex neurons

Human prefrontal cortex (PFC) is associated with broad individual variabilities in functions linked to personality, social behaviors, and cognitive functions. The phenotype variabilities associated with brain functions can be caused by genetic or epigenetic factors. The interactions between these factors in human subjects is, as of yet, poorly understood. The heterogeneity of cerebral tissue, consisting of neuronal and nonneuronal cells, complicates the comparative analysis of gene activities in brain specimens. To approach the underlying neurogenomic determinants, we performed a deep analysis of open chromatin-associated histone methylation in PFC neurons sorted from multiple human individuals in conjunction with whole-genome and transcriptome sequencing. Integrative analyses produced novel unannotated neuronal genes and revealed individual-specific chromatin "blueprints" of neurons that, in part, relate to genetic background. Surprisingly, we observed gender-dependent epigenetic signals, implying that gender may contribute to the chromatin variabilities in neurons. Finally, we found epigenetic, allele-specific activation of the testis-specific gene nucleoporin 210 like (NUP210L) in brain in some individuals, which we link to a genetic variant occurring in <3% of the human population. Recently, the NUP210L locus has been associated with intelligence and mathematics ability. Our findings highlight the significance of epigenetic-genetic footprinting for exploring neurologic function in a subject-specific manner.-Gusev, F. E., Reshetov, D. A., Mitchell, A. C., Andreeva, T. V., Dincer, A., Grigorenko, A. P., Fedonin, G., Halene, T., Aliseychik, M., Goltsov, A. Y., Solovyev, V., Brizgalov, L., Filippova, E., Weng, Z., Akbarian, S., Rogaev, E. I. Epigenetic-genetic chromatin footprinting identifies novel and subject-specific genes active in prefrontal cortex neurons.