BioProject

Understanding how uniquely human genetic changes altered developmental processes is essential to understanding human evolution. More...

Understanding how uniquely human genetic changes altered developmental processes is essential to understanding human evolution. We investigated the role of the Human Accelerated Region HACNS1 in human limb evolution by directly interrogating its biological functions in a humanized mouse model. Using genome-wide epigenetic profiling, we found that HACNS1 maintains its human-specific transcriptional enhancer activity compared to its chimpanzee ortholog in the mouse embryonic limb, and that it alters promoter activity of the transcription factor gene Gbx2. Using single-cell transcriptional profiling, we demonstrate that Gbx2 is upregulated in humanized limb bud chondrogenic mesenchyme, providing insight into the developmental processes altered due to human-specific alterations in enhancer activity. Our findings establish that HACNS1 directs changes in the level and distribution of gene expression during development, and illustrate how humanized mouse models provide insight into regulatory pathways altered in human evolution. Overall design: For ChIP-seq, tissue was collected from E11.5 forelimb and hindlimb bud pairs or pharyngeal arch tissue from HACNS1 and chimpanzee ortholog line heterozygous crosses to obtain two biological replicates each of pooled, litter matched limb bud or pharyngeal arch samples for all three genotypes (HACNS1+/+, chimpanzee ortholog line, and wild type). Each replicate is comprised of H3K27ac ChIP, H3K4me2 ChIP, and input control data. For scRNA-seq, tissue was collected from E11.5 hindlimb from HACNS1+/+, chimpanzee ortholog line, and wild type litters from homozygous crosses. Left hindlimb buds from three embryos per genotype per replicate were pooled. Less...