Aberrant phase separation of transcription factors in human developmental disorders

Components of the transcription machinery can undergo liquid-liquid phase separation, but the functional importance of phase-separated condensates in transcriptional control is not well understood. Here we report that disease-causing mutations in several transcription factors (TFs) alter the phase separation capacity of those TFs. We first demonstrate that the Hoxd13 TF, and its intrinsically disordered N-terminus form phase-separated condensates. Expansions of a polyalanine repeat, which cause hereditary synpolydactyly in humans, facilitate phase separation of Hoxd13, and alter the transcriptional program of several cell types in a cell-specific manner in vivo. Disease-associated expansions of aminoacid repeats in intrinsically disordered regions of other TFs were similarly found to alter phase separation. These results suggest that aberrant phase separation of transcriptional regulators may underlie a spectrum of human pathologies. The paper is available at https://doi.org/10.1016/j.cell.2020.04.018 Single-cell RNAseq data was performed on mouse limb buds from embyros at developmental stage E12.5 from a WT and a SPDH mutant condition. Samples from each condition were sequenced with the 10X Genomics singlecell RNA sequencing system. Further, we use H3K27ac and H3K27me3 ChIPseq to see if transcriptional changes are reflected in chromosome structure. Reanalysis of Samples GSM3568504 and GSM3568505 (processed data file: H3K27Ac-L-E125-Wt-Mm_merged_8_peaks.bed ). Third-party reanalysis of Samples GSM2151014 and GSM2151018 (processed data file: hoxd13_peaks_pv1e10_e11_5.bed). Data processing steps same as those for the other ChIP-seq samples in GSE128818.