Multi-dimensional mapping of lineage specific transcription factors through time and space

Objective

Here I propose an ambitious project designed to explore an exciting new hypothesis: TFs are non-randomly spatially organised within the cell nucleus, forming radial gradients that likely play an important role in regulating gene expression. This idea was born from one of the intriguing discoveries revealed by Genomic loci Positioning by Sequencing (GPSeq), a technique developed in the host lab, that the binding motifs of the majority of human transcription factors (TFs) seem to form radial density gradients, with some TF binding motifs being more abundant towards the nuclear periphery, whilst others more abundant in the centre. Furthermore, preliminary analysis showed that the predicted binding motifs of master regulator TFs specifying lymphoid vs myeloid lineages form opposing radial gradients, suggesting that this mode of transcriptional regulation is critical for cell fate specification. In this project, I will differentiate hematopoietic stem cell (HSC) into opposing lineages (lymphoid/myeloid) and perform TF CUT&RUN to assay TF occupancy and chromatin landscape, coupled with GPSeq to assay the radial arrangement of chromatin in these lineages. The intersection of these two genome-wide datasets will provide the first ever map of the occupancy of lineage specific transcription factors through differentiation time and nuclear space with respect to radiality. In parallel I will generate additional omics datasets in these cell populations to assay chromatin accessibility, transcription and chromatin interactions to build a comprehensive, multi-dimensional genomic atlas in which the spatial arrangement of TFs can be linked with gene expression dynamics. Crucially, no other study has thus far addressed this novel hypothesis; my work will provide significant advancements in understanding the interplay of genome architecture with transcriptional regulation and cell-fate specification.