Engineering Material Properties of Transcription Factor Condensates to Control Gene Expression in HEK-293T Cells

Phase separation of biomolecules into condensates is a key mechanism in the spatiotemporal organization of biochemical processes in cells. We systematically engineered light-inducible transcription factor condensates with different material properties and analyzed their influence on transcription activation. When transcription factor condensates were transformed into solid-like gels, we observed a reduced activation of gene expression. We wanted to evaluate the impact that the condensate formation of the transcription factor RelA had on its endogenous promoters using expression data. To this aim, HEK-293T cells were transfected either with empty vector (1-3) or eGFP-RelA (4-6) or eGFP-RelA, Cry2olig-mCh-FUSN-NLS-NbGFP and Cry2olig-mCh-FUSN-NLS, along with an NF-?B-responsive SEAP reporter (7-9). In each of the three groups of transfected cells, 8 h after transfection, 3 samples were kept in the dark (D) and 3 under blue light illumination (BL, 5 µmol m-² s-1) for 24 h prior to RNA extraction. RNA-seq libraries from the 18 samples were sequenced by BGI on a DNBSEQ platform using paired-end chemistry with a read length of 100 base pairs each. Each strand was sequenced across two separate lanes (L03, L04), generating a total of 4 FASTQ files per sample.