Estecio, M. R. | bioRxiv Science

bioRxiv2022

GSK-3484862 targets DNMT1 for degradation in cells

Maintenance of genomic methylation patterns at DNA replication forks by DNMT1 is the key to faithful mitotic inheritance. DNMT1 is often overexpressed in cancer cells and the DNA hypomethylating agents azacytidine and decitabine are currently used in the treatment of hematologic malignancies. However, the toxicity of these cytidine analogs and their ineffectiveness in treating solid tumors have limited wider clinical use. GSK-3484862 is a newly-developed, dicyanopyridine containing, non-nucleoside DNMT1-selective inhibitor with low cellular toxicity. Here, we show that GSK-3484862 targets DNMT1 for protein degradation in both cancer cell lines and murine embryonic stem cells (mESCs). DNMT1 depletion was rapid, taking effect within hours following GSK-3484862 treatment, leading to global hypomethylation. Inhibitor-induced DNMT1 degradation was proteasome-dependent, with no discernible loss of DNMT1 mRNA. In mESCs, GSK-3484862-induced Dnmt1 degradation requires Uhrf1, an accessory factor of Dnmt1 with E3 ubiquitin ligase activity. We also show that Dnmt1 depletion and DNA hypomethylation induced by the compound are reversible after its removal. Together, these results indicate that this DNMT1-selective degrader/inhibitor will be a valuable tool for dissecting both coordinated events linking DNA methylation to gene expression and identifying downstream effectors that ultimately regulate cellular response to altered DNA methylation patterns in a tissue/cell-specific manner. HighlightsO_LIGSK-3484862 targets DNMT1 for protein degradation in a wide-range of cancer cell lines, without a decrease in DNMT1 mRNA levels C_LIO_LIDNMT1 depletion leads to a >50% loss of global DNA methylation in cells within 2-days of treatment with GSK-3484862 C_LIO_LIGSK-3484862-induced DNMT1 degradation is proteasome-dependent C_LIO_LIIn mESCs, Uhrf1 is required for GSK-3484862 to induce Dnmt1 degradation C_LI

cancer biology↗

bioRxiv2022

Commercial ChIP-Seq library preparation kits performed differently for different classes of protein targets

BackgroundChIP-Seq is a powerful method commonly used to study global protein-DNA interactions including both transcription factors and histone modifications. We have found that the choice of ChIP-Seq library preparation protocol plays an important role in overall ChIP-Seq data quality. However, very few studies have compared ChIP-Seq libraries prepared by different protocols using multiple targets and a broad range of input DNA levels. ResultsIn this study, we evaluated the performance of four ChIP-Seq library preparation protocols [NEB NEBNext Ultra II, Roche KAPA HyperPrep, Diagenode MicroPlex, and Bioo (now PerkinElmer) NEXTflex] on three target proteins, chosen to represent the three typical signal enrichment patterns in ChIP-Seq experiments: sharp peaks (H3K4me3), broad domains (H3K27me3) and punctate peaks with a protein binding motif (CTCF). We also tested a broad range of different input DNA levels from 0.10 to 10 ng for H3K4me3 and H3K27me3 experiments. ConclusionsOur results suggest that the NEB protocol may be better for preparing H3K4me3 (and potentially other histone modifications with sharp peak enrichment) libraries; the Bioo protocol may be better for preparing H3K27me3 (and potentially other histone modifications with broad domain enrichment) libraries, and the Diagenode protocol may be better for preparing CTCF (and potentially other transcription factors with well-defined binding motifs) libraries. For ChIP-Seq experiments using novel targets without a known signal enrichment pattern, the NEB protocol might be the best choice as it performed well for each of the three targets we tested across a wide array of input DNA levels.

bioinformatics↗