Pearce, K. | Search bioRxiv

bioRxiv2019

Degradation of Polycomb Repressive Complex 2 with an EED-targeted Bivalent Chemical Degrader

Protein degradation via the use of bivalent chemical degraders provides an alternative strategy to block protein function and assess the biological roles of putative drug targets. This approach capitalizes on the advantages of small molecule inhibitors while moving beyond the restrictions of traditional pharmacology. Herein we report a first-in-class chemical degrader (UNC6852) that targets Polycomb Repressive Complex 2 (PRC2). UNC6852 contains an EED226 derived ligand and a ligand for VHL which bind to the WD40 aromatic cage of EED and CRL2VHL, respectively, to induce proteasomal degradation of PRC2 components, EED, EZH2, and SUZ12. Degradation of PRC2 with UNC6852 blocks the histone methyltransferase activity of EZH2, decreasing H3K27me3 levels in HeLa cells and diffuse large B-cell lymphoma (DLBCL) cells containing an EZH2Y641N gain-of-function mutation. UNC6852 degrades both wild type EZH2 and EZH2Y641N, and additionally displays anti-proliferative effects in this cancer model system.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC=\"FIGDIR/small/676965v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (34K):\norg.highwire.dtl.DTLVardef@5b8f01org.highwire.dtl.DTLVardef@1098ff7org.highwire.dtl.DTLVardef@caa1a9org.highwire.dtl.DTLVardef@13b6bfc_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2019

DECODING THE MECHANOCHEMISTRY OF NEURITE PLASTICITY

The formation and disruption of synaptic connections during development is a fundamental step in neural circuit formation. Subneuronal structures such as neurites are known to be sensitive to the level of spontaneous neuronal activity but the specifics of how neurotransmitter-induced calcium activity regulates neurite homeostasis are not yet fully understood. In response to stimulation by neurotransmitters such as acetylcholine, calcium responses in cells are mediated the Gq/phospholipase C{beta} (PLC{beta})/ phosphatidylinositol 4,5 bisphosphate (PI(4, 5)P2) signaling pathway. Here, we show that prolonged Gq stimulation results in the retraction of neurites in PC12 cells and rupture of neuronal synapses by modulating membrane tension. To understand the underlying cause, we dissected the behavior of individual components of the Gq/PLC{beta}/PI(4, 5)P2 pathway during retraction, and correlated these to the retraction of the membrane and cytoskeletal elements impacted by calcium signaling. We developed a mathematical model that combines biochemical signaling with membrane tension and cytoskeletal mechanics, to show how signaling events are coupled to retraction velocity, membrane tension and actin dynamics. The coupling between calcium and neurite retraction is shown to be operative in the C. elegans nervous system. This study uncovers a novel mechanochemical connection between the Gq/PLC{beta}/(PI(4, 5)P2 pathway that couples calcium responses with neural plasticity.

biophysics↗