Biology subjects

Al-Awar, R.

Publications and source records attributed to Al-Awar, R..

5 recordsLinked to original sources

bioRxiv2024

Targeting synthetic lethality between non-homologous end joining and radiation in very high-risk SHH medulloblastoma

Specific and biologically informed treatments for medulloblastoma, especially the highly lethal TP53 mutant SHH subgroup, remain elusive, where radiotherapy is the primary treatment option. Applying genome-wide CRISPR-Cas9 screening in combination with lethal doses of radiotherapy, we identified the main driver of radiation resistance in SHH medulloblastoma is loss of p53. A negative selection CRISPR-Cas9 screen across multiple models of Trp53-deficient SHH medulloblastoma revealed a strong synthetic lethal interaction between components of the non-homologous end-joining pathway and radiation, particularly DNA protein kinase (DNA-PK) and its binding partners. Both genetic and pharmacological perturbation of DNA-PK enhanced radiosensitivity in TP53-deficient SHH medulloblastoma, leading to cell death. In vivo treatment of somatic and germline TP53-mutant SHH medulloblastoma models with peposertib, a small-molecule inhibitor of DNA-PK, significantly improved survival when combined with radiotherapy, strongly supporting further clinical investigation.

cancer biology↗

bioRxiv2021

Structure Activity Relationship of USP5 Allosteric Inhibitors

USP5 is a deubiquitinase that has been implicated in a range of diseases, including cancer, but no USP5-targeting chemical probe has been reported to date. Here, we present the progression of a chemical series that occupies the C-terminal ubiquitin-binding site of a poorly characterized zinc-finger ubiquitin binding domain (ZnF-UBD) of USP5 and allosterically inhibits the catalytic activity of the enzyme. Systematic exploration of the structure-activity relationship, complemented with crystallographic characterization of the ZnF-UBD bound to multiple ligands, led to the identification of 64, which binds to the USP5 ZnF-UBD with a KD of 2.8 {micro}M. 64 is selective over the structurally similar ZnF-UBD domain of HDAC6 and inhibits USP5 catalytic activity in vitro with an IC50 of 26 {micro}M. This study provides a chemical and structural framework for the discovery of a chemical probe to delineate USP5 function in cells. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/444542v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@3fc7bcorg.highwire.dtl.DTLVardef@15233e0org.highwire.dtl.DTLVardef@1cbf34corg.highwire.dtl.DTLVardef@d237d0_HPS_FORMAT_FIGEXP M_FIG Table of Contents Graphic C_FIG

biochemistry↗

bioRxiv2020

A First-in-class, Highly Selective and Cell-active AllostericInhibitor of Protein Arginine Methyltransferase 6 (PRMT6)

PRMT6 catalyzes monomethylation and asymmetric dimethylation of arginine residues in various proteins, plays important roles in biological processes and is associated with multiple cancers. While there are several reported PRMT6 inhibitors, a highly selective PRMT6 inhibitor has not been reported to date. Furthermore, allosteric inhibitors of protein methyltransferases are rare. Here we report the discovery and characterization of a first-in-class, highly selective allosteric inhibitor of PRMT6, SGC6870. SGC6870 is a potent PRMT6 inhibitor (IC50 = 77 {+/-} 6 nM) with outstanding selectivity for PRMT6 over a broad panel of other methyltransferases and non-epigenetic targets. Notably, the crystal structure of the PRMT6-SGC6870 complex and kinetic studies revealed SGC6870 binds a unique, induced allosteric pocket. Additionally, SGC6870 engages PRMT6 and potently inhibits its methyltransferase activity in cells. Moreover, SGC6870s enantiomer, SGC6870N, is inactive against PRMT6 and can be utilized as a negative control. Collectively, SGC6870 is a well-characterized PRMT6 chemical probe and valuable tool for further investigating PRMT6 functions in health and disease.

biochemistry↗

bioRxiv2020

Discovery of Small-Molecule Antagonists of the PWWP Domain of NSD2

Increased activity of the lysine methyltrans-ferase NSD2 driven by translocation and activating mutations is associated with multiple myeloma and acute lymphoblastic leukemia, but no NSD2-targeting chemical probe has been reported to date. Here, we present the first antagonists that block the protein-protein interaction between the N-terminal PWWP domain of NSD2 and H3K36me2. Using virtual screening and experimental validation, we identified the small-molecule antagonist 3f, which binds to the NSD2-PWWP1 domain with a Kd of 3.4 M and abrogates histone H3K36me2 binding in cells. This study establishes an alternative approach to targeting NSD2 and provides a small-molecule antagonist that can be further optimized into a chemical probe to better understand the cellular function of this protein.

pharmacology and toxicology↗

bioRxiv2018

Pharmacological inhibition of PRMT7 links arginine monomethylation to the cellular stress response

Protein arginine methyltransferases (PRMTs) regulate diverse biological processes and are increasingly being recognized for their potential as drug targets. Here we report the discovery of a potent, selective and cell active chemical probe for PRMT7. SGC3027 is a cell permeable prodrug, which in cells, is converted to SGC8158, a potent, SAM-competitive PRMT7 inhibitor. Inhibition or knockout of cellular PRMT7 resulted in drastically reduced levels of arginine monomethylation of HSP70 family members and other stress-associated proteins. Structural and biochemical analysis revealed that PRMT7-driven in vitro methylation of HSP70 at R469 requires an ATP-bound, open conformation of HSP70. In cells, SGC3027 inhibited methylation of both constitutive and inducible forms of HSP70, and led to decreased tolerance for perturbations of proteostasis including heat shock and proteasome inhibitors. These results demonstrate a role for PRMT7 and arginine methylation in stress response.

biochemistry↗