6 research outputs found
Self-Assembled Porphyrin Nanodiscs with Structure-Dependent Activation for Phototherapy and Photodiagnostic Applications
The abilities to deliver and subsequently activate a therapeutic at the intended site of action are two important challenges in the synthesis of novel nanoparticles. Poor tumor permeability as a result of a dense microenvironment can impede the delivery of nanoparticles to the site of action. The design of a sub-40 nm activatable porphyrin nanodisc, based on protein-induced lipid constriction, is described. The biophotonic nanoparticle, self-assembled from aggregated porphyrin–lipid, is stabilized by an amphipathic alpha helical protein and becomes photoactive when its structure is perturbed. Enzymatic cleavage of the constricting protein leads to conversion of the particle from a disc- to a vesicle-shaped structure and provides further evidence that the apolipoprotein serves a functional role on the nanodisc. Fluorescence measurements of these nanodiscs in a detergent show that fluorescence is over 99% quenched in the intact state with a 12-fold increase in singlet oxygen generation upon disruption. Cellular fluorescence unquenching and dose-dependent phototoxicity demonstrate that these nanodiscs can be internalized and unquenched intracellularly. Finally, nanodiscs were found to display a 5-fold increase in diffusion coefficient when compared with the protein-free control ((3.5 ± 0.1) × 10<sup>–7</sup> <i>vs</i> (0.7 ± 0.03) × 10<sup>–7</sup> cm<sup>2</sup> s<sup>–1</sup>). The ability to incorporate large amounts of photosensitizer drugs into its compact structure allows for phototherapeutic action, fluorescence diagnostic applications, and the potential to effectively deliver photosensitizers deep into poorly permeable tumors
Sinefungin Derivatives as Inhibitors and Structure Probes of Protein Lysine Methyltransferase SETD2
Epigenetic regulation is involved in numerous physiological
and
pathogenic processes. Among the key regulators that orchestrate epigenetic
signaling are over 50 human protein lysine methyltransferases (PKMTs).
Interrogation of the functions of individual PKMTs can be facilitated
by target-specific PKMT inhibitors. Given the emerging need for such
small molecules, we envisioned an approach to identify target-specific
methyltransferase inhibitors by screening privileged small-molecule
scaffolds against diverse methyltransferases. In this work, we demonstrated
the feasibility of such an approach by identifying the inhibitors
of SETD2. <i>N</i>-propyl sinefungin (Pr-SNF) was shown
to interact preferentially with SETD2 by matching the distinct transition-state
features of SETD2’s catalytically active conformer. With Pr-SNF
as a structure probe, we further revealed the dual roles of SETD2’s
post-SET loop in regulating substrate access through a distinct topological
reconfiguration. Privileged sinefungin scaffolds are expected to have
broad use as structure and chemical probes of methyltransferases
Structure-Based Optimization of a Small Molecule Antagonist of the Interaction Between WD Repeat-Containing Protein 5 (WDR5) and Mixed-Lineage Leukemia 1 (MLL1)
WD
repeat-containing protein 5 (WDR5) is an important component
of the multiprotein complex essential for activating mixed-lineage
leukemia 1 (MLL1). Rearrangement of the MLL1 gene is associated with
onset and progression of acute myeloid and lymphoblastic leukemias,
and targeting the WDR5-MLL1 interaction may result in new cancer therapeutics.
Our previous work showed that binding of small molecule ligands to
WDR5 can modulate its interaction with MLL1, suppressing MLL1 methyltransferase
activity. Initial structure–activity relationship studies identified <i>N</i>-(2-(4-methylpiperazin-1-yl)-5-substituted-phenyl) benzamides
as potent and selective antagonists of this protein–protein
interaction. Guided by crystal structure data and supported by in
silico library design, we optimized the scaffold by varying the C-1
benzamide and C-5 substituents. This allowed us to develop the first
highly potent (<i>K</i><sub>disp</sub> < 100 nM) small
molecule antagonists of the WDR5-MLL1 interaction and demonstrate
that <i>N</i>-(4-(4-methylpiperazin-1-yl)-3′-(morpholinomethyl)-[1,1′-biphenyl]-3-yl)-6-oxo-4-(trifluoromethyl)-1,6-dihydropyridine-3-carboxamide <b>16d</b> (OICR-9429) is a potent and selective chemical probe suitable
to help dissect the biological role of WDR5
Synthesis, Optimization, and Evaluation of Novel Small Molecules as Antagonists of WDR5‑MLL Interaction
The WD40-repeat protein WDR5 plays a critical role in
maintaining
the integrity of MLL complexes and fully activating their methyltransferase
function. MLL complexes, the trithorax-like family of SET1 methyltransferases,
catalyze trimethylation of lysine 4 on histone 3, and they have been
widely implicated in various cancers. Antagonism of WDR5 and MLL subunit
interaction by small molecules has recently been presented as a practical
way to inhibit activity of the MLL1 complex, and <i>N</i>-(2-(4-methylpiperazin-1-yl)-5-substituted-phenyl) benzamides were
reported as potent and selective antagonists of such an interaction.
Here, we describe the protein crystal structure guided optimization
of prototypic compound <b>2</b> (<i>K</i><sub>dis</sub> = 7 μM), leading to identification of more potent antagonist <b>47</b> (<i>K</i><sub>dis</sub> = 0.3 μM)
Structure-Based Optimization of a Small Molecule Antagonist of the Interaction Between WD Repeat-Containing Protein 5 (WDR5) and Mixed-Lineage Leukemia 1 (MLL1)
WD
repeat-containing protein 5 (WDR5) is an important component
of the multiprotein complex essential for activating mixed-lineage
leukemia 1 (MLL1). Rearrangement of the MLL1 gene is associated with
onset and progression of acute myeloid and lymphoblastic leukemias,
and targeting the WDR5-MLL1 interaction may result in new cancer therapeutics.
Our previous work showed that binding of small molecule ligands to
WDR5 can modulate its interaction with MLL1, suppressing MLL1 methyltransferase
activity. Initial structure–activity relationship studies identified <i>N</i>-(2-(4-methylpiperazin-1-yl)-5-substituted-phenyl) benzamides
as potent and selective antagonists of this protein–protein
interaction. Guided by crystal structure data and supported by in
silico library design, we optimized the scaffold by varying the C-1
benzamide and C-5 substituents. This allowed us to develop the first
highly potent (<i>K</i><sub>disp</sub> < 100 nM) small
molecule antagonists of the WDR5-MLL1 interaction and demonstrate
that <i>N</i>-(4-(4-methylpiperazin-1-yl)-3′-(morpholinomethyl)-[1,1′-biphenyl]-3-yl)-6-oxo-4-(trifluoromethyl)-1,6-dihydropyridine-3-carboxamide <b>16d</b> (OICR-9429) is a potent and selective chemical probe suitable
to help dissect the biological role of WDR5
DS_DISC766278 – Supplemental material for Discovery of Small-Molecule Antagonists of the H3K9me3 Binding to UHRF1 Tandem Tudor Domain
<p>Supplemental material, DS_DISC766278 for Discovery of Small-Molecule Antagonists of the H3K9me3 Binding to UHRF1 Tandem Tudor Domain by Guillermo Senisterra, Hugh Y. Zhu, Xiao Luo, Hailong Zhang, Guoliang Xun, Chunliang Lu, Wen Xiao, Taraneh Hajian, Peter Loppnau, Irene Chau, Fengling Li, Abdellah Allali-Hassani, Peter Atadja, Counde Oyang, En Li, Peter J. Brown, Cheryl H. Arrowsmith, Kehao Zhao, Zhengtian Yu, and Masoud Vedadi in SLAS Discovery</p