Lysine-specific demethylase 1 (LSD1/KDM1) demethylates histone H3, in addition to tumor suppressor p53 and DNA methyltransferase 1 (Dnmt1), thus regulating eukaryotic gene expression by altering chromatin structure. Specific inhibitors of LSD1 are desired as anticancer agents, because LSD1 aberrations are associated with several cancers, and LSD1 inhibition restores the expression of abnormally silenced genes in cancerous cells. In this study, we designed and synthesized several candidate compounds to inhibit LSD1, based on the structures of LSD1 and monoamine oxidase B (MAO-B), in complex with an antidepressant tranylcypromine (2-PCPA) derivative. Compound S2101 exhibited stronger LSD1 inhibition than tranylcypromine and the known small LSD1 inhibitors in LSD1 demethylation assays, with a k(inact)/K(I) value of 4560 M(-1) s(-1). In comparison with tranylcypromine, the compound displayed weaker inhibition to the monoamine oxidases. The inhibition modes of the two 2-PCPA derivatives, 2-PFPA and S1201, were identified by determination of the inhibitor-bound LSD1 structures, which revealed the enhanced stability of the inhibitor-FAD adducts by their interactions with the surrounding LSD1 residues. These molecules are potential pharmaceutical candidates for cancer or latent virus infection, as well as research tools for LSD1-related biological investigations.
OH stretching vibrations of hydrogen-bonded cluster ions of phenol
(PhOH),
[PhOH−(H2O)
n
]+
(n = 1−4),
(PhOH)2
+, and
(PhOH−methanol)+ have been observed with infrared
photodissociation spectroscopy in
combination with an ion-trapping technique. Cluster ions were
efficiently generated by ionization of phenol
followed by a jet expansion and were mass-selectively stored by the
radio frequency ion trap method, which
allows us to observe infrared multiphoton dissociation yield spectra of
size-selected cluster ions. For [PhOH−(H2O)
n
]+, the OH
stretching vibrations of the water moieties strongly suggested that the
n ≥ 3 cluster ions
exhibit the proton-transferred form,
[PhO−H3O+(H2O)
n
-
1],
while the n = 1 and 2 ions are of the
nontransferred
form,
[PhOH+−(H2O)
n
].
As for (PhOH)2
+, the infrared spectra
indicate that the dimer ion is characterized
as the open form, in which the phenol ion acts as a proton donor and
the neutral phenol as an acceptor
through their single hydrogen bond. The similar open form is also
found for (PhOH−methanol)+, in which
the phenol ion acts as a proton donor.
The canonical WNT pathway plays an
important role in cancer pathogenesis.
Inhibition of poly(ADP-ribose) polymerase catalytic activity of the
tankyrases (TNKS/TNKS2) has been reported to reduce the Wnt/β-catenin
signal by preventing poly ADP-ribosylation-dependent degradation of
AXIN, a negative regulator of Wnt/β-catenin signaling. With
the goal of investigating the effects of tankyrase and Wnt pathway
inhibition on tumor growth, we set out to find small-molecule inhibitors
of TNKS/TNKS2 with suitable drug-like properties. Starting from 1a, a high-throughput screening hit, the spiroindoline derivative 40c (RK-287107) was discovered as a potent TNKS/TNKS2 inhibitor
with >7000-fold selectivity against the PARP1 enzyme, which inhibits
WNT-responsive TCF reporter activity and proliferation of human colorectal
cancer cell line COLO-320DM. RK-287107 also demonstrated dose-dependent
tumor growth inhibition in a mouse xenograft model. These observations
suggest that RK-287107 is a promising lead compound for the development
of novel tankyrase inhibitors as anticancer agents.
The benzophenone photophore is widely used to photo-cross-link macromolecules. Recent developments in genetic code expansion have allowed the biosynthesis of proteins with p-benzoyl-L-phenylalanine (pBpa) at defined sites, for covalent bonding with interacting proteins. However, the structure of a photo-cross-linked protein complex had not been revealed, and thus neither the actual structure of the "photobridge" in a complex nor the influence of this covalent bridge on the overall complex structure was known. In this study, we determine the crystal structure of the cross-linked complex of the liver oncoprotein gankyrin and the C-terminal domain of S6 proteasomal protein (S6C), at 2.05 Å resolution. First, the photoreactive amino acid was separately incorporated into gankyrin at 16 sites on the protein surface, and two variants that efficiently formed a covalent bond with S6C were found. The yield of one of the cross-linked products, with pBpa in place of Arg85 in gankyrin, was maximized for crystallization via optimization of the duration of complex exposure to 365 nm light. The structure revealed that the carbonyl group of the benzophenone of pBpa85 formed a covalent bond exclusively with the Cγ atom of Glu356 in S6C, showing the high selectivity of formation of cross-links by pBpa. In addition, the cross-linked structure exhibited little structural distortion from the native complex structure. Our results demonstrated that cross-linking with site-specifically incorporated pBpa preserves the native binding mode and is useful for probing protein-protein interactions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.