14 research outputs found
The role of phosphodiesterase 12 (PDE12) as a negative regulator of the innate immune response and the discovery of antiviral inhibitors
2',5'-Oligoadenylate synthetase (OAS) enzymes and RNase-L constitute a major effector arm of interferon (IFN)-mediated antiviral defense. OAS produces a unique oligonucleotide second messenger, 2',5'-oligoadenylate (2-5A), that binds and activates RNase-L. This pathway is down-regulated by virus- and host-encoded enzymes that degrade 2-5A. Phosphodiesterase 12 (PDE12) was the first cellular 2-5A- degrading enzyme to be purified and described at a molecular level. Inhibition of PDE12 may up-regulate the OAS/RNase-L pathway in response to viral infection resulting in increased resistance to a variety of viral pathogens. We generated a PDE12-null cell line, HeLaΔPDE12, using transcription activator-like effector nuclease-mediated gene inactivation. This cell line has increased 2-5A levels in response to IFN and poly(I-C), a double-stranded RNA mimic compared with the parental cell line. Moreover, HeLaΔPDE12 cells were resistant to viral pathogens, including encephalomyocarditis virus, human rhinovirus, and respiratory syncytial virus. Based on these results, we used DNA-encoded chemical library screening to identify starting points for inhibitor lead optimization. Compounds derived from this effort raise 2-5A levels and exhibit antiviral activity comparable with the effects observed with PDE12 gene inactivation. The crystal structure of PDE12 complexed with an inhibitor was solved providing insights into the structure-activity relationships of inhibitor potency and selectivity
Georgia marble at the Minnesota State Capitol The Effects of Mineralogy and Climate on Durability
Based on visual observations and tests made
of Georgia marble units that have been in service at the
historic Minnesota State Capitol for 110 years, a fielddiscernible
correlation exists between marble unit mineralogical
composition and unit weathering performance.
Field studies noted over the course of a five-year restoration
project of the capitol exterior were used to categorize
the original marble cladding into four perceptible types,
which were evaluated by field testing that suggested a
correlation between the textural and mineralogical differences
within the marble and its long-term durability.
To test this theory, field-issued repair assignments made
during an exterior marble restoration project at the capitol
were examined statistically. The nature and frequency
of assigned repairs were compared to the type of marble
from which they were originally fabricated to determine
whether a correlation existed. The results of this comparison
provided convincing statistical verification of the link
between mineralogy and durability. This hypothesis was
then verified through detailed petrographic analysis in a
laboratory setting, which determined that marble consisting
of a smaller, more interlocked grain configuration that
was more dolomitic than calcitic in its basic chemistry consistently
proved to be more durable in weathering performance
over time. The paper describes the process followed
by the authors to categorize and study the distinct varieties
of Georgia marble present on the Minnesota State Capitol,
and how this information was used to guide the restoration
process with the intent of maximizing the anticipated
service life of new marble replacements
Efficient Protiodesilylation of Unactivated C(sp3)-SiMe2Ph Bonds Using Tetrabutylammonium Fluoride
Discovery of Selective Small Molecule Type III Phosphatidylinositol 4‑Kinase Alpha (PI4KIIIα) Inhibitors as Anti Hepatitis C (HCV) Agents
Hepatitis C virus (HCV) assembles
many host cellular proteins into
unique membranous replication structures as a prerequisite for viral
replication, and PI4KIIIα is an essential component of these
replication organelles. RNA interference of PI4KIIIα results
in a breakdown of this replication complex and cessation of HCV replication
in Huh-7 cells. PI4KIIIα is a lipid kinase that interacts with
the HCV nonstructural 5A protein (NS5A) and enriches the HCV replication
complex with its product, phosphoinositol 4-phosphate (PI4P). Elevated
levels of PI4P at the endoplasmic reticulum have been linked to HCV
infection in the liver of HCV infected patients. We investigated if small molecule inhibitors of PI4KIIIα
could inhibit HCV replication in vitro. The synthesis and structure–activity
relationships associated with the biological inhibition of PI4KIIIα
and HCV replication are described. These efforts led directly to identification
of quinazolinone <b>28</b> that displays high selectivity for
PI4KIIIα and potently inhibits HCV replication in vitro
Imidazo[1,2-<i>a</i>]pyridines That Directly Interact with Hepatitis C NS4B: Initial Preclinical Characterization
A series of imidazo[1,2-<i>a</i>]pyridines
which directly
bind to HCV Non-Structural Protein 4B (NS4B) is described. This series
demonstrates potent <i>in vitro</i> inhibition of HCV replication
(EC<sub>50</sub> < 10 nM), direct binding to purified NS4B protein
(IC<sub>50</sub> < 20 nM), and an HCV resistance pattern associated
with NS4B (H94N/R, V105L/M, F98L) that are unique among reported HCV
clinical assets, suggestive of the potential for additive or synergistic
combination with other small molecule inhibitors of HCV replication
Discovery of a Potent Boronic Acid Derived Inhibitor of the HCV RNA-Dependent RNA Polymerase
Novel Modes of Inhibition of Wild-Type Isocitrate Dehydrogenase 1 (IDH1): Direct Covalent Modification of His315
IDH1 plays a critical
role in a number of metabolic processes and
serves as a key source of cytosolic NADPH under conditions of cellular
stress. However, few inhibitors of wild-type IDH1 have been reported.
Here we present the discovery and biochemical characterization of
two novel inhibitors of wild-type IDH1. In addition, we present the
first ligand-bound crystallographic characterization of these novel
small molecule IDH1 binding pockets. Importantly, the NADPH competitive
α,β-unsaturated enone <b>1</b> makes a unique covalent
linkage through active site H315. As few small molecules have been
shown to covalently react with histidine residues, these data support
the potential utility of an underutilized strategy for reversible
covalent small molecule design
Novel Modes of Inhibition of Wild-Type Isocitrate Dehydrogenase 1 (IDH1): Direct Covalent Modification of His315
IDH1 plays a critical
role in a number of metabolic processes and
serves as a key source of cytosolic NADPH under conditions of cellular
stress. However, few inhibitors of wild-type IDH1 have been reported.
Here we present the discovery and biochemical characterization of
two novel inhibitors of wild-type IDH1. In addition, we present the
first ligand-bound crystallographic characterization of these novel
small molecule IDH1 binding pockets. Importantly, the NADPH competitive
α,β-unsaturated enone <b>1</b> makes a unique covalent
linkage through active site H315. As few small molecules have been
shown to covalently react with histidine residues, these data support
the potential utility of an underutilized strategy for reversible
covalent small molecule design