Chikungunya virus (CHIKV) nonstructural protein 1 (nsP1) harbors the methyltransferase (MTase) and guanylyltransferase (GTase) activities needed for viral RNA capping and represents a promising... Show moreChikungunya virus (CHIKV) nonstructural protein 1 (nsP1) harbors the methyltransferase (MTase) and guanylyltransferase (GTase) activities needed for viral RNA capping and represents a promising antiviral drug target. We compared the antiviral efficacies of nsP1 inhibitors belonging to the MADTP, CHVB, and FHNA series (6'-fluoro-homoneplanocin A [FHNA], its 3'-keto form, and 6'-beta-fluoro-homoaristeromycin). Cell-based phenotypic cross-resistance assays revealed that the CHVB and MADTP series had similar modes of action that differed from that of the FHNA series. In biochemical assays with purified Semliki Forest virus and CHIKV nsP1, CHVB compounds strongly inhibited MTase and GTase activities, while MADTP-372 had a moderate inhibitory effect. FHNA did not directly inhibit the enzymatic activity of CHIKV nsP1. The first-of-their-kind molecular-docking studies with the cryo-electron microscopy (cryo-EM) structure of CHIKV nsP1, which is assembled into a dodecameric ring, revealed that the MADTP and CHVB series bind at the S-adenosylmethionine (SAM)-binding site in the capping domain, where they would function as competitive or noncompetitive inhibitors. The FHNA series was predicted to bind at the secondary binding pocket in the ring-aperture membrane-binding and oligomerization (RAMBO) domain, potentially interfering with the membrane binding and oligomerization of nsP1. Our cell-based and enzymatic assays, in combination with molecular docking and mapping of compound resistance mutations to the nsP1 structure, allowed us to group nsP1 inhibitors into functionally distinct classes. This study identified druggable pockets in the nsP1 dodecameric structure and provides a basis for the rational design, optimization, and combination of inhibitors of this unique and promising antiviral drug target. Show less
The ubiquitylation machinery regulates several fundamental biological processes from protein homeostasis to a wide variety of cellular signaling pathways. As a consequence, its dysregulation is... Show moreThe ubiquitylation machinery regulates several fundamental biological processes from protein homeostasis to a wide variety of cellular signaling pathways. As a consequence, its dysregulation is linked to diseases including cancer, neurodegeneration, and autoimmunity. With this review, we aim to highlight the therapeutic potential of targeting E3 ligases, with a special focus on an emerging class of RING ligases, named tri-partite motif (TRIM) proteins, whose role as targets for drug development is currently gaining pharmaceutical attention. TRIM proteins exert their catalytic activity as scaffolds involved in many protein-protein interactions, whose multidomains and adapter-like nature make their druggability very challenging. Herein, we give an overview of the current understanding of this class of single polypeptide RING E3 ligases and discuss potential targeting options. Show less
Madern, J.M.; Kim, R.Q.; Misra, M.; Dikic, I.; Zhang, Y.; Ovaa, H.; ... ; Noort, G.J.V. van 2020
Stable NAD(+)analogues carrying single atom substitutions in either the furanose ring or the nicotinamide part have proven their value as inhibitors for NAD(+)-consuming enzymes. To investigate the... Show moreStable NAD(+)analogues carrying single atom substitutions in either the furanose ring or the nicotinamide part have proven their value as inhibitors for NAD(+)-consuming enzymes. To investigate the potential of such compounds to inhibit the adenosine diphosphate ribosyl (ADPr) transferase activity of the Legionella SdeC enzyme, we prepared three NAD(+)analogues, namely carbanicotinamide adenosine dinucleotide (c-NAD(+)), thionicotinamide adenosine dinucleotide (S-NAD(+)) and benzamide adenosine dinucleotide (BAD). We optimized the chemical synthesis of thionicotinamide riboside and for the first time used an enzymatic approach to convert all three ribosides into the corresponding NAD(+)mimics. We thus expanded the known scope of substrates for the NRK1/NMNAT1 enzyme combination by turning all three modified ribosides into NAD(+)analogues in a scalable manner. We then compared the three NAD(+)mimics side-by-side in a single assay for enzyme inhibition on Legionella effector enzyme SdeC. The class of SidE enzymes to which SdeC belongs was recently identified to be important in bacterial virulence, and we found SdeC to be inhibited by S-NAD(+)and BAD with IC(50)values of 28 and 39 mu M, respectively. Show less
Objectives: In hemophilia A the presence of non-neutralizing antibodies (NNAs) against Factor VIII (FVIII) may predict the development of neutralizing antibodies (inhibitors) and accelerate the... Show moreObjectives: In hemophilia A the presence of non-neutralizing antibodies (NNAs) against Factor VIII (FVIII) may predict the development of neutralizing antibodies (inhibitors) and accelerate the clearance of administrated FVIII concentrates. This systematic review aimed to assess: (1) the prevalence and incidence of NNAs in patients with congenital hemophilia without inhibitors and (2) the association between NNAs and patient and treatment characteristics.Methods: We conducted a search in MEDLINE, Embase, Web of Science and the Cochrane database. We included cross-sectional and longitudinal studies reporting on NNAs in patients with hemophilia A and B, who were inhibitor-negative at the start of the observation period. Data were extracted on: hemophilia type and severity, patient and treatment characteristics, NNA prevalence and incidence, NNA assays and inhibitor development. Two independent reviewers performed study selection, data extraction and risk of bias assessment, using adapted criteria of the Joanna Briggs Institute. Studies were classified as high-quality when >= 5/9 criteria were met. NNA assays were classified as high-quality when both quality criteria were met: (1) use of positive controls and (2) competition with FVIII to establish FVIII-specificity. We reported NNA prevalence and incidence for each study. The pooled NNA prevalence was assessed for well-designed studies in previously treated patients, employing high-quality NNA assays.Results: We included data from 2,723 inhibitor-negative patients with hemophilia A, derived from 28 studies. Most studies were cross-sectional (19/28) and none reported on NNAs in hemophilia B. Study design was of high quality in 16/28 studies and the NNA assay quality was high in 9/28 studies. Various NNA assays were used, predominantly ELISA (18/28) with different cut-off values. We found a large variety in NNA prevalence (Range, 0-100%). The pooled NNA prevalence in high-quality studies was 25% (95% CI, 16-38%). The incidence of new NNA development was reported in one study (0.01 NNA per person-exposure day).Conclusion: This systematic review identified studies that were heterogeneous in study design, patient population and NNA assay type, with NNA prevalence ranging from 0 to 100% in inhibitor-negative patients with hemophilia A. The pooled NNA prevalence was 25% in high-quality studies including only previously treated patients and performing high-quality NNA assays. Show less
Oranje, P.; Gouka, R.; Burggraaff, L.; Vermeer, M.; Chalet, C.; Duchateau, G.; ... ; Westen, G.J.P. van 2019
Selective analogs of the natural glycoside phloridzin are marketed drugs that reducehyperglycemia in diabetes by inhibiting the active sodium glucose cotransporterSGLT2 in the kidneys. In addition,... Show moreSelective analogs of the natural glycoside phloridzin are marketed drugs that reducehyperglycemia in diabetes by inhibiting the active sodium glucose cotransporterSGLT2 in the kidneys. In addition, intestinal SGLT1 is now recognized as atarget for glycemic control. To expand available type 2 diabetes remedies, weaimed to find novel SGLT1 inhibitors beyond the chemical space of glycosides. Wescreened a bioactive compound library for SGLT1 inhibitors and tested primary hitsand additional structurally similar molecules on SGLT1 and SGLT2 (SGLT1/2). NovelSGLT1/2 inhibitors were discovered in separate chemical clusters of natural and syntheticcompounds. These have IC50‐values in the 10‐100 μmol/L range. The mostpotent identified novel inhibitors from different chemical clusters are (SGLT1‐IC50Mean ± SD, SGLT2‐IC50 Mean ± SD): (+)‐pteryxin (12 ± 2 μmol/L, 9 ± 4 μmol/L), (+)‐ε‐viniferin (58 ± 18 μmol/L, 110 μmol/L), quinidine (62 μmol/L, 56 μmol/L), cloperastine(9 ± 3 μmol/L, 9 ± 7 μmol/L), bepridil (10 ± 5 μmol/L, 14 ± 12 μmol/L), trihexyphenidyl(12 ± 1 μmol/L, 20 ± 13 μmol/L) and bupivacaine (23 ± 14 μmol/L, 43 ± 29 μmol/L).The discovered natural inhibitors may be further investigated as new potential (prophylactic)agents for controlling dietary glucose uptake. The new diverse structureactivity data can provide a starting point for the optimization of novel SGLT1/2 inhibitorsand support the development of virtual SGLT1/2 inhibitor screening models. Show less
