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1.
Proc Natl Acad Sci U S A ; 117(12): 6521-6530, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32156734

RESUMO

Necroptosis is a regulated necrotic cell death pathway involved in development and disease. Its signaling cascade results in the formation of disulfide bond-dependent amyloid-like polymers of mixed lineage kinase domain-like protein (MLKL), which mediate proinflammatory cell membrane disruption. We screened compound libraries provided by the National Cancer Institute and identified a small-molecule inhibitor of necroptosis named necroptosis-blocking compound 1 (NBC1). Biotin-labeled NBC1 specifically conjugates to heat shock protein Hsp70. NBC1 and PES-Cl, a known Hsp70 substrate-binding inhibitor, block the formation of MLKL polymers, but not MLKL tetramers in necroptosis-induced cells. In vitro, recombinant Hsp70 interacts with the N-terminal domain (NTD) of MLKL and promotes NTD polymerization, which has been shown to mediate the cell killing activity. Furthermore, the substrate-binding domain (SBD) of Hsp70 is sufficient to promote MLKL polymerization. NBC1 covalently conjugates cysteine 574 and cysteine 603 of the SBD to block its function. In addition, an SBD mutant with both cysteines mutated to serines loses its ability to promote MLKL polymerization. Interestingly, knockdown of Hsp70 in cells leads to MLKL destabilization, suggesting that MLKL might also be a client protein of Hsp70. In summary, using NBC1, an inhibitor of necroptosis, we identified Hsp70 as a molecular chaperone performing dual functions in necroptosis. It stabilizes MLKL protein under normal condition and promotes MLKL polymerization through its substrate-binding domain during necroptosis.


Assuntos
Proteínas de Choque Térmico HSP70/antagonistas & inibidores , Proteínas de Choque Térmico HSP70/metabolismo , Necroptose/efeitos dos fármacos , Piperidinas/farmacologia , Proteínas Quinases/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP70/genética , Células HT29 , Humanos , Estrutura Molecular , Mutação , Piperidinas/química , Ligação Proteica , Domínios Proteicos , Proteínas Quinases/química , Proteínas Quinases/genética , Multimerização Proteica/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia
2.
J Biol Chem ; 294(16): 6273-6282, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30737280

RESUMO

The maintenance of adult animal tissues depends upon highly conserved intercellular signaling molecules that include the secreted WNT proteins. Although it is generally accepted that lipidation of WNTs by the acyltransferase Porcupine (PORCN) and their subsequent recognition by the Wntless (WLS) protein is essential for their cellular secretion, the molecular understanding of this process remains limited. Using structurally diverse fatty acyl donor analogs and mouse embryonic fibroblasts expressing PORCN protein from different metazoan phyla, we demonstrate here that PORCN active-site features, which are conserved across the animal kingdom, enforce cis-Δ9 fatty acylation of WNTs. Aberrant acylation of a WNT with an exogenously supplied trans-Δ9 fatty acid induced the accumulation of WNT-PORCN complexes, suggesting that the fatty acyl species is critical for the extrication of lipidated WNTs from PORCN. Our findings reveal a previously unrecognized fatty acyl-selective checkpoint in the manufacturing of a lipoprotein that forms a basis for WNT signaling sensitivity to trans fats and to PORCN inhibitors in clinical development.


Assuntos
Aciltransferases/metabolismo , Ácidos Graxos/metabolismo , Proteínas de Membrana/metabolismo , Processamento de Proteína Pós-Traducional , Via de Sinalização Wnt , Acilação , Aciltransferases/genética , Animais , Células COS , Caenorhabditis elegans , Galinhas , Chlorocebus aethiops , Ácidos Graxos/genética , Células HEK293 , Células HeLa , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Schistosoma mansoni , Xenopus
3.
Nat Chem Biol ; 13(5): 486-493, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28244987

RESUMO

The proteasome is a vital cellular machine that maintains protein homeostasis, which is of particular importance in multiple myeloma and possibly other cancers. Targeting of proteasome 20S peptidase activity with bortezomib and carfilzomib has been widely used to treat myeloma. However, not all patients respond to these compounds, and those who do eventually suffer relapse. Therefore, there is an urgent and unmet need to develop new drugs that target proteostasis through different mechanisms. We identified quinoline-8-thiol (8TQ) as a first-in-class inhibitor of the proteasome 19S subunit Rpn11. A derivative of 8TQ, capzimin, shows >5-fold selectivity for Rpn11 over the related JAMM proteases and >2 logs selectivity over several other metalloenzymes. Capzimin stabilized proteasome substrates, induced an unfolded protein response, and blocked proliferation of cancer cells, including those resistant to bortezomib. Proteomic analysis revealed that capzimin stabilized a subset of polyubiquitinated substrates. Identification of capzimin offers an alternative path to develop proteasome inhibitors for cancer therapy.


Assuntos
Inibidores de Proteassoma/farmacologia , Quinolinas/farmacologia , Transativadores/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/química , Quinolinas/química , Relação Estrutura-Atividade , Transativadores/metabolismo
4.
Proc Natl Acad Sci U S A ; 111(40): 14571-6, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25246581

RESUMO

African cactiform Hoodia gordonii (Asclepiadaceae) has been used for thousands of years by Xhomani Bushmen as an anorexant during hunting trips and has been proposed as a new agent for the management of body weight. However, its in vivo targets and molecular mechanisms remain elusive. GPR119, a G protein-coupled receptor highly expressed in pancreatic ß cells and intestinal L cells, has been demonstrated to facilitate glucose-stimulated insulin secretion (GSIS) and represents a novel and attractive target for the therapy of metabolic disorders. Here, we disclose that Gordonoside F (a steroid glycoside isolated from H. gordonii), but not the widely known P57, activates specifically GPR119. Successful synthesis of Gordonoside F facilitates further characterization of this compound. Gordonoside F promotes GSIS both in vitro and in vivo and reduces food intake in mice. These effects are mediated by GPR119 because GPR119 knockout prevents the therapeutic effects of Gordonoside F. Interestingly, the appetite-suppressing effect of Hoodia extract was also partially blocked by GPR119 knockout. Our results demonstrate for the first time, to our knowledge, that GPR119 is a direct target and one of the major mechanisms underlying the therapeutic effect of the popular "weight loss" herb H. gordonii. Given the long history of safe application of this herb in weight control, it is foreseeable that the novel scaffold of Gordonoside F provides a promising opportunity to develop new drugs in treating metabolic diseases.


Assuntos
Apocynaceae/química , Doenças Metabólicas/tratamento farmacológico , Extratos Vegetais/farmacologia , Receptores Acoplados a Proteínas G/metabolismo , Redução de Peso/efeitos dos fármacos , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Teste de Tolerância a Glucose , Glicosídeos/química , Glicosídeos/farmacologia , Células HEK293 , Humanos , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Masculino , Doenças Metabólicas/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estrutura Molecular , Terapia de Alvo Molecular/métodos , Fitoterapia/métodos , Extratos Vegetais/química , Plantas Medicinais/química , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/genética , Esteroides/química , Esteroides/farmacologia
5.
Angew Chem Int Ed Engl ; 55(15): 4763-6, 2016 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-27037993

RESUMO

Axinellamines A and B are broad-spectrum antibacterial pyrrole-imidazole alkaloids that have a complex polycyclic skeleton. A new asymmetric synthesis of these marine sponge metabolites is described herein, featuring an oxidative rearrangement and an anchimeric chlorination reaction.


Assuntos
Imidazóis/síntese química , Pirróis/síntese química , Isomerismo
6.
Tetrahedron ; 71(8): 1145-1173, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25684829

RESUMO

Naturally occurring guanidine derivatives frequently display medicinally useful properties. Among them, the higher order pyrrole-imidazole alkaloids, the dragmacidins, the crambescidins/batzelladines, and the saxitoxins/tetradotoxins have stimulated the development of many new synthetic methods over the past decades. We provide here an overview of the syntheses of these cyclic guanidine-containing natural products.

7.
Org Lett ; 26(14): 2691-2696, 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38011311

RESUMO

The conventional N-glycosylation methods for nucleoside synthesis usually require strongly acidic or basic conditions. Here we report the decarboxylative C(sp3)-N coupling of glycosyl N-hydroxyphthalimide esters with nucleobases via dual photoredox/Cu catalysis, which offered a mild approach to nucleoside analogues. A total synthesis of oxetanocin A, an antiviral natural product containing an oxetanose moiety, has been achieved by using this method.

8.
Adv Sci (Weinh) ; 11(29): e2305593, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38873820

RESUMO

Centromere protein A (CENP-A), a centromere-specific histone H3 variant, is crucial for kinetochore positioning and chromosome segregation. However, its regulatory mechanism in human cells remains incompletely understood. A structure-activity relationship (SAR) study of the cell-cycle-arresting indole terpenoid mimic JP18 leads to the discovery of two more potent analogs, (+)-6-Br-JP18 and (+)-6-Cl-JP18. Tubulin is identified as a potential cellular target of these halogenated analogs by using the drug affinity responsive target stability (DARTS) based method. X-ray crystallography analysis reveals that both molecules bind to the colchicine-binding site of ß-tubulin. Treatment of human cells with microtubule-targeting agents (MTAs), including these two compounds, results in CENP-A accumulation by destabilizing Cdh1, a co-activator of the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase. This study establishes a link between microtubule dynamics and CENP-A accumulation using small-molecule tools and highlights the role of Cdh1 in CENP-A proteolysis.


Assuntos
Proteína Centromérica A , Microtúbulos , Proteólise , Humanos , Antígenos CD , Proteínas Cdh1/metabolismo , Proteínas Cdh1/genética , Proteína Centromérica A/metabolismo , Proteína Centromérica A/genética , Cristalografia por Raios X/métodos , Indóis/metabolismo , Indóis/farmacologia , Indóis/química , Microtúbulos/metabolismo , Microtúbulos/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Fuso Acromático/metabolismo , Fuso Acromático/efeitos dos fármacos , Relação Estrutura-Atividade
9.
J Org Chem ; 76(23): 9748-56, 2011 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-22054226

RESUMO

Digitoxin, a clinically important cardiac trisaccharide, was assembled efficiently from digitoxigenin and 3,4-di-O-tert-butyldiphenylsilyl-d-digitoxosyl o-cyclopropylethynylbenzoate in 9 steps and 52% overall yield via alternate glycosylation and protecting group manipulation. The present synthesis showcases the advantage of the gold(I)-catalyzed glycosylation protocol in the synthesis of glycoconjugates containing acid-labile 2-deoxysugar linkages.


Assuntos
Benzoatos/química , Digitoxina/síntese química , Glicosídeos/química , Ouro/química , Catálise , Digitoxina/química , Conformação Molecular
10.
Cell Chem Biol ; 25(11): 1350-1358.e9, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30146242

RESUMO

The 26S proteasome is the major proteolytic machine for breaking down cytosolic and nuclear proteins in eukaryotes. Due to the lack of a suitable assay, it is difficult to measure routinely and quantitatively the breakdown of proteins by the 26S proteasome in vitro. In the present study, we developed an assay to monitor proteasome-mediated protein degradation. Using this assay, we discovered that epidithiodiketopiperazine (ETPs) blocked the degradation of our model substrate in vitro. Further characterization revealed that ETPs inhibited proteasome function by targeting the essential proteasomal deubiquitinase Rpn11 (POH1/PSMD14). ETPs also inhibited other JAMM (JAB1/MPN/Mov34 metalloenzyme) proteases such as Csn5 and AMSH. An improved ETP with fewer non-specific effects, SOP11, stabilized a subset of proteasome substrates in cells, induced the unfolded protein response, and led to cell death. SOP11 represents a class of Rpn11 inhibitor and provides an alternative route to develop proteasome inhibitors.


Assuntos
Piperazinas/química , Piperazinas/farmacologia , Inibidores de Proteassoma/química , Inibidores de Proteassoma/farmacologia , Proteólise/efeitos dos fármacos , Transativadores/antagonistas & inibidores , Linhagem Celular Tumoral , Humanos , Complexo de Endopeptidases do Proteassoma/metabolismo , Transativadores/metabolismo , Ubiquitina/metabolismo , Ubiquitinação/efeitos dos fármacos , Resposta a Proteínas não Dobradas/efeitos dos fármacos
11.
J Med Chem ; 60(4): 1343-1361, 2017 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-28191850

RESUMO

The proteasome plays a crucial role in degradation of normal proteins that happen to be constitutively or inducibly unstable, and in this capacity it plays a regulatory role. Additionally, it degrades abnormal/damaged/mutant/misfolded proteins, which serves a quality-control function. Inhibitors of the proteasome have been validated in the treatment of multiple myeloma, with several FDA-approved therapeutics. Rpn11 is a Zn2+-dependent metalloisopeptidase that hydrolyzes ubiquitin from tagged proteins that are trafficked to the proteasome for degradation. A fragment-based drug discovery (FBDD) approach was utilized to identify fragments with activity against Rpn11. Screening of a library of metal-binding pharmacophores (MBPs) revealed that 8-thioquinoline (8TQ, IC50 value ∼2.5 µM) displayed strong inhibition of Rpn11. Further synthetic elaboration of 8TQ yielded a small molecule compound (35, IC50 value ∼400 nM) that is a potent and selective inhibitor of Rpn11 that blocks proliferation of tumor cells in culture.


Assuntos
Inibidores de Proteassoma/química , Inibidores de Proteassoma/farmacologia , Quinolinas/química , Quinolinas/farmacologia , Transativadores/antagonistas & inibidores , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Descoberta de Drogas , Humanos , Modelos Moleculares , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Transativadores/metabolismo , Zinco/metabolismo
12.
Carbohydr Res ; 432: 36-40, 2016 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-27366975

RESUMO

During our synthesis toward the unique nucleoside antibiotic A201A, we were surprised to find that a benzyl arabino-pent-4-enofuranoside underwent a Ferrier II-like rearrangement readily to provide the corresponding cyclopentanone derivative in high yield and stereoselectivity upon hydrogenolysis of the anomeric benzyl group.


Assuntos
Aminoglicosídeos/síntese química , Ciclopentanos/química , Glicosídeos/química , Aminoglicosídeos/química , Compostos de Benzil/química , Hidrogênio/química , Estrutura Molecular , Estereoisomerismo
13.
Science ; 349(6244): 149, 2015 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-26160939

RESUMO

Sherman et al. commented on the precedence of enantiodivergence, listing a number of congeneric natural products with opposite chirality. However, these "congeners" are not derived from enantiodivergent biosyntheses. Instead, they are antipodes arising from separate enantiomeric biosyntheses. A distinct feature of the biosynthesis of the cyclic pyrrole-imidazole dimers is the production of antipodal congeners without the corresponding enantiomers.


Assuntos
Reação de Cicloadição , Poríferos/metabolismo , Pirróis/síntese química , Animais
14.
Org Chem Front ; 1(5): 468-472, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24976971

RESUMO

Vanadium(III) oxide catalyzes the direct fluorination of C(sp3)-H groups with Selectfluor. This reaction is operationally simple. The catalyst and the reaction byproduct can be removed easily by filtration. Using this method, a fluorine atom can be introduced to the tertiary position of 1,4-cineole and L-menthone selectively.

15.
Chem Commun (Camb) ; 50(63): 8628-39, 2014 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-24828265

RESUMO

The pyrrole-imidazole alkaloids are a group of structurally unique and biologically interesting marine sponge metabolites. Among them, the cyclic dimers have caught synthetic chemists' attention particularly. Numerous synthetic strategies have been developed and various biosynthetic hypotheses have been proposed for these fascinating natural products. We discuss herein the synthetic approaches and the biosynthetic insights obtained from these studies.


Assuntos
Alcaloides/biossíntese , Alcaloides/síntese química , Produtos Biológicos/síntese química , Imidazóis/síntese química , Pirróis/síntese química , Animais , Poríferos/química
16.
Science ; 346(6206): 219-24, 2014 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-25301624

RESUMO

Cycloaddition is an essential tool in chemical synthesis. Instead of using light or heat as a driving force, marine sponges promote cycloaddition with a more versatile but poorly understood mechanism in producing pyrrole-imidazole alkaloids sceptrin, massadine, and ageliferin. Through de novo synthesis of sceptrin and massadine, we show that sponges may use single-electron oxidation as a central mechanism to promote three different types of cycloaddition. Additionally, we provide surprising evidence that, in contrast to previous reports, sceptrin, massadine, and ageliferin have mismatched chirality. Therefore, massadine cannot be an oxidative rearrangement product of sceptrin or ageliferin, as is commonly believed. Taken together, our results demonstrate unconventional chemical approaches to achieving cycloaddition reactions in synthesis and uncover enantiodivergence as a new biosynthetic paradigm for natural products.


Assuntos
Reação de Cicloadição , Poríferos/metabolismo , Pirróis/síntese química , Animais , Vias Biossintéticas , Estrutura Molecular , Pirróis/química , Pirróis/metabolismo , Estereoisomerismo
17.
Carbohydr Res ; 377: 63-74, 2013 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-23811084

RESUMO

Three trisaccharides, one pentasaccharide, and one heptasaccharide, namely α-D-GalA-(1→2)-α-L-Rha-(1→4)-ß-D-GalA-OC3H7 (1), α-L-Rha-(1→4)-α-D-GalA-(1→4)-ß-D-GalA-OC3H7 (2), α-D-GalA-(1→4)-α-D-GalA-(1→2)-α-L-Rha-OC3H7 (3), α-D-GalA-(1→2)-α-L-Rha-(1→4)-α-D-GalA-(1→2)-α-L-Rha-(1→4)-ß-D-GalA-OC3H7 (4), and α-D-GalA-(1→2)-α-L-Rha-(1→4)-α-D-GalA-(1→2)-α-L-Rha-(1→4)-α-D-GalA-(1→2)-α-L-Rha-(1→4)-ß-D-GalA-OC3H7 (5), which are relevant to the fragments of the rhamnogalacturonan of Nerium indicum, were concisely synthesized. The syntheses feature highly stereoselective formation of the α-D-GalA-linkage with GalA N-phenyltrifluoroacetimidates as donors.


Assuntos
Nerium/química , Oligossacarídeos/síntese química , Pectinas/química , Sequência de Carboidratos , Glicosilação , Ácidos Hexurônicos/química , Imidoésteres/química , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular
18.
Chem Commun (Camb) ; 48(69): 8679-81, 2012 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-22825075

RESUMO

Pregnane glycoside P57, the appetite suppressant component from Hoodia, was synthesized expeditiously, featuring preparation of the aglycone Hoodigogenin A from digoxin and assembly of the deoxytrisaccharide with glycosyl o-alkynylbenzoates as donors.


Assuntos
Apocynaceae/química , Depressores do Apetite/síntese química , Extratos Vegetais/síntese química , Saponinas/síntese química , Depressores do Apetite/química , Extratos Vegetais/química , Saponinas/química
20.
Chem Commun (Camb) ; 47(26): 7515-7, 2011 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-21625694

RESUMO

The formation of 3,6-di-O-acetyl-1,2,4-O-orthoacetyl-α-D-glucopyranose was observed in the gold(I)-catalyzed glycosidation of peracetyl glucopyranosyl ortho-hexynylbenzoate; experiments with substrates bearing deuterium labeled 2-O-acetyl or 4-O-acetyl groups indicated that the orthoacetate was derived from the 4-O-acetyl group, which provided a direct evidence for the remote participation of the 4-O-acyl group in glycosylation.


Assuntos
Glucosídeos/química , Glicosilação , Estereoisomerismo
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