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1.
Cell ; 182(2): 481-496.e21, 2020 07 23.
Artículo en Inglés | MEDLINE | ID: mdl-32649862

RESUMEN

The response to DNA damage is critical for cellular homeostasis, tumor suppression, immunity, and gametogenesis. In order to provide an unbiased and global view of the DNA damage response in human cells, we undertook 31 CRISPR-Cas9 screens against 27 genotoxic agents in the retinal pigment epithelium-1 (RPE1) cell line. These screens identified 890 genes whose loss causes either sensitivity or resistance to DNA-damaging agents. Mining this dataset, we discovered that ERCC6L2 (which is mutated in a bone-marrow failure syndrome) codes for a canonical non-homologous end-joining pathway factor, that the RNA polymerase II component ELOF1 modulates the response to transcription-blocking agents, and that the cytotoxicity of the G-quadruplex ligand pyridostatin involves trapping topoisomerase II on DNA. This map of the DNA damage response provides a rich resource to study this fundamental cellular system and has implications for the development and use of genotoxic agents in cancer therapy.


Asunto(s)
Daño del ADN , Redes Reguladoras de Genes/fisiología , Aminoquinolinas/farmacología , Animales , Sistemas CRISPR-Cas/genética , Línea Celular , Citocromo-B(5) Reductasa/genética , Citocromo-B(5) Reductasa/metabolismo , Daño del ADN/efectos de los fármacos , ADN Helicasas/genética , ADN Helicasas/metabolismo , Reparación del ADN , ADN-Topoisomerasas de Tipo II/genética , ADN-Topoisomerasas de Tipo II/metabolismo , Humanos , Ratones , Ácidos Picolínicos/farmacología , ARN Guía de Kinetoplastida/metabolismo , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/genética
2.
Proc Natl Acad Sci U S A ; 121(36): e2322399121, 2024 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-39190343

RESUMEN

Religious fundamentalism, characterized by rigid adherence to a set of beliefs putatively revealing inerrant truths, is ubiquitous across cultures and has a global impact on society. Understanding the psychological and neurobiological processes producing religious fundamentalism may inform a variety of scientific, sociological, and cultural questions. Research indicates that brain damage can alter religious fundamentalism. However, the precise brain regions involved with these changes remain unknown. Here, we analyzed brain lesions associated with varying levels of religious fundamentalism in two large datasets from independent laboratories. Lesions associated with greater fundamentalism were connected to a specific brain network with nodes in the right orbitofrontal, dorsolateral prefrontal, and inferior parietal lobe. This fundamentalism network was strongly right hemisphere lateralized and highly reproducible across the independent datasets (r = 0.82) with cross-validations between datasets. To explore the relationship of this network to lesions previously studied by our group, we tested for similarities to twenty-one lesion-associated conditions. Lesions associated with confabulation and criminal behavior showed a similar connectivity pattern as lesions associated with greater fundamentalism. Moreover, lesions associated with poststroke pain showed a similar connectivity pattern as lesions associated with lower fundamentalism. These findings are consistent with the current understanding of hemispheric specializations for reasoning and lend insight into previously observed epidemiological associations with fundamentalism, such as cognitive rigidity and outgroup hostility.


Asunto(s)
Red Nerviosa , Humanos , Masculino , Femenino , Red Nerviosa/fisiopatología , Red Nerviosa/patología , Persona de Mediana Edad , Encéfalo/fisiopatología , Encéfalo/patología , Adulto , Religión , Imagen por Resonancia Magnética , Lesiones Encefálicas/patología , Lesiones Encefálicas/fisiopatología , Anciano
3.
PLoS Pathog ; 20(6): e1012333, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38935804

RESUMEN

The bloodstream form of Trypanosoma brucei expresses large poly-N-acetyllactosamine (pNAL) chains on complex N-glycans of a subset of glycoproteins. It has been hypothesised that pNAL may be required for receptor-mediated endocytosis. African trypanosomes contain a unique family of glycosyltransferases, the GT67 family. Two of these, TbGT10 and TbGT8, have been shown to be involved in pNAL biosynthesis in bloodstream form Trypanosoma brucei, raising the possibility that deleting both enzymes simultaneously might abolish pNAL biosynthesis and provide clues to pNAL function and/or essentiality. In this paper, we describe the creation of a TbGT10 null mutant containing a single TbGT8 allele that can be excised upon the addition of rapamycin and, from that, a TbGT10 and TbGT8 double null mutant. These mutants were analysed by lectin blotting, glycopeptide methylation linkage analysis and flow cytometry. The data show that the mutants are defective, but not abrogated, in pNAL synthesis, suggesting that other GT67 family members can compensate to some degree for loss of TbGT10 and TbGT8. Despite there being residual pNAL synthesis in these mutants, certain glycoproteins appear to be particularly affected. These include the lysosomal CBP1B serine carboxypeptidase, cell surface ESAG2 and the ESAG6 subunit of the essential parasite transferrin receptor (TfR). The pNAL deficient TfR in the mutants continued to function normally with respect to protein stability, transferrin binding, receptor mediated endocytosis of transferrin and subcellular localisation. Further the pNAL deficient mutants were as viable as wild type parasites in vitro and in in vivo mouse infection experiments. Although we were able to reproduce the inhibition of transferrin uptake with high concentrations of pNAL structural analogues (N-acetylchito-oligosaccharides), this effect disappeared at lower concentrations that still inhibited tomato lectin uptake, i.e., at concentrations able to outcompete lectin-pNAL binding. Based on these findings, we recommend revision of the pNAL-dependent receptor mediated endocytosis hypothesis.


Asunto(s)
Endocitosis , Glicosiltransferasas , Transferrina , Trypanosoma brucei brucei , Trypanosoma brucei brucei/metabolismo , Trypanosoma brucei brucei/genética , Animales , Endocitosis/fisiología , Ratones , Transferrina/metabolismo , Glicosiltransferasas/metabolismo , Glicosiltransferasas/genética , Tripanosomiasis Africana/parasitología , Tripanosomiasis Africana/metabolismo , Mutación , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Receptores de Transferrina/metabolismo , Receptores de Transferrina/genética , Polisacáridos
4.
J Neurosci ; 44(15)2024 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-38423761

RESUMEN

Music is a universal human attribute. The study of amusia, a neurologic music processing deficit, has increasingly elaborated our view on the neural organization of the musical brain. However, lesions causing amusia occur in multiple brain locations and often also cause aphasia, leaving the distinct neural networks for amusia unclear. Here, we utilized lesion network mapping to identify these networks. A systematic literature search was carried out to identify all published case reports of lesion-induced amusia. The reproducibility and specificity of the identified amusia network were then tested in an independent prospective cohort of 97 stroke patients (46 female and 51 male) with repeated structural brain imaging, specifically assessed for both music perception and language abilities. Lesion locations in the case reports were heterogeneous but connected to common brain regions, including bilateral temporoparietal and insular cortices, precentral gyrus, and cingulum. In the prospective cohort, lesions causing amusia mapped to a common brain network, centering on the right superior temporal cortex and clearly distinct from the network causally associated with aphasia. Lesion-induced longitudinal structural effects in the amusia circuit were confirmed as reduction of both gray and white matter volume, which correlated with the severity of amusia. We demonstrate that despite the heterogeneity of lesion locations disrupting music processing, there is a common brain network that is distinct from the language network. These results provide evidence for the distinct neural substrate of music processing, differentiating music-related functions from language, providing a testable target for noninvasive brain stimulation to treat amusia.


Asunto(s)
Red Nerviosa , Humanos , Femenino , Masculino , Persona de Mediana Edad , Anciano , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/patología , Red Nerviosa/fisiopatología , Música , Trastornos de la Percepción Auditiva/etiología , Trastornos de la Percepción Auditiva/fisiopatología , Encéfalo/patología , Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética , Mapeo Encefálico , Adulto , Estudios Prospectivos , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/diagnóstico por imagen
5.
J Biol Chem ; 300(8): 107500, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38944124

RESUMEN

In eukaryotes, the D-enantiomer of arabinose (D-Ara) is an intermediate in the biosynthesis of D-erythroascorbate in yeast and fungi and in the biosynthesis of the nucleotide sugar GDP-α-D-arabinopyranose (GDP-D-Arap) and complex α-D-Arap-containing surface glycoconjugates in certain trypanosomatid parasites. Whereas the biosynthesis of D-Ara in prokaryotes is well understood, the route from D-glucose (D-Glc) to D-Ara in eukaryotes is unknown. In this paper, we study the conversion of D-Glc to D-Ara in the trypanosomatid Crithidia fasciculata using positionally labeled [13C]-D-Glc and [13C]-D-ribose ([13C]-D-Rib) precursors and a novel derivatization and gas chromatography-mass spectrometry procedure applied to a terminal metabolite, lipoarabinogalactan. These data implicate the both arms of pentose phosphate pathway and a likely role for D-ribulose-5-phosphate (D-Ru-5P) isomerization to D-Ara-5P. We tested all C. fasciculata putative sugar and polyol phosphate isomerase genes for their ability to complement a D-Ara-5P isomerase-deficient mutant of Escherichia coli and found that one, the glutamine fructose-6-phosphate aminotransferase (GFAT) of glucosamine biosynthesis, was able to rescue the E. coli mutant. We also found that GFAT genes of other trypanosomatid parasites, and those of yeast and human origin, could complement the E. coli mutant. Finally, we demonstrated biochemically that recombinant human GFAT can isomerize D-Ru-5P to D-Ara5P. From these data, we postulate a general eukaryotic pathway from D-Glc to D-Ara and discuss its possible significance. With respect to C. fasciculata, we propose that D-Ara is used not only for the synthesis of GDP-D-Arap and complex surface glycoconjugates but also in the synthesis of D-erythroascorbate.


Asunto(s)
Arabinosa , Glucosa , Arabinosa/metabolismo , Glucosa/metabolismo , Vía de Pentosa Fosfato , Escherichia coli/metabolismo , Escherichia coli/genética , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética
6.
J Biol Chem ; 300(8): 107557, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39002668

RESUMEN

Glycosylphosphatidylinositol (GPI) anchor protein modification in Plasmodium species is well known and represents the principal form of glycosylation in these organisms. The structure and biosynthesis of GPI anchors of Plasmodium spp. has been primarily studied in the asexual blood stage of Plasmodium falciparum and is known to contain the typical conserved GPI structure of EtN-P-Man3GlcN-PI. Here, we have investigated the circumsporozoite protein (CSP) for the presence of a GPI anchor. CSP is the major surface protein of Plasmodium sporozoites, the infective stage of the malaria parasite. While it is widely assumed that CSP is a GPI-anchored cell surface protein, compelling biochemical evidence for this supposition is absent. Here, we employed metabolic labeling and mass-spectrometry-based approaches to confirm the presence of a GPI anchor in CSP. Biosynthetic radiolabeling of CSP with [3H]-palmitic acid and [3H]-ethanolamine, with the former being base-labile and therefore ester-linked, provided strong evidence for the presence of a GPI anchor on CSP, but these data alone were not definitive. To provide further evidence, immunoprecipitated CSP was analyzed for the presence of myo-inositol (a characteristic component of GPI anchor) using strong acid hydrolysis and GC-MS for highly sensitive and quantitative detection. The single ion monitoring (SIM) method for GC-MS analysis confirmed the presence of the myo-inositol component in CSP. Taken together, these data provide confidence that the long-assumed presence of a GPI anchor on this important parasite protein is correct.


Asunto(s)
Membrana Celular , Glicosilfosfatidilinositoles , Plasmodium falciparum , Proteínas Protozoarias , Esporozoítos , Proteínas Protozoarias/metabolismo , Glicosilfosfatidilinositoles/metabolismo , Glicosilfosfatidilinositoles/química , Membrana Celular/metabolismo , Esporozoítos/metabolismo , Plasmodium falciparum/metabolismo , Animales , Proteínas de la Membrana/metabolismo , Humanos
7.
Ann Neurol ; 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38949221

RESUMEN

OBJECTIVE: Alice in Wonderland syndrome (AIWS) profoundly affects human perception of size and scale, particularly regarding one's own body and the environment. Its neuroanatomical basis has remained elusive, partly because brain lesions causing AIWS can occur in different brain regions. Here, we aimed to determine if brain lesions causing AIWS map to a distributed brain network. METHODS: A retrospective case-control study analyzing 37 cases of lesion-induced AIWS identified through systematic literature review was conducted. Using resting-state functional connectome data from 1,000 healthy individuals, the whole-brain connections of each lesion were estimated and contrasted with those from a control dataset comprising 1,073 lesions associated with 25 other neuropsychiatric syndromes. Additionally, connectivity findings from lesion-induced AIWS cases were compared with functional neuroimaging results from 5 non-lesional AIWS cases. RESULTS: AIWS-associated lesions were located in various brain regions with minimal overlap (≤33%). However, the majority of lesions (≥85%) demonstrated shared connectivity to the right extrastriate body area, known to be selectively activated by viewing body part images, and the inferior parietal cortex, involved in size and scale judgements. This pattern was uniquely characteristic of AIWS when compared with other neuropsychiatric disorders (family-wise error-corrected p < 0.05) and consistent with functional neuroimaging observations in AIWS due to nonlesional causes (median correlation r = 0.56, interquartile range 0.24). INTERPRETATION: AIWS-related perceptual distortions map to one common brain network, encompassing regions critical for body representation and size-scale processing. These findings lend insight into the neuroanatomical localization of higher-order perceptual functions, and may inform future therapeutic strategies for perceptual disorders. ANN NEUROL 2024.

8.
Cereb Cortex ; 34(1)2024 01 14.
Artículo en Inglés | MEDLINE | ID: mdl-38100330

RESUMEN

There is disagreement regarding the major components of the brain network supporting spatial cognition. To address this issue, we applied a lesion mapping approach to the clinical phenomenon of topographical disorientation. Topographical disorientation is the inability to maintain accurate knowledge about the physical environment and use it for navigation. A review of published topographical disorientation cases identified 65 different lesion sites. Our lesion mapping analysis yielded a topographical disorientation brain map encompassing the classic regions of the navigation network: medial parietal, medial temporal, and temporo-parietal cortices. We also identified a ventromedial region of the prefrontal cortex, which has been absent from prior descriptions of this network. Moreover, we revealed that the regions mapped are correlated with the Default Mode Network sub-network C. Taken together, this study provides causal evidence for the distribution of the spatial cognitive system, demarking the major components and identifying novel regions.


Asunto(s)
Orientación Espacial , Orientación , Humanos , Encéfalo/patología , Mapeo Encefálico , Confusión/etiología , Confusión/patología , Imagen por Resonancia Magnética
9.
J Biol Chem ; 299(8): 105016, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37414151

RESUMEN

The biosynthesis of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) in the parasitic protozoan Trypanosoma brucei involves fatty acid remodeling of the GPI precursor molecules before they are transferred to protein in the endoplasmic reticulum. The genes encoding the requisite phospholipase A2 and A1 activities for this remodeling have thus far been elusive. Here, we identify a gene, Tb927.7.6110, that encodes a protein that is both necessary and sufficient for GPI-phospholipase A2 (GPI-PLA2) activity in the procyclic form of the parasite. The predicted protein product belongs to the alkaline ceramidase, PAQR receptor, Per1, SID-1, and TMEM8 (CREST) superfamily of transmembrane hydrolase proteins and shows sequence similarity to Post-GPI-Attachment to Protein 6 (PGAP6), a GPI-PLA2 that acts after transfer of GPI precursors to protein in mammalian cells. We show the trypanosome Tb927.7.6110 GPI-PLA2 gene resides in a locus with two closely related genes Tb927.7.6150 and Tb927.7.6170, one of which (Tb927.7.6150) most likely encodes a catalytically inactive protein. The absence of GPI-PLA2 in the null mutant procyclic cells not only affected fatty acid remodeling but also reduced GPI anchor sidechain size on mature GPI-anchored procyclin glycoproteins. This reduction in GPI anchor sidechain size was reversed upon the re-addition of Tb927.7.6110 and of Tb927.7.6170, despite the latter not encoding GPI precursor GPI-PLA2 activity. Taken together, we conclude that Tb927.7.6110 encodes the GPI-PLA2 of GPI precursor fatty acid remodeling and that more work is required to assess the roles and essentiality of Tb927.7.6170 and the presumably enzymatically inactive Tb927.7.6150.


Asunto(s)
Glicosilfosfatidilinositoles , Trypanosoma brucei brucei , Animales , Glicosilfosfatidilinositoles/genética , Glicosilfosfatidilinositoles/metabolismo , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/metabolismo , Ácidos Grasos/genética , Ácidos Grasos/metabolismo , Proteínas de la Membrana/metabolismo , Fosfolipasas A2/metabolismo , Proteínas Ligadas a GPI/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Mamíferos/metabolismo
10.
J Am Chem Soc ; 146(15): 10875-10888, 2024 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-38579119

RESUMEN

Two isomeric pentacene dimers, each linked by a diamantane spacer, have been synthesized. These dimers are designed to provide experimental evidence to support quantum mechanical calculations, which predict the substitution pattern on the carbon-rich diethynyldiamantane spacer to be decisive in controlling the interpentacene coupling. Intramolecular singlet fission (i-SF) serves as a probe for the existence and strength of the electronic coupling between the two pentacenes, with transient absorption spectroscopy as the method of choice to characterize i-SF. 4,9-Substitution of diamantane provides a pentacene dimer (4,9-dimer) in which the two chromophores are completely decoupled and that, following photoexcitation, deactivates to the ground state analogous to a monomeric pentacene chromophore. Conversely, 1,6-substitution provides a pentacene dimer (1,6-dimer) that exhibits sufficiently strong coupling to drive i-SF, resulting in correlated triplet M(T1T1) yields close to unity and free triplet (T1 + T1) yields of ca. 50%. Thus, the diamantane spacer effectively switches "on" or "off" the coupling between the chromophores, based on the substitution pattern. The binary control of diamantane contrasts other known molecular spacers designed only to modulate the coupling strength between two pentacenes.

11.
Chemistry ; : e202402899, 2024 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-39212600

RESUMEN

Several complexes of the intramolecular frustrated Lewis pair (FLP)-supported P(-1) ligand [iPr2P(C6H4)BCy2{P}]- are presented (Cy = cyclohexyl). Chief among these is the first example of a monomeric zinc bis(phosphido) complex, which was synthesized as a potential precursor for the solution-phase deposition of Zn3P2. While this goal was ultimately unsuccessful, the Zn(II) complex acts as a convenient springboard to other metal phosphide species via transmetallation: namely, a tellurium bis(phosphido) and a formal adduct of the phosphorus subhalide PPCl2. Trapping experiments show that the PPCl2 adduct can also be prepared directly through the in situ reduction of PCl3 in the presence of an intramolecular FLP ligand. Lastly, we report a formal η2-phosphaborene complex of cobalt(-1) which is isoelectronic to olefin complexes, and explore its bonding via density functional theory (DFT) computations.

12.
Chemistry ; : e202402651, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39222033

RESUMEN

6,13-Diethynylpentacene derivatives with sterically bulky substituents (Tr*, tris(3,5-di-tert-butylphenyl)methyl groups) appended to the ethynyl moieties at the 6- and 13-positions have been synthesized, as well as derivatives with electron withdrawing fluorine groups on the eight pro-cata positions. These molecules are designed to investigate relationships between steric and electronic effects on the stability of pentacene toward endoperoxide formation via reaction with photosensitized oxygen in solution under conditions of ambient light (i.e., 'laboratory' conditions). It is evident from the study that stabilization through changes to the electronic characteristics of pentacene are more effective than the incorporation of sterically bulky groups at the acetylenic termini. Selected pentacene derivatives have been made into binary, amorphous films with the fullerene derivative PCBM to investigate the stability imparted by substituents against cycloaddition reactions. Overall, the introduction of steric protection through incorporation of Tr* groups is not an efficient strategy for enhancing persistence of pentacenes. Stabilization through fluorination proves successful for extending the lifetime of the pentacene derivatives by an order of magnitude in solution. Notably, the persistence of pentacene derivatives in solution can also be enhanced through the use ethereal solvents stabilized with butylated hydroxy toluene (BHT) and/or an increased number of trialkylsilyl groups as substituents.

13.
J Neuropsychiatry Clin Neurosci ; 36(1): 45-52, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37415502

RESUMEN

OBJECTIVE: Spontaneous confabulation is a symptom in which false memories are conveyed by the patient as true. The purpose of the study was to identify the neuroanatomical substrate of this complex symptom and evaluate the relationship to related symptoms, such as delusions and amnesia. METHODS: Twenty-five lesion locations associated with spontaneous confabulation were identified in a systematic literature search. The network of brain regions functionally connected to each lesion location was identified with a large connectome database (N=1,000) and compared with networks derived from lesions associated with nonspecific (i.e., variable) symptoms (N=135), delusions (N=32), or amnesia (N=53). RESULTS: Lesions associated with spontaneous confabulation occurred in multiple brain locations, but they were all part of a single functionally connected brain network. Specifically, 100% of lesions were connected to the mammillary bodies (familywise error rate [FWE]-corrected p<0.05). This connectivity was specific for lesions associated with confabulation compared with lesions associated with nonspecific symptoms or delusions (FWE-corrected p<0.05). Lesions associated with confabulation were more connected to the orbitofrontal cortex than those associated with amnesia (FWE-corrected p<0.05). CONCLUSIONS: Spontaneous confabulation maps to a common functionally connected brain network that partially overlaps, but is distinct from, networks associated with delusions or amnesia. These findings lend new insight into the neuroanatomical bases of spontaneous confabulation.


Asunto(s)
Conectoma , Trastornos de la Memoria , Humanos , Amnesia/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Corteza Prefrontal/patología , Conjuntos de Datos como Asunto
14.
Phys Chem Chem Phys ; 26(13): 9940-9947, 2024 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-38497243

RESUMEN

The solid-state reaction of the active pharmaceutical ingredient theophylline with citric acid is a well-established example of a mechanochemical reaction, leading to a model pharmaceutical cocrystal. Here, classical force field molecular dynamics was employed to investigate the molecular mixing and structural distortion that take place on the mechanically driven indentation of a citric acid nanoparticle on a slab of crystalline theophylline. Through non-equilibrium molecular dynamics simulations, a 6 nm diameter nanoparticle of citric acid was introduced onto an open (001) surface of a theophylline crystal, varying both the angle of incidence of the nanoparticle between 15° and 90° and the indentation speed between 1 m s-1 and 16 m s-1. This theoretical study enabled the evaluation of how these two parameters promote molecular mixing and overall structural deformation upon the mechanical contraction of theophylline and citric acid, both of which are important parameters underlying mechanochemical cocrystallisation. The results show that the angle of incidence plays a key role in the molecular transfer ability between the two species and in the structural disruption of the initially spherical nanoparticles. Changing the indentation speed, however, did not lead to a discernible trend in molecular mixing, highlighting the importance of the incident angle in mechanochemical events in the context of supramolecular chemistry, such as the disruption of the crystal structure and molecular transfer between molecular crystals.

15.
Nature ; 560(7717): 192-197, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-30046105

RESUMEN

Visceral leishmaniasis causes considerable mortality and morbidity in many parts of the world. There is an urgent need for the development of new, effective treatments for this disease. Here we describe the development of an anti-leishmanial drug-like chemical series based on a pyrazolopyrimidine scaffold. The leading compound from this series (7, DDD853651/GSK3186899) is efficacious in a mouse model of visceral leishmaniasis, has suitable physicochemical, pharmacokinetic and toxicological properties for further development, and has been declared a preclinical candidate. Detailed mode-of-action studies indicate that compounds from this series act principally by inhibiting the parasite cdc-2-related kinase 12 (CRK12), thus defining a druggable target for visceral leishmaniasis.


Asunto(s)
Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Leishmania donovani/efectos de los fármacos , Leishmania donovani/enzimología , Leishmaniasis Visceral/tratamiento farmacológico , Leishmaniasis Visceral/parasitología , Terapia Molecular Dirigida , Pirazoles/farmacología , Pirimidinas/farmacología , Animales , Quinasa 9 Dependiente de la Ciclina/química , Quinasas Ciclina-Dependientes/química , Quinasas Ciclina-Dependientes/metabolismo , Modelos Animales de Enfermedad , Humanos , Ratones , Simulación del Acoplamiento Molecular , Proteoma/efectos de los fármacos , Proteómica , Pirazoles/química , Pirazoles/uso terapéutico , Pirimidinas/química , Pirimidinas/uso terapéutico , Reproducibilidad de los Resultados , Especificidad por Sustrato
17.
Proc Natl Acad Sci U S A ; 118(33)2021 08 17.
Artículo en Inglés | MEDLINE | ID: mdl-34385330

RESUMEN

Glycoconjugates play major roles in the infectious cycle of the trypanosomatid parasite Leishmania While GDP-Fucose synthesis is essential, fucosylated glycoconjugates have not been reported in Leishmania major [H. Guo et al., J. Biol. Chem. 292, 10696-10708 (2017)]. Four predicted fucosyltransferases appear conventionally targeted to the secretory pathway; SCA1/2 play a role in side-chain modifications of lipophosphoglycan, while gene deletion studies here showed that FUT2 and SCAL were not essential. Unlike most eukaryotic glycosyltransferases, the predicted α 1-2 fucosyltransferase encoded by FUT1 localized to the mitochondrion. A quantitative "plasmid segregation" assay, expressing FUT1 from the multicopy episomal pXNG vector in a chromosomal null ∆fut1- background, established that FUT1 is essential. Similarly, "plasmid shuffling" confirmed that both enzymatic activity and mitochondrial localization were required for viability, comparing import-blocked or catalytically inactive enzymes, respectively. Enzymatic assays of tagged proteins expressed in vivo or of purified recombinant FUT1 showed it had a broad fucosyltransferase activity including glycan and peptide substrates. Unexpectedly, a single rare ∆fut1- segregant (∆fut1s ) was obtained in rich media, which showed severe growth defects accompanied by mitochondrial dysfunction and loss, all of which were restored upon FUT1 reexpression. Thus, FUT1 along with the similar Trypanosoma brucei enzyme TbFUT1 [G. Bandini et al., bioRxiv, https://www.biorxiv.org/content/10.1101/726117v2 (2021)] joins the eukaryotic O-GlcNAc transferase isoform as one of the few glycosyltransferases acting within the mitochondrion. Trypanosomatid mitochondrial FUT1s may offer a facile system for probing mitochondrial glycosylation in a simple setting, and their essentiality for normal growth and mitochondrial function renders it an attractive target for chemotherapy of these serious human pathogens.


Asunto(s)
Fucosiltransferasas/metabolismo , Regulación Enzimológica de la Expresión Génica/fisiología , Leishmania major/metabolismo , Mitocondrias/enzimología , Proteínas Protozoarias/metabolismo , Secuencia de Aminoácidos , Medios de Cultivo , Fucosiltransferasas/genética , Mutación , Plásmidos , Transporte de Proteínas , Proteínas Protozoarias/genética , Galactósido 2-alfa-L-Fucosiltransferasa
18.
J Am Chem Soc ; 145(33): 18260-18275, 2023 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-37531628

RESUMEN

Photon energy conversion can be accomplished in many different ways, including the two opposing manners, down-conversion (i.e., singlet fission, SF) and up-conversion (i.e., triplet-triplet annihilation up-conversion, TTA-UC). Both processes have the potential to help overcome the detailed balance limit of single-junction solar cells. Tetracene, in which the energies of the lowest singlet excited state and twice the triplet excited state are comparable, exhibits both down- and up-conversion. Here, we have designed meta-diethynylphenylene- and 1,3-diethynyladamantyl-linked tetracene dimers, which feature different electronic coupling, to characterize the interplay between intramolecular SF (intra-SF) and intramolecular TTA-UC (intra-TTA-UC) via steady-state and time-resolved absorption and fluorescence spectroscopy. Furthermore, we have used Pd-phthalocyanine as a sensitizer to enable intra-TTA-UC in the two dimers via indirect photoexcitation in the near-infrared part of the solar spectrum. The work is rounded off by temperature-dependent measurements, which outline key aspects of how thermal effects impact intra-SF and intra-TTA-UC in different dimers.

19.
J Am Chem Soc ; 145(17): 9548-9563, 2023 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-37083447

RESUMEN

The goal of harnessing the theoretical potential of singlet fission (SF), a process in which one singlet excited state is split into two triplet excited states, has become a central challenge in solar energy research. Covalently linked dimers provide crucial models for understanding the role of chromophore arrangement and coupling in SF. Sensitizers can be integrated into these systems to expand the absorption bandwidth through which SF can be accessed. Here, we define the role of the sensitizer-chromophore geometry in a sensitized SF model system. To this end, two conjugates have been synthesized consisting of a pentacene dimer (SF motif) connected via a rigid alkynyl bridge to a subphthalocyanine (the sensitizer motif) in either an axial or a peripheral arrangement. Steady-state and time-resolved photophysical measurements are used to confirm that both conjugates operate as per design, displaying near unity energy transfer efficiencies and high triplet quantum yields from SF. Decisively, energy transfer between the subphthalocyanine and pentacene dimer occurs ca. 26 times faster in the peripheral conjugate, even though the two chromophores are ca. 3 Å farther apart than in the axial conjugate. Following a theoretical evaluation of the dipolar coupling, Vdip2, and the orientation factor, κ2, of both the axial (Vdip2 = 140 cm-2; κ2 = 0.08) and the peripheral (Vdip2 = 724 cm-2; κ2 = 1.46) arrangements, we establish that this rate acceleration is due to a more favorable (nearly co-planar) relative orientation of the transition dipole moments of the subphthalocyanine and pentacenes in the peripheral constellation.

20.
Ann Neurol ; 91(2): 217-224, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34961965

RESUMEN

OBJECTIVE: Blindsight is a disorder where brain injury causes loss of conscious but not unconscious visual perception. Prior studies have produced conflicting results regarding the neuroanatomical pathways involved in this unconscious perception. METHODS: We performed a systematic literature search to identify lesion locations causing visual field loss in patients with blindsight (n = 34) and patients without blindsight (n = 35). Resting state functional connectivity between each lesion location and all other brain voxels was computed using a large connectome database (n = 1,000). Connections significantly associated with blindsight (vs no blindsight) were identified. RESULTS: Functional connectivity between lesion locations and the ipsilesional medial pulvinar was significantly associated with blindsight (family wise error p = 0.029). No significant connectivity differences were found to other brain regions previously implicated in blindsight. This finding was independent of methods (eg, flipping lesions to the left or right) and stimulus type (moving vs static). INTERPRETATION: Connectivity to the ipsilesional medial pulvinar best differentiates lesion locations associated with blindsight versus those without blindsight. Our results align with recent data from animal models and provide insight into the neuroanatomical substrate of unconscious visual abilities in patients. ANN NEUROL 2022;91:217-224.


Asunto(s)
Red Nerviosa/fisiopatología , Inconsciencia/psicología , Percepción Visual , Adulto , Anciano , Mapeo Encefálico , Conectoma , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Red Nerviosa/diagnóstico por imagen , Pulvinar/diagnóstico por imagen , Pulvinar/fisiopatología , Descanso , Trastornos de la Visión , Campos Visuales , Adulto Joven
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