RESUMEN
Apolipoprotein E transports lipids and couples metabolism between astrocytes and neurons. The E4 variant (APOE4) affects these functions and represents a genetic predisposition for Alzheimer's disease, but the molecular mechanisms remain elusive. We show that ApoE produces different types of lipoproteins via distinct lipidation pathways. ApoE forms high-density lipoprotein (HDL)-like, cholesterol-rich particles via the ATP-binding cassette transporter 1 (ABCA1), a mechanism largely unaffected by ApoE polymorphism. Alternatively, ectopic accumulation of fat in astrocytes, a stress-associated condition, redirects ApoE toward the assembly and secretion of triacylglycerol-rich lipoproteins, a process boosted by the APOE4 variant. We demonstrate in vitro that ApoE can detect triacylglycerol in membranes and spontaneously assemble lipoprotein particles (10-20 nm) rich in unsaturated triacylglycerol, and that APOE4 has remarkable properties behaving as a strong triacylglycerol binder. We propose that fatty APOE4 astrocytes have reduced ability to clear toxic fatty acids from the extracellular milieu, because APOE4 reroutes them back to secretion.
Asunto(s)
Apolipoproteína E4 , Astrocitos , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Apolipoproteínas E/metabolismo , Astrocitos/metabolismo , Isoformas de Proteínas/metabolismo , Triglicéridos/metabolismoRESUMEN
Apolipoprotein E (ApoE) particles are responsible for packing and transporting lipids throughout aqueous environments. We detail steps to assess in vitro particles forming from artificial membranes using right-angle light scattering and to measure their size using dynamic light scattering. We further describe how to generate in cellulo ApoE particles containing triacylglycerol under fatty-acid-induced stress. We also detail steps to isolate them from cell secretome by immunoprecipitation and analyze their lipid cargo by thin-layer chromatography. For complete details on the use and execution of this protocol, please refer to Lindner et al. (2022).1.
Asunto(s)
Apolipoproteínas E , Ácidos Grasos , Apolipoproteínas E/químicaRESUMEN
Herein we disclose SAR studies that led to a series of isoindoline ureas which we recently reported were first-in-class, non-substrate nicotinamide phosphoribosyltransferase (NAMPT) inhibitors. Modification of the isoindoline and/or the terminal functionality of screening hit 5 provided inhibitors such as 52 and 58 with nanomolar antiproliferative activity and preclinical pharmacokinetics properties which enabled potent antitumor activity when dosed orally in mouse xenograft models. X-ray crystal structures of two inhibitors bound in the NAMPT active-site are discussed.
Asunto(s)
Antineoplásicos/química , Antineoplásicos/farmacología , Citocinas/antagonistas & inhibidores , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Nicotinamida Fosforribosiltransferasa/antagonistas & inhibidores , Urea/análogos & derivados , Urea/farmacología , Animales , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Cristalografía por Rayos X , Citocinas/química , Citocinas/metabolismo , Descubrimiento de Drogas , Inhibidores Enzimáticos/farmacocinética , Inhibidores Enzimáticos/uso terapéutico , Humanos , Isoindoles/química , Isoindoles/farmacocinética , Isoindoles/farmacología , Isoindoles/uso terapéutico , Ratones , Modelos Moleculares , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Nicotinamida Fosforribosiltransferasa/química , Nicotinamida Fosforribosiltransferasa/metabolismo , Relación Estructura-Actividad , Urea/farmacocinética , Urea/uso terapéuticoRESUMEN
Cancer cells are highly reliant on NAD+-dependent processes, including glucose metabolism, calcium signaling, DNA repair, and regulation of gene expression. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for NAD+ salvage from nicotinamide, has been investigated as a target for anticancer therapy. Known NAMPT inhibitors with potent cell activity are composed of a nitrogen-containing aromatic group, which is phosphoribosylated by the enzyme. Here, we identified two novel types of NAM-competitive NAMPT inhibitors, only one of which contains a modifiable, aromatic nitrogen that could be a phosphoribosyl acceptor. Both types of compound effectively deplete cellular NAD+, and subsequently ATP, and produce cell death when NAMPT is inhibited in cultured cells for more than 48 hours. Careful characterization of the kinetics of NAMPT inhibition in vivo allowed us to optimize dosing to produce sufficient NAD+ depletion over time that resulted in efficacy in an HCT116 xenograft model. Our data demonstrate that direct phosphoribosylation of competitive inhibitors by the NAMPT enzyme is not required for potent in vitro cellular activity or in vivo antitumor efficacy. Mol Cancer Ther; 16(7); 1236-45. ©2017 AACR.
Asunto(s)
Neoplasias Colorrectales/tratamiento farmacológico , Citocinas/antagonistas & inhibidores , Inhibidores Enzimáticos/administración & dosificación , Nicotinamida Fosforribosiltransferasa/antagonistas & inhibidores , Adenosina Trifosfato/genética , Adenosina Trifosfato/metabolismo , Animales , Señalización del Calcio/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Citocinas/genética , Reparación del ADN/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Células HCT116 , Humanos , Ratones , NAD/metabolismo , Nicotinamida Fosforribosiltransferasa/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Transient receptor potential subfamily V, member 1 (TRPV1) is a nonselective cation channel expressed in both the peripheral and central nervous systems (CNS). TRPV1 protein levels in rat tissues were determined under normal and pain states using enzyme-linked immunosorbent assay. In naive rats, brain TRPV1 protein concentrations ranged from 1.5 to 4 ng/mg in hippocampus, cortex, hypothalamus, and cerebellum. Rat spinal cord TRPV1 protein levels were 40-50 ng/mg in L1-L5 of the lumbar regions, but increased to 97 ± 9.3 ng/mg toward the end of the lumbar region (L6-S1). In the complete Freund's adjuvant (CFA)-induced inflammatory pain model, TRPV1 protein level significantly increased on both the contralateral (36.5 %, p < 0.05) and ipsilateral (31.4 %, p < 0.05) L4-L6 dorsal root ganglia (DRG). TRPV1 protein levels also increased 33.3 % (p < 0.05) on the ipsilateral sciatic nerve, but no significant change in the lumbar spinal cord of CFA rats. In the monoiodoacetate-induced rat knee joint pain model, TRPV1 protein level was significantly reduced in the ipsilateral L3-L5 DRG (33.3 %, p < 0.01), no significant difference was detected in the lumbar region of the spinal cord. Quantitative determination of TRPV1 protein levels may help to elucidate the TRPV1 physiological roles and regulatory mechanisms in various pain states.
Asunto(s)
Encéfalo/metabolismo , Sistema Nervioso Periférico/metabolismo , Médula Espinal/metabolismo , Canales Catiónicos TRPV/metabolismo , Animales , Células HEK293 , Humanos , Masculino , Dolor Nociceptivo/inducido químicamente , Dolor Nociceptivo/metabolismo , Especificidad de Órganos , Osteoartritis/inducido químicamente , Osteoartritis/metabolismo , Ratas , Ratas Sprague-Dawley , Canales Catiónicos TRPV/genéticaRESUMEN
The transient receptor potential vanilloid receptor type 1 (TRPV1) is a non-selective cation channel expressed in both the peripheral and the central nervous systems. To quantitatively determine TRPV1 protein levels in native rat tissues, novel monoclonal antibodies were raised against full-length recombinant human TRPV1 protein and utilized to develop a sandwich ELISA assay. Monoclonal antibody 10E3-1A2 specifically recognized TRPV1 protein and the recognition epitope was determined to reside in amino acids 45-58 of human and rat TRPV1. Using the TRPV1 polyclonal antibody ABRK4 as the capturing antibody and the monoclonal antibody 10E3-1A2 as the detection antibody, a sandwich ELISA that detected both human and rat TRPV1 protein was established. Recombinant human TRPV1 heterologously expressed in mammalian HEK293-F cells, which showed high ligand-binding affinity, was purified by TRPV1 monoclonal antibody affinity chromatography and used as protein standard to quantify TRPV1 protein levels. This ELISA detected TRPV1 protein as low as 1.5ng/ml (15pM), and was able to determine TRPV1 protein levels in native rat tissues such as DRG and spinal cord. This is the first TRPV1 sandwich ELISA that determines the abundance of TRPV1 protein in different tissues. It provides a powerful tool to quantify changes of TRPV1 protein levels in pathological states.