RESUMEN
Understanding the normal function of the Huntingtin (HTT) protein is of significance in the design and implementation of therapeutic strategies for Huntington's disease (HD). Expansion of the CAG repeat in the HTT gene, encoding an expanded polyglutamine (polyQ) repeat within the HTT protein, causes HD and may compromise HTT's normal activity contributing to HD pathology. Here, we investigated the previously defined role of HTT in autophagy specifically through studying HTT's association with ubiquitin. We find that HTT interacts directly with ubiquitin in vitro. Tandem affinity purification was used to identify ubiquitinated and ubiquitin-associated proteins that copurify with a HTT N-terminal fragment under basal conditions. Copurification is enhanced by HTT polyQ expansion and reduced by mimicking HTT serine 421 phosphorylation. The identified HTT-interacting proteins include RNA-binding proteins (RBPs) involved in mRNA translation, proteins enriched in stress granules, the nuclear proteome, the defective ribosomal products (DRiPs) proteome and the brain-derived autophagosomal proteome. To determine whether the proteins interacting with HTT are autophagic targets, HTT knockout (KO) cells and immunoprecipitation of lysosomes were used to investigate autophagy in the absence of HTT. HTT KO was associated with reduced abundance of mitochondrial proteins in the lysosome, indicating a potential compromise in basal mitophagy, and increased lysosomal abundance of RBPs which may result from compensatory up-regulation of starvation-induced macroautophagy. We suggest HTT is critical for appropriate basal clearance of mitochondrial proteins and RBPs, hence reduced HTT proteostatic function with mutation may contribute to the neuropathology of HD.
Asunto(s)
Proteína Huntingtina , Lisosomas , Mitocondrias , Proteínas de Unión al ARN , Ubiquitina , Proteína Huntingtina/metabolismo , Proteína Huntingtina/genética , Lisosomas/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Humanos , Ubiquitina/metabolismo , Mitocondrias/metabolismo , Autofagia , Animales , Proteínas Mitocondriales/metabolismo , Proteínas Mitocondriales/genética , Ratones , Unión Proteica , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Péptidos/metabolismoRESUMEN
The high heritability of amyotrophic lateral sclerosis (ALS) contrasts with its low molecular diagnosis rate post-genetic testing, pointing to potential undiscovered genetic factors. To aid the exploration of these factors, we introduced EpiOut, an algorithm to identify chromatin accessibility outliers that are regions exhibiting divergent accessibility from the population baseline in a single or few samples. Annotation of accessible regions with histone chromatin immunoprecipitation sequencing and Hi-C indicates that outliers are concentrated in functional loci, especially among promoters interacting with active enhancers. Across different omics levels, outliers are robustly replicated, and chromatin accessibility outliers are reliable predictors of gene expression outliers and aberrant protein levels. When promoter accessibility does not align with gene expression, our results indicate that molecular aberrations are more likely to be linked to post-transcriptional regulation rather than transcriptional regulation. Our findings demonstrate that the outlier detection paradigm can uncover dysregulated regions in rare diseases. EpiOut is available at github.com/uci-cbcl/EpiOut.
Asunto(s)
Esclerosis Amiotrófica Lateral , Cromatina , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Humanos , Cromatina/metabolismo , Cromatina/genética , Regiones Promotoras Genéticas/genética , Algoritmos , Regulación de la Expresión Génica , Secuenciación de Inmunoprecipitación de Cromatina , Histonas/metabolismo , Histonas/genéticaRESUMEN
Huntington's disease (HD), a genetic neurodegenerative disorder, primarily affects the striatum and cortex with progressive loss of medium-sized spiny neurons (MSNs) and pyramidal neurons, disrupting cortico-striatal circuitry. A promising regenerative therapeutic strategy of transplanting human neural stem cells (hNSCs) is challenged by the need for long-term functional integration. We previously described that, with short-term hNSC transplantation into the striatum of HD R6/2 mice, human cells differentiated into electrophysiologically active immature neurons, improving behavior and biochemical deficits. Here, we show that long-term (8 months) implantation of hNSCs into the striatum of HD zQ175 mice ameliorates behavioral deficits, increases brain-derived neurotrophic factor (BDNF) levels, and reduces mutant huntingtin (mHTT) accumulation. Patch clamp recordings, immunohistochemistry, single-nucleus RNA sequencing (RNA-seq), and electron microscopy demonstrate that hNSCs differentiate into diverse neuronal populations, including MSN- and interneuron-like cells, and form connections. Single-nucleus RNA-seq analysis also shows restoration of several mHTT-mediated transcriptional changes of endogenous striatal HD mouse cells. Remarkably, engrafted cells receive synaptic inputs, innervate host neurons, and improve membrane and synaptic properties. Overall, the findings support hNSC transplantation for further evaluation and clinical development for HD.
Asunto(s)
Enfermedad de Huntington , Células-Madre Neurales , Humanos , Ratones , Animales , Enfermedad de Huntington/genética , Enfermedad de Huntington/terapia , Cuerpo Estriado , Neuronas , Fenotipo , Modelos Animales de Enfermedad , Ratones Transgénicos , Proteína Huntingtina/genéticaRESUMEN
Using induced pluripotent stem cells (iPSCs) to understand the mechanisms of neurological disease holds great promise; however, there is a lack of well-curated lines from a large array of participants. Answer ALS has generated over 1,000 iPSC lines from control and amyotrophic lateral sclerosis (ALS) patients along with clinical and whole-genome sequencing data. The current report summarizes cell marker and gene expression in motor neuron cultures derived from 92 healthy control and 341 ALS participants using a 32-day differentiation protocol. This is the largest set of iPSCs to be differentiated into motor neurons, and characterization suggests that cell composition and sex are significant sources of variability that need to be carefully controlled for in future studies. These data are reported as a resource for the scientific community that will utilize Answer ALS data for disease modeling using a wider array of omics being made available for these samples.
Asunto(s)
Esclerosis Amiotrófica Lateral , Células Madre Pluripotentes Inducidas , Humanos , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas Motoras/metabolismo , Diferenciación CelularRESUMEN
Huntington disease (HD) is a neurodegenerative disorder caused by expanded CAG repeats in the huntingtin gene that alters cellular homeostasis, particularly in the striatum and cortex. Astrocyte signaling that establishes and maintains neuronal functions are often altered under pathological conditions. We performed single-nuclei RNA-sequencing on human HD patient-induced pluripotent stem cell (iPSC)-derived astrocytes and on striatal and cortical tissue from R6/2 HD mice to investigate high-resolution HD astrocyte cell state transitions. We observed altered maturation and glutamate signaling in HD human and mouse astrocytes. Human HD astrocytes also showed upregulated actin-mediated signaling, suggesting that some states may be cell-autonomous and human specific. In both species, astrogliogenesis transcription factors may drive HD astrocyte maturation deficits, which are supported by rescued climbing deficits in HD drosophila with NFIA knockdown. Thus, dysregulated HD astrocyte states may induce dysfunctional astrocytic properties, in part due to maturation deficits influenced by astrogliogenesis transcription factor dysregulation.
RESUMEN
Astrocytes and brain endothelial cells are components of the neurovascular unit that comprises the blood-brain barrier (BBB) and their dysfunction contributes to pathogenesis in Huntington's disease (HD). Defining the contribution of these cells to disease can inform cell-type-specific effects and uncover new disease-modifying therapeutic targets. These cells express integrin (ITG) adhesion receptors that anchor the cells to the extracellular matrix (ECM) to maintain the integrity of the BBB. We used HD patient-derived induced pluripotent stem cell (iPSC) modeling to study the ECM-ITG interface in astrocytes and brain microvascular endothelial cells and found ECM-ITG dysregulation in human iPSC-derived cells that may contribute to the dysfunction of the BBB in HD. This disruption has functional consequences since reducing ITG expression in glia in an HD Drosophila model suppressed disease-associated CNS dysfunction. Since ITGs can be targeted therapeutically and manipulating ITG signaling prevents neurodegeneration in other diseases, defining the role of ITGs in HD may provide a novel strategy of intervention to slow CNS pathophysiology to treat HD.
Asunto(s)
Enfermedad de Huntington , Integrinas , Humanos , Integrinas/metabolismo , Células Endoteliales/metabolismo , Enfermedad de Huntington/patología , Neuroglía/metabolismo , Barrera Hematoencefálica/metabolismo , Matriz Extracelular/metabolismoRESUMEN
The complexity of affected brain regions and cell types is a challenge for Huntington's disease (HD) treatment. Here we use single nucleus RNA sequencing to investigate molecular pathology in the cortex and striatum from R6/2 mice and human HD post-mortem tissue. We identify cell type-specific and -agnostic signatures suggesting oligodendrocytes (OLs) and oligodendrocyte precursors (OPCs) are arrested in intermediate maturation states. OL-lineage regulators OLIG1 and OLIG2 are negatively correlated with CAG length in human OPCs, and ATACseq analysis of HD mouse NeuN-negative cells shows decreased accessibility regulated by OL maturation genes. The data implicates glucose and lipid metabolism in abnormal cell maturation and identify PRKCE and Thiamine Pyrophosphokinase 1 (TPK1) as central genes. Thiamine/biotin treatment of R6/1 HD mice to compensate for TPK1 dysregulation restores OL maturation and rescues neuronal pathology. Our insights into HD OL pathology spans multiple brain regions and link OL maturation deficits to abnormal thiamine metabolism.
Asunto(s)
Biotina , Enfermedad de Huntington , Oligodendroglía , Tiamina , Animales , Humanos , Ratones , Biotina/metabolismo , Biotina/farmacología , Suplementos Dietéticos , Modelos Animales de Enfermedad , Enfermedad de Huntington/metabolismo , Ratones Transgénicos , Proteínas del Tejido Nervioso/metabolismo , Oligodendroglía/metabolismo , Núcleo Solitario/metabolismo , Tiamina/metabolismo , Tiamina/farmacologíaRESUMEN
Answer ALS is a biological and clinical resource of patient-derived, induced pluripotent stem (iPS) cell lines, multi-omic data derived from iPS neurons and longitudinal clinical and smartphone data from over 1,000 patients with ALS. This resource provides population-level biological and clinical data that may be employed to identify clinical-molecular-biochemical subtypes of amyotrophic lateral sclerosis (ALS). A unique smartphone-based system was employed to collect deep clinical data, including fine motor activity, speech, breathing and linguistics/cognition. The iPS spinal neurons were blood derived from each patient and these cells underwent multi-omic analytics including whole-genome sequencing, RNA transcriptomics, ATAC-sequencing and proteomics. The intent of these data is for the generation of integrated clinical and biological signatures using bioinformatics, statistics and computational biology to establish patterns that may lead to a better understanding of the underlying mechanisms of disease, including subgroup identification. A web portal for open-source sharing of all data was developed for widespread community-based data analytics.
Asunto(s)
Esclerosis Amiotrófica Lateral , Células Madre Pluripotentes Inducidas , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Línea Celular , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas Motoras/fisiologíaRESUMEN
Neurodegenerative diseases are challenging for systems biology because of the lack of reliable animal models or patient samples at early disease stages. Induced pluripotent stem cells (iPSCs) could address these challenges. We investigated DNA, RNA, epigenetics, and proteins in iPSC-derived motor neurons from patients with ALS carrying hexanucleotide expansions in C9ORF72. Using integrative computational methods combining all omics datasets, we identified novel and known dysregulated pathways. We used a C9ORF72 Drosophila model to distinguish pathways contributing to disease phenotypes from compensatory ones and confirmed alterations in some pathways in postmortem spinal cord tissue of patients with ALS. A different differentiation protocol was used to derive a separate set of C9ORF72 and control motor neurons. Many individual -omics differed by protocol, but some core dysregulated pathways were consistent. This strategy of analyzing patient-specific neurons provides disease-related outcomes with small numbers of heterogeneous lines and reduces variation from single-omics to elucidate network-based signatures.
RESUMEN
Chronic cellular stress associated with neurodegenerative disease can result in the persistence of stress granule (SG) structures, membraneless organelles that form in response to cellular stress. In Huntington's disease (HD), chronic expression of mutant huntingtin generates various forms of cellular stress, including activation of the unfolded protein response and oxidative stress. However, it has yet to be determined whether SGs are a feature of HD neuropathology. We examined the miRNA composition of extracellular vesicles (EVs) present in the cerebrospinal fluid (CSF) of patients with HD and show that a subset of their target mRNAs were differentially expressed in the prefrontal cortex. Of these targets, SG components were enriched, including the SG-nucleating Ras GTPase-activating protein-binding protein 1 (G3BP1). We investigated localization and levels of G3BP1 and found a significant increase in the density of G3BP1-positive granules in the cortex and hippocampus of R6/2 transgenic mice and in the superior frontal cortex of the brains of patients with HD. Intriguingly, we also observed that the SG-associated TAR DNA-binding protein 43 (TDP43), a nuclear RNA/DNA binding protein, was mislocalized to the cytoplasm of G3BP1 granule-positive HD cortical neurons. These findings suggest that G3BP1 SG dynamics may play a role in the pathophysiology of HD.
Asunto(s)
Gránulos Citoplasmáticos/metabolismo , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Hipocampo/metabolismo , Enfermedad de Huntington/metabolismo , Neuronas/metabolismo , Proteínas de Unión a Poli-ADP-Ribosa/metabolismo , Corteza Prefrontal/metabolismo , ARN Helicasas/metabolismo , Proteínas con Motivos de Reconocimiento de ARN/metabolismo , Animales , Gránulos Citoplasmáticos/patología , ADN Helicasas/genética , Proteínas de Unión al ADN/genética , Femenino , Hipocampo/patología , Humanos , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Masculino , Ratones , MicroARNs/genética , MicroARNs/metabolismo , Neuronas/patología , Proteínas de Unión a Poli-ADP-Ribosa/genética , Corteza Prefrontal/patología , Transporte de Proteínas/genética , ARN Helicasas/genética , Proteínas con Motivos de Reconocimiento de ARN/genéticaRESUMEN
DNA damage repair genes are modifiers of disease onset in Huntington's disease (HD), but how this process intersects with associated disease pathways remains unclear. Here we evaluated the mechanistic contributions of protein inhibitor of activated STAT-1 (PIAS1) in HD mice and HD patient-derived induced pluripotent stem cells (iPSCs) and find a link between PIAS1 and DNA damage repair pathways. We show that PIAS1 is a component of the transcription-coupled repair complex, that includes the DNA damage end processing enzyme polynucleotide kinase-phosphatase (PNKP), and that PIAS1 is a SUMO E3 ligase for PNKP. Pias1 knockdown (KD) in HD mice had a normalizing effect on HD transcriptional dysregulation associated with synaptic function and disease-associated transcriptional coexpression modules enriched for DNA damage repair mechanisms as did reduction of PIAS1 in HD iPSC-derived neurons. KD also restored mutant HTT-perturbed enzymatic activity of PNKP and modulated genomic integrity of several transcriptionally normalized genes. The findings here now link SUMO modifying machinery to DNA damage repair responses and transcriptional modulation in neurodegenerative disease.
Asunto(s)
Enzimas Reparadoras del ADN/genética , Reparación del ADN , ADN/genética , Proteína Huntingtina/genética , Enfermedad de Huntington/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Proteínas Inhibidoras de STAT Activados/genética , Procesamiento Proteico-Postraduccional , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/genética , Animales , Diferenciación Celular , ADN/metabolismo , Daño del ADN , Enzimas Reparadoras del ADN/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neuronas/metabolismo , Neuronas/patología , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Células Madre Pluripotentes/metabolismo , Células Madre Pluripotentes/patología , Cultivo Primario de Células , Proteínas Inhibidoras de STAT Activados/antagonistas & inhibidores , Proteínas Inhibidoras de STAT Activados/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/antagonistas & inhibidores , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/metabolismo , Sumoilación , Transcripción GenéticaRESUMEN
Aberrant neuronal development and the persistence of mitotic cellular populations have been implicated in a multitude of neurological disorders, including Huntington's disease (HD). However, the mechanism underlying this potential pathology remains unclear. We used a modified protocol to differentiate induced pluripotent stem cells (iPSCs) from HD patients and unaffected controls into neuronal cultures enriched for medium spiny neurons, the cell type most affected in HD. We performed single-cell and bulk transcriptomic and epigenomic analyses and demonstrated that a persistent cyclin D1+ neural stem cell (NSC) population is observed selectively in adult-onset HD iPSCs during differentiation. Treatment with a WNT inhibitor abrogates this NSC population while preserving neurons. Taken together, our findings identify a mechanism that may promote aberrant neurodevelopment and adult neurogenesis in adult-onset HD striatal neurons with the potential for therapeutic compensation.
Asunto(s)
Enfermedad de Huntington/patología , Células Madre Pluripotentes Inducidas/patología , Neuronas/patología , Vía de Señalización Wnt , Adulto , Edad de Inicio , Ciclo Celular/genética , Diferenciación Celular/genética , Células Cultivadas , Epigénesis Genética , Humanos , Enfermedad de Huntington/genética , Mitosis , Neostriado/patología , Células-Madre Neurales/metabolismo , Factores de Transcripción/metabolismo , Transcriptoma/genética , Regulación hacia Arriba/genéticaRESUMEN
Transcriptional and epigenetic alterations occur early in Huntington's disease (HD), and treatment with epigenetic modulators is beneficial in several HD animal models. The drug JQ1, which inhibits histone acetyl-lysine reader bromodomains, has shown promise for multiple cancers and neurodegenerative disease. We tested whether JQ1 could improve behavioral phenotypes in the R6/2 mouse model of HD and modulate HD-associated changes in transcription and epigenomics. R6/2 and non-transgenic (NT) mice were treated with JQ1 daily from 5 to 11 weeks of age and behavioral phenotypes evaluated over this period. Following the trial, cortex and striatum were isolated and subjected to mRNA-seq and ChIP-seq for the histone marks H3K4me3 and H3K27ac. Initially, JQ1 enhanced motor performance in NT mice. In R6/2 mice, however, JQ1 had no effect on rotarod or grip strength but exacerbated weight loss and worsened performance on the pole test. JQ1-induced gene expression changes in NT mice were distinct from those in R6/2 and primarily involved protein translation and bioenergetics pathways. Dysregulation of HD-related pathways in striatum was exacerbated by JQ1 in R6/2 mice, but not in NTs, and JQ1 caused a corresponding increase in the formation of a mutant huntingtin protein-dependent high molecular weight species associated with pathogenesis. This study suggests that drugs predicted to be beneficial based on their mode of action and effects in wild-type or in other neurodegenerative disease models may have an altered impact in the HD context. These observations have important implications in the development of epigenetic modulators as therapies for HD.
Asunto(s)
Azepinas/farmacología , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/metabolismo , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/metabolismo , Triazoles/farmacología , Acetilación , Animales , Escala de Evaluación de la Conducta , Síntomas Conductuales/tratamiento farmacológico , Corteza Cerebral/patología , Secuenciación de Inmunoprecipitación de Cromatina , Cuerpo Estriado/patología , Modelos Animales de Enfermedad , Metabolismo Energético/efectos de los fármacos , Epigénesis Genética/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Ontología de Genes , Histonas/metabolismo , Proteína Huntingtina/genética , Enfermedad de Huntington/tratamiento farmacológico , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Masculino , Ratones , Ratones Transgénicos , Actividad Motora/efectos de los fármacos , Biosíntesis de Proteínas/efectos de los fármacos , RNA-Seq , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genéticaRESUMEN
Neuroinflammation is an important contributor to neuronal pathology and death in neurodegenerative diseases and neuronal injury. Therapeutic interventions blocking the activity of the inflammatory kinase IKKß, a key regulator of neuroinflammatory pathways, is protective in several animal models of neurodegenerative disease and neuronal injury. In Huntington's disease (HD), however, significant questions exist as to the impact of blocking or diminishing the activity of IKKß on HD pathology given its potential role in Huntingtin (HTT) degradation. In cell culture, IKKß phosphorylates HTT serine (S) 13 and activates HTT degradation, a process that becomes impaired with polyQ expansion. To investigate the in vivo relationship of IKKß to HTT S13 phosphorylation and HD progression, we crossed conditional tamoxifen-inducible IKKß knockout mice with R6/1 HD mice. Behavioral assays in these mice showed a significant worsening of HD pathological phenotypes. The increased behavioral pathology correlated with reduced levels of endogenous mouse full-length phospho-S13 HTT, supporting the importance of IKKß in the phosphorylation of HTT S13 in vivo. Notably, many striatal autophagy genes were up-regulated in HD vs. control mice; however, IKKß knockout partially reduced this up-regulation in HD, increased striatal neurodegeneration, and enhanced an activated microglial response. We propose that IKKß is protective in striatal neurons early in HD progression via phosphorylation of HTT S13. As IKKß is also required for up-regulation of some autophagy genes and HTT is a scaffold for selective autophagy, IKKß may influence autophagy through multiple mechanisms to maintain healthy striatal function, thereby reducing neuronal degeneration to slow HD onset.
Asunto(s)
Enfermedad de Huntington , Quinasa I-kappa B , Animales , Autofagia/genética , Cuerpo Estriado/citología , Cuerpo Estriado/patología , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Quinasa I-kappa B/genética , Quinasa I-kappa B/metabolismo , Masculino , Ratones , Ratones Noqueados , Microglía/citología , Microglía/patología , Fosforilación/genéticaRESUMEN
Brain microvascular endothelial cells (BMECs) are an essential component of the blood-brain barrier (BBB) that shields the brain against toxins and immune cells. While BBB dysfunction exists in neurological disorders, including Huntington's disease (HD), it is not known if BMECs themselves are functionally compromised to promote BBB dysfunction. Further, the underlying mechanisms of BBB dysfunction remain elusive given limitations with mouse models and post-mortem tissue to identify primary deficits. We undertook a transcriptome and functional analysis of human induced pluripotent stem cell (iPSC)-derived BMECs (iBMEC) from HD patients or unaffected controls. We demonstrate that HD iBMECs have intrinsic abnormalities in angiogenesis and barrier properties, as well as in signaling pathways governing these processes. Thus, our findings provide an iPSC-derived BBB model for a neurodegenerative disease and demonstrate autonomous neurovascular deficits that may underlie HD pathology with implications for therapeutics and drug delivery.
Asunto(s)
Barrera Hematoencefálica/patología , Células Endoteliales/patología , Enfermedad de Huntington/patología , Células Madre Pluripotentes Inducidas/patología , Microvasos/patología , Neovascularización Fisiológica , Vía de Señalización Wnt , Redes Reguladoras de Genes , Humanos , Enfermedad de Huntington/genética , Células Madre Pluripotentes Inducidas/metabolismo , Transcriptoma/genética , Transcitosis , beta Catenina/metabolismoRESUMEN
Inactivating mutations in the thyroid hormone (TH) transporter Monocarboxylate transporter 8 (MCT8) cause severe psychomotor retardation in children. Animal models do not reflect the biology of the human disease. Using patient-specific induced pluripotent stem cells (iPSCs), we generated MCT8-deficient neural cells that showed normal TH-dependent neuronal properties and maturation. However, the blood-brain barrier (BBB) controls TH entry into the brain, and reduced TH availability to neural cells could instead underlie the diseased phenotype. To test potential BBB involvement, we generated an iPSC-based BBB model of MCT8 deficiency, and we found that MCT8 was necessary for polarized influx of the active form of TH across the BBB. We also found that a candidate drug did not appreciably cross the mutant BBB. Our results therefore clarify the underlying physiological basis of this disorder, and they suggest that circumventing the diseased BBB to deliver active TH to the brain could be a viable therapeutic strategy.
Asunto(s)
Barrera Hematoencefálica/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Transportadores de Ácidos Monocarboxílicos/deficiencia , Neuronas/metabolismo , Trastornos Psicomotores/metabolismo , Barrera Hematoencefálica/patología , Línea Celular , Femenino , Humanos , Células Madre Pluripotentes Inducidas/patología , Masculino , Neuronas/patología , Trastornos Psicomotores/genética , Trastornos Psicomotores/patología , SimportadoresRESUMEN
There are currently no disease-modifying therapies for the neurodegenerative disorder Huntington's disease (HD). This study identified novel thiazole-containing inhibitors of the deacetylase sirtuin-2 (SIRT2) with neuroprotective activity in ex vivo brain slice and Drosophila models of HD. A systems biology approach revealed an additional SIRT2-independent property of the lead-compound, MIND4, as an inducer of cytoprotective NRF2 (nuclear factor-erythroid 2 p45-derived factor 2) activity. Structure-activity relationship studies further identified a potent NRF2 activator (MIND4-17) lacking SIRT2 inhibitory activity. MIND compounds induced NRF2 activation responses in neuronal and non-neuronal cells and reduced production of reactive oxygen species and nitrogen intermediates. These drug-like thiazole-containing compounds represent an exciting opportunity for development of multi-targeted agents with potentially synergistic therapeutic benefits in HD and related disorders.