RESUMEN
Characterizing somatic mutations in the brain is important for disentangling the complex mechanisms of aging, yet little is known about mutational patterns in different brain cell types. Here, we performed whole-genome sequencing (WGS) of 86 single oligodendrocytes, 20 mixed glia, and 56 single neurons from neurotypical individuals spanning 0.4-104 years of age and identified >92,000 somatic single-nucleotide variants (sSNVs) and small insertions/deletions (indels). Although both cell types accumulate somatic mutations linearly with age, oligodendrocytes accumulated sSNVs 81% faster than neurons and indels 28% slower than neurons. Correlation of mutations with single-nucleus RNA profiles and chromatin accessibility from the same brains revealed that oligodendrocyte mutations are enriched in inactive genomic regions and are distributed across the genome similarly to mutations in brain cancers. In contrast, neuronal mutations are enriched in open, transcriptionally active chromatin. These stark differences suggest an assortment of active mutagenic processes in oligodendrocytes and neurons.
Asunto(s)
Envejecimiento , Encéfalo , Neuronas , Oligodendroglía , Humanos , Envejecimiento/genética , Envejecimiento/patología , Cromatina/genética , Cromatina/metabolismo , Mutación , Neuronas/metabolismo , Neuronas/patología , Oligodendroglía/metabolismo , Oligodendroglía/patología , Análisis de Expresión Génica de una Sola Célula , Secuenciación Completa del Genoma , Encéfalo/metabolismo , Encéfalo/patología , Polimorfismo de Nucleótido Simple , Mutación INDEL , Bancos de Muestras Biológicas , Células Precursoras de Oligodendrocitos/metabolismo , Células Precursoras de Oligodendrocitos/patologíaRESUMEN
The discovery of tissue-resident innate lymphoid cell populations effecting different forms of type 1, 2, and 3 immunity; tissue repair; and immune regulation has transformed our understanding of mucosal immunity and allergy. The emerging complexity of these populations along with compounding issues of redundancy and plasticity raise intriguing questions about their precise lineage relationship. Here we review advances in mapping the emergence of these lineages from early lymphoid precursors. We discuss the identification of a common innate lymphoid cell precursor characterized by transient expression of the transcription factor PLZF, and the lineage relationships of innate lymphoid cells with conventional natural killer cells and lymphoid tissue inducer cells. We also review the rapidly growing understanding of the network of transcription factors that direct the development of these lineages.
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Diferenciación Celular , Hipersensibilidad/inmunología , Inmunidad Innata , Linfocitos/inmunología , Células Progenitoras Linfoides/inmunología , Animales , Linaje de la Célula , Citocinas/metabolismo , Regulación de la Expresión Génica/inmunología , Redes Reguladoras de Genes , Humanos , Factores de Transcripción de Tipo Kruppel/genética , Factores de Transcripción de Tipo Kruppel/metabolismo , Proteína de la Leucemia Promielocítica con Dedos de Zinc , Células TH1/inmunología , Células Th2/inmunologíaRESUMEN
Expansion of CAG trinucleotide repeats in ATXN1 causes spinocerebellar ataxia type 1 (SCA1), a neurodegenerative disease that impairs coordination and cognition. While ATXN1 is associated with increased Alzheimer's disease (AD) risk, CAG repeat number in AD patients is not changed. Here, we investigated the consequences of ataxin-1 loss of function and discovered that knockout of Atxn1 reduced CIC-ETV4/5-mediated inhibition of Bace1 transcription, leading to increased BACE1 levels and enhanced amyloidogenic cleavage of APP, selectively in AD-vulnerable brain regions. Elevated BACE1 expression exacerbated Aß deposition and gliosis in AD mouse models and impaired hippocampal neurogenesis and olfactory axonal targeting. In SCA1 mice, polyglutamine-expanded mutant ataxin-1 led to the increase of BACE1 post-transcriptionally, both in cerebrum and cerebellum, and caused axonal-targeting deficit and neurodegeneration in the hippocampal CA2 region. These findings suggest that loss of ataxin-1 elevates BACE1 expression and Aß pathology, rendering it a potential contributor to AD risk and pathogenesis.
Asunto(s)
Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Ataxina-1/metabolismo , Encéfalo/metabolismo , Enfermedad de Alzheimer/metabolismo , Secretasas de la Proteína Precursora del Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Ataxina-1/deficiencia , Ataxina-1/genética , Encéfalo/patología , Región CA2 Hipocampal/metabolismo , Región CA2 Hipocampal/patología , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Modelos Animales de Enfermedad , Femenino , Frecuencia de los Genes , Humanos , Masculino , Ratones , Ratones Transgénicos , Neurogénesis , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Proto-Oncogénicas c-ets/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética , Repeticiones de Trinucleótidos/genética , Regulación hacia ArribaRESUMEN
V2-glycan/apex broadly neutralizing antibodies (bnAbs) recognize a closed quaternary epitope of the HIV-1 envelope glycoprotein (Env). This closed structure is necessary to elicit apex antibodies and useful to guide the maturation of other bnAb classes. To compare antigens designed to maintain this conformation, we evaluated apex-specific responses in mice engrafted with a diverse repertoire of B cells expressing the HCDR3 of the apex bnAb VRC26.25. Engineered B cells affinity matured, guiding the improvement of VRC26.25 itself. We found that soluble Env (SOSIP) variants differed significantly in their ability to raise anti-apex responses. A transmembrane SOSIP (SOSIP-TM) delivered as an mRNA-lipid nanoparticle elicited more potent neutralizing responses than multimerized SOSIP proteins. Importantly, SOSIP-TM elicited neutralizing sera from B cells engineered with the predicted VRC26.25-HCDR3 progenitor, which also affinity matured. Our data show that HCDR3-edited B cells facilitate efficient in vivo comparisons of Env antigens and highlight the potential of an HCDR3-focused vaccine approach.
Asunto(s)
Vacunas contra el SIDA , Infecciones por VIH , VIH-1 , Vacunas , Animales , Ratones , Anticuerpos Anti-VIH , Anticuerpos Neutralizantes , Anticuerpos ampliamente neutralizantes , Antígenos Virales , Productos del Gen env del Virus de la Inmunodeficiencia HumanaRESUMEN
Cleavage of membrane-anchored proteins by ADAM (a disintegrin and metalloproteinase) endopeptidases plays a key role in a wide variety of biological signal transduction and protein turnover processes. Among ADAM family members, ADAM10 stands out as particularly important because it is both responsible for regulated proteolysis of Notch receptors and catalyzes the non-amyloidogenic α-secretase cleavage of the Alzheimer's precursor protein (APP). We present here the X-ray crystal structure of the ADAM10 ectodomain, which, together with biochemical and cellular studies, reveals how access to the enzyme active site is regulated. The enzyme adopts an unanticipated architecture in which the C-terminal cysteine-rich domain partially occludes the enzyme active site, preventing unfettered substrate access. Binding of a modulatory antibody to the cysteine-rich domain liberates the catalytic domain from autoinhibition, enhancing enzymatic activity toward a peptide substrate. Together, these studies reveal a mechanism for regulation of ADAM activity and offer a roadmap for its modulation.
Asunto(s)
Proteína ADAM10/química , Secretasas de la Proteína Precursora del Amiloide/química , Proteínas de la Membrana/química , Proteolisis , Proteína ADAM10/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Cristalografía por Rayos X , Humanos , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Receptores Notch/metabolismo , Transducción de SeñalRESUMEN
Alzheimer's disease (AD)-linked mutations in Presenilins (PSEN) and the amyloid precursor protein (APP) lead to production of longer amyloidogenic Aß peptides. The shift in Aß length is fundamental to the disease; however, the underlying mechanism remains elusive. Here, we show that substrate shortening progressively destabilizes the consecutive enzyme-substrate (E-S) complexes that characterize the sequential γ-secretase processing of APP. Remarkably, pathogenic PSEN or APP mutations further destabilize labile E-S complexes and thereby promote generation of longer Aß peptides. Similarly, destabilization of wild-type E-S complexes by temperature, compounds, or detergent promotes release of amyloidogenic Aß. In contrast, E-Aßn stabilizers increase γ-secretase processivity. Our work presents a unifying model for how PSEN or APP mutations enhance amyloidogenic Aß production, suggests that environmental factors may increase AD risk, and provides the theoretical basis for the development of γ-secretase/substrate stabilizing compounds for the prevention of AD.
Asunto(s)
Enfermedad de Alzheimer/enzimología , Enfermedad de Alzheimer/genética , Precursor de Proteína beta-Amiloide/metabolismo , Proteínas de la Membrana/metabolismo , Péptido Hidrolasas/metabolismo , Presenilina-1/metabolismo , Precursor de Proteína beta-Amiloide/química , Animales , Encéfalo/metabolismo , Encéfalo/patología , Línea Celular , Endopeptidasas , Estabilidad de Enzimas , Femenino , Células HEK293 , Humanos , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Ratones , Modelos Moleculares , Mutación , Péptido Hidrolasas/química , Péptido Hidrolasas/genética , Presenilina-1/química , Presenilina-1/genéticaRESUMEN
The lateral ventricle subventricular zone (SVZ) is a frequent and consequential site of pediatric and adult glioma spread, but the cellular and molecular mechanisms mediating this are poorly understood. We demonstrate that neural precursor cell (NPC):glioma cell communication underpins this propensity of glioma to colonize the SVZ through secretion of chemoattractant signals toward which glioma cells home. Biochemical, proteomic, and functional analyses of SVZ NPC-secreted factors revealed the neurite outgrowth-promoting factor pleiotrophin, along with required binding partners SPARC/SPARCL1 and HSP90B, as key mediators of this chemoattractant effect. Pleiotrophin expression is strongly enriched in the SVZ, and pleiotrophin knock down starkly reduced glioma invasion of the SVZ in the murine brain. Pleiotrophin, in complex with the binding partners, activated glioma Rho/ROCK signaling, and ROCK inhibition decreased invasion toward SVZ NPC-secreted factors. These findings demonstrate a pathogenic role for NPC:glioma interactions and potential therapeutic targets to limit glioma invasion. PAPERCLIP.
Asunto(s)
Neoplasias Encefálicas/patología , Proteínas Portadoras/metabolismo , Citocinas/metabolismo , Glioma/patología , Ventrículos Laterales/patología , Invasividad Neoplásica/patología , Anciano , Animales , Neoplasias Encefálicas/metabolismo , Comunicación Celular , Niño , Sistemas de Liberación de Medicamentos , Femenino , Glioma/tratamiento farmacológico , Proteínas HSP90 de Choque Térmico/antagonistas & inhibidores , Xenoinjertos , Humanos , Ventrículos Laterales/metabolismo , Masculino , Ratones , Trasplante de Neoplasias , Transducción de Señal , Proteínas de Unión al GTP rho/metabolismoRESUMEN
C2c2, the effector of type VI CRISPR-Cas systems, has two RNase activities-one for cutting its RNA target and the other for processing the CRISPR RNA (crRNA). Here, we report the structures of Leptotrichia shahii C2c2 in its crRNA-free and crRNA-bound states. While C2c2 has a bilobed structure reminiscent of all other Class 2 effectors, it also exhibits different structural characteristics. It contains the REC lobe with a Helical-1 domain and the NUC lobe with two HEPN domains. The two RNase catalytic pockets responsible for cleaving pre-crRNA and target RNA are independently located on Helical-1 and HEPN domains, respectively. crRNA binding induces significant conformational changes that are likely to stabilize crRNA binding and facilitate target RNA recognition. These structures provide important insights into the molecular mechanism of dual RNase activities of C2c2 and establish a framework for its future engineering as a RNA editing tool.
Asunto(s)
Sistemas CRISPR-Cas , Leptotrichia/química , Leptotrichia/enzimología , Ribonucleasas/química , Secuencia de Aminoácidos , Dominio Catalítico , Leptotrichia/clasificación , Leptotrichia/metabolismo , Modelos Moleculares , Mutagénesis , Procesamiento Postranscripcional del ARN , ARN Bacteriano/química , ARN no Traducido/química , Alineación de SecuenciaRESUMEN
Human apolipoprotein E (ApoE) apolipoprotein is primarily expressed in three isoforms (ApoE2, ApoE3, and ApoE4) that differ only by two residues. ApoE4 constitutes the most important genetic risk factor for Alzheimer's disease (AD), ApoE3 is neutral, and ApoE2 is protective. How ApoE isoforms influence AD pathogenesis, however, remains unclear. Using ES-cell-derived human neurons, we show that ApoE secreted by glia stimulates neuronal Aß production with an ApoE4 > ApoE3 > ApoE2 potency rank order. We demonstrate that ApoE binding to ApoE receptors activates dual leucine-zipper kinase (DLK), a MAP-kinase kinase kinase that then activates MKK7 and ERK1/2 MAP kinases. Activated ERK1/2 induces cFos phosphorylation, stimulating the transcription factor AP-1, which in turn enhances transcription of amyloid-ß precursor protein (APP) and thereby increases amyloid-ß levels. This molecular mechanism also regulates APP transcription in mice in vivo. Our data describe a novel signal transduction pathway in neurons whereby ApoE activates a non-canonical MAP kinase cascade that enhances APP transcription and amyloid-ß synthesis.
Asunto(s)
Precursor de Proteína beta-Amiloide/genética , Apolipoproteínas E/metabolismo , Sistema de Señalización de MAP Quinasas , Enfermedad de Alzheimer/metabolismo , Animales , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Fibroblastos/metabolismo , Humanos , Ratones , Neuronas/metabolismo , Isoformas de Proteínas/metabolismoRESUMEN
Innate lymphoid cells (ILCs) are critical effectors of innate immunity and inflammation, whose development and activation pathways make for attractive therapeutic targets. However, human ILC generation has not been systematically explored, and previous in vitro investigations relied on the analysis of few markers or cytokines, which are suboptimal to assign lineage identity. Here, we developed a platform that reliably generated human ILC lineages from CD34+ hematopoietic progenitors derived from cord blood and bone marrow. We showed that one culture condition is insufficient to generate all ILC subsets, and instead, distinct combination of cytokines and Notch signaling are essential. The identity of natural killer (NK)/ILC1s, ILC2s, and ILC3s generated in vitro was validated by protein expression, functional assays, and both global and single-cell transcriptome analysis, recapitulating the signatures and functions of their ex vivo ILC counterparts. These data represent a resource to aid in clarifying ILC biology and differentiation.
Asunto(s)
Técnicas de Cultivo de Célula/métodos , Linaje de la Célula/inmunología , Células Madre Hematopoyéticas/inmunología , Inmunidad Innata/inmunología , Linfocitos/inmunología , Antígenos CD34/inmunología , Diferenciación Celular/inmunología , Células Madre Hematopoyéticas/citología , Humanos , Linfocitos/citología , Análisis de la Célula Individual/métodosRESUMEN
During the approximately 5 days of Drosophila neurogenesis (late embryogenesis to the beginning of pupation), a limited number of neural stem cells produce approximately 200,000 neurons comprising hundreds of cell types. To build a functional nervous system, neuronal types need to be produced in the proper places, appropriate numbers, and correct times. We discuss how neural stem cells (neuroblasts) obtain so-called area codes for their positions in the nervous system (spatial patterning) and how they keep time to sequentially produce neurons with unique fates (temporal patterning). We focus on specific examples that demonstrate how a relatively simple patterning system (Notch) can be used reiteratively to generate different neuronal types. We also speculate on how different modes of temporal patterning that operate over short versus long time periods might be linked. We end by discussing how specification programs are integrated and lead to the terminal features of different neuronal types.
Asunto(s)
Proteínas de Drosophila , Células-Madre Neurales , Animales , Drosophila , Proteínas de Drosophila/genética , Neurogénesis , NeuronasRESUMEN
Specialized regulatory T (Treg) cells accumulate and perform homeostatic and regenerative functions in nonlymphoid tissues. Whether common precursors for nonlymphoid-tissue Treg cells exist and how they differentiate remain elusive. Using transcription factor nuclear factor, interleukin 3 regulated (Nfil3) reporter mice and single-cell RNA-sequencing (scRNA-seq), we identified two precursor stages of interleukin 33 (IL-33) receptor ST2-expressing nonlymphoid tissue Treg cells, which resided in the spleen and lymph nodes. Global chromatin profiling of nonlymphoid tissue Treg cells and the two precursor stages revealed a stepwise acquisition of chromatin accessibility and reprogramming toward the nonlymphoid-tissue Treg cell phenotype. Mechanistically, we identified and validated the transcription factor Batf as the driver of the molecular tissue program in the precursors. Understanding this tissue development program will help to harness regenerative properties of tissue Treg cells for therapy.
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Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Ganglios Linfáticos/inmunología , Bazo/inmunología , Linfocitos T Reguladores/citología , Traslado Adoptivo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/deficiencia , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Diferenciación Celular/genética , Cromatina/metabolismo , Factor de Transcripción GATA3/genética , Factor de Transcripción GATA3/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica/inmunología , Proteína 1 Similar al Receptor de Interleucina-1/metabolismo , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Ratones , Especificidad de Órganos/inmunología , Receptores Inmunológicos/genética , Receptores Inmunológicos/metabolismo , Linfocitos T Reguladores/metabolismoRESUMEN
During neocortical development, tight regulation of neurogenesis-to-astrogenesis switching of neural precursor cells (NPCs) is critical to generate a balanced number of each neural cell type for proper brain functions. Accumulating evidence indicates that a complex array of epigenetic modifications and the availability of extracellular factors control the timing of neuronal and astrocytic differentiation. However, our understanding of NPC fate regulation is still far from complete. Bone morphogenetic proteins (BMPs) are renowned as cytokines that induce astrogenesis of gliogenic late-gestational NPCs. They also promote neurogenesis of mid-gestational NPCs, although the underlying mechanisms remain elusive. By performing multiple genome-wide analyses, we demonstrate that Smads, transcription factors that act downstream from BMP signaling, target dramatically different genomic regions in neurogenic and gliogenic NPCs. We found that histone H3K27 trimethylation and DNA methylation around Smad-binding sites change rapidly as gestation proceeds, strongly associated with the alteration of accessibility of Smads to their target binding sites. Furthermore, we identified two lineage-specific Smad-interacting partners-Sox11 for neurogenic and Sox8 for astrocytic differentiation-that further ensure Smad-regulated fate-specific gene induction. Our findings illuminate an exquisite regulation of NPC property change mediated by the interplay between cell-extrinsic cues and -intrinsic epigenetic programs during cortical development.
Asunto(s)
Células-Madre Neurales , Encéfalo , Diferenciación Celular/genética , Epigénesis Genética , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Neurogénesis/genética , Embarazo , Factores de Transcripción SOXE/genéticaRESUMEN
Oligodendrocyte precursor cells (OPCs) are not merely a transitory progenitor cell type, but rather a distinct and heterogeneous population of glia with various functions in the developing and adult central nervous system. In this review, we discuss the fate and function of OPCs in the brain beyond their contribution to myelination. OPCs are electrically sensitive, form synapses with neurons, support blood-brain barrier integrity, and mediate neuroinflammation. We explore how sex and age may influence OPC activity, and we review how OPC dysfunction may play a primary role in numerous neurological and neuropsychiatric diseases. Finally, we highlight areas of future research.
Asunto(s)
Encéfalo/citología , Células Precursoras de Oligodendrocitos/citología , Células Precursoras de Oligodendrocitos/inmunología , Factores de Edad , Animales , Encéfalo/embriología , Encéfalo/inmunología , Encéfalo/metabolismo , Sinapsis Eléctricas/fisiología , Humanos , Trastornos Mentales/patología , Enfermedades del Sistema Nervioso/patología , Células Precursoras de Oligodendrocitos/patología , Células Precursoras de Oligodendrocitos/fisiología , Factores SexualesRESUMEN
Sequential proteolysis of the amyloid precursor protein (APP) by γ-secretases generates amyloid-ß (Aß) peptides and defines the proportion of short-to-long Aß peptides, which is tightly connected to Alzheimer's disease (AD) pathogenesis. Here, we study the mechanism that controls substrate processing by γ-secretases and Aß peptide length. We found that polar interactions established by the APPC99 ectodomain (ECD), involving but not limited to its juxtamembrane region, restrain both the extent and degree of γ-secretases processive cleavage by destabilizing enzyme-substrate interactions. We show that increasing hydrophobicity, via mutation or ligand binding, at APPC99 -ECD attenuates substrate-driven product release and rescues the effects of Alzheimer's disease-associated pathogenic γ-secretase and APP variants on Aß length. In addition, our study reveals that APPC99 -ECD facilitates the paradoxical production of longer Aßs caused by some γ-secretase inhibitors, which act as high-affinity competitors of the substrate. These findings assign a pivotal role to the substrate ECD in the sequential proteolysis by γ-secretases and suggest it as a sweet spot for the potential design of APP-targeting compounds selectively promoting its processing by these enzymes.
Asunto(s)
Enfermedad de Alzheimer , Precursor de Proteína beta-Amiloide , Humanos , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Secretasas de la Proteína Precursora del Amiloide/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Enfermedad de Alzheimer/metabolismo , ProteolisisRESUMEN
Disease-associated variants identified from genome-wide association studies (GWASs) frequently map to non-coding areas of the genome such as introns and intergenic regions. An exclusive reliance on gene-agnostic methods of genomic investigation could limit the identification of relevant genes associated with polygenic diseases such as Alzheimer disease (AD). To overcome such potential restriction, we developed a gene-constrained analytical method that considers only moderate- and high-risk variants that affect gene coding sequences. We report here the application of this approach to publicly available datasets containing 181,388 individuals without and with AD and the resulting identification of 660 genes potentially linked to the higher AD prevalence among Africans/African Americans. By integration with transcriptome analysis of 23 brain regions from 2,728 AD case-control samples, we concentrated on nine genes that potentially enhance the risk of AD: AACS, GNB5, GNS, HIPK3, MED13, SHC2, SLC22A5, VPS35, and ZNF398. GNB5, the fifth member of the heterotrimeric G protein beta family encoding Gß5, is primarily expressed in neurons and is essential for normal neuronal development in mouse brain. Homozygous or compound heterozygous loss of function of GNB5 in humans has previously been associated with a syndrome of developmental delay, cognitive impairment, and cardiac arrhythmia. In validation experiments, we confirmed that Gnb5 heterozygosity enhanced the formation of both amyloid plaques and neurofibrillary tangles in the brains of AD model mice. These results suggest that gene-constrained analysis can complement the power of GWASs in the identification of AD-associated genes and may be more broadly applicable to other polygenic diseases.
Asunto(s)
Enfermedad de Alzheimer , Subunidades beta de la Proteína de Unión al GTP , Ratones , Humanos , Animales , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Estudio de Asociación del Genoma Completo , Ovillos Neurofibrilares/metabolismo , Fenotipo , Genómica , Péptidos beta-Amiloides/genética , Encéfalo/metabolismo , Miembro 5 de la Familia 22 de Transportadores de Solutos/genética , Miembro 5 de la Familia 22 de Transportadores de Solutos/metabolismo , Subunidades beta de la Proteína de Unión al GTP/genética , Subunidades beta de la Proteína de Unión al GTP/metabolismoRESUMEN
Cholinergic signaling plays a crucial role in the regulation of adult hippocampal neurogenesis; however, the mechanisms by which acetylcholine mediates neurogenic effects are not completely understood. Here, we report the expression of muscarinic acetylcholine receptor subtype M4 (M4 mAChR) on a subpopulation of neural precursor cells (NPCs) in the adult mouse hippocampus, and demonstrate that its pharmacological stimulation promotes their proliferation, thereby enhancing the production of new neurons in vivo. Using a targeted ablation approach, we also show that medial septum (MS) and the diagonal band of Broca (DBB) cholinergic neurons support both the survival and morphological maturation of adult-born neurons in the mouse hippocampus. Although the systemic administration of an M4-selective allosteric potentiator fails to fully rescue the MS/DBB cholinergic lesion-induced decrease in hippocampal neurogenesis, it further exacerbates the impairment in the morphological maturation of adult-born neurons. Collectively, these findings reveal stage-specific roles of M4 mAChRs in regulating adult hippocampal neurogenesis, uncoupling their positive role in enhancing the production of new neurons from the M4-induced inhibition of their morphological maturation, at least in the context of cholinergic signaling dysfunction.
Asunto(s)
Células-Madre Neurales , Receptor Muscarínico M4 , Ratones , Animales , Receptor Muscarínico M4/metabolismo , Células-Madre Neurales/metabolismo , Hipocampo/metabolismo , Neurogénesis/genética , Colinérgicos/metabolismo , Colinérgicos/farmacología , Proliferación CelularRESUMEN
Melanocytes evolved to produce the melanin that gives colour to our hair, eyes and skin. The melanocyte lineage also gives rise to melanoma, the most lethal form of skin cancer. The melanocyte lineage differentiates from neural crest cells during development, and most melanocytes reside in the skin and hair, where they are replenished by melanocyte stem cells. Because the molecular mechanisms necessary for melanocyte specification, migration, proliferation and differentiation are co-opted during melanoma initiation and progression, studying melanocyte development is directly relevant to human disease. Here, through the lens of advances in cellular omic and genomic technologies, we review the latest findings in melanocyte development and differentiation, and how these developmental pathways become dysregulated in disease.
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Diferenciación Celular , Linaje de la Célula , Melanocitos , Melanoma , Melanocitos/metabolismo , Melanocitos/citología , Humanos , Animales , Melanoma/patología , Melanoma/metabolismo , Melanoma/genética , Cresta Neural/metabolismo , Proliferación Celular , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/metabolismo , Neoplasias Cutáneas/genéticaRESUMEN
Development of effective targeted cancer therapies is fundamentally limited by our molecular understanding of disease pathogenesis. Diffuse intrinsic pontine glioma (DIPG) is a fatal malignancy of the childhood pons characterized by a unique substitution to methionine in histone H3 at lysine 27 (H3K27M) that results in globally altered epigenetic marks and oncogenic transcription. Through primary DIPG tumor characterization and isogenic oncohistone expression, we show that the same H3K27M mutation displays distinct modes of oncogenic reprogramming and establishes distinct enhancer architecture depending upon both the variant of histone H3 and the cell context in which the mutation occurs. Compared with non-malignant pediatric pontine tissue, we identify and functionally validate both shared and variant-specific pathophysiology. Altogether, we provide a powerful resource of epigenomic data in 25 primary DIPG samples and 5 rare normal pediatric pontine tissue samples, revealing clinically relevant functional distinctions previously unidentified in DIPG.
Asunto(s)
Glioma Pontino Intrínseco Difuso/genética , Histonas/genética , Encéfalo/patología , Neoplasias Encefálicas/genética , Reprogramación Celular/genética , Glioma Pontino Intrínseco Difuso/metabolismo , Elementos de Facilitación Genéticos/genética , Epigénesis Genética/genética , Epigenómica , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica/genética , Glioma/genética , Glioma/metabolismo , Humanos , Lisina/genética , Mutación/genética , Puente/metabolismo , Transducción de Señal , Transcriptoma/fisiologíaRESUMEN
Alzheimer's disease is associated with increased levels of amyloid beta (Aß) generated by sequential intracellular cleavage of amyloid precursor protein (APP) by membrane-bound secretases. However, the spatial and temporal APP cleavage events along the trafficking pathways are poorly defined. Here, we use the Retention Using Selective Hooks (RUSH) to compare in real time the anterograde trafficking and temporal cleavage events of wild-type APP (APPwt) with the pathogenic Swedish APP (APPswe) and the disease-protective Icelandic APP (APPice). The analyses revealed differences in the trafficking profiles and processing between APPwt and the APP familial mutations. While APPwt was predominantly processed by the ß-secretase, BACE1, following Golgi transport to the early endosomes, the transit of APPswe through the Golgi was prolonged and associated with enhanced amyloidogenic APP processing and Aß secretion. A 20°C block in cargo exit from the Golgi confirmed ß- and γ-secretase processing of APPswe in the Golgi. Inhibition of the ß-secretase, BACE1, restored APPswe anterograde trafficking profile to that of APPwt. APPice was transported rapidly through the Golgi to the early endosomes with low levels of Aß production. This study has revealed different intracellular locations for the preferential cleavage of APPwt and APPswe and Aß production, and the Golgi as the major processing site for APPswe, findings relevant to understand the molecular basis of Alzheimer's disease.