RESUMEN
ZFTA-RELA is the most recurrent genetic alteration seen in pediatric supratentorial ependymoma (EPN) and is sufficient to initiate tumors in mice. Despite ZFTA-RELA's potent oncogenic potential, ZFTA-RELA gene fusions are observed exclusively in childhood EPN, with tumors located distinctly in the supratentorial region of the central nervous system (CNS). We hypothesized that specific chromatin modules accessible during brain development would render distinct cell lineage programs at direct risk of transformation by ZFTA-RELA. To this end, we performed combined single cell ATAC and RNA-seq analysis (scMultiome) of the developing mouse forebrain as compared to ZR-driven mouse and human EPN. We demonstrate that specific developmental lineage programs present in radial glial cells and regulated by Plagl family transcription factors are at risk of neoplastic transformation. Binding of this chromatin network by ZFTA-RELA or other PLAGL family motif targeting fusion proteins leads to persistent chromatin accessibility at oncogenic loci and oncogene expression. Cross-species analysis of mouse and human EPN reveals significant cell type heterogeneity mirroring incomplete neurogenic and gliogenic differentiation, with a small percentage of cycling intermediate progenitor-like cells that establish a putative tumor cell hierarchy. In vivo lineage tracing studies reveal single neoplastic clones that aggressively dominate tumor growth and establish the entire EPN cellular hierarchy. These findings unravel developmental epigenomic states critical for fusion oncoprotein driven transformation and elucidate how these states continue to shape tumor progression. HIGHLIGHTS: 1. Specific chromatin modules accessible during brain development render distinct cell lineage programs at risk of transformation by pediatric fusion oncoproteins.2. Cross-species single cell ATAC and RNA (scMultiome) of mouse and human ependymoma (EPN) reveals diverse patterns of lineage differentiation programs that restrain oncogenic transformation.3. Early intermediate progenitor-like EPN cells establish a tumor cell hierarchy that mirrors neural differentiation programs.4. ZFTA-RELA transformation is compatible with distinct developmental epigenetic states requiring precise 'goldilocks' levels of fusion oncoprotein expression.5. Dominant tumor clones establish the entire EPN cellular hierarchy that reflects normal gliogenic and neurogenic differentiation programs.
RESUMEN
Bidirectional communication between tumours and neurons has emerged as a key facet of the tumour microenvironment that drives malignancy1,2. Another hallmark feature of cancer is epigenomic dysregulation, in which alterations in gene expression influence cell states and interactions with the tumour microenvironment3. Ependymoma (EPN) is a paediatric brain tumour that relies on epigenomic remodelling to engender malignancy4,5; however, how these epigenetic mechanisms intersect with extrinsic neuronal signalling during EPN tumour progression is unknown. Here we show that the activity of serotonergic neurons regulates EPN tumorigenesis, and that serotonin itself also serves as an activating modification on histones. We found that inhibiting histone serotonylation blocks EPN tumorigenesis and regulates the expression of a core set of developmental transcription factors. High-throughput, in vivo screening of these transcription factors revealed that ETV5 promotes EPN tumorigenesis and functions by enhancing repressive chromatin states. Neuropeptide Y (NPY) is one of the genes repressed by ETV5, and its overexpression suppresses EPN tumour progression and tumour-associated network hyperactivity through synaptic remodelling. Collectively, this study identifies histone serotonylation as a key driver of EPN tumorigenesis, and also reveals how neuronal signalling, neuro-epigenomics and developmental programs are intertwined to drive malignancy in brain cancer.
Asunto(s)
Carcinogénesis , Ependimoma , Histonas , Animales , Femenino , Humanos , Masculino , Ratones , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Carcinogénesis/genética , Carcinogénesis/patología , Carcinogénesis/metabolismo , Línea Celular Tumoral , Cromatina/metabolismo , Cromatina/genética , Progresión de la Enfermedad , Proteínas de Unión al ADN/metabolismo , Ependimoma/genética , Ependimoma/metabolismo , Ependimoma/patología , Epigénesis Genética , Regulación Neoplásica de la Expresión Génica , Histonas/química , Histonas/metabolismo , Factores de Transcripción/metabolismo , Microambiente Tumoral , Neuronas Serotoninérgicas/metabolismo , Serotonina/metabolismoRESUMEN
Background: Supplementation of a high-fat obesogenic diet (HFD) with cholic acid (CA) suppresses the development of obesity, insulin resistance, and hepatic steatosis in mice. Objective: We investigated the role of fibroblast growth factor 21 (FGF21) in mediating the beneficial actions of CA on metabolic syndrome. Methods: Male 7-wk-old wild-type (WT) mice and FGF21 knockout (FGF21KO) mice were fed an HFD for 12 wk followed by a 4-wk period in which the mice were fed the HFD alone or supplemented with 0.5% CA. Body composition, gross energy efficiency, glucose tolerance, homeostasis model assessment of insulin resistance (HOMA-IR), and hepatic triacylglycerol (TG) concentrations were measured. Results: CA administration improved glucose tolerance and decreased total body fat accretion, gross energy efficiency, fasting blood glucose concentrations, and HOMA-IR in both WT mice and FGF21KO mice. The extent of the effect of CA on glucose tolerance, fasting blood glucose concentrations, and HOMA-IR was similar in both mouse strains, whereas the extent of the effect of CA on total body fat accretion and gross energy efficiency was 4.2- to 4.4-fold greater in FGF21KO mice than in WT mice. Further analyses showed that CA decreased hepatic TG concentrations in WT mice (49%) but had no effect on hepatic TG concentrations in FGF21KO mice. CA decreased the activation state of hepatic acetyl-CoA carboxylase 1 (ACC1) and adipose tissue hormone-sensitive lipase (HSL) in WT mice but was not effective in decreasing the activation of ACC1 and HSL in FGF21KO mice. Conclusions: FGF21 signaling is required for the beneficial effect of CA on hepatic TG accumulation in mice fed an HFD. We propose that FGF21 signaling potentiates the ability of CA to decrease the activation of ACC1 and HSL, key enzymes controlling the supply of long-chain fatty acid precursors for hepatic TG synthesis.
Asunto(s)
Ácido Cólico/farmacología , Dieta Alta en Grasa/efectos adversos , Hígado Graso/metabolismo , Factores de Crecimiento de Fibroblastos/metabolismo , Lipogénesis/efectos de los fármacos , Hígado/metabolismo , Triglicéridos/metabolismo , Acetil-CoA Carboxilasa/metabolismo , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Animales , Glucemia/metabolismo , Ácido Cólico/uso terapéutico , Grasas de la Dieta/efectos adversos , Grasas de la Dieta/metabolismo , Suplementos Dietéticos , Metabolismo Energético , Ácidos Grasos/metabolismo , Hígado Graso/etiología , Hígado Graso/prevención & control , Factores de Crecimiento de Fibroblastos/genética , Insulina/sangre , Resistencia a la Insulina , Masculino , Ratones , Ratones Noqueados , Obesidad/etiología , Obesidad/metabolismo , Obesidad/prevención & control , Transducción de Señal , Esterol Esterasa/metabolismoRESUMEN
Previous studies have shown that whole body deletion of the glucagon receptor suppresses the ability of starvation to increase hepatic fibroblast growth factor 21 (FGF21) expression and plasma FGF21 concentration. Here, we investigate the mechanism by which glucagon receptor activation increases hepatic FGF21 production. Incubating primary rat hepatocyte cultures with glucagon, dibutyryl cAMP or forskolin stimulated a 3-4-fold increase in FGF21 secretion. The effect of these agents on FGF21 secretion was not associated with an increase in FGF21 mRNA abundance. Glucagon induction of FGF21 secretion was additive with the stimulatory effect of a PPARα activator (GW7647) on FGF21 secretion. Inhibition of protein kinase A (PKA) and downstream components of the PKA pathway [i.e. AMP-activated protein kinase and p38 MAPK] suppressed glucagon activation of FGF21 secretion. Incubating hepatocytes with an exchange protein directly activated by cAMP (EPAC)-selective cAMP analog [i.e. 8-(4-chlorophenylthio)-2'-O-methyladenosine-3', 5'-cyclic monophosphate (cpTOME)], stimulated a 3.9-fold increase FGF21 secretion, whereas inhibition of the EPAC effector, Rap1, suppressed glucagon activation of FGF21 secretion. Treatment of hepatocytes with insulin also increased FGF21 secretion. In contrast to glucagon, insulin activation of FGF21 secretion was associated with an increase in FGF21 mRNA abundance. Glucagon synergistically interacted with insulin to stimulate a further increase in FGF21 secretion and FGF21 mRNA abundance. These results demonstrate that glucagon increases hepatic FGF21 secretion via a posttranscriptional mechanism and provide evidence that both the PKA branch and EPAC branch of the cAMP pathway play a role in mediating this effect. These results also identify a novel synergistic interaction between glucagon and insulin in the regulation of FGF21 secretion and FGF21 mRNA abundance. We propose that this insulin/glucagon synergism plays a role in mediating the elevation in FGF21 production during starvation and conditions related to metabolic syndrome.