RESUMEN
How the age-associated decline of immune function leads to increased cancer incidence is poorly understood. Here, we have characterised the cellular composition of the γδ T-cell pool in peripheral lymph nodes (pLNs) upon ageing. We find that ageing has minimal cell-intrinsic effects on function and global gene expression of γδ T cells, and γδTCR diversity remains stable. However, ageing alters TCRδ chain usage and clonal structure of γδ T-cell subsets. Importantly, IL-17-producing γδ17 T cells dominate the γδ T-cell pool of aged mice-mainly due to the selective expansion of Vγ6+ γδ17 T cells and augmented γδ17 polarisation of Vγ4+ T cells. Expansion of the γδ17 T-cell compartment is mediated by increased IL-7 expression in the T-cell zone of old mice. In a Lewis lung cancer model, pro-tumourigenic Vγ6+ γδ17 T cells are exclusively activated in the tumour-draining LN and their infiltration into the tumour correlates with increased tumour size in aged mice. Thus, upon ageing, substantial compositional changes in γδ T-cell pool in the pLN lead to an unbalanced γδ T-cell response in the tumour that is associated with accelerated tumour growth.
Asunto(s)
Envejecimiento/genética , Carcinoma Pulmonar de Lewis/genética , Regulación Neoplásica de la Expresión Génica , Interleucina-7/genética , Ganglios Linfáticos/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Subgrupos de Linfocitos T/inmunología , Envejecimiento/inmunología , Animales , Carcinoma Pulmonar de Lewis/inmunología , Carcinoma Pulmonar de Lewis/patología , Diferenciación Celular , Linaje de la Célula/genética , Linaje de la Célula/inmunología , Inmunofenotipificación , Interleucina-17/genética , Interleucina-17/inmunología , Interleucina-7/inmunología , Ganglios Linfáticos/patología , Ratones , Ratones Endogámicos C57BL , Receptores de Antígenos de Linfocitos T gamma-delta/clasificación , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Transducción de Señal , Subgrupos de Linfocitos T/clasificación , Subgrupos de Linfocitos T/patología , Carga Tumoral/genética , Carga Tumoral/inmunologíaRESUMEN
To study the in vivo role of TFIID in the transcriptional regulation of hepatic genes, we generated mice with liver-specific disruption of the TAF10 gene. Inactivation of TAF10 in hepatocytes resulted in the dissociation of TFIID into individual components. This correlated with the downregulation of most hepatocyte-specific genes during embryonic life and a defect in liver organogenesis. Unexpectedly, however, the transcription of less than 5% of active genes was affected by TAF10 inactivation and TFIID disassembly in adult liver. The extent of changes in transcription of the affected genes was dependent on the timing of their activation during liver development, relative to that of TAF10 inactivation. Furthermore, TFIID dissociation from promoters leads to the re-expression of several postnatally silenced hepatic genes. Promoter occupancy analyses, combined with expression profiling, demonstrate that TFIID is required for the initial activation or postnatal repression of genes, while it is dispensable for maintaining ongoing transcription.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Hígado/metabolismo , Factor de Transcripción TFIID/metabolismo , Animales , Perfilación de la Expresión Génica , Marcación de Gen , Hepatocitos/citología , Hepatocitos/metabolismo , Hígado/embriología , Ratones , Ratones Noqueados , Modelos Genéticos , Especificidad de Órganos , Fenotipo , Regiones Promotoras Genéticas/genética , Unión Proteica , Subunidades de Proteína/metabolismo , ARN Polimerasa II/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
BACKGROUND: The Ibizan Hound is a canine breed native to the Mediterranean region, where leishmaniasis is an endemic zoonosis. Several studies indicate a low prevalence of this disease in Ibizan Hound dogs, whereas other canine breeds present a high prevalence. However, the underlying molecular mechanisms still remain unknown. The aim of this work is to analyse the relationship between serum levels of cytokines and the genomic profiles in two canine breeds, Ibizan Hound (resistant canine breed model) and Boxer (susceptible canine breed model). METHODS: In this study, we analyse the haplotypes of genes encoding cytokines related to immune response of Leishmania infantum infection in twenty-four Boxers and twenty-eight Ibizan Hounds apparently healthy using CanineHD DNA Analysis BeadChip including 165,480 mapped positions. The haplo.glm extension of haplo.score was used to perform a General Linear Model (GLM) regression to estimate the magnitude of individual haplotype effects within each cytokine. RESULTS: Mean levels of interferon gamma (IFN-γ), interleukin 2 (IL-2) and IL-18 in Boxer dogs were 0.19 ± 0.05 ng/ml, 46.70 ± 4.54 ng/ml, and 36.37 ± 30.59 pg/ml, whereas Ibizan Hound dogs present 0.49 ± 0.05 ng/ml, 64.55 ± 4.54 ng/ml, and 492.10 ± 31.18 pg/ml, respectively. The GLM regression shows fifteen haplotypes with statistically significant effect on the cytokine serum levels (P < 0.05). The more relevant are IL6-CGAAG and IFNG-GCA haplotypes, which increase and decrease the IL-2, IL-8 and IFN-γ serum levels, respectively. CONCLUSIONS: Haplotypes in the IFNG and IL6 genes have been correlated to serum levels of IFN-γ, IL-2 and IL-18, and a moderate effect has been found on IL8 haplotype correlated to IL-8 and IL-18 serum levels. The results indicate that the resistance to L. infantum infection could be a consequence of certain haplotypes with a high frequency in the Ibizan Hound dog breed, while susceptibility to the disease would be related to other specific haplotypes, with high frequency in Boxer. Future studies are needed to elucidate whether these differences and haplotypes are related to different phenotypes in immune response and expression gene regulation to L. infantum infections in dogs and their possible application in new treatments and vaccines.
Asunto(s)
Enfermedades de los Perros , Leishmania infantum , Leishmaniasis Visceral , Leishmaniasis , Animales , Perros , Citocinas/genética , Interleucina-6 , Interferón gamma/genética , Interleucina-2/genética , Interleucina-18/genética , Leishmania infantum/genética , Haplotipos , Interleucina-8/genética , Enfermedades de los Perros/epidemiología , Leishmaniasis Visceral/epidemiología , Leishmaniasis Visceral/genética , Leishmaniasis Visceral/veterinariaRESUMEN
BACKGROUND: Xenobiotics are primarily metabolized by hepatocytes in the liver, and primary human hepatocytes are the gold standard model for the assessment of drug efficacy, safety, and toxicity in the early phases of drug development. Recent advances in single-cell genomics demonstrate liver zonation and ploidy as main drivers of cellular heterogeneity. However, little is known about the impact of hepatocyte specialization on liver function upon metabolic challenge, including hepatic metabolism, detoxification, and protein synthesis. RESULTS: Here, we investigate the metabolic capacity of individual human hepatocytes in vitro. We assess how chronic accumulation of lipids enhances cellular heterogeneity and impairs the metabolisms of drugs. Using a phenotyping five-probe cocktail, we identify four functional subgroups of hepatocytes responding differently to drug challenge and fatty acid accumulation. These four subgroups display differential gene expression profiles upon cocktail treatment and xenobiotic metabolism-related specialization. Notably, intracellular fat accumulation leads to increased transcriptional variability and diminishes the drug-related metabolic capacity of hepatocytes. CONCLUSIONS: Our results demonstrate that, upon a metabolic challenge such as exposure to drugs or intracellular fat accumulation, hepatocyte subgroups display different and heterogeneous transcriptional responses.
Asunto(s)
Hepatocitos , Hígado , Humanos , Hepatocitos/metabolismo , Ácidos Grasos/metabolismoRESUMEN
Aging is characterized by progressive loss of physiological and cellular functions, but the molecular basis of this decline remains unclear. We explored how aging affects transcriptional dynamics using single-cell RNA sequencing of unstimulated and stimulated naïve and effector memory CD4+ T cells from young and old mice from two divergent species. In young animals, immunological activation drives a conserved transcriptomic switch, resulting in tightly controlled gene expression characterized by a strong up-regulation of a core activation program, coupled with a decrease in cell-to-cell variability. Aging perturbed the activation of this core program and increased expression heterogeneity across populations of cells in both species. These discoveries suggest that increased cell-to-cell transcriptional variability will be a hallmark feature of aging across most, if not all, mammalian tissues.
Asunto(s)
Envejecimiento/genética , Envejecimiento/inmunología , Linfocitos T CD4-Positivos/inmunología , Memoria Inmunológica/genética , Transcriptoma , Animales , Senescencia Celular/genética , Senescencia Celular/inmunología , Variación Genética , Activación de Linfocitos/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Receptores de Antígenos de Linfocitos T/metabolismo , Análisis de Secuencia de ARN , Análisis de la Célula IndividualRESUMEN
Recent technological and computational advances in understanding the transcriptional and chromatin features of single cells have begun answering longstanding questions in the extent and impact of biological heterogeneity. Here, we outline the intrinsic and extrinsic mechanisms that underlie the transcriptional and functional diversity within superficially homogeneous populations, and we discuss how fascinating new studies have afforded novel insight into each mechanism. The studies are chosen in part to include initial reports of novel functional genomics tools where the eventual applications will clearly have profound impact on our understanding the dynamics of cell-to-cell transcriptional variation-from individual cells to whole organisms.
Asunto(s)
Cromatina/genética , Genómica , Transcripción Genética , Linaje de la Célula/genética , Humanos , Análisis de la Célula IndividualRESUMEN
Chromatin structure complexity requires the interaction and coordinated work of a multiplicity of factors at different transcriptional regulation stages. Transcription control comprises a set of processes that ensures proper balance in the gene expression under different conditions, such as signals, metabolic states, or development. We could frame those steps from epigenetic marks to mRNA stability to support the holistic view of a fine-tune balance of final mRNA levels through mRNA transcription, export, stability, translation, and degradation. Transport of mRNA from the nucleus to the cytoplasm is a key process in regulated gene expression. Transcriptional elongation and mRNA export are coregulated steps that determine the mature mRNA levels in the cytoplasm. In this paper, recent insights into the coordination of these processes in eukaryotes will be summarised.
RESUMEN
Adaptation of liver to nutritional signals is regulated by several transcription factors that are modulated by intracellular metabolites. Here, we demonstrate a transcription factor network under the control of hepatocyte nuclear factor 4alpha (HNF4alpha) that coordinates the reciprocal expression of fatty acid transport and metabolizing enzymes during fasting and feeding conditions. Hes6 is identified as a novel HNF4alpha target, which in normally fed animals, together with HNF4alpha, maintains PPARgamma expression at low levels and represses several PPARalpha-regulated genes. During fasting, Hes6 expression is diminished, and peroxisome proliferator-activated receptor alpha (PPARalpha) replaces the HNF4alpha/Hes6 complex on regulatory regions of target genes to activate transcription. Gene expression and promoter occupancy analyses confirmed that HNF4alpha is a direct activator of the Pparalpha gene in vivo and that its expression is subject to feedback regulation by PPARalpha and Hes6 proteins. These results establish the fundamental role of dynamic regulatory interactions between HNF4alpha, Hes6, PPARalpha, and PPARgamma in the coordinated expression of genes involved in fatty acid transport and metabolism.