RESUMEN
The urochordate Ciona robusta exhibits numerous functional and morphogenetic traits that are shared with vertebrate models. While prior investigations have identified several analogies between the gastrointestinal tract (i.e., gut) of Ciona and mice, the molecular mechanisms responsible for these similarities remain poorly understood. This study seeks to address this knowledge gap by investigating the transcriptional landscape of the adult stage gut. Through comparative genomics analyses, we identified several evolutionarily conserved components of signaling pathways of pivotal importance for gut development (such as WNT, Notch, and TGFß-BMP) and further evaluated their expression in three distinct sections of the gastrointestinal tract by RNA-seq. Despite the presence of lineage-specific gene gains, losses, and often unclear orthology relationships, the investigated pathways were characterized by well-conserved molecular machinery, with most components being expressed at significant levels throughout the entire intestinal tract of C. robusta. We also showed significant differences in the transcriptional landscape of the stomach and intestinal tract, which were much less pronounced between the proximal and distal portions of the intestine. This study confirms that C. robusta is a reliable model system for comparative studies, supporting the use of ascidians as a model to study gut physiology.
Asunto(s)
Transducción de Señal , Animales , Tracto Gastrointestinal/metabolismo , Ciona/genética , Ciona/metabolismo , Ciona intestinalis/genética , Ciona intestinalis/metabolismo , Receptores Notch/metabolismo , Receptores Notch/genética , Perfilación de la Expresión GénicaRESUMEN
Colorectal cancers (CRCs) are highly heterogeneous and show a hierarchical organization, with cancer stem cells (CSCs) responsible for tumor development, maintenance, and drug resistance. Our previous studies showed the importance of thyroid hormone-dependent signaling on intestinal tumor development and progression through action on stem cells. These results have a translational value, given that the thyroid hormone nuclear receptor TRα1 is upregulated in human CRCs, including in the molecular subtypes associated with CSC features. We used an established spheroid model generated from the human colon adenocarcinoma cell line Caco2 to study the effects of T3 and TRα1 on spheroid formation, growth, and response to conventional chemotherapies. Our results show that T3 treatment and/or increased TRα1 expression in spheroids impaired the response to FOLFIRI and conferred a survival advantage. This was achieved by stimulating drug detoxification pathways and increasing ALDH1A1-expressing cells, including CSCs, within spheroids. These results suggest that clinical evaluation of the thyroid axis and assessing TRα1 levels in CRCs could help to select optimal therapeutic regimens for patients with CRC. Proposed mechanism of action of T3/TRα1 in colon cancer spheroids. In the control condition, TRα1 participates in maintaining homeostatic cell conditions. The presence of T3 in the culture medium activates TRα1 action on target genes, including the drug efflux pumps ABCG2 and ABCB1. In the case of chemotherapy FOLFIRI, the increased expression of ABC transcripts and proteins induced by T3 treatment is responsible for the augmented efflux of 5-FU and Irinotecan from the cancer cells. Taken together, these mechanisms contribute to the decreased efficacy of the chemotherapy and allow cells to escape the treatment. Created with BioRender.com .
Asunto(s)
Camptotecina/análogos & derivados , Neoplasias del Colon , Fluorouracilo , Células Madre Neoplásicas , Esferoides Celulares , Receptores alfa de Hormona Tiroidea , Triyodotironina , Humanos , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/patología , Fluorouracilo/farmacología , Fluorouracilo/uso terapéutico , Receptores alfa de Hormona Tiroidea/metabolismo , Receptores alfa de Hormona Tiroidea/genética , Células CACO-2 , Neoplasias del Colon/metabolismo , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/patología , Neoplasias del Colon/genética , Esferoides Celulares/efectos de los fármacos , Esferoides Celulares/metabolismo , Esferoides Celulares/patología , Triyodotironina/farmacología , Leucovorina/farmacología , Leucovorina/uso terapéutico , Camptotecina/farmacología , Camptotecina/uso terapéutico , Fenotipo , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Familia de Aldehído Deshidrogenasa 1/metabolismo , Familia de Aldehído Deshidrogenasa 1/genética , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Retinal-Deshidrogenasa/metabolismo , Retinal-Deshidrogenasa/genética , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/metabolismo , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/genética , Subfamilia B de Transportador de Casetes de Unión a ATP/metabolismo , Subfamilia B de Transportador de Casetes de Unión a ATP/genéticaRESUMEN
Taf4 (TATA-box binding protein-associated factor 4) is a subunit of the general transcription factor TFIID, a component of the RNA polymerase II pre-initiation complex that interacts with tissue-specific transcription factors to regulate gene expression. Properly regulated gene expression is particularly important in the intestinal epithelium that is constantly renewed from stem cells. Tissue-specific inactivation of Taf4 in murine intestinal epithelium during embryogenesis compromised gut morphogenesis and the emergence of adult-type stem cells. In adults, Taf4 loss impacted the stem cell compartment and associated Paneth cells in the stem cell niche, epithelial turnover and differentiation of mature cells, thus exacerbating the response to inflammatory challenge. Taf4 inactivation ex vivo in enteroids prevented budding formation and maintenance and caused broad chromatin remodeling and a strong reduction in the numbers of stem and progenitor cells with a concomitant increase in an undifferentiated cell population that displayed high activity of the Ezh2 and Suz12 components of Polycomb Repressive Complex 2 (PRC2). Treatment of Taf4-mutant enteroids with a specific Ezh2 inhibitor restored buddings, cell proliferation and the stem/progenitor compartment. Taf4 loss also led to increased PRC2 activity in cells of adult crypts associated with modification of the immune/inflammatory microenvironment that potentiated Apc-driven tumorigenesis. Our results reveal a novel function of Taf4 in antagonizing PRC2-mediated repression of the stem cell gene expression program to assure normal development, homeostasis, and immune-microenvironment of the intestinal epithelium.
Asunto(s)
Proteínas de Drosophila , Células Madre , Ratones , Animales , Diferenciación Celular/genética , Células Madre/metabolismo , Factor de Transcripción TFIID/genética , Mucosa Intestinal/metabolismo , Proteínas de Drosophila/metabolismo , Complejo Represivo Polycomb 2/metabolismo , Epigénesis GenéticaRESUMEN
The THRA gene, encoding the thyroid hormone nuclear receptor TRα1, is expressed in an increasing gradient at the bottom of intestinal crypts, overlapping with high Wnt and Notch activities. Importantly, THRA is upregulated in colorectal cancers, particularly in the high-Wnt molecular subtype. The basis of this specific and/or altered expression pattern has remained unknown. To define the mechanisms controlling THRA transcription and TRα1 expression, we used multiple in vitro and ex vivo approaches. Promoter analysis demonstrated that transcription factors important for crypt homeostasis and altered in colorectal cancers, such as transcription factor 7-like 2 (TCF7L2; Wnt pathway), recombining binding protein suppressor of hairless (RBPJ; Notch pathway), and homeobox protein CDX2 (epithelial cell identity), modulate THRA activity. Specifically, although TCF7L2 and CDX2 stimulated THRA, RBPJ induced its repression. In-depth analysis of the Wnt-dependent increase showed direct regulation of the THRA promoter in cells and of TRα1 expression in murine enteroids. Given our previous results on the control of the Wnt pathway by TRα1, our new results unveil a complex regulatory loop and synergy between these endocrine and epithelial-cell-intrinsic signals. Our work describes, for the first time, the regulation of the THRA gene in specific cell and tumor contexts.
Asunto(s)
Neoplasias Colorrectales , Genes erbA , Humanos , Ratones , Animales , Receptores de Hormona Tiroidea/genética , Receptores alfa de Hormona Tiroidea/genética , Receptores alfa de Hormona Tiroidea/metabolismo , Hormonas Tiroideas/metabolismo , Neoplasias Colorrectales/genéticaRESUMEN
Several studies emphasized the function of the thyroid hormones in stem cell biology. These hormones act through the nuclear hormone receptor TRs, which are T3-modulated transcription factors. Pioneer work on T3-dependent amphibian metamorphosis showed that the crosstalk between the epithelium and the underlying mesenchyme is absolutely required for intestinal maturation and stem cell emergence. With the recent advances of powerful animal models and 3D-organoid cultures, similar findings have now begun to be described in mammals, where the action of T3 and TRα1 control physiological and cancer-related stem cell biology. In this review, we have summarized recent findings on the multiple functions of T3 and TRα1 in intestinal epithelium stem cells, cancer stem cells and their niche. In particular, we have highlighted the regulation of metabolic functions directly linked to normal and/or cancer stem cell biology. These findings help explain other possible mechanisms by which TRα1 controls stem cell biology, beyond the more classical Wnt and Notch signaling pathways.
Asunto(s)
Intestinos , Hormonas Tiroideas , Animales , Mucosa Intestinal/metabolismo , Mamíferos/metabolismo , Receptores de Hormona Tiroidea/metabolismo , Transducción de Señal , Células Madre , Hormonas Tiroideas/metabolismoRESUMEN
According to Brown and Cai, Thyroid hormones (THs) have been considered "the first developmental morphogen ever discovered" [...].
Asunto(s)
Transducción de Señal , Hormonas TiroideasRESUMEN
A pivotal role of thyroid hormones and their nuclear receptors in intestinal development and homeostasis have been described, whereas their involvement in intestinal carcinogenesis is still controversial. In this perspective article we briefly summarize the recent advances in this field and present new data regarding their functional interaction with one of the most important signaling pathway, such as WNT, regulating intestinal development and carcinogenesis. These complex interactions unveil new concepts and will surely be of importance for translational research.
Asunto(s)
Regulación de la Expresión Génica , Genes erbA , Neoplasias Intestinales/patología , Intestinos/patología , Receptores de Hormona Tiroidea/metabolismo , Hormonas Tiroideas/metabolismo , Vía de Señalización Wnt , Homeostasis , Humanos , Neoplasias Intestinales/genética , Neoplasias Intestinales/metabolismo , Intestinos/metabolismo , Receptores de Hormona Tiroidea/genéticaRESUMEN
RNA-binding proteins (RBPs) function as master regulators of gene expression. Alterations in their levels are often observed in tumors with numerous oncogenic RBPs identified in recent years. Musashi1 (Msi1) is an RBP and stem cell gene that controls the balance between self-renewal and differentiation. High Msi1 levels have been observed in multiple tumors including glioblastoma and are often associated with poor patient outcomes and tumor growth. A comprehensive genomic analysis identified a network of cell cycle/division and DNA replication genes and established these processes as Msi1's core regulatory functions in glioblastoma. Msi1 controls this gene network via two mechanisms: direct interaction and indirect regulation mediated by the transcription factors E2F2 and E2F8. Moreover, glioblastoma lines with Msi1 knockout (KO) displayed increased sensitivity to cell cycle and DNA replication inhibitors. Our results suggest that a drug combination strategy (Msi1 + cell cycle/DNA replication inhibitors) could be a viable route to treat glioblastoma.
RESUMEN
The thyroid hormone T3 and its nuclear receptor TRα1 control gut development and homeostasis through the modulation of intestinal crypt cell proliferation. Despite increasing data, in-depth analysis on their specific action on intestinal stem cells is lacking. By using ex vivo 3D organoid cultures and molecular approaches, we observed early responses to T3 involving the T3-metabolizing enzyme Dio1 and the transporter Mct10, accompanied by a complex response of stem cell- and progenitor-enriched genes. Interestingly, specific TRα1 loss-of-function (inducible or constitutive) was responsible for low ex vivo organoid development and impaired stem cell activity. T3 treatment of animals in vivo not only confirmed the positive action of this hormone on crypt cell proliferation but also demonstrated its key action in modulating the number of stem cells, the expression of their specific markers and the commitment of progenitors into lineage-specific differentiation. In conclusion, T3 treatment or TRα1 modulation has a rapid and strong effect on intestinal stem cells, broadening our perspectives in the study of T3/TRα1-dependent signaling in these cells.
Asunto(s)
Proliferación Celular , Intestinos , Transducción de Señal , Células Madre/metabolismo , Receptores alfa de Hormona Tiroidea/metabolismo , Triyodotironina/metabolismo , Sistemas de Transporte de Aminoácidos Neutros/genética , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Animales , Femenino , Yoduro Peroxidasa/genética , Yoduro Peroxidasa/metabolismo , Masculino , Ratones , Ratones Transgénicos , Células Madre/citología , Receptores alfa de Hormona Tiroidea/genética , Triyodotironina/genéticaRESUMEN
Intestinal crypts are composed of heterogeneous and highly plastic cell populations. Lgr5high-stem cells (SC) are responsible for homeostatic renewal, but other cells can revert to an SC-like phenotype to maintain epithelial integrity. Despite their distinct roles in orchestrating homeostasis, both populations have been designated as the putative "cell-of-origin" of colorectal cancer. However, their respective involvement in the emergence of drug-resistant cancer SCs (CSC), responsible for tumor relapse and associated with poor outcome of colorectal cancer, remains elusive. In this context, the intestinal SC/progenitor-marker Musashi1 (MSI1) is interesting as it plays important functions in intestinal homeostasis and is frequently overexpressed in human colorectal cancer. Therefore, our aims were: (i) to study the impact of chemotherapy on Lgr5-expressing and MSI1-expressing cell populations, (ii) to explore the effect of increased MSI1 levels in response to treatment, and (iii) to evaluate the relevance in human colorectal cancer. Engineered mouse models treated with the therapeutic agent 5-fluorouracil showed that upon increased MSI1 levels, Lgr5high SCs remain sensitive while Lgr5low progenitors reprogram to a drug-resistant phenotype. This resulted in the expansion of an MSI1-expressing cell subpopulation with improved resistance to DNA damage and increased detoxification, typical properties of dormant-CSCs that can reactivate after chemotherapy. Analysis in patients with colorectal cancer revealed a correlation between MSI1 levels and tumor grading, CSC phenotype, and chemoresistance. Altogether, these results shed new light on the biology and plasticity of normal crypt and cancer cell populations and also open new perspectives to target MSI1 to improve chemotherapy outcome. SIGNIFICANCE: This study unveils paradoxical roles for MSI1, underlining its importance in facilitating intestinal regeneration upon injury but also unraveling its new function in drug-resistant colorectal cancer stem cells.
Asunto(s)
Neoplasias Colorrectales/tratamiento farmacológico , Resistencia a Antineoplásicos , Fluorouracilo/farmacología , Mucosa Intestinal/efectos de los fármacos , Células Madre Neoplásicas/efectos de los fármacos , Proteínas del Tejido Nervioso/metabolismo , Proteínas de Unión al ARN/metabolismo , Receptores Acoplados a Proteínas G/fisiología , Animales , Antimetabolitos Antineoplásicos/farmacología , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Modelos Animales de Enfermedad , Femenino , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Proteínas del Tejido Nervioso/genética , Fenotipo , Proteínas de Unión al ARN/genéticaRESUMEN
Colorectal cancers are characterized by heterogeneity and a hierarchical organization comprising a population of cancer stem cells (CSCs) responsible for tumor development, maintenance, and resistance to drugs. A better understanding of CSC properties for their specific targeting is, therefore, a pre-requisite for effective therapy. However, there is a paucity of suitable preclinical models for in-depth investigations. Although in vitro two-dimensional (2D) cancer cell lines provide valuable insights into tumor biology, they do not replicate the phenotypic and genetic tumor heterogeneity. In contrast, three-dimensional (3D) models address and reproduce near-physiological cancer complexity and cell heterogeneity. The aim of this work was to design a robust and reproducible 3D culture system to study CSC biology. The present methodology describes the development and optimization of conditions to generate 3D spheroids, which are homogenous in size, from Caco2 colon adenocarcinoma cells, a model that can be used for long-term culture. Importantly, within the spheroids, the cells which were organized around lumen-like structures, were characterized by differential cell proliferation patterns and by the presence of CSCs expressing a panel of markers. These results provide the first proof-of-concept for the appropriateness of this 3D approach to study cell heterogeneity and CSC biology, including the response to chemotherapy.
Asunto(s)
Neoplasias del Colon/patología , Células Madre Neoplásicas/patología , Esferoides Celulares/patología , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Biomarcadores de Tumor/metabolismo , Células CACO-2 , Diferenciación Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Neoplasias del Colon/tratamiento farmacológico , Enterocitos/efectos de los fármacos , Enterocitos/patología , Técnica del Anticuerpo Fluorescente , Humanos , Células Madre Neoplásicas/efectos de los fármacos , Esferoides Celulares/efectos de los fármacos , Coloración y EtiquetadoRESUMEN
Prominent changes in the gut microbiota (referred to as "dysbiosis") play a key role in the development of allergic disorders, but the underlying mechanisms remain unknown. Study of the delayed-type hypersensitivity (DTH) response in mice contributed to our knowledge of the pathophysiology of human allergic contact dermatitis. Here we report a negative regulatory role of the RIG-I-like receptor adaptor mitochondrial antiviral signaling (MAVS) on DTH by modulating gut bacterial ecology. Cohousing and fecal transplantation experiments revealed that the dysbiotic microbiota of Mavs-/- mice conferred a proallergic phenotype that is communicable to wild-type mice. DTH sensitization coincided with increased intestinal permeability and bacterial translocation within lymphoid organs that enhanced DTH severity. Collectively, we unveiled an unexpected impact of RIG-I-like signaling on the gut microbiota with consequences on allergic skin disease outcome. Primarily, these data indicate that manipulating the gut microbiota may help in the development of therapeutic strategies for the treatment of human allergic skin pathologies.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/fisiología , Disbiosis/complicaciones , Microbioma Gastrointestinal/inmunología , Hipersensibilidad/etiología , Intestinos/inmunología , Enfermedades Cutáneas Bacterianas/etiología , Animales , Modelos Animales de Enfermedad , Femenino , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Hipersensibilidad/metabolismo , Hipersensibilidad/patología , Intestinos/microbiología , Intestinos/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Fenotipo , Transducción de Señal , Enfermedades Cutáneas Bacterianas/metabolismo , Enfermedades Cutáneas Bacterianas/patologíaRESUMEN
Our previous work demonstrated a key function of the thyroid hormone nuclear receptor TRα1, a T3-modulated transcription factor, in controlling intestinal development and homeostasis via the Wnt and Notch pathways. Importantly, increased expression of TRα1 in the intestinal epithelium in a mutated Apc genetic background (vil-TRα1/Apc+/1638N mice) accelerated tumorigenesis and contributed to a more aggressive tumor phenotype compared to that of the Apc mutants alone. Therefore, the aim of this study was to determine the relevance of this synergistic effect in human colorectal cancers and to gain insights into the mechanisms involved. We analyzed cohorts of patients by in silico and experimental approaches and observed increased TRα1 expression and a significant correlation between TRα1 levels and Wnt activity. TRα1 loss-of-function and gain-of-function in Caco2 cell lines not only confirmed that TRα1 levels control Wnt activity but also demonstrated the role of TRα1 in regulating cell proliferation and migration. Finally, upon investigation of the molecular mechanisms responsible for the Wnt-TRα1 association, we described the repression by TRα1 of several Wnt inhibitors, including Frzb, Sox17 and Wif1. In conclusion, our results underline an important functional interplay between the thyroid hormone nuclear receptor TRα1 and the canonical Wnt pathway in intestinal cancer initiation and progression. More importantly, we show for the first time that the expression of TRα1 is induced in human colorectal cancers.
RESUMEN
BACKGROUND & AIMS: The enzyme stearoyl-coenzyme A desaturase 1 (SCD or SCD1) produces monounsaturated fatty acids by introducing double bonds into saturated bonds between carbons 9 and 10, with oleic acid as the main product. SCD1 is present in the intestinal epithelium, and fatty acids regulate cell proliferation, so we investigated the effects of SCD1-induced production of oleic acid in enterocytes in mice. METHODS: We generated mice with disruption of Scd1 selectively in the intestinal epithelium (iScd1-/- mice) on a C57BL/6 background; iScd1+/+ mice were used as controls. We also generated iScd1-/-ApcMin/+ mice and studied cancer susceptibility. Mice were fed a chow, oleic acid-deficient, or oleic acid-rich diet. Intestinal tissues were collected and analyzed by histology, reverse transcription quantitative polymerase chain reaction, immunohistochemistry, and mass spectrometry, and tumors were quantified and measured. RESULTS: Compared with control mice, the ileal mucosa of iScd1-/- mice had a lower proportion of palmitoleic (C16:1 n-7) and oleic acids (C18:1 n-9), with accumulation of stearic acid (C18:0); this resulted a reduction of the Δ9 desaturation ratio between monounsaturated (C16:1 n-7 and C18:1 n-9) and saturated (C16:0 and C18:0) fatty acids. Ileal tissues from iScd1-/- mice had increased expression of markers of inflammation activation and crypt proliferative genes compared with control mice. The iScd1-/-ApcMin/+ mice developed more and larger tumors than iScd1+/+ApcMin/+ mice. iScd1-/-ApcMin/+ mice fed the oleic acid-rich diet had reduced intestinal inflammation and significantly lower tumor burden compared with mice fed a chow diet. CONCLUSIONS: In studies of mice, we found intestinal SCD1 to be required for synthesis of oleate in the enterocytes and maintenance of fatty acid homeostasis. Dietary supplementation with oleic acid reduces intestinal inflammation and tumor development in mice.
Asunto(s)
Grasas Insaturadas en la Dieta/administración & dosificación , Enteritis/etiología , Mucosa Intestinal/enzimología , Neoplasias Intestinales/etiología , Ácido Oléico/administración & dosificación , Estearoil-CoA Desaturasa/fisiología , Animales , Femenino , Mucosa Intestinal/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ácido Oléico/metabolismo , Carga TumoralRESUMEN
Thyroid hormone receptors (TRs) were cloned based on their homology with the retroviral oncogene v-ERBA. In Vertebrates two genes, THRA and THRB, encode respectively many isotypes and isoforms of receptors TRα and TRß, resulting from alternative splicing and/or internal transcription start sites. We present here a wide overview of this diversity and of their mechanisms of action as transcription regulators, as well as alternative actions through cytoplasmic signaling.
Asunto(s)
Receptores de Hormona Tiroidea/genética , Receptores de Hormona Tiroidea/metabolismo , Animales , Regulación de la Expresión Génica , Humanos , Especificidad de Órganos/genética , Isoformas de Proteínas , Receptores de Hormona Tiroidea/química , Investigación , Transducción de Señal , Transcripción GenéticaRESUMEN
The thyroid hormones act through their nuclear receptor TRs that are T3-modulated transcription factors. To elucidate the molecular mechanisms at the basis of specific physiological responses to TH-TR, in vitro approaches are commonly used to demonstrate the activation or repression of target genes. These approaches allow identifying direct transcriptional targets of TRs which can eventually be confirmed by using in vivo chromatin binding assays.Here, we describe two classical approaches in vitro and in cell lines such as Electro-Mobility Shift Assay and thyroid-hormone-responsive Luciferase-reporter assay (EMSA and Luc, respectively) we have been largely using to investigate TRα1-driven TH-TRs intestinal epithelium cell autonomous action.
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Regulación de la Expresión Génica , Receptores de Hormona Tiroidea/metabolismo , Transcripción Genética , Animales , Línea Celular , Ensayo de Cambio de Movilidad Electroforética/métodos , Genes Reporteros , Humanos , Regiones Promotoras Genéticas , Unión Proteica , Elementos de Respuesta , Activación TranscripcionalRESUMEN
BACKGROUND: Resistance to thyroid hormone due to THRA mutations (RTHα) is a recently discovered genetic disease, displaying important variability in its clinical presentation. The mutations alter the function of TRα1, one of the two nuclear receptors for thyroid hormone. METHODS: The aim of this study was to understand the relationship between specific THRA mutations and phenotype. CRISPR/Cas9 genome editing was used to generate five new mouse models of RTHα, with frameshift or missense mutations. RESULTS: Like human patients, mutant mice displayed a hypothyroid-like phenotype, with altered development. Phenotype severity varied between the different mouse models, mainly depending on the ability of the mutant receptor to interact with transcription corepressor in the presence of thyroid hormone. CONCLUSION: The present mutant mice represent highly relevant models for the human genetic disease which will be useful for future investigations.
Asunto(s)
Genes erbA/genética , Síndrome de Resistencia a Hormonas Tiroideas/genética , Animales , Sistemas CRISPR-Cas , Ratones , Mutación , FenotipoRESUMEN
The gastrointestinal tract is a well-characterized target of thyroid hormones and thyroid hormone nuclear receptors TRs, as extensively described in the literature. The paradigm is its important remodelling in amphibians during thyroid hormone-dependent metamorphosis. Interestingly, several studies have described the conservation of this hormonal signal during intestinal development in mammals. Additional data suggested that it may also play a role in intestinal homeostasis, stem cell physiology and progenitor commitment as well as in tumour development. It is worth underlining that in the mammalian intestine the functionality of the TRα1 receptor is coordinated and integrated with other signalling pathways, such as Wnt and Notch, specifically at the level of stem/progenitor cell populations. Here, we summarize these data and concepts and discuss this new role for thyroid hormones and the TRα1 receptor in the biology of intestinal epithelial precursor cells.
Asunto(s)
Células Epiteliales/metabolismo , Mucosa Intestinal/metabolismo , Receptores Notch/genética , Células Madre/metabolismo , Receptores alfa de Hormona Tiroidea/genética , Hormonas Tiroideas/genética , Anfibios/genética , Anfibios/crecimiento & desarrollo , Anfibios/metabolismo , Animales , Células Epiteliales/citología , Regulación del Desarrollo de la Expresión Génica , Homeostasis/genética , Intestinos/citología , Metamorfosis Biológica/genética , Ratones , Receptores Notch/metabolismo , Células Madre/citología , Glándula Tiroides/fisiología , Receptores alfa de Hormona Tiroidea/metabolismo , Hormonas Tiroideas/metabolismo , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Vía de Señalización WntRESUMEN
The thyroid hormones, T3 and T4, control several developmental and homeostatic processes. From a molecular point of view, most of their actions depend on the activity of the thyroid hormone nuclear receptors (TRs), which are T3-modulated transcription factors. Recent studies have not only highlighted that the physiological response induced by T3 within a cell depends on the expression of specific TRs, but also that the functions of TRs are coordinated by and integrated in other signalling pathways. This is particularly the case for the multilevel interactions between TRs and the Wnt signalling pathway. Interestingly both signals are involved in development and homeostasis, and their alterations are responsible for the development of pathologies, such as cancer. Here, we present findings on the complex crosstalk between TRs and Wnt in several organisms and in different tissue contexts, and speculate on the biological relevance of modulating TR-Wnt functionality in therapeutic approaches aimed to target cancer cells or applications for regenerative medicine.