RESUMO
Epithelial-mesenchymal transitions (EMTs) are the epitome of cell plasticity in embryonic development and cancer; during EMT, epithelial cells undergo dramatic phenotypic changes and become able to migrate to form different tissues or give rise to metastases, respectively. The importance of EMTs in other contexts, such as tissue repair and fibrosis in the adult, has become increasingly recognized and studied. In this Review, we discuss the function of EMT in the adult after tissue damage and compare features of embryonic and adult EMT. Whereas sustained EMT leads to adult tissue degeneration, fibrosis and organ failure, its transient activation, which confers phenotypic and functional plasticity on somatic cells, promotes tissue repair after damage. Understanding the mechanisms and temporal regulation of different EMTs provides insight into how some tissues heal and has the potential to open new therapeutic avenues to promote repair or regeneration of tissue damage that is currently irreversible. We also discuss therapeutic strategies that modulate EMT that hold clinical promise in ameliorating fibrosis, and how precise EMT activation could be harnessed to enhance tissue repair.
Assuntos
Transição Epitelial-Mesenquimal , Fibrose , Humanos , Animais , Cicatrização/fisiologia , Regeneração/fisiologia , Células Epiteliais/patologia , Células Epiteliais/metabolismoRESUMO
Epithelial-mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by 'the EMT International Association' (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT.
Assuntos
Pesquisa Biomédica/normas , Transição Epitelial-Mesenquimal , Animais , Movimento Celular , Plasticidade Celular , Consenso , Biologia do Desenvolvimento/normas , Humanos , Neoplasias/patologia , Terminologia como AssuntoRESUMO
The significant parallels between cell plasticity during embryonic development and carcinoma progression have helped us understand the importance of the epithelial-mesenchymal transition (EMT) in human disease. Our expanding knowledge of EMT has led to a clarification of the EMT program as a set of multiple and dynamic transitional states between the epithelial and mesenchymal phenotypes, as opposed to a process involving a single binary decision. EMT and its intermediate states have recently been identified as crucial drivers of organ fibrosis and tumor progression, although there is some need for caution when interpreting its contribution to metastatic colonization. Here, we discuss the current state-of-the-art and latest findings regarding the concept of cellular plasticity and heterogeneity in EMT. We raise some of the questions pending and identify the challenges faced in this fast-moving field.
Assuntos
Transição Epitelial-Mesenquimal , Fibrose/patologia , Neoplasias/patologia , Animais , Desenvolvimento Embrionário , Epigênese Genética , Humanos , Transcrição GênicaRESUMO
The epithelial to mesenchymal transition (EMT) converts epithelial cells into migratory and invasive cells and is a fundamental event in morphogenesis. Although its relevance in the progression of cancer and organ fibrosis had been debated until recently, the EMT is now established as an important step in the metastatic cascade of epithelial tumors. The similarities between pathological and developmental EMTs validate the embryo as the best model to understand the molecular and cellular mechanisms involved in this process, identifying those that are hijacked during the progression of cancer and organ degeneration. Our ever-increasing understanding of how transcription factors regulate the EMT has revealed complex regulatory loops coupled to posttranscriptional and epigenetic regulatory programs. The EMT is now integrated into the systemic activities of whole organisms, establishing links with cell survival, stemness, inflammation, and immunity. In addition, the EMT now constitutes a promising target for the treatment of cancer and organ-degenerative diseases.
Assuntos
Movimento Celular/fisiologia , Doença , Transição Epitelial-Mesenquimal/fisiologia , Animais , Caderinas/metabolismo , Diferenciação Celular , Transformação Celular Neoplásica/patologia , Progressão da Doença , Epigênese Genética , Células Epiteliais/patologia , Células Epiteliais/fisiologia , Matriz Extracelular/metabolismo , Humanos , Hipóxia/metabolismo , Imunidade , Inflamação/metabolismo , Mesoderma/patologia , Mesoderma/fisiologia , Neoplasias/patologia , Neoplasias/fisiopatologia , RNA não Traduzido/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
The epithelial to mesenchymal transition (EMT) plays crucial roles in the formation of the body plan and in the differentiation of multiple tissues and organs. EMT also contributes to tissue repair, but it can adversely cause organ fibrosis and promote carcinoma progression through a variety of mechanisms. EMT endows cells with migratory and invasive properties, induces stem cell properties, prevents apoptosis and senescence, and contributes to immunosuppression. Thus, the mesenchymal state is associated with the capacity of cells to migrate to distant organs and maintain stemness, allowing their subsequent differentiation into multiple cell types during development and the initiation of metastasis.
Assuntos
Transformação Celular Neoplásica , Metástase Neoplásica , Neoplasias/patologia , Células-Tronco Neoplásicas/citologia , Animais , Células Epiteliais/citologia , Gastrulação , HumanosRESUMO
Most animals show external bilateral symmetry, which hinders the observation of multiple internal left-right (L/R) asymmetries that are fundamental to organ packaging and function. In vertebrates, left identity is mediated by the left-specific Nodal-Pitx2 axis that is repressed on the right-hand side by the epithelial-mesenchymal transition (EMT) inducer Snail1 (refs 3, 4). Despite some existing evidence, it remains unclear whether an equivalent instructive pathway provides right-hand-specific information to the embryo. Here we show that, in zebrafish, BMP mediates the L/R asymmetric activation of another EMT inducer, Prrx1a, in the lateral plate mesoderm with higher levels on the right. Prrx1a drives L/R differential cell movements towards the midline, leading to a leftward displacement of the cardiac posterior pole through an actomyosin-dependent mechanism. Downregulation of Prrx1a prevents heart looping and leads to mesocardia. Two parallel and mutually repressed pathways, respectively driven by Nodal and BMP on the left and right lateral plate mesoderm, converge on the asymmetric activation of the transcription factors Pitx2 and Prrx1, which integrate left and right information to govern heart morphogenesis. This mechanism is conserved in the chicken embryo, and in the mouse SNAIL1 acts in a similar manner to Prrx1a in zebrafish and PRRX1 in the chick. Thus, a differential L/R EMT produces asymmetric cell movements and forces, more prominent from the right, that drive heart laterality in vertebrates.
Assuntos
Coração/embriologia , Morfogênese , Miocárdio/metabolismo , Transdução de Sinais , Peixe-Zebra/embriologia , Peixe-Zebra/metabolismo , Actomiosina/metabolismo , Animais , Movimento Celular , Embrião de Galinha , Transição Epitelial-Mesenquimal , Feminino , Proteínas de Homeodomínio/metabolismo , Mesoderma/embriologia , Mesoderma/metabolismo , Camundongos , Fatores de Transcrição da Família Snail/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Peixe-Zebra/metabolismoRESUMO
Eph receptor (Eph) and ephrin signaling regulate fundamental developmental processes through both forward and reverse signaling triggered upon cell-cell contact. In vertebrates, they are both classified into classes A and B, and some representatives have been identified in many metazoan groups, where their expression and functions have been well studied. We have extended previous phylogenetic analyses and examined the presence of Eph and ephrins in the tree of life to determine their origin and evolution. We have found that 1) premetazoan choanoflagellates may already have rudimental Eph/ephrin signaling as they have an Eph-/ephrin-like pair and homologs of downstream-signaling genes; 2) both forward- and reverse-downstream signaling might already occur in Porifera since sponges have most genes involved in these types of signaling; 3) the nonvertebrate metazoan Eph is a type-B receptor that can bind ephrins regardless of their membrane-anchoring structure, glycosylphosphatidylinositol, or transmembrane; 4) Eph/ephrin cross-class binding is specific to Gnathostomata; and 5) kinase-dead Eph receptors can be traced back to Gnathostomata. We conclude that Eph/ephrin signaling is of older origin than previously believed. We also examined the presence of protein domains associated with functional characteristics and the appearance and conservation of downstream-signaling pathways to understand the original and derived functions of Ephs and ephrins. We find that the evolutionary history of these gene families points to an ancestral function in cell-cell interactions that could contribute to the emergence of multicellularity and, in particular, to the required segregation of cell populations.
Assuntos
Efrinas/genética , Efrinas/metabolismo , Receptores da Família Eph/genética , Receptores da Família Eph/metabolismo , Animais , Comunicação Celular , Coanoflagelados/genética , Coanoflagelados/metabolismo , Evolução Molecular , Humanos , Filogenia , Poríferos/genética , Poríferos/metabolismo , Transdução de Sinais , Vertebrados/genética , Vertebrados/metabolismoRESUMO
Head and neck squamous cell carcinoma (HNSCC) arises from the mucosal lining of the upper aerodigestive tract and display few treatment options in advanced stages. Despite increased knowledge of HNSCC molecular biology, the identification of new players involved in triggering HNSCC recurrence and metastatic disease is needed. We uncover that G-protein-coupled receptor kinase-2 (GRK2) expression is reduced in undifferentiated, high-grade human HNSCC tumors, whereas its silencing in model human HNSCC cells is sufficient to trigger epithelial-to-mesenchymal transition (EMT) phenotypic features, an EMT-like transcriptional program and enhanced lymph node colonization from orthotopic tongue tumors in mice. Conversely, enhancing GRK2 expression counteracts mesenchymal cells traits by mechanisms involving phosphorylation and decreased functionality of the key EMT inducer Snail1. Our results suggest that GRK2 safeguards the epithelial phenotype, whereas its downregulation contributes to the activation of EMT programs in HNSCC.
Assuntos
Quinase 2 de Receptor Acoplado a Proteína G/metabolismo , Neoplasias de Cabeça e Pescoço/enzimologia , Neoplasias de Cabeça e Pescoço/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/enzimologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Animais , Linhagem Celular Tumoral , Progressão da Doença , Regulação para Baixo , Células Epiteliais/enzimologia , Células Epiteliais/patologia , Transição Epitelial-Mesenquimal , Quinase 2 de Receptor Acoplado a Proteína G/biossíntese , Quinase 2 de Receptor Acoplado a Proteína G/genética , Neoplasias de Cabeça e Pescoço/genética , Xenoenxertos , Humanos , Camundongos , Camundongos Nus , Fosforilação , Fatores de Transcrição da Família Snail/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/genéticaRESUMO
Snail and Zeb transcription factors induce epithelial-to-mesenchymal transition (EMT) in embryonic and adult tissues by direct repression of E-cadherin transcription. The repression of E-cadherin transcription by the EMT inducers Snail1 and Zeb2 plays a fundamental role in defining embryonic territories in the mouse, as E-cadherin needs to be downregulated in the primitive streak and in the epiblast, concomitant with the formation of mesendodermal precursors and the neural plate, respectively. Here, we show that in the chick embryo, E-cadherin is weakly expressed in the epiblast at pre-primitive streak stages where it is substituted for by P-cadherin We also show that Snail2 and Zeb2 repress P-cadherin transcription in the primitive streak and the neural plate, respectively. This indicates that E- and P-cadherin expression patterns evolved differently between chick and mouse. As such, the Snail1/E-cadherin axis described in the early mouse embryo corresponds to Snail2/P-cadherin in the chick, but both Snail factors and Zeb2 fulfil a similar role in chick and mouse in directly repressing ectodermal cadherin genes to contribute to the delamination of mesendodermal precursors at gastrulation and the proper specification of the neural ectoderm during neural induction.
Assuntos
Caderinas/metabolismo , Proteínas de Homeodomínio/fisiologia , Proteínas Repressoras/fisiologia , Fatores de Transcrição da Família Snail/fisiologia , Animais , Embrião de Galinha , Galinhas , Regulação para Baixo , Ectoderma/metabolismo , Transição Epitelial-Mesenquimal/genética , Gastrulação/genética , Proteínas de Homeodomínio/genética , Camundongos , Neurônios/metabolismo , Linha Primitiva/embriologia , Regiões Promotoras Genéticas , Proteínas Repressoras/genética , Fatores de Transcrição da Família Snail/genéticaRESUMO
In the developing telencephalon, the medial ganglionic eminence (MGE) generates many cortical and virtually all striatal interneurons. While the molecular mechanisms controlling the migration of interneurons to the cortex have been extensively studied, very little is known about the nature of the signals that guide interneurons to the striatum. Here we report that the allocation of MGE-derived interneurons in the developing striatum of the mouse relies on a combination of chemoattractive and chemorepulsive activities. Specifically, interneurons migrate toward the striatum in response to Nrg1/ErbB4 chemoattraction, and avoid migrating into the adjacent cortical territories by a repulsive activity mediated by EphB/ephrinB signaling. Our results also suggest that the responsiveness of MGE-derived striatal interneurons to these cues is at least in part controlled by the postmitotic activity of the transcription factor Nkx2-1. This study therefore reveals parallel mechanisms for the migration of MGE-derived interneurons to the striatum and the cerebral cortex.
Assuntos
Movimento Celular/genética , Corpo Estriado/citologia , Interneurônios/fisiologia , Vias Neurais/fisiologia , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Animais , Animais Geneticamente Modificados , Diferenciação Celular , Córtex Cerebelar/citologia , Embrião de Mamíferos , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos C57BL , Mutação/genética , Proteínas Nucleares/genética , Técnicas de Cultura de Órgãos , Receptor EphB1/genética , Receptor EphB1/metabolismo , Receptor EphB3/genética , Receptor EphB3/metabolismo , Receptor ErbB-4/genética , Receptor ErbB-4/metabolismo , Transdução de Sinais , Telencéfalo/citologia , Telencéfalo/embriologia , Fator Nuclear 1 de Tireoide , Fatores de Transcrição/genéticaRESUMO
Snail1 is a central regulator of epithelial cell adhesion and movement in epithelial-to-mesenchymal transitions (EMTs) during embryo development; a process reactivated during cancer metastasis. While induction of Snail1 transcription precedes EMT induction, post-translational regulation of Snail1 is also critical for determining Snail1's protein level, subcellular localization, and capacity to induce EMT. To identify novel post-translational regulators of Snail1, we developed a live cell, bioluminescence-based screen. From a human kinome RNAi screen, we have identified Lats2 kinase as a novel regulator of Snail1 protein level, subcellular localization, and thus, activity. We show that Lats2 interacts with Snail1 and directly phosphorylates Snail1 at residue T203. This occurs in the nucleus and serves to retain Snail1 in the nucleus thereby enhancing its stability. Lats2 was found to positively influence cellular EMT and tumour cell invasion, in a Snail1-dependent manner. Indeed during TGFß-induced EMT Lats2 is activated and Snail1 phosphorylated at T203. Analysis in mouse and zebrafish embryo development confirms that Lats2 acts as a positive modulator of Snail1 protein level and potentiates its in vivo EMT activity.
Assuntos
Núcleo Celular/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Sequência de Aminoácidos , Animais , Células Cultivadas , Cães , Embrião de Mamíferos/metabolismo , Embrião não Mamífero/metabolismo , Transição Epitelial-Mesenquimal , Células HCT116 , Células HEK293 , Humanos , Camundongos , Dados de Sequência Molecular , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Interferência de RNA , Fatores de Transcrição da Família Snail , Fatores de Transcrição/genética , Transfecção , Proteínas Supressoras de Tumor/genética , Peixe-ZebraRESUMO
During the development of the nervous system the regulation of cell cycle, differentiation, and survival is tightly interlinked. Newly generated neurons must keep cell cycle components under strict control, as cell cycle re-entry leads to neuronal degeneration and death. However, despite their relevance, the mechanisms controlling this process remain largely unexplored. Here we show that Scratch2 is involved in the control of the cell cycle in neurons in the developing spinal cord of the zebrafish embryo. scratch2 knockdown induces postmitotic neurons to re-enter mitosis. Scratch2 prevents cell cycle re-entry by maintaining high levels of the cycle inhibitor p57 through the downregulation of miR-25. Thus, Scratch2 appears to safeguard the homeostasis of postmitotic primary neurons by preventing cell cycle re-entry.
Assuntos
MicroRNAs/fisiologia , Mitose/fisiologia , Neurônios/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo , Animais , Animais Geneticamente Modificados , Diferenciação Celular/fisiologia , Sobrevivência Celular/fisiologia , Inibidor de Quinase Dependente de Ciclina p57/genética , Inibidor de Quinase Dependente de Ciclina p57/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Técnicas de Silenciamento de Genes , Proteínas de Fluorescência Verde/genética , Homeostase/fisiologia , Proteínas Luminescentes/genética , MicroRNAs/genética , Neurogênese/fisiologia , Neurônios/citologia , Medula Espinal/citologia , Medula Espinal/embriologia , Medula Espinal/fisiologia , Peixe-Zebra , Proteína Vermelha FluorescenteRESUMO
The epithelial to mesenchymal transition or EMT has become one of the most exciting fields in cancer research. Nevertheless, its relevance in tumor biology and the metastatic process still faces some controversy. Clarification may arise when considering the EMT as a reversible and often incomplete process, essentially a manifestation of strong epithelial plasticity. Transient cellular states are generated to fulfill specific requirements in each and all the steps of the metastatic process, from primary tumor cell detachment to dissemination and colonization. Opposing multiple cellular programs that promote or prevent EMT, thereby destabilizing or reinforcing epithelial integrity, play a central role in the inherent cellular dynamics of cancer progression. These cell biology programs not only drive cells towards the epithelial or the mesenchymal state but also impinge into multiple cellular and global responses including proliferation, stemness, chemo and immunotherapy resistance, inflammation and immunity, all relevant for the development of the metastatic disease.
Assuntos
Transição Epitelial-Mesenquimal/fisiologia , Animais , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Células Epiteliais/fisiologia , Humanos , Neoplasias/etiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The adult mammalian brain retains some capacity to replenish neurons and glia, holding promise for brain regeneration. Thus, understanding the mechanisms controlling adult neural stem cell (NSC) differentiation is crucial. Paradoxically, adult NSCs in the subependymal zone transcribe genes associated with both multipotency maintenance and neural differentiation, but the mechanism that prevents conflicts in fate decisions due to these opposing transcriptional programmes is unknown. Here we describe intron detention as such control mechanism. In NSCs, while multiple mRNAs from stemness genes are spliced and exported to the cytoplasm, transcripts from differentiation genes remain unspliced and detained in the nucleus, and the opposite is true under neural differentiation conditions. We also show that m6A methylation is the mechanism that releases intron detention and triggers nuclear export, enabling rapid and synchronized responses. m6A RNA methylation operates as an on/off switch for transcripts with antagonistic functions, tightly controlling the timing of NSCs commitment to differentiation.
Assuntos
Células-Tronco Neurais , Animais , Íntrons/genética , Diferenciação Celular/genética , Neurônios , Neurogênese/genética , MamíferosRESUMO
Bone undergoes continuous remodelling throughout adult life, and the equilibrium between bone formation by osteoblasts and bone resorption by osteoclasts defines the final bone mass. Here we show that Snail1 regulates this balance by controlling osteoblast differentiation. Snail1 is necessary for the early steps of osteoblast development, and it must be downregulated for their final differentiation. At the molecular level, Snail1 controls bone mass by repressing the transcription of both the osteoblast differentiation factor Runx2 and the vitamin D receptor (VDR) genes in osteoblasts. Sustained activation of Snail1 in transgenic mice provokes deficient osteoblast differentiation, which, together with the loss of vitamin D signalling in the bone, also impairs osteoclastogenesis. Indeed, the mineralisation of the bone matrix is severely affected, leading to hypocalcemia-independent osteomalacia. Our data show that the impact of Snail1 activity on the osteoblast population regulates the course of bone cells differentiation and ensures normal bone remodelling.