RESUMO
Wnt signalling induces a gradient of stem/progenitor cell proliferation along the crypt-villus axis of the intestine, which becomes expanded during intestinal regeneration or tumour formation. The YAP transcriptional co-activator is known to be required for intestinal regeneration, but its mode of regulation remains controversial. Here we show that the YAP-TEAD transcription factor is a key downstream effector of Wnt signalling in the intestine. Loss of YAP activity by Yap/Taz conditional knockout results in sensitivity of crypt stem cells to apoptosis and reduced cell proliferation during regeneration. Gain of YAP activity by Lats1/2 conditional knockout is sufficient to drive a crypt hyperproliferation response. In particular, Wnt signalling acts transcriptionally to induce YAP and TEAD1/2/4 expression. YAP normally localises to the nucleus only in crypt base stem cells, but becomes nuclear in most intestinal epithelial cells during intestinal regeneration after irradiation, or during organoid growth, in a Src family kinase-dependent manner. YAP-driven crypt expansion during regeneration involves an elongation and flattening of the Wnt signalling gradient. Thus, Wnt and Src-YAP signals cooperate to drive intestinal regeneration.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Intestinos/fisiologia , Regeneração/genética , Regeneração/fisiologia , Fatores de Transcrição/genética , Via de Sinalização Wnt/genética , Quinases da Família src/genética , Animais , Apoptose/genética , Proteínas de Ciclo Celular/genética , Proliferação de Células/genética , Células Epiteliais/fisiologia , Mucosa Intestinal/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco/fisiologia , Proteínas de Sinalização YAPRESUMO
Inactivation of APC is a strongly predisposing event in the development of colorectal cancer, prompting the search for vulnerabilities specific to cells that have lost APC function. Signalling through the mTOR pathway is known to be required for epithelial cell proliferation and tumour growth, and the current paradigm suggests that a critical function of mTOR activity is to upregulate translational initiation through phosphorylation of 4EBP1 (refs 6, 7). This model predicts that the mTOR inhibitor rapamycin, which does not efficiently inhibit 4EBP1 (ref. 8), would be ineffective in limiting cancer progression in APC-deficient lesions. Here we show in mice that mTOR complex 1 (mTORC1) activity is absolutely required for the proliferation of Apc-deficient (but not wild-type) enterocytes, revealing an unexpected opportunity for therapeutic intervention. Although APC-deficient cells show the expected increases in protein synthesis, our study reveals that it is translation elongation, and not initiation, which is the rate-limiting component. Mechanistically, mTORC1-mediated inhibition of eEF2 kinase is required for the proliferation of APC-deficient cells. Importantly, treatment of established APC-deficient adenomas with rapamycin (which can target eEF2 through the mTORC1-S6K-eEF2K axis) causes tumour cells to undergo growth arrest and differentiation. Taken together, our data suggest that inhibition of translation elongation using existing, clinically approved drugs, such as the rapalogs, would provide clear therapeutic benefit for patients at high risk of developing colorectal cancer.
Assuntos
Transformação Celular Neoplásica/patologia , Neoplasias Intestinais/metabolismo , Neoplasias Intestinais/patologia , Complexos Multiproteicos/metabolismo , Elongação Traducional da Cadeia Peptídica , Serina-Treonina Quinases TOR/metabolismo , Proteína da Polipose Adenomatosa do Colo/deficiência , Proteína da Polipose Adenomatosa do Colo/genética , Animais , Proliferação de Células , Transformação Celular Neoplásica/metabolismo , Quinase do Fator 2 de Elongação/deficiência , Quinase do Fator 2 de Elongação/genética , Quinase do Fator 2 de Elongação/metabolismo , Ativação Enzimática , Genes APC , Neoplasias Intestinais/genética , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos , Camundongos Endogâmicos C57BL , Proteína Oncogênica p55(v-myc)/metabolismo , Fator 2 de Elongação de Peptídeos/metabolismo , Proteínas Quinases S6 Ribossômicas/metabolismo , Transdução de Sinais , Proteínas Wnt/metabolismoRESUMO
Cancer cachexia is a common deleterious paraneoplastic syndrome that represents an area of unmet clinical need, partly due to its poorly understood aetiology and complex multifactorial nature. We have interrogated multiple genetically defined larval Drosophila models of tumourigenesis against key features of human cancer cachexia. Our results indicate that cachectic tissue wasting is dependent on the genetic characteristics of the tumour and demonstrate that host malnutrition or tumour burden are not sufficient to drive wasting. We show that JAK/STAT and TNF-α/Egr signalling are elevated in cachectic muscle and promote tissue wasting. Furthermore, we introduce a dual driver system that allows independent genetic manipulation of tumour and host skeletal muscle. Overall, we present a novel Drosophila larval paradigm to study tumour/host tissue crosstalk in vivo, which may contribute to future research in cancer cachexia and impact the design of therapeutic approaches for this pathology.
Assuntos
Caquexia/patologia , Carcinogênese/patologia , Modelos Animais de Doenças , Larva/crescimento & desenvolvimento , Neoplasias/complicações , Animais , Caquexia/etiologia , Caquexia/metabolismo , Carcinogênese/genética , Carcinogênese/metabolismo , Drosophila , Perfilação da Expressão Gênica , Humanos , Janus Quinases/genética , Janus Quinases/metabolismo , Larva/genética , Larva/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Transdução de SinaisRESUMO
Wnt/ß-catenin signal transduction directs intestinal stem cell (ISC) proliferation during homeostasis. Hyperactivation of Wnt signaling initiates colorectal cancer, which most frequently results from truncation of the tumor suppressor Adenomatous polyposis coli (APC). The ß-catenin-TCF transcription complex activates both the physiological expression of Wnt target genes in the normal intestinal epithelium and their aberrantly increased expression in colorectal tumors. Whether mechanistic differences in the Wnt transcription machinery drive these distinct levels of target gene activation in physiological versus pathological states remains uncertain, but is relevant for the design of new therapeutic strategies. Here, using a Drosophila model, we demonstrate that two evolutionarily conserved transcription cofactors, Earthbound (Ebd) and Erect wing (Ewg), are essential for all major consequences of Apc1 inactivation in the intestine: the hyperactivation of Wnt target gene expression, excess number of ISCs, and hyperplasia of the epithelium. In contrast, only Ebd, but not Ewg, mediates the Wnt-dependent regulation of ISC proliferation during homeostasis. Therefore, in the adult intestine, Ebd acts independently of Ewg in physiological Wnt signaling, but cooperates with Ewg to induce the hyperactivation of Wnt target gene expression following Apc1 loss. These findings have relevance for human tumorigenesis, as Jerky (JRK/JH8), the human Ebd homolog, promotes Wnt pathway hyperactivation and is overexpressed in colorectal, breast, and ovarian cancers. Together, our findings reveal distinct requirements for Ebd and Ewg in physiological Wnt pathway activation versus oncogenic Wnt pathway hyperactivation following Apc1 loss. Such differentially utilized transcription cofactors may offer new opportunities for the selective targeting of Wnt-driven cancers.
Assuntos
Proteína B de Centrômero/genética , Proteínas do Citoesqueleto/genética , Proteínas de Drosophila/genética , Neoplasias/genética , Neuropeptídeos/genética , Proteínas Nucleares/biossíntese , Fatores de Transcrição/genética , Animais , Carcinogênese/genética , Proliferação de Células/genética , Proteína B de Centrômero/biossíntese , Proteínas de Ligação a DNA , Modelos Animais de Doenças , Proteínas de Drosophila/biossíntese , Epitélio/crescimento & desenvolvimento , Epitélio/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação Neoplásica da Expressão Gênica , Humanos , Hiperplasia/genética , Hiperplasia/patologia , Intestinos/crescimento & desenvolvimento , Neoplasias/patologia , Neuropeptídeos/biossíntese , Proteínas Nucleares/genética , Proteínas de Ligação a RNA , Células-Tronco/metabolismo , Fatores de Transcrição/biossíntese , Via de Sinalização Wnt/genéticaRESUMO
The skin is a squamous epithelium that is continuously renewed by a population of basal layer stem/progenitor cells and can heal wounds. Here, we show that the transcription regulators YAP and TAZ localise to the nucleus in the basal layer of skin and are elevated upon wound healing. Skin-specific deletion of both YAP and TAZ in adult mice slows proliferation of basal layer cells, leads to hair loss and impairs regeneration after wounding. Contact with the basal extracellular matrix and consequent integrin-Src signalling is a key determinant of the nuclear localisation of YAP/TAZ in basal layer cells and in skin tumours. Contact with the basement membrane is lost in differentiating daughter cells, where YAP and TAZ become mostly cytoplasmic. In other types of squamous epithelia and squamous cell carcinomas, a similar control mechanism is present. By contrast, columnar epithelia differentiate an apical domain that recruits CRB3, Merlin (also known as NF2), KIBRA (also known as WWC1) and SAV1 to induce Hippo signalling and retain YAP/TAZ in the cytoplasm despite contact with the basal layer extracellular matrix. When columnar epithelial tumours lose their apical domain and become invasive, YAP/TAZ becomes nuclear and tumour growth becomes sensitive to the Src inhibitor Dasatinib.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Homeostase , Integrinas/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fosfoproteínas/metabolismo , Transdução de Sinais , Pele/metabolismo , Animais , Proteínas de Ciclo Celular , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Linhagem Celular , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Dasatinibe/farmacologia , Epitélio/efeitos dos fármacos , Epitélio/metabolismo , Receptores ErbB/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Humanos , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Camundongos , Neoplasias de Células Escamosas/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Estabilidade Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Pele/efeitos dos fármacos , Pele/patologia , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Transativadores , Fatores de Transcrição , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional , Cicatrização/efeitos dos fármacos , Proteínas de Sinalização YAP , Quinases da Família src/metabolismoRESUMO
The non-receptor tyrosine kinase c-Src, hereafter referred to as Src, is overexpressed or activated in multiple human malignancies. There has been much speculation about the functional role of Src in colorectal cancer (CRC), with Src amplification and potential activating mutations in up to 20% of the human tumours, although this has never been addressed due to multiple redundant family members. Here, we have used the adult Drosophila and mouse intestinal epithelium as paradigms to define a role for Src during tissue homeostasis, damage-induced regeneration and hyperplasia. Through genetic gain and loss of function experiments, we demonstrate that Src is necessary and sufficient to drive intestinal stem cell (ISC) proliferation during tissue self-renewal, regeneration and tumourigenesis. Surprisingly, Src plays a non-redundant role in the mouse intestine, which cannot be substituted by the other family kinases Fyn and Yes. Mechanistically, we show that Src drives ISC proliferation through upregulation of EGFR and activation of Ras/MAPK and Stat3 signalling. Therefore, we demonstrate a novel essential role for Src in intestinal stem/progenitor cell proliferation and tumourigenesis initiation in vivo.
Assuntos
Transformação Celular Neoplásica/metabolismo , Neoplasias Colorretais/enzimologia , Proteínas de Drosophila/metabolismo , Mucosa Intestinal/enzimologia , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Regeneração , Células-Tronco/enzimologia , Quinases da Família src/metabolismo , Animais , Proteína Tirosina Quinase CSK , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Proteínas de Drosophila/genética , Drosophila melanogaster , Receptores ErbB/genética , Receptores ErbB/metabolismo , Amplificação de Genes , Humanos , Mucosa Intestinal/patologia , Sistema de Sinalização das MAP Quinases/genética , Camundongos , Camundongos Transgênicos , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas/genética , Receptores de Peptídeos de Invertebrados/genética , Receptores de Peptídeos de Invertebrados/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Células-Tronco/patologia , Quinases da Família src/genéticaRESUMO
The ability to regenerate following stress is a hallmark of self-renewing tissues. However, little is known about how regeneration differs from homeostatic tissue maintenance. Here, we study the role and regulation of Wingless (Wg)/Wnt signalling during intestinal regeneration using the Drosophila adult midgut. We show that Wg is produced by the intestinal epithelial compartment upon damage or stress and it is exclusively required for intestinal stem cell (ISC) proliferation during tissue regeneration. Reducing Wg or downstream signalling components from the intestinal epithelium blocked tissue regeneration. Importantly, we demonstrate that Wg from the undifferentiated progenitor cell, the enteroblast, is required for Myc-dependent ISC proliferation during regeneration. Similar to young regenerating tissues, ageing intestines required Wg and Myc for ISC hyperproliferation. Unexpectedly, our results demonstrate that epithelial but not mesenchymal Wg is essential for ISC proliferation in response to damage, while neither source of the ligand is solely responsible for ISC maintenance and tissue self-renewal in unchallenged tissues. Therefore, fine-tuning Wnt results in optimal balance between the ability to respond to stress without negatively affecting organismal viability.
Assuntos
Proteínas de Drosophila/fisiologia , Drosophila melanogaster/fisiologia , Intestinos/fisiologia , Regeneração/fisiologia , Células-Tronco/fisiologia , Proteína Wnt1/fisiologia , Animais , Proliferação de Células , Feminino , Transdução de Sinais/fisiologiaRESUMO
Inactivating mutations within adenomatous polyposis coli (APC), a negative regulator of Wnt signaling, are responsible for most sporadic and hereditary forms of colorectal cancer (CRC). Here, we use the adult Drosophila midgut as a model system to investigate the molecular events that mediate intestinal hyperplasia following loss of Apc in the intestine. Our results indicate that the conserved Wnt target Myc and its binding partner Max are required for the initiation and maintenance of intestinal stem cell (ISC) hyperproliferation following Apc1 loss. Importantly, we find that loss of Apc1 leads to the production of the interleukin-like ligands Upd2/3 and the EGF-like Spitz in a Myc-dependent manner. Loss of Apc1 or high Wg in ISCs results in non-cell-autonomous upregulation of upd3 in enterocytes and subsequent activation of Jak/Stat signaling in ISCs. Crucially, knocking down Jak/Stat or Spitz/Egfr signaling suppresses Apc1-dependent ISC hyperproliferation. In summary, our results uncover a novel non-cell-autonomous interplay between Wnt/Myc, Egfr and Jak/Stat signaling in the regulation of intestinal hyperproliferation. Furthermore, we present evidence suggesting potential conservation in mouse models and human CRC. Therefore, the Drosophila adult midgut proves to be a powerful genetic system to identify novel mediators of APC phenotypes in the intestine.
Assuntos
Proteínas de Drosophila/fisiologia , Drosophila , Receptores ErbB/fisiologia , Intestinos/patologia , Janus Quinases/fisiologia , Receptores de Peptídeos de Invertebrados/fisiologia , Fatores de Transcrição STAT/fisiologia , Fatores de Transcrição/fisiologia , Células-Tronco Adultas/metabolismo , Células-Tronco Adultas/patologia , Células-Tronco Adultas/fisiologia , Fatores Etários , Animais , Animais Geneticamente Modificados , Subunidade Apc1 do Ciclossomo-Complexo Promotor de Anáfase , Replicação do DNA/genética , Replicação do DNA/fisiologia , Drosophila/genética , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Enterócitos/metabolismo , Enterócitos/patologia , Enterócitos/fisiologia , Receptores ErbB/genética , Receptores ErbB/metabolismo , Hiperplasia/genética , Mucosa Intestinal/metabolismo , Janus Quinases/genética , Janus Quinases/metabolismo , Receptor Cross-Talk/fisiologia , Receptores de Peptídeos de Invertebrados/genética , Receptores de Peptídeos de Invertebrados/metabolismo , Fatores de Transcrição STAT/genética , Fatores de Transcrição STAT/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoAssuntos
Carcinogênese/genética , Transformação Celular Neoplásica/genética , Modelos Animais de Doenças , Drosophila melanogaster , Epigênese Genética/fisiologia , Modelos Biológicos , Animais , Animais Geneticamente Modificados , Pesquisa Biomédica/métodos , Carcinogênese/patologia , Linhagem Celular , Transformação Celular Neoplásica/patologia , Ensaios de Seleção de Medicamentos Antitumorais , Epistasia Genética/fisiologia , Humanos , Pesquisa Translacional Biomédica/métodosRESUMO
OBJECTIVE: Colorectal cancer (CRC) is a major contributor to cancer mortality and morbidity. LIM kinase 2 (LIMK2) promotes tumour cell invasion and metastasis. The objectives of this study were to determine how LIMK2 expression is associated with CRC progression and patient outcome, and to use genetically modified Drosophila and mice to determine how LIMK2 deletion affects gastrointestinal stem cell regulation and tumour development. DESIGN: LIMK2 expression and activity were measured by immunostaining tumours from CRC-prone mice, human CRC cell lines and 650 human tumours. LIMK knockdown in Drosophila or Limk2 deletion in mice allowed for assessment of their contributions to gastrointestinal stem cell homeostasis and tumour development. RESULTS: LIMK2 expression was reduced in intestinal tumours of cancer-prone mice, as well as in human CRC cell lines and tumours. Reduced LIMK2 expression and substrate phosphorylation were associated with shorter patient survival. Genetic analysis in Drosophila midgut and intestinal epithelial cells isolated from genetically modified mice revealed a conserved role for LIMK2 in constraining gastrointestinal stem cell proliferation. Limk2 deletion increased colon tumour size in a colitis-associated colorectal mouse cancer model. CONCLUSIONS: This study revealed that LIMK2 expression and activity progressively decrease with advancing stage, and supports the hypothesis that there is selective pressure for reduced LIMK2 expression in CRC to relieve negative constraints imposed upon gastrointestinal stem cells.
Assuntos
Biomarcadores Tumorais/metabolismo , Colo/enzimologia , Neoplasias Colorretais/enzimologia , Mucosa Intestinal/enzimologia , Quinases Lim/metabolismo , Células-Tronco Neoplásicas/enzimologia , Animais , Biomarcadores Tumorais/deficiência , Linhagem Celular Tumoral , Proliferação de Células , Colo/patologia , Colo/fisiopatologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Neoplasias Colorretais/fisiopatologia , Metilação de DNA , Progressão da Doença , Regulação para Baixo , Drosophila melanogaster , Regulação Neoplásica da Expressão Gênica , Humanos , Imuno-Histoquímica , Mucosa Intestinal/patologia , Mucosa Intestinal/fisiopatologia , Quinases Lim/deficiência , Camundongos , Camundongos Knockout , Células-Tronco Neoplásicas/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise Serial de TecidosRESUMO
Whole-body health relies on complex inter-organ signalling networks that enable organisms to adapt to environmental perturbations and to changes in tissue homeostasis. The intestine plays a major role as a signalling centre by producing local and systemic signals that are relayed to the body and that maintain intestinal and organismal homeostasis. Consequently, disruption of intestinal homeostasis and signalling are associated with systemic diseases and multi-organ dysfunction. In recent years, the fruit fly Drosophila melanogaster has emerged as a prime model organism to study tissue-intrinsic and systemic signalling networks of the adult intestine due to its genetic tractability and functional conservation with mammals. In this Review, we highlight Drosophila research that has contributed to our understanding of how the adult intestine interacts with its microenvironment and with distant organs. We discuss the implications of these findings for understanding intestinal and whole-body pathophysiology, and how future Drosophila studies might advance our knowledge of the complex interplay between the intestine and the rest of the body in health and disease.
Assuntos
Drosophila melanogaster , Drosophila , Animais , Drosophila melanogaster/genética , Homeostase , Intestinos/fisiologia , Mamíferos , Transdução de Sinais/genéticaRESUMO
Over recent decades, increased longevity has not been paralleled by extended health span, resulting in more years spent with multiple diseases in older age. As such, interventions to improve health span are urgently required. Zoledronate (Zol) is a nitrogen-containing bisphosphonate, which inhibits the farnesyl pyrophosphate synthase enzyme, central to the mevalonate pathway. It is already used clinically to prevent fractures in osteoporotic patients, who have been reported to derive unexpected and unexplained survival benefits. Using Drosophila as a model we determined the effects of Zol on life span, parameters of health span (climbing ability and intestinal dysplasia), and the ability to confer resistance to oxidative stress using a combination of genetically manipulated Drosophila strains and Western blotting. Our study shows that Zol extended life span, improved climbing activity, and reduced intestinal epithelial dysplasia and permeability with age. Mechanistic studies showed that Zol conferred resistance to oxidative stress and reduced accumulation of X-ray-induced DNA damage via inhibition of farnesyl pyrophosphate synthase. Moreover, Zol was associated with inhibition of phosphorylated AKT in the mammalian traget of rapamycin pathway downstream of the mevalonate pathway and required dFOXO for its action, both molecules associated with increased longevity. Taken together, our work indicates that Zol, a drug already widely used to prevent osteoporosis and dosed only once a year, modulates important mechanisms of aging. Its repurposing holds great promise as a treatment to improve health span.
Assuntos
Proteínas de Drosophila , Ácido Mevalônico , Animais , Linhagem Celular Tumoral , Drosophila , Proteínas de Drosophila/metabolismo , Fatores de Transcrição Forkhead , Imidazóis/farmacologia , Mamíferos , Ácido Mevalônico/metabolismo , Ácido Zoledrônico/farmacologiaRESUMO
We present a computer simulation and associated experimental validation of assembly of glial-like support cells into the interweaving hexagonal lattice that spans the Drosophila pupal eye. This process of cell movements organizes the ommatidial array into a functional pattern. Unlike earlier simulations that focused on the arrangements of cells within individual ommatidia, here we examine the local movements that lead to large-scale organization of the emerging eye field. Simulations based on our experimental observations of cell adhesion, cell death, and cell movement successfully patterned a tracing of an emerging wild-type pupal eye. Surprisingly, altering cell adhesion had only a mild effect on patterning, contradicting our previous hypothesis that the patterning was primarily the result of preferential adhesion between IRM-class surface proteins. Instead, our simulations highlighted the importance of programmed cell death (PCD) as well as a previously unappreciated variable: the expansion of cells' apical surface areas, which promoted rearrangement of neighboring cells. We tested this prediction experimentally by preventing expansion in the apical area of individual cells: patterning was disrupted in a manner predicted by our simulations. Our work demonstrates the value of combining computer simulation with in vivo experiments to uncover novel mechanisms that are perpetuated throughout the eye field. It also demonstrates the utility of the Glazier-Graner-Hogeweg model (GGH) for modeling the links between local cellular interactions and emergent properties of developing epithelia as well as predicting unanticipated results in vivo.
Assuntos
Olho Composto de Artrópodes , Simulação por Computador , Drosophila/crescimento & desenvolvimento , Morfogênese/fisiologia , Pupa/crescimento & desenvolvimento , Animais , Apoptose/genética , Apoptose/fisiologia , Adesão Celular , Movimento Celular , Proliferação de Células , Olho Composto de Artrópodes/citologia , Olho Composto de Artrópodes/crescimento & desenvolvimento , Olho Composto de Artrópodes/ultraestrutura , Microscopia Eletrônica de Transmissão , Modelos Biológicos , Mutação , Propriedades de SuperfícieRESUMO
Correct tissue patterning during development involves multiple morphogenetic events that include specification of different cell fates, cell proliferation, cell death, and coordinated changes in cell shape, position, and adhesion. Here, we use the Drosophila retina to explore the molecular mechanisms that regulate and integrate these various events. In a previous report, we found that wingless (wg) was required to induce a previously unknown surge of cell death ("early death") in the pupal retina. Here, we show that wg is also required to induce the more widely studied mid-pupal cell death ("late death") in a process that involves regulation of DIAP1. Furthermore, our data suggest that wg has a previously unreported role in specifying the glial-like cone cells. This activity requires canonical Wg signaling and is linked with Notch pathway activity. Our work broadens the role of canonical Wg signaling to encompass multiple patterning steps in the emerging Drosophila retina.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Retina/embriologia , Transdução de Sinais , Proteína Wnt1/metabolismo , Animais , Padronização Corporal , Morte Celular , Linhagem da Célula , Receptores Frizzled/metabolismo , Modelos Biológicos , Neuroglia/citologia , Neuroglia/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores Notch/metabolismo , Células Fotorreceptoras Retinianas Cones/citologiaRESUMO
Coordination of stem cell function by local and niche-derived signals is essential to preserve adult tissue homeostasis and organismal health. The vasculature is a prominent component of multiple stem cell niches. However, its role in adult intestinal homeostasis remains largely understudied. Here we uncover a previously unrecognised crosstalk between adult intestinal stem cells in Drosophila and the vasculature-like tracheal system, which is essential for intestinal regeneration. Following damage to the intestinal epithelium, gut-derived reactive oxygen species activate tracheal HIF-1α and bidirectional FGF/FGFR signalling, leading to reversible remodelling of gut-associated terminal tracheal cells and intestinal stem cell proliferation following damage. Unexpectedly, reactive oxygen species-induced adult tracheal plasticity involves downregulation of the tracheal specification factor trachealess (trh) and upregulation of IGF2 messenger RNA-binding protein (IGF2BP2/Imp). Our results reveal an intestine-vasculature inter-organ communication programme that is essential to adapt the stem cell response to the proliferative demands of the intestinal epithelium.
Assuntos
Adaptação Fisiológica/fisiologia , Células-Tronco Adultas/metabolismo , Homeostase/fisiologia , Células-Tronco/metabolismo , Animais , Drosophila/metabolismo , Mucosa Intestinal/metabolismo , Proteínas de Ligação a RNA/metabolismo , Regeneração/fisiologia , Transdução de Sinais/fisiologia , Nicho de Células-Tronco/fisiologiaRESUMO
RAS-like (RAL) GTPases function in Wnt signalling-dependent intestinal stem cell proliferation and regeneration. Whether RAL proteins work as canonical RAS effectors in the intestine and the mechanisms of how they contribute to tumourigenesis remain unclear. Here, we show that RAL GTPases are necessary and sufficient to activate EGFR/MAPK signalling in the intestine, via induction of EGFR internalisation. Knocking down Drosophila RalA from intestinal stem and progenitor cells leads to increased levels of plasma membrane-associated EGFR and decreased MAPK pathway activation. Importantly, in addition to influencing stem cell proliferation during damage-induced intestinal regeneration, this role of RAL GTPases impacts on EGFR-dependent tumourigenic growth in the intestine and in human mammary epithelium. However, the effect of oncogenic RAS in the intestine is independent from RAL function. Altogether, our results reveal previously unrecognised cellular and molecular contexts where RAL GTPases become essential mediators of adult tissue homeostasis and malignant transformation.
Assuntos
Proliferação de Células , Transformação Celular Neoplásica/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimologia , Receptores ErbB/metabolismo , Mucosa Intestinal/metabolismo , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Receptores de Peptídeos de Invertebrados/metabolismo , Células-Tronco/metabolismo , Proteínas ral de Ligação ao GTP/metabolismo , Animais , Animais Geneticamente Modificados , Neoplasias da Mama/enzimologia , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Endocitose , Receptores ErbB/genética , Feminino , Humanos , Hiperplasia , Mucosa Intestinal/patologia , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Glândulas Mamárias Humanas/enzimologia , Glândulas Mamárias Humanas/patologia , Camundongos Endogâmicos C57BL , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas Monoméricas de Ligação ao GTP/genética , Receptores de Peptídeos de Invertebrados/genética , Transdução de Sinais , Células-Tronco/patologia , Proteínas ral de Ligação ao GTP/genéticaRESUMO
Stem cells drive tissue regeneration due to their capacity to proliferate and differentiate in response to damage. In this issue of Developmental cell, Du et al. reveal a mechanism regulating intestinal stem cell differentiation and epithelial repair following injury, which depends on peroxisomes and their action inducing JAK/Stat signaling and Sox21a.
Assuntos
Janus Quinases , Fatores de Transcrição STAT , Diferenciação Celular , Intestinos , Janus Quinases/metabolismo , Peroxissomos , Fatores de Transcrição STAT/metabolismoRESUMO
Antimicrobial peptides (AMPs) are small cationic molecules best known as mediators of the innate defence against microbial infection. While in vitro and ex vivo evidence suggest AMPs' capacity to kill cancer cells, in vivo demonstration of an anti-tumour role of endogenous AMPs is lacking. Using a Drosophila model of tumourigenesis, we demonstrate a role for the AMP Defensin in the control of tumour progression. Our results reveal that Tumour Necrosis Factor mediates exposure of phosphatidylserine (PS), which makes tumour cells selectively sensitive to the action of Defensin remotely secreted from tracheal and fat tissues. Defensin binds tumour cells in PS-enriched areas, provoking cell death and tumour regression. Altogether, our results provide the first in vivo demonstration for a role of an endogenous AMP as an anti-cancer agent, as well as a mechanism that explains tumour cell sensitivity to the action of AMPs.
Assuntos
Morte Celular , Defensinas/metabolismo , Fatores Imunológicos/metabolismo , Neoplasias/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Animais , Modelos Animais de Doenças , Drosophila , Análise de SobrevidaRESUMO
The control of systemic metabolic homeostasis involves complex inter-tissue programs that coordinate energy production, storage, and consumption, to maintain organismal fitness upon environmental challenges. The mechanisms driving such programs are largely unknown. Here, we show that enteroendocrine cells in the adult Drosophila intestine respond to nutrients by secreting the hormone Bursicon α, which signals via its neuronal receptor DLgr2. Bursicon α/DLgr2 regulate energy metabolism through a neuronal relay leading to the restriction of glucagon-like, adipokinetic hormone (AKH) production by the corpora cardiaca and subsequent modulation of AKH receptor signaling within the adipose tissue. Impaired Bursicon α/DLgr2 signaling leads to exacerbated glucose oxidation and depletion of energy stores with consequent reduced organismal resistance to nutrient restrictive conditions. Altogether, our work reveals an intestinal/neuronal/adipose tissue inter-organ communication network that is essential to restrict the use of energy and that may provide insights into the physiopathology of endocrine-regulated metabolic homeostasis.
Assuntos
Tecido Adiposo/metabolismo , Drosophila melanogaster/metabolismo , Células Enteroendócrinas/metabolismo , Intestinos/citologia , Hormônios de Invertebrado/metabolismo , Neurônios/metabolismo , Animais , Proteínas de Drosophila/metabolismo , Metabolismo Energético , Células Enteroendócrinas/citologia , Feminino , Glucose/metabolismo , Homeostase , Hormônios de Inseto/metabolismo , Nutrientes/metabolismo , Oligopeptídeos/metabolismo , Ácido Pirrolidonocarboxílico/análogos & derivados , Ácido Pirrolidonocarboxílico/metabolismoRESUMO
Ral GTPases are RAS effector molecules and by implication a potential therapeutic target for RAS mutant cancer. However, very little is known about their roles in stem cells and tissue homeostasis. Using Drosophila, we identified expression of RalA in intestinal stem cells (ISCs) and progenitor cells of the fly midgut. RalA was required within ISCs for efficient regeneration downstream of Wnt signaling. Within the murine intestine, genetic deletion of either mammalian ortholog, Rala or Ralb, reduced ISC function and Lgr5 positivity, drove hypersensitivity to Wnt inhibition, and impaired tissue regeneration following damage. Ablation of both genes resulted in rapid crypt death. Mechanistically, RALA and RALB were required for efficient internalization of the Wnt receptor Frizzled-7. Together, we identify a conserved role for RAL GTPases in the promotion of optimal Wnt signaling, which defines ISC number and regenerative potential.