RESUMO
The crosstalk between cancer and stromal cells plays a critical role in tumor progression. Syntenin is a small scaffold protein involved in the regulation of intercellular communication that is emerging as a target for cancer therapy. Here, we show that certain aggressive forms of acute myeloid leukemia (AML) reduce the expression of syntenin in bone marrow stromal cells (BMSC). Stromal syntenin deficiency, in turn, generates a pro-tumoral microenvironment. From serial transplantations in mice and co-culture experiments, we conclude that syntenin-deficient BMSC stimulate AML aggressiveness by promoting AML cell survival and protein synthesis. This pro-tumoral activity is supported by increased expression of endoglin, a classical marker of BMSC, which in trans stimulates AML translational activity. In short, our study reveals a vicious signaling loop potentially at the heart of AML-stroma crosstalk and unsuspected tumor-suppressive effects of syntenin that need to be considered during systemic targeting of syntenin in cancer therapy.
Assuntos
Leucemia Mieloide Aguda , Sinteninas , Animais , Camundongos , Sinteninas/genética , Sinteninas/metabolismo , Regulação para Baixo , Leucemia Mieloide Aguda/metabolismo , Transdução de Sinais , Células Estromais/metabolismo , Microambiente TumoralRESUMO
SCOPE: Adipocyte-derived extracellular vesicles (AdEVs) convey lipids that can play a role in the energy homeostasis. Vitamin D (VD) has been shown to limit the metabolic inflammation as it decreases inflammatory markers expression in adipose tissue (AT). However, VD effect on adipocytes-derived EVs has never been investigated. METHODS AND RESULTS: Thus, the aim of this study is to evaluate the AdEVs lipid composition by LC-MS/MS approach in 3T3-L1 cells treated with VD or/and pro-inflammatory factor (tumor necrosis factor α [TNFα]). Among all lipid species, four are highlighted (glycerolipids, phospholipids, lysophospholipids, and sphingolipids) with a differential content between small (sEVs) and large EVs (lEVs). This study also observes that VD alone modulates EV lipid species involved in membrane fluidity and in the budding of membrane. EVs treated with VD under inflammatory conditions have different lipid profiles than the control group, which is more pronounced in lEVs. Indeed, 25 lipid species are significantly modulated in lEVs, compared with only seven lipid species in sEVs. CONCLUSIONS: This study concludes that VD, alone or under inflammatory conditions, is associated with specific lipidomic signature of sEVs and lEVs. These observations reinforce current knowledge on the anti-inflammatory effect of VD.
Assuntos
Vesículas Extracelulares , Vitamina D , Vitamina D/farmacologia , Vitamina D/metabolismo , Cromatografia Líquida , Espectrometria de Massas em Tandem , Vitaminas/farmacologia , Adipócitos , Lipídeos/farmacologiaRESUMO
Matrix metalloproteinases (MMPs) are key players in matrix remodeling and their function has been particularly investigated in cancer biology. Indeed, through extracellular matrix (ECM) degradation and shedding of diverse cell surface macromolecules, they are implicated in different steps of tumor development, from local expansion by growth to tissue invasion and metastasis. Interestingly, MMPs are also components of extracellular vesicles (EVs). EVs are membrane-limited organelles that cells release in their extracellular environment. These "secreted" vesicles are now well accepted players in cell-to-cell communication. EVs have received a lot of interest in recent years as they are also envisioned as sources of biomarkers and as potentially outperforming vehicles for the delivery of therapeutics. Molecular machineries governing EV biogenesis, cargo loading and delivery to recipient cells are complex and still under intense investigation. In this review, we will summarize the state of the art of our knowledge about the molecular mechanisms implicated in MMP trafficking and secretion. We focus on MT1-MMP, a major effector of invasive cell behavior. We will also discuss how this knowledge is of interest for a better understanding of EV-loading of MMPs. Such knowledge might be of use to engineer novel strategies for cancer treatment. A better understanding of these mechanisms could also be used to design more efficient EV-based therapies.
RESUMO
Exosomes, extracellular vesicles (EVs) of endosomal origin, emerge as master regulators of cell-to-cell signaling in physiology and disease. Exosomes are highly enriched in tetraspanins (TSPNs) and syndecans (SDCs), the latter occurring mainly in proteolytically cleaved form, as membrane-spanning C-terminal fragments of the proteins. While both protein families are membrane scaffolds appreciated for their role in exosome formation, composition, and activity, we currently ignore whether these work together to control exosome biology. Here we show that TSPN6, a poorly characterized tetraspanin, acts as a negative regulator of exosome release, supporting the lysosomal degradation of SDC4 and syntenin. We demonstrate that TSPN6 tightly associates with SDC4, the SDC4-TSPN6 association dictating the association of TSPN6 with syntenin and the TSPN6-dependent lysosomal degradation of SDC4-syntenin. TSPN6 also inhibits the shedding of the SDC4 ectodomain, mimicking the effects of matrix metalloproteinase inhibitors. Taken together, our data identify TSPN6 as a regulator of the trafficking and processing of SDC4 and highlight an important physical and functional interconnection between these membrane scaffolds for the production of exosomes. These findings clarify our understanding of the molecular determinants governing EV formation and have potentially broad impact for EV-related biomedicine.
Assuntos
Exossomos/metabolismo , Sinteninas/metabolismo , Tetraspaninas/metabolismo , Comunicação Celular , Exossomos/genética , Vesículas Extracelulares/metabolismo , Humanos , Lisossomos/metabolismo , Células MCF-7 , Metaloproteinases da Matriz/metabolismo , Transporte Proteico , Sindecana-4/metabolismo , Sindecanas/metabolismoRESUMO
The cytoplasmic tyrosine kinase SRC controls cell growth, proliferation, adhesion, and motility. The current view is that SRC acts primarily downstream of cell-surface receptors to control intracellular signaling cascades. Here we reveal that SRC functions in cell-to-cell communication by controlling the biogenesis and the activity of exosomes. Exosomes are viral-like particles from endosomal origin that can reprogram recipient cells. By gain- and loss-of-function studies, we establish that SRC stimulates the secretion of exosomes having promigratory activity on endothelial cells and that syntenin is mandatory for SRC exosomal function. Mechanistically, SRC impacts on syndecan endocytosis and on syntenin-syndecan endosomal budding, upstream of ARF6 small GTPase and its effector phospholipase D2, directly phosphorylating the conserved juxtamembrane DEGSY motif of the syndecan cytosolic domain and syntenin tyrosine 46. Our study uncovers a function of SRC in cell-cell communication, supported by syntenin exosomes, which is likely to contribute to tumor-host interactions.
Assuntos
Comunicação Celular/genética , Exossomos/metabolismo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Proteína Oncogênica pp60(v-src)/genética , Sinteninas/genética , Fator 6 de Ribosilação do ADP , Fatores de Ribosilação do ADP/genética , Fatores de Ribosilação do ADP/metabolismo , Motivos de Aminoácidos , Movimento Celular , Proliferação de Células , Meios de Cultivo Condicionados/farmacologia , Endocitose , Endossomos/metabolismo , Regulação da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Células MCF-7 , Proteína Oncogênica pp60(v-src)/metabolismo , Fosfolipase D/genética , Fosfolipase D/metabolismo , Fosforilação , Transdução de Sinais , Sindecanas/genética , Sindecanas/metabolismo , Sinteninas/metabolismoRESUMO
Syntenin has crucial roles in cell adhesion, cell migration and synaptic transmission. Its closely linked postsynaptic density-95, discs large 1, zonula occludens-1 (PDZ) domains typically interact with C-terminal ligands. We profile syntenin PDZ1-2 through proteomic peptide phage display (ProP-PD) using a library that displays C-terminal regions of the human proteome. The protein recognizes a broad range of peptides, with a preference for hydrophobic motifs and has a tendency to recognize cryptic internal ligands. We validate the interaction with nectin-1 through orthogonal assays. The study demonstrates the power of ProP-PD as a complementary approach to uncover interactions of potential biological relevance.
Assuntos
Modelos Moleculares , Sinteninas/metabolismo , Motivos de Aminoácidos , Animais , Sítios de Ligação , Células COS , Moléculas de Adesão Celular/química , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Chlorocebus aethiops , Biologia Computacional , Humanos , Interações Hidrofóbicas e Hidrofílicas , Proteínas Imobilizadas/química , Proteínas Imobilizadas/genética , Proteínas Imobilizadas/metabolismo , Cinética , Ligantes , Células MCF-7 , Nectinas , Domínios PDZ , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/classificação , Fragmentos de Peptídeos/metabolismo , Biblioteca de Peptídeos , Proteômica/métodos , Proteínas Recombinantes/química , Proteínas Recombinantes/classificação , Proteínas Recombinantes/metabolismo , Sinteninas/química , Sinteninas/genética , Técnicas do Sistema de Duplo-HíbridoRESUMO
Arl13b belongs to the ADP-ribosylation factor family within the Ras superfamily of regulatory GTPases. Mutations in Arl13b cause Joubert syndrome, which is characterized by congenital cerebellar ataxia, hypotonia, oculomotor apraxia, and mental retardation. Arl13b is highly enriched in cilia and is required for ciliogenesis in multiple organs. Nevertheless, the precise role of Arl13b remains elusive. Here we report that the exocyst subunits Sec8, Exo70, and Sec5 bind preferentially to the GTP-bound form of Arl13b, consistent with the exocyst being an effector of Arl13b. Moreover, we show that Arl13b binds directly to Sec8 and Sec5. In zebrafish, depletion of arl13b or the exocyst subunit sec10 causes phenotypes characteristic of defective cilia, such as curly tail up, edema, and abnormal pronephric kidney development. We explored this further and found a synergistic genetic interaction between arl13b and sec10 morphants in cilia-dependent phenotypes. Through conditional deletion of Arl13b or Sec10 in mice, we found kidney cysts and decreased ciliogenesis in cells surrounding the cysts. Moreover, we observed a decrease in Arl13b expression in the kidneys from Sec10 conditional knockout mice. Taken together, our results indicate that Arl13b and the exocyst function together in the same pathway leading to functional cilia.
Assuntos
Fatores de Ribosilação do ADP/metabolismo , Cílios/metabolismo , Fatores de Ribosilação do ADP/genética , Anormalidades Múltiplas , Animais , Cerebelo/anormalidades , Anormalidades do Olho , Estudos de Associação Genética , Células HeLa , Humanos , Rim/metabolismo , Doenças Renais Císticas , Camundongos , Camundongos Knockout , Microtúbulos/metabolismo , Mutação , Células NIH 3T3 , Retina/anormalidades , Proteínas de Transporte Vesicular/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
The scaffold protein syntenin abounds during fetal life where it is important for developmental movements. In human adulthood, syntenin gain-of-function is increasingly associated with various cancers and poor prognosis. Depending on the cancer model analyzed, syntenin affects various signaling pathways. We previously have shown that syntenin allows syndecan heparan sulfate proteoglycans to escape degradation. This indicates that syntenin has the potential to support sustained signaling of a plethora of growth factors and adhesion molecules. Here, we aim to clarify the impact of syntenin loss-of-function on cancer cell migration, growth, and proliferation, using cells from various cancer types and syntenin shRNA and siRNA silencing approaches. We observed decreased migration, growth, and proliferation of the mouse melanoma cell line B16F10, the human colon cancer cell line HT29 and the human breast cancer cell line MCF7. We further documented that syntenin controls the presence of active ß1 integrin at the cell membrane and G1/S cell cycle transition as well as the expression levels of CDK4, Cyclin D2, and Retinoblastoma proteins. These data confirm that syntenin supports the migration and growth of tumor cells, independently of their origin, and further highlight the attractiveness of syntenin as potential therapeutic target.
RESUMO
Exosomes are small vesicles that are secreted by cells and act as mediators of cell to cell communication. Because of their potential therapeutic significance, important efforts are being made towards characterizing exosomal contents. However, little is known about the mechanisms that govern exosome biogenesis. We have recently shown that the exosomal protein syntenin supports exosome production. Here we identify the small GTPase ADP ribosylation factor 6 (ARF6) and its effector phospholipase D2 (PLD2) as regulators of syntenin exosomes. ARF6 and PLD2 affect exosomes by controlling the budding of intraluminal vesicles (ILVs) into multivesicular bodies (MVBs). ARF6 also controls epidermal growth factor receptor degradation, suggesting a role in degradative MVBs. Yet ARF6 does not affect HIV-1 budding, excluding general effects on Endosomal Sorting Complexes Required for Transport. Our study highlights a novel pathway controlling ILV budding and exosome biogenesis and identifies an unexpected role for ARF6 in late endosomal trafficking.
Assuntos
Fatores de Ribosilação do ADP/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Exossomos/metabolismo , Corpos Multivesiculares/metabolismo , Fosfolipase D/metabolismo , Sinteninas/metabolismo , Fator 6 de Ribosilação do ADP , Fatores de Ribosilação do ADP/genética , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ciclo Celular/genética , Linhagem Celular , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Receptores ErbB/metabolismo , Exossomos/enzimologia , Exossomos/genética , Infecções por HIV/genética , Infecções por HIV/metabolismo , Infecções por HIV/virologia , HIV-1/fisiologia , Humanos , Corpos Multivesiculares/enzimologia , Corpos Multivesiculares/genética , Fosfolipase D/genética , Transporte Proteico , Sinteninas/genéticaRESUMO
Septins are a large, evolutionarily conserved family of GTPases that form hetero-oligomers and interact with the actin-based cytoskeleton and microtubules. They are involved in scaffolding functions, and form diffusion barriers in budding yeast, the sperm flagellum and the base of primary cilia of kidney epithelial cells. We investigated the role of septins in the primary cilium of retinal pigmented epithelial (RPE) cells, and found that SEPT2 forms a 1:1:1 complex with SEPT7 and SEPT9 and that the three members of this complex colocalize along the length of the axoneme. Similar to observations in kidney epithelial cells, depletion of cilium-localized septins by siRNA-based approaches inhibited ciliogenesis. MAP4, which is a binding partner of SEPT2 and controls the accessibility of septins to microtubules, was also localized to the axoneme where it appeared to negatively regulate ciliary length. Taken together, our data provide new insights into the functions and regulation of septins and MAP4 in the organization of the primary cilium and microtubule-based activities in cells.