RESUMO
Although macrophages are armed with potent antibacterial functions, Mycobacterium tuberculosis (Mtb) replicates inside these innate immune cells. Determinants of macrophage intrinsic bacterial control, and the Mtb strategies to overcome them, are poorly understood. To further study these processes, we used an affinity tag purification mass spectrometry (AP-MS) approach to identify 187 Mtb-human protein-protein interactions (PPIs) involving 34 secreted Mtb proteins. This interaction map revealed two factors involved in Mtb pathogenesis-the secreted Mtb protein, LpqN, and its binding partner, the human ubiquitin ligase CBL. We discovered that an lpqN Mtb mutant is attenuated in macrophages, but growth is restored when CBL is removed. Conversely, Cbl-/- macrophages are resistant to viral infection, indicating that CBL regulates cell-intrinsic polarization between antibacterial and antiviral immunity. Collectively, these findings illustrate the utility of this Mtb-human PPI map for developing a deeper understanding of the intricate interactions between Mtb and its host.
Assuntos
Proteínas de Bactérias/genética , HIV/genética , Interações Hospedeiro-Patógeno , Mycobacterium tuberculosis/genética , Proteínas Proto-Oncogênicas c-cbl/genética , Fatores de Virulência/genética , Animais , Proteínas de Bactérias/imunologia , Linhagem Celular Tumoral , Chlamydia trachomatis/genética , Chlamydia trachomatis/imunologia , Regulação da Expressão Gênica , HIV/imunologia , Herpesvirus Humano 8/genética , Herpesvirus Humano 8/imunologia , Humanos , Linfócitos/microbiologia , Linfócitos/virologia , Macrófagos/microbiologia , Macrófagos/virologia , Camundongos , Mycobacterium tuberculosis/imunologia , Cultura Primária de Células , Ligação Proteica , Mapeamento de Interação de Proteínas , Proteínas Proto-Oncogênicas c-cbl/deficiência , Proteínas Proto-Oncogênicas c-cbl/imunologia , Células RAW 264.7 , Transdução de Sinais , Fatores de Virulência/imunologiaRESUMO
The ubiquitin ligases CBL and CBL-B are negative regulators of tyrosine kinase signaling with established roles in the immune system. However, their physiological roles in epithelial tissues are unknown. Here, we used MMTV-Cre-mediated Cbl gene deletion on a Cbl-b null background, as well as a tamoxifen-inducible mammary stem cell (MaSC)-specific Cbl and Cbl-b double knockout (Cbl/Cbl-b DKO) using Lgr5-EGFP-IRES-CreERT2, to demonstrate a mammary epithelial cell-autonomous requirement of CBL and CBL-B in the maintenance of MaSCs. Using a newly engineered tamoxifen-inducible Cbl and Cbl-b deletion model with a dual fluorescent reporter (Cblflox/flox; Cbl-bflox/flox; Rosa26-CreERT; mT/mG), we show that Cbl/Cbl-b DKO in mammary organoids leads to hyperactivation of AKT-mTOR signaling with depletion of MaSCs. Chemical inhibition of AKT or mTOR rescued MaSCs from Cbl/Cbl-b DKO-induced depletion. Our studies reveal a novel, cell-autonomous requirement of CBL and CBL-B in epithelial stem cell maintenance during organ development and remodeling through modulation of mTOR signaling.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Glândulas Mamárias Animais/citologia , Proteínas Proto-Oncogênicas c-cbl/metabolismo , Células-Tronco/citologia , Animais , Autorrenovação Celular/efeitos dos fármacos , Separação Celular , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Feminino , Deleção de Genes , Integrases/metabolismo , Glândulas Mamárias Animais/crescimento & desenvolvimento , Vírus do Tumor Mamário do Camundongo/metabolismo , Camundongos , Camundongos Knockout , Organoides/citologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Células-Tronco/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Tamoxifeno/farmacologiaRESUMO
T cells use the endocytic pathway for key cell biological functions, including receptor turnover and maintenance of the immunological synapse. Some of the established players include the Rab GTPases, the SNARE complex proteins, and others, which function together with EPS-15 homology domain-containing (EHD) proteins in non-T cell systems. To date, the role of the EHD protein family in T cell function remains unexplored. We generated conditional EHD1/3/4 knockout mice using CD4-Cre and crossed these with mice bearing a myelin oligodendrocyte glycoprotein-specific TCR transgene. We found that CD4+ T cells from these mice exhibited reduced Ag-driven proliferation and IL-2 secretion in vitro. In vivo, these mice exhibited reduced severity of experimental autoimmune encephalomyelitis. Further analyses showed that recycling of the TCR-CD3 complex was impaired, leading to increased lysosomal targeting and reduced surface levels on CD4+ T cells of EHD1/3/4 knockout mice. Our studies reveal a novel role of the EHD family of endocytic recycling regulatory proteins in TCR-mediated T cell functions.
Assuntos
Endocitose , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Animais , Complexo CD3/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Proteínas de Transporte/genética , Proteínas de Ligação a DNA/genética , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/imunologia , Encefalomielite Autoimune Experimental/metabolismo , Feminino , Expressão Gênica , Técnicas de Inativação de Genes , Ativação Linfocitária , Tecido Linfoide/imunologia , Tecido Linfoide/metabolismo , Lisossomos/metabolismo , Camundongos , Camundongos Knockout , Família Multigênica , Complexos Multiproteicos/metabolismo , Proteínas Nucleares/genética , Ligação Proteica , Transporte Proteico , Proteólise , Proteínas de Transporte Vesicular/genéticaRESUMO
Mutations of the tyrosine kinase-directed ubiquitin ligase CBL cause myeloid leukemias, but the molecular determinants of the dominant leukemogenic activity of mutant CBL oncogenes are unclear. Here, we first define a gain-of-function attribute of the most common leukemia-associated CBL mutant, Y371H, by demonstrating its ability to increase proliferation of hematopoietic stem/progenitor cells (HSPCs) derived from CBL-null and CBL/CBL-B-null mice. Next, we express second-site point/deletion mutants of CBL-Y371H in CBL/CBL-B-null HSPCs or the cytokine-dependent human leukemic cell line TF-1 to show that individual or combined Tyr â Phe mutations of established phosphotyrosine residues (Tyr-700, Tyr-731, and Tyr-774) had little impact on the activity of the CBL-Y371H mutant in HSPCs, and the triple Tyr â Phe mutant was only modestly impaired in TF-1 cells. In contrast, intact tyrosine kinase-binding (TKB) domain and proline-rich region (PRR) were critical in both cell models. PRR deletion reduced the stem cell factor (SCF)-induced hyper-phosphorylation of the CBL-Y371H mutant and the c-KIT receptor and eliminated the sustained p-ERK1/2 and p-AKT induction by SCF. GST fusion protein pulldowns followed by phospho-specific antibody array analysis identified distinct CBL TKB domains or PRR-binding proteins that are phosphorylated in CBL-Y371H-expressing TF-1 cells. Our results support a model of mutant CBL gain-of-function in which mutant CBL proteins effectively compete with the remaining wild type CBL-B and juxtapose TKB domain-associated PTKs with PRR-associated signaling proteins to hyper-activate signaling downstream of hematopoietic growth factor receptors. Elucidation of mutant CBL domains required for leukemogenesis should facilitate targeted therapy approaches for patients with mutant CBL-driven leukemias.
Assuntos
Proteínas Mutantes/química , Mutação , Oncogenes , Proteínas Proto-Oncogênicas c-cbl/química , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Separação Celular , Citocinas/metabolismo , Citometria de Fluxo , Regulação Leucêmica da Expressão Gênica , Glutationa Transferase/metabolismo , Células-Tronco Hematopoéticas/citologia , Humanos , Camundongos , Camundongos Knockout , Mutagênese , Proteínas Mutantes/genética , Fenótipo , Fenilalanina/química , Fosforilação , Prolina/química , Domínios Proteicos , Proteínas Proto-Oncogênicas c-cbl/genética , Proteínas Recombinantes de Fusão/química , Transdução de Sinais , Tirosina/químicaRESUMO
The Eps15-homology domain-containing (EHD) protein family comprises 4 members that regulate endocytic recycling. Although the kidney expresses all 4 EHD proteins, their physiologic roles are largely unknown. This study focused on EHD4, which we found to be expressed differentially across nephron segments with the highest expression in the inner medullary collecting duct. Under baseline conditions, Ehd4-/- [EHD4-knockout (KO)] mice on a C57Bl/6 background excreted a higher volume of more dilute urine than control C57Bl/6 wild-type (WT) mice while maintaining a similar plasma osmolality. Urine excretion after an acute intraperitoneal water load was significantly increased in EHD4-KO mice compared to WT mice, and although EHD4-KO mice concentrated their urine during 24-h water restriction, urinary osmolality remained significantly lower than in WT mice, suggesting that EHD4 plays a role in renal water handling. Total aquaporin 2 (AQP2) and phospho-S256-AQP2 (pAQP2) protein expression in the inner medulla was similar in the two groups in baseline conditions. However, localization of both AQP2 and pAQP2 in the renal inner medullary principal cells appeared more dispersed, and the intensity of apical membrane staining for AQP2 was reduced significantly (by â¼20%) in EHD4-KO mice compared to WT mice in baseline conditions, suggesting an important role of EHD4 in trafficking of AQP2. Together, these data indicate that EHD4 play important roles in the regulation of water homeostasis.-Rahman, S. S., Moffitt, A. E. J., Trease, A. J., Foster, K. W., Storck, M. D., Band, H., Boesen, E. I. EHD4 is a novel regulator of urinary water homeostasis.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas Nucleares/metabolismo , Urina/química , Água/metabolismo , Animais , Aquaporina 2/metabolismo , Aquaporina 4/metabolismo , Arginina Vasopressina/metabolismo , Linhagem Celular , Proteínas de Ligação a DNA/genética , Feminino , Homeostase/genética , Homeostase/fisiologia , Medula Renal/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Nucleares/genéticaRESUMO
The C-terminal Eps15 homology domain-containing (EHD) proteins play a key role in endocytic recycling, a fundamental cellular process that ensures the return of endocytosed membrane components and receptors back to the cell surface. To define the in vivo biological functions of EHD1, we have generated Ehd1 knockout mice and previously reported a requirement of EHD1 for spermatogenesis. Here, we show that approximately 56% of the Ehd1-null mice displayed gross ocular abnormalities, including anophthalmia, aphakia, microphthalmia and congenital cataracts. Histological characterization of ocular abnormalities showed pleiotropic defects that include a smaller or absent lens, persistence of lens stalk and hyaloid vasculature, and deformed optic cups. To test whether these profound ocular defects resulted from the loss of EHD1 in the lens or in non-lenticular tissues, we deleted the Ehd1 gene selectively in the presumptive lens ectoderm using Le-Cre. Conditional Ehd1 deletion in the lens resulted in developmental defects that included thin epithelial layers, small lenses and absence of corneal endothelium. Ehd1 deletion in the lens also resulted in reduced lens epithelial proliferation, survival and expression of junctional proteins E-cadherin and ZO-1. Finally, Le-Cre-mediated deletion of Ehd1 in the lens led to defects in corneal endothelial differentiation. Taken together, these data reveal a unique role for EHD1 in early lens development and suggest a previously unknown link between the endocytic recycling pathway and regulation of key developmental processes including proliferation, differentiation and morphogenesis.
Assuntos
Endocitose , Cristalino/embriologia , Cristalino/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Animais , Catarata/complicações , Catarata/embriologia , Catarata/genética , Catarata/patologia , Diferenciação Celular , Polaridade Celular , Sobrevivência Celular , Embrião de Mamíferos/patologia , Endotélio Corneano/metabolismo , Endotélio Corneano/patologia , Células Epiteliais/patologia , Anormalidades do Olho/genética , Anormalidades do Olho/patologia , Deleção de Genes , Regulação da Expressão Gênica no Desenvolvimento , Cristalino/patologia , Camundongos Knockout , Microftalmia/complicações , Microftalmia/embriologia , Microftalmia/genética , Fenótipo , Proteínas de Transporte Vesicular/deficiênciaRESUMO
Receptor tyrosine kinases (RTKs) control stem cell maintenance vs. differentiation decisions. Casitas B-lineage lymphoma (CBL) family ubiquitin ligases are negative regulators of RTKs, but their stem cell regulatory roles remain unclear. Here, we show that Lgr5+ intestinal stem cell (ISC)-specific inducible Cbl-knockout (KO) on a Cblb null mouse background (iDKO) induced rapid loss of the Lgr5 Hi ISCs with transient expansion of the Lgr5 Lo transit-amplifying population. LacZ-based lineage tracing revealed increased ISC commitment toward enterocyte and goblet cell fate at the expense of Paneth cells. Functionally, Cbl/Cblb iDKO impaired the recovery from radiation-induced intestinal epithelial injury. In vitro, Cbl/Cblb iDKO led to inability to maintain intestinal organoids. Single-cell RNA sequencing in organoids identified Akt-mTOR (mammalian target of rapamycin) pathway hyperactivation upon iDKO, and pharmacological Akt-mTOR axis inhibition rescued the iDKO defects. Our results demonstrate a requirement for Cbl/Cblb in the maintenance of ISCs by fine-tuning the Akt-mTOR axis to balance stem cell maintenance vs. commitment to differentiation.
RESUMO
While better management of loco-regional prostate cancer (PC) has greatly improved survival, advanced PC remains a major cause of cancer deaths. Identification of novel targetable pathways that contribute to tumor progression in PC could open new therapeutic options. The di-ganglioside GD2 is a target of FDA-approved antibody therapies in neuroblastoma, but the role of GD2 in PC is unexplored. Here, we show that GD2 is expressed in a small subpopulation of PC cells in a subset of patients and a higher proportion of metastatic tumors. Variable levels of cell surface GD2 expression were seen on many PC cell lines, and the expression was highly upregulated by experimental induction of lineage progression or enzalutamide resistance in CRPC cell models. GD2high cell fraction was enriched upon growth of PC cells as tumorspheres and GD2high fraction was enriched in tumorsphere-forming ability. CRISPR-Cas9 knockout (KO) of the rate-limiting GD2 biosynthetic enzyme GD3 Synthase (GD3S) in GD2high CRPC cell models markedly impaired the in vitro oncogenic traits and growth as bone-implanted xenograft tumors and reduced the cancer stem cell and epithelial-mesenchymal transition marker expression. Our results support the potential role of GD3S and its product GD2 in promoting PC tumorigenesis by maintaining cancer stem cells and suggest the potential for GD2 targeting in advanced PC.
Assuntos
Carcinogênese , Gangliosídeos , Células-Tronco Neoplásicas , Sialiltransferases , Masculino , Humanos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Sialiltransferases/metabolismo , Sialiltransferases/genética , Animais , Linhagem Celular Tumoral , Gangliosídeos/metabolismo , Camundongos , Carcinogênese/genética , Neoplasias da Próstata/patologia , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Feniltioidantoína/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica , Benzamidas/farmacologia , Nitrilas/farmacologiaRESUMO
Among the signaling pathways that control the stem cell self-renewal and maintenance vs. acquisition of differentiated cell fates, those mediated by receptor tyrosine kinase (RTK) activation are well established as key players. CBL family ubiquitin ligases are negative regulators of RTKs but their physiological roles in regulating stem cell behaviors are unclear. While hematopoietic Cbl/Cblb knockout (KO) leads to a myeloproliferative disease due to expansion and reduced quiescence of hematopoietic stem cells, mammary epithelial KO led to stunted mammary gland development due to mammary stem cell depletion. Here, we examined the impact of inducible Cbl/Cblb double-KO (iDKO) selectively in the Lgr5-defined intestinal stem cell (ISC) compartment. Cbl/Cblb iDKO led to rapid loss of the Lgr5 Hi ISC pool with a concomitant transient expansion of the Lgr5 Lo transit amplifying population. LacZ reporter-based lineage tracing showed increased ISC commitment to differentiation, with propensity towards enterocyte and goblet cell fate at the expense of Paneth cells. Functionally, Cbl/Cblb iDKO impaired the recovery from radiation-induced intestinal epithelial injury. In vitro , Cbl/Cblb iDKO led to inability to maintain intestinal organoids. Single cell RNAseq analysis of organoids revealed Akt-mTOR pathway hyperactivation in iDKO ISCs and progeny cells, and pharmacological inhibition of the Akt-mTOR axis rescued the organoid maintenance and propagation defects. Our results demonstrate a requirement for Cbl/Cblb in the maintenance of ISCs by fine tuning the Akt-mTOR axis to balance stem cell maintenance vs. commitment to differentiation.
RESUMO
With nearly all cancer deaths a result of metastasis, elucidating novel pro-metastatic cellular adaptations could provide new therapeutic targets. Here, we show that overexpression of the EPS15-Homology Domain-containing 2 (EHD2) protein in a large subset of breast cancers (BCs), especially the triple-negative (TNBC) and HER2+ subtypes, correlates with shorter patient survival. The mRNAs for EHD2 and Caveolin-1/2, structural components of caveolae, show co-overexpression across breast tumors, predicting shorter survival in basal-like BC. EHD2 shRNA knockdown and CRISPR-Cas9 knockout with mouse Ehd2 rescue, in TNBC cell line models demonstrate a major positive role of EHD2 in promoting tumorigenesis and metastasis. Mechanistically, we link these roles of EHD2 to store-operated calcium entry (SOCE), with EHD2-dependent stabilization of plasma membrane caveolae ensuring high cell surface expression of the SOCE-linked calcium channel Orai1. The novel EHD2-SOCE oncogenic axis represents a potential therapeutic target in EHD2- and CAV1/2-overexpressing BC.
Assuntos
Neoplasias de Mama Triplo Negativas , Humanos , Camundongos , Animais , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Cálcio/metabolismo , Membrana Celular/metabolismo , Carcinogênese/genética , Carcinogênese/metabolismo , Transformação Celular Neoplásica/metabolismo , Molécula 1 de Interação Estromal/metabolismoRESUMO
Overexpression of EPS15 Homology Domain containing 1 (EHD1) has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD mRNA expression specifying shorter patient survival. ShRNA and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified the IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.
RESUMO
Overexpression of the EPS15 Homology Domain containing 1 (EHD1) protein has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD1 mRNA expression specifying shorter patient survival. ShRNA-knockdown and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.
Assuntos
Sarcoma de Ewing , Camundongos , Animais , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologia , Receptor IGF Tipo 1/genética , Receptor IGF Tipo 1/metabolismo , Membrana Celular/metabolismo , Transdução de Sinais/fisiologia , Carcinogênese/genética , Carcinogênese/metabolismo , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismoRESUMO
Ecdysoneless (ECD) protein is essential for embryogenesis, cell-cycle progression, and cellular stress mitigation with an emerging role in mRNA biogenesis. We have previously shown that ECD protein as well as its mRNA are overexpressed in breast cancer and ECD overexpression predicts shorter survival in patients with breast cancer. However, the genetic evidence for an oncogenic role of ECD has not been established. Here, we generated transgenic mice with mammary epithelium-targeted overexpression of an inducible human ECD transgene (ECDTg). Significantly, ECDTg mice develop mammary hyperplasia, preneoplastic lesions, and heterogeneous tumors with occasional lung metastasis. ECDTg tumors exhibit epithelial to mesenchymal transition and cancer stem cell characteristics. Organoid cultures of ECDTg tumors showed ECD dependency for in vitro oncogenic phenotype and in vivo growth when implanted in mice. RNA sequencing (RNA-seq) analysis of ECDTg tumors showed a c-MYC signature, and alterations in ECD levels regulated c-MYC mRNA and protein levels as well as glucose metabolism. ECD knockdown-induced decrease in glucose uptake was rescued by overexpression of mouse ECD as well as c-MYC. Publicly available expression data analyses showed a significant correlation of ECD and c-MYC overexpression in breast cancer, and ECD and c-MYC coexpression exhibits worse survival in patients with breast cancer. Taken together, we establish a novel role of overexpressed ECD as an oncogenesis driver in the mouse mammary gland through upregulation of c-MYC-mediated glucose metabolism. IMPLICATIONS: We demonstrate ECD overexpression in the mammary gland of mice led to the development of a tumor progression model through upregulation of c-MYC signaling and glucose metabolism.
Assuntos
Neoplasias da Mama , Carcinogênese , Carcinógenos , Proteínas de Transporte , Glucose , Proteínas Proto-Oncogênicas c-myc , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Carcinogênese/genética , Carcinogênese/patologia , Proteínas de Transporte/genética , Transição Epitelial-Mesenquimal/genética , Feminino , Glucose/metabolismo , Humanos , Hiperplasia/genética , Hiperplasia/patologia , Neoplasias Pulmonares/secundário , Glândulas Mamárias Animais/patologia , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Transgênicos , Lesões Pré-Cancerosas/genética , Lesões Pré-Cancerosas/patologia , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , RNA Mensageiro , Transdução de Sinais , Regulação para CimaRESUMO
Overexpression of the epidermal growth factor receptor (EGFR) family member ErbB2 (HER2) drives oncogenesis in up to 25% of invasive breast cancers. ErbB2 expression at the cell surface is required for oncogenesis but mechanisms that ensure the optimal cell surface display of overexpressed ErbB2 following its biosynthesis in the endoplasmic reticulum are poorly understood. ErbB2 is dependent on continuous association with HSP90 molecular chaperone for its stability and function as an oncogenic driver. Here, we use knockdown and overexpression studies to show that the HSP90/HSC70-interacting negative co-chaperone CHIP (C-terminus of HSC70-Interacting protein)/STUB1 (STIP1-homologous U-Box containing protein 1) targets the newly synthesized, HSP90/HSC70-associated, ErbB2 for ubiquitin/proteasome-dependent degradation in the endoplasmic reticulum and Golgi, thus identifying a novel mechanism that negatively regulates cell surface ErbB2 levels in breast cancer cells, consistent with frequent loss of CHIP expression previously reported in ErbB2-overexpressing breast cancers. ErbB2-overexpressing breast cancer cells with low CHIP expression exhibited higher endoplasmic reticulum stress inducibility. Accordingly, the endoplasmic reticulum stress-inducing anticancer drug Bortezomib combined with ErbB2-targeted humanized antibody Trastuzumab showed synergistic inhibition of ErbB2-overexpressing breast cancer cell proliferation. Our findings reveal new insights into mechanisms that control the surface expression of overexpressed ErbB2 and suggest that reduced CHIP expression may specify ErbB2-overexpressing breast cancers suitable for combined treatment with Trastuzumab and ER stress inducing agents.
RESUMO
Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While postactivation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/preactivation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular structures and at the Golgi compartment. Inducible EHD1 knockdown reduced the cell surface EGFR expression with accumulation at the Golgi compartment, a phenotype rescued by exogenous EHD1. RUSC2 knockdown phenocopied the EHD1 depletion effects. EHD1 or RUSC2 depletion impaired the EGF-induced cell proliferation, demonstrating that the novel, EHD1- and RUSC2-dependent transport of unstimulated EGFR from the Golgi compartment to the cell surface that we describe is functionally important, with implications for physiologic and oncogenic roles of EGFR and targeted cancer therapies.
Assuntos
Proteínas de Transporte/metabolismo , Complexo de Golgi/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Animais , Comunicação Celular/fisiologia , Linhagem Celular , Membrana Celular/metabolismo , Proliferação de Células/fisiologia , Receptores ErbB/metabolismo , Humanos , Camundongos , Transporte Proteico/fisiologia , Interferência de RNA , RNA Interferente Pequeno/genética , Proteínas de Transporte Vesicular/genéticaRESUMO
CHIP/STUB1 ubiquitin ligase is a negative co-chaperone for HSP90/HSC70, and its expression is reduced or lost in several cancers, including breast cancer. Using an extensive and well-annotated breast cancer tissue collection, we identified the loss of nuclear but not cytoplasmic CHIP to predict more aggressive tumorigenesis and shorter patient survival, with loss of CHIP in two thirds of ErbB2+ and triple-negative breast cancers (TNBC) and in one third of ER+ breast cancers. Reduced CHIP expression was seen in breast cancer patient-derived xenograft tumors and in ErbB2+ and TNBC cell lines. Ectopic CHIP expression in ErbB2+ lines suppressed in vitro oncogenic traits and in vivo xenograft tumor growth. An unbiased screen for CHIP-regulated nuclear transcription factors identified many candidates whose DNA-binding activity was up- or downregulated by CHIP. We characterized myeloid zinc finger 1 (MZF1) as a CHIP target, given its recently identified role as a positive regulator of cathepsin B/L (CTSB/L)-mediated tumor cell invasion downstream of ErbB2. We show that CHIP negatively regulates CTSB/L expression in ErbB2+ and other breast cancer cell lines. CTSB inhibition abrogates invasion and matrix degradation in vitro and halts ErbB2+ breast cancer cell line xenograft growth. We conclude that loss of CHIP remodels the cellular transcriptome to unleash critical pro-oncogenic pathways, such as the matrix-degrading enzymes of the cathepsin family, whose components can provide new therapeutic opportunities in breast and other cancers with loss of CHIP expression.Significance: These findings reveal a novel targetable pathway of breast oncogenesis unleashed by the loss of tumor suppressor ubiquitin ligase CHIP/STUB1. Cancer Res; 78(10); 2524-35. ©2018 AACR.
Assuntos
Catepsina B/metabolismo , Catepsina L/metabolismo , Transformação Celular Neoplásica/genética , Neoplasias de Mama Triplo Negativas/patologia , Ubiquitina-Proteína Ligases/metabolismo , Catepsina B/biossíntese , Catepsina L/biossíntese , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Células HEK293 , Humanos , Fatores de Transcrição Kruppel-Like/metabolismo , Células MCF-7 , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismo , Transdução de Sinais , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/mortalidade , Ubiquitina-Proteína Ligases/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Colony stimulating factor-1 receptor (CSF-1R), a receptor tyrosine kinase (RTK), is the master regulator of macrophage biology. CSF-1 can bind CSF-1R resulting in receptor activation and signalling essential for macrophage functions such as proliferation, differentiation, survival, polarization, phagocytosis, cytokine secretion, and motility. CSF-1R activation can only occur after the receptor is presented on the macrophage cell surface. This process is reliant upon the underlying macrophage receptor trafficking machinery. However, the mechanistic details governing this process are incompletely understood. C-terminal Eps15 Homology Domain-containing (EHD) proteins have recently emerged as key regulators of receptor trafficking but have not yet been studied in the context of macrophage CSF-1R signalling. In this manuscript, we utilize primary bone-marrow derived macrophages (BMDMs) to reveal a novel function of EHD1 as a regulator of CSF-1R abundance on the cell surface. We report that EHD1-knockout (EHD1-KO) macrophages cell surface and total CSF-1R levels are significantly decreased. The decline in CSF-1R levels corresponds with reduced downstream macrophage functions such as cell proliferation, migration, and spreading. In EHD1-KO macrophages, transport of newly synthesized CSF-1R to the macrophage cell surface was reduced and was associated with the shunting of the receptor to the lysosome, which resulted in receptor degradation. These findings reveal a novel and functionally important role for EHD1 in governing CSF-1R signalling via regulation of anterograde transport of CSF-1R to the macrophage cell surface.
Assuntos
Membrana Celular/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Receptor de Fator Estimulador de Colônias de Macrófagos/metabolismo , Transdução de Sinais , Proteínas de Transporte Vesicular/metabolismo , Animais , Autoantígenos/metabolismo , Compartimento Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Macrolídeos/farmacologia , Fator Estimulador de Colônias de Macrófagos/metabolismo , Macrófagos/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Biossíntese de Proteínas/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
CBL and CBL-B ubiquitin ligases play key roles in hematopoietic stem cell homeostasis and their aberrations are linked to leukemogenesis. Mutations of CBL, often genetically-inherited, are particularly common in Juvenile Myelomonocytic Leukemia (JMML), a disease that manifests early in children. JMML is fatal unless corrected by bone marrow transplant, which is effective in only half of the recipients, stressing the need for animal models that recapitulate the key clinical features of this disease. However, mouse models established so far only develop hematological malignancy in adult animals. Here, using VAV1-Cre-induced conditional CBL/CBL-B double knockout (DKO) in mice, we established an animal model that exhibits a neonatal myeloproliferative disease (MPD). VAV1-Cre induced DKO mice developed a strong hematological phenotype at postnatal day 10, including severe leukocytosis and hepatomegaly, bone marrow cell hypersensitivity to cytokines including GM-CSF, and rapidly-progressive disease and invariable lethality. Interestingly, leukemic stem cells were most highly enriched in neonatal liver rather than bone marrow, which, along with the spleen and thymus, were hypo-cellular. Nonetheless, transplantation assays showed that both DKO bone marrow and liver cells can initiate leukemic disease in the recipient mice with seeding of both spleen and bone marrow. Together, our results support the usefulness of the new hematopoietic-specific CBL/CBL-B double KO animal model to study JMML-related pathogenesis and to further understand the function of CBL family proteins in regulating fetal and neonatal hematopoiesis. To our knowledge, this is the first mouse model that exhibits neonatal MPD in infancy, by day 10 of postnatal life.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Leucemia Mielomonocítica Juvenil/genética , Mutação/genética , Transtornos Mieloproliferativos/genética , Proteínas Proto-Oncogênicas c-cbl/genética , Proteínas Proto-Oncogênicas c-vav/genética , Animais , Animais Recém-Nascidos , Transplante de Medula Óssea , Células Cultivadas , Hematopoese , Integrases/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
CBL-family ubiquitin ligases are critical negative regulators of tyrosine kinase signaling, with a clear redundancy between CBL and CBL-B evident in the immune cell and hematopoietic stem cell studies. Since CBL and CBL-B are negative regulators of immune cell activation, elimination of their function to boost immune cell activities could be beneficial in tumor immunotherapy. However, mutations of CBL are associated with human leukemias, pointing to tumor suppressor roles of CBL proteins; hence, it is critical to assess the tumor-intrinsic roles of CBL and CBL-B in cancers. This has not been possible since the only available whole-body CBL-B knockout mice exhibit constitutive tumor rejection. We engineered a new CBL-Bflox/flox mouse, combined this with an existing CBLflox/flox mouse to generate CBLflox/flox; CBL-Bflox/flox mice, and tested the tissue-specific concurrent deletion of CBL and CBL-B using the widely-used CD4-Cre transgenic allele to produce a T-cell-specific double knockout. Altered T-cell development, constitutive peripheral T-cell activation, and a lethal multi-organ immune infiltration phenotype largely resembling the previous Lck-Cre driven floxed-CBL deletion on a CBL-B knockout background establish the usefulness of the new model for tissue-specific CBL/CBL-B deletion. Unexpectedly, CD4-Cre-induced deletion in a small fraction of hematopoietic stem cells led to expansion of certain non-T-cell lineages, suggesting caution in the use of CD4-Cre for T-cell-restricted gene deletion. The establishment of a new model of concurrent tissue-selective CBL/CBL-B deletion should allow a clear assessment of the tumor-intrinsic roles of CBL/CBL-B in non-myeloid malignancies and help test the potential for CBL/CBL-B inactivation in immunotherapy of tumors.