RESUMEN
ABSTRACT: Scombrotoxin fish poisoning (SFP) is caused by the ingestion of certain fish species with elevated concentrations of histamine due to decomposition. In fall 2019, the U.S. Food and Drug Administration (FDA) was notified of 51 SFP cases including two hospitalizations from 11 states through the FDA consumer complaint system or directly from state partners. A case patient was defined as an individual who experienced a histamine-type reaction after consumption of tuna imported from Vietnam and an illness onset between 14 August and 24 November 2019. A traceback investigation was initiated at 19 points of service to identify a common tuna source. The FDA and state partners collected 34 product samples throughout the distribution chain, including from a case patient's home, points of service, distributors, and the port of entry. Samples were analyzed for histamine by sensory evaluation and/or chemical testing. Case patients reported exposure to tuna imported from Vietnam. The traceback investigation identified two Vietnamese manufacturers as the sources of the tuna. Twenty-nine samples were confirmed as decomposed by sensory evaluation and/or were positive for elevated histamine concentrations by chemical testing. Both Vietnamese companies were placed on an import alert. Seven U.S. companies and one Vietnamese company initiated voluntary recalls. The FDA released public communication naming the U.S. importers to help suppliers and distributors identify the product and effectuate the foreign company's recall. This SFP outbreak investigation highlights the complexities of the federal outbreak response, specifically related to imported food. Cultural considerations regarding imported foods should be addressed during outbreak responses when timing is critical. Collaboration with countries where confidentiality agreements are not in place can limit information sharing and the speed of public health responses.
Asunto(s)
Enfermedades Transmitidas por los Alimentos , Atún , Animales , Brotes de Enfermedades , Enfermedades Transmitidas por los Alimentos/epidemiología , Histamina , Humanos , Toxinas Marinas , Estados Unidos/epidemiología , Vietnam/epidemiologíaRESUMEN
Synaptojanin 2 (SYNJ2) is a phosphatidylinositol (PI) phosphatase that controls two distinct functions, clathrin-mediated endocytosis and tumor cell invadopodia formation and invasion. Here, we identify a number of novel SYNJ2 binding partners, several of which have previously been shown to be necessary for invadopodia formation or clathrin-mediated endocytosis. We focus on Src family kinases. We found that Src phosphorylates SYNJ2 on Tyr ( 490) , thereby stimulating SYNJ2 5'-phosphatase activity in vitro. We also provide evidence that Src-mediated phosphorylation of SYNJ2 contributes to invadopodia formation.
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Vesículas Cubiertas por Clatrina/metabolismo , Cortactina/metabolismo , Monoéster Fosfórico Hidrolasas/metabolismo , Proteínas Proto-Oncogénicas c-fyn/metabolismo , Western Blotting , Membrana Celular/metabolismo , Cortactina/genética , Endocitosis , Activación Enzimática , Células HEK293 , Humanos , Inmunoprecipitación , Monoéster Fosfórico Hidrolasas/genética , Fosforilación , Plásmidos/genética , Plásmidos/metabolismo , Unión Proteica , Mapeo de Interacción de Proteínas , Proteínas Proto-Oncogénicas c-fyn/genética , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transfección , Tirosina/metabolismo , Dominios Homologos src , Familia-src Quinasas/genética , Familia-src Quinasas/metabolismoRESUMEN
BACKGROUND: The invasion of glioblastoma cells into regions of the normal brain is a critical factor that limits current therapies for malignant astrocytomas. Previous work has identified roles for the Rho family guanine nucleotide exchange factors Trio and Vav3 in glioblastoma invasion. Both Trio and Vav3 act on the small GTPase RhoG. We therefore examined the role of RhoG in the invasive behavior of glioblastoma cells. RESULTS: We found that siRNA-mediated depletion of RhoG strongly inhibits invasion of glioblastoma cells through brain slices ex vivo. In addition, depletion of RhoG has a marginal effect on glioblastoma cell proliferation, but significantly inhibits glioblastoma cell survival in colony formation assays. We also observed that RhoG is activated by both HGF and EGF, two factors that are thought to be clinically relevant drivers of glioblastoma invasive behavior, and that RhoG is overexpressed in human glioblastoma tumors versus non-neoplastic brain. In search of a mechanism for the contribution of RhoG to the malignant behavior of glioblastoma cells, we found that depletion of RhoG strongly inhibits activation of the Rac1 GTPase by both HGF and EGF. In line with this observation, we also show that RhoG contributes to the formation of lamellipodia and invadopodia, two functions that have been shown to be Rac1-dependent. CONCLUSIONS: Our functional analysis of RhoG in the context of glioblastoma revealed a critical role for RhoG in tumor cell invasion and survival. These results suggest that targeting RhoG-mediated signaling presents a novel avenue for glioblastoma therapy.
Asunto(s)
Neoplasias Encefálicas/enzimología , Neoplasias Encefálicas/patología , Glioblastoma/enzimología , Glioblastoma/patología , Proteínas de Unión al GTP rho/metabolismo , Animales , Neoplasias Encefálicas/química , Neoplasias Encefálicas/metabolismo , Procesos de Crecimiento Celular/fisiología , Factor de Crecimiento Epidérmico/metabolismo , Receptores ErbB/metabolismo , Glioblastoma/química , Glioblastoma/metabolismo , Humanos , Ratones , Invasividad Neoplásica , Neuropéptidos/metabolismo , Seudópodos/metabolismo , Seudópodos/ultraestructura , Putamen/química , Putamen/metabolismo , ARN Interferente Pequeño/genética , Proteínas de Unión al GTP rac/metabolismo , Proteína de Unión al GTP rac1 , Proteínas de Unión al GTP rho/análisis , Proteínas de Unión al GTP rho/genéticaRESUMEN
Wrch-1 (Wnt-regulated Cdc42 homolog) is a new member of the Rho family that was identified as a gene transcriptionally upregulated by Wnt-1. Wrch-1 has no detectable GTPase activity and displays very high intrinsic guanine nucleotide exchange, implying that it is constitutively GTP-bound. The biological functions of Wrch-1 largely remain to be characterized. Here, we report that Wrch-1 prominently localizes to focal adhesions. Depletion of Wrch-1 by small interfering RNA increases focal adhesion formation, whereas Wrch-1 overexpression disassembles focal adhesions. Wrch-1 depletion inhibits myosin-light-chain phosphorylation, which in turn leads to an increase in the number of focal adhesions and inhibits cell migration in response to wound healing. Depletion of Wrch-1 also inhibits Akt and JNK activation. Although pharmacological inhibitors of Akt and JNK inhibit cell migration, they do not affect focal adhesions. Thus, our data suggest that Wrch-1 regulates cell migration by multiple mechanisms: on the one hand Wrch-1 controls focal adhesions by regulating myosin light chain and on the other hand Wrch-1 stimulates the activation of Akt and JNK.
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Movimiento Celular , Adhesiones Focales/metabolismo , Proteínas de Unión al GTP rho/metabolismo , Activación Enzimática , Expresión Génica , Células HeLa , Humanos , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Cadenas Ligeras de Miosina/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Fosforilación , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Transporte de Proteínas , Proteínas Proto-Oncogénicas c-akt/metabolismo , Quinasas p21 Activadas , Proteínas de Unión al GTP rho/deficienciaRESUMEN
Members of the Rho family of small GTPases have been shown to be involved in tumorigenesis and metastasis. Currently, most of the available information on the function of Rho proteins in malignant transformation is based on the use of dominant-negative mutants of these GTPases. The specificity of these dominant-negative mutants is limited however. In this study, we used small interfering RNA directed against either Rac1 or Rac3 to reduce their expression specifically. In line with observations using dominant-negative Rac1 in other cell types, we show that RNA interference-mediated depletion of Rac1 strongly inhibits lamellipodia formation, cell migration and invasion in SNB19 glioblastoma cells. Surprisingly however, Rac1 depletion has a much smaller inhibitory effect on SNB19 cell proliferation and survival. Interestingly, whereas depletion of Rac3 strongly inhibits SNB19 cell invasion, it does not affect lamellipodia formation and has only minor effects on cell migration and proliferation. Similar results were obtained in BT549 breast carcinoma cells. Thus, functional analysis of Rac1 and Rac3 using RNA interference reveals a critical role for these GTPases in the invasive behavior of glioma and breast carcinoma cells.
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Neoplasias Encefálicas/patología , Neoplasias de la Mama/patología , Glioblastoma/patología , Invasividad Neoplásica/fisiopatología , Interferencia de ARN , Movimiento Celular , Proliferación Celular , Supervivencia Celular , Femenino , Humanos , Seudópodos/fisiología , ARN Interferente Pequeño , Células Tumorales Cultivadas , Proteínas de Unión al GTP rac , Proteína de Unión al GTP rac1RESUMEN
The small GTPase Rac1 is thought to play an important role in cell migration and invasion. We have previously identified synaptojanin 2, a phosphoinositide phosphatase, as an effector of Rac1. Here, we show that small interfering RNA-mediated depletion of either Rac1 or synaptojanin 2 inhibits invasion of SNB19 and U87MG glioblastoma cells through Matrigel and rat brain slices. Depletion of Rac1 or synaptojanin 2 also inhibits migration of SNB19 and U87MG cells on glioma-derived extracellular matrix. In addition, we found that depletion of Rac1 or synaptojanin 2 inhibits the formation of lamellipodia and invadopodia, specialized membrane structures that are thought to be involved in extracellular matrix degradation. These results suggest that synaptojanin 2 contributes to the role of Rac1 in cell invasion and migration by regulating the formation of invadopodia and lamellipodia. This study also identifies synaptojanin 2 as a novel potential target for therapeutic intervention in malignant tumors.