RESUMEN
BACKGROUND: Environments within schools including the physical, social-cultural and policy/practice environments have the potential to influence children's physical activity (PA) behaviours and weight status. This Australian first study comprehensively examined the association(s) of physical, social-cultural and policy/practice environments with PA, active transport (AT) and weight status among regional primary school children. METHODS: Data were from two childhood obesity monitoring systems in regional Victoria, Australia. Measured height and weight were collected from students in Year 2 (aged approx. 7-8 years), Year 4 (9-10 years), and Year 6 (11-12 years). Self-reported PA behaviour, including AT were collected from students in Year 4 and 6 and a sub-sample wore an ActiGraph (wGT3X-BT) accelerometer for 7-days. A school physical activity environment audit was completed by the school principal and responses were used to calculate school physical activity environment scores (PAES) and active transport environment scores (ATES). Mixed effects logistic regression was used to assess the relationship between the proportion of students meeting the PA guidelines (≥60mins/day of moderate-to-vigorous PA) and PAES tertiles (low, medium, high) and those using AT and school ATES tertiles, controlling for gender, school size/type and socioeconomic composition. RESULTS: The analysed sample included 54/146 (37%) schools and 3360/5376 (64%) students. In stratified analysis, girls in schools with a medium PAES score were more likely to meet the objectively measured PA guideline compared to low PAES score (OR 2.3, 95%CI 1.27, 4.16). Similarly, students in schools with a medium or high ATES score had higher odds of self-reported AT (medium OR 3.15, 95%CI 1.67, 5.94; high OR 3.71, 95%CI: 1.80, 7.64). No association between PAES or ATES and weight status were observed. Self-reported AT among boys (OR 1.59, 95%CI 1.19, 2.13) and girls (OR 1.56, 95%CI 1.08, 2.27) was associated with higher odds of meeting self-reported PA guidelines on all 7-days than those who did not report using AT. CONCLUSIONS: In this study of regional Victorian primary schools, PA environments were only associated with girls' adherence to PA guidelines. School AT environments were strongly associated with students' AT behaviours and with increased likelihood of students being physically active.
Asunto(s)
Ejercicio Físico , Estudiantes , Anciano , Niño , Estudios Transversales , Ambiente , Femenino , Humanos , Masculino , Obesidad Infantil/prevención & control , Instituciones Académicas , Autoinforme , VictoriaRESUMEN
Stimulation of epidermal growth factor receptor (EGFR) initiates RAS signaling simultaneously with EGFR internalization. Endocytosed EGFR is then either recycled or degraded. EGFR fate is determined in part by the RAS effector RIN1, a guanine nucleotide exchange factor (GEF) for RAB5 GTPases. EGFR degradation was slowed by RIN1 silencing, enhanced by RIN1 overexpression and accelerated by RIN1 localization to the plasma membrane. RIN1 also directly activates ABL tyrosine kinases, which regulate actin remodeling, a function not previously connected to endocytosis. We report that RIN1-RAB5 signaling favors EGFR downregulation over EGFR recycling, whereas RIN1-ABL signaling stabilizes EGFR and inhibits macropinocytosis. RIN1(QM), a mutant that blocks ABL activation, caused EGF-stimulated membrane ruffling, actin remodeling, dextran uptake and EGFR degradation. An ABL kinase inhibitor phenocopied these effects in cells overexpressing RIN1. EGFR activation also promotes RIN1 interaction with BIN1, a membrane bending protein. These findings suggest that RIN1 orchestrates RAB5 activation, ABL kinase activation and BIN1 recruitment to determine EGFR fate.
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Receptores ErbB/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas de Unión al GTP rab5/metabolismo , Membrana Celular/metabolismo , Técnica del Anticuerpo Fluorescente , Células HeLa , Humanos , Immunoblotting , Inmunoprecipitación , Microscopía Confocal , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The amygdala is known to have a crucial role in both the acquisition and extinction of conditioned fear, but the physiological changes and biochemical mechanisms underlying these forms of learning are only partly understood. The Ras effector Rin1 activates Abl tyrosine kinases and Rab5 GTPases and is highly expressed in mature neurons of the telencephalon including the amygdala, where it inhibits the acquisition of fear memories (Rin1(-/-) mice show enhanced learning of conditioned fear). Here we report that Rin1(-/-) mice exhibit profound deficits in both latent inhibition and fear extinction, suggesting a critical role for Rin1 in gating the acquisition and persistence of cue-dependent fear conditioning. Surprisingly, we also find that depotentiation, a proposed cellular mechanism of extinction, is enhanced at lateral-basolateral (LA-BLA) amygdaloid synapses in Rin1(-/-) mice. Inhibition of a single Rin1 downstream effector pathway, the Abl tyrosine kinases, led to reduced amygdaloid depotentiation, arguing that proper coordination of Abl and Rab5 pathways is critical for Rin1-mediated effects on plasticity. While demonstrating a correlation between amygdala plasticity and fear learning, our findings argue against models proposing a direct causative relationship between amygdala depotentiation and fear extinction. Taken together, the behavior and physiology of Rin1(-/-) mice provide new insights into the regulation of memory acquisition and maintenance. In addition, Rin1(-/-) mice should prove useful as a model for pathologies marked by enhanced fear acquisition and retention, such as posttraumatic stress disorder.
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Condicionamiento Clásico/fisiología , Extinción Psicológica/fisiología , Miedo/fisiología , Plasticidad Neuronal/fisiología , Transducción de Señal/fisiología , Proteínas de Unión al GTP rab/metabolismo , Estimulación Acústica/métodos , Amígdala del Cerebelo/fisiología , Animales , Atención/fisiología , Biofisica , Encéfalo/citología , Estimulación Eléctrica/métodos , Conducta Exploratoria/fisiología , Hipocampo/fisiología , Técnicas In Vitro , Péptidos y Proteínas de Señalización Intracelular , Depresión Sináptica a Largo Plazo/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Inhibición Neural/genética , Plasticidad Neuronal/genética , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Reflejo de Sobresalto/genética , Proteínas de Unión al GTP rab/deficienciaRESUMEN
The Ras effector Rin1 is induced concomitant with synaptogenesis in forebrain neurons, where it inhibits fear conditioning and amygdala LTP. In epithelial cells, lower levels of Rin1 orchestrate receptor endocytosis. A 945 bp Rin1 promoter fragment was active in hippocampal neurons and directed accurate tissue-specific and temporal expression in transgenic mice. Regulated expression in neurons and epithelial cells was mediated in part by Snail transcriptional repressors: mutation of a conserved Snail site increased expression and endogenous Snai1 was detected at the Rin1 promoter. We also describe an element closely related to, but distinct from, the consensus site for REST, a master repressor of neuronal genes. Conversion to a consensus REST sequence reduced expression in both cell types. These results provide insight into regulated expression of a neuronal Ras effector, define a promoter useful in telencephalic neuron studies, and describe a novel REST site variant directing expression to mature neurons.
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Regulación de la Expresión Génica , Neuronas/fisiología , Prosencéfalo/citología , Proteínas de Unión al GTP rab/metabolismo , Animales , Células Cultivadas , Genes Reporteros , Humanos , Péptidos y Proteínas de Señalización Intracelular , Ratones , Ratones Transgénicos , Neuronas/citología , Regiones Promotoras Genéticas , Prosencéfalo/metabolismo , Transducción de Señal/fisiología , Factores de Transcripción de la Familia Snail , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteínas de Unión al GTP rab/genéticaRESUMEN
Transforming growth factor beta (TGF-beta) receptor (TbetaR) signaling contributes to normal development as well as tumorigenesis. Here we report that RIN1, a RAB5 guanine nucleotide exchange factor (GEF) and down regulator of receptor tyrosine kinases (RTKs), promotes TbetaR signaling through enhanced endocytosis. TbetaR activation induces SNAI1 (Snail), a transcription repressor that reduces RIN1 expression, providing a negative feedback mechanism to control TbetaR trafficking and downstream signaling. Persistent RAS signaling disrupts this equilibrium by stabilizing SNAI1 protein, resulting in strong silencing of RIN1 and stabilization of RTKs. TGF-beta-induced RIN1 silencing in breast cancer cells prolonged sensitivity to hepatocyte growth factor, a ligand for the MET-type RTK, and enhanced growth factor-directed cell motility. We conclude that in some tumor cells TbetaR and RAS signals are integrated through the silencing of RIN1, leading to a reduction in RAB5-mediated endocytosis. These findings shed new light on the basis for distinct interpretations of TGF-beta signaling by normal versus transformed cells.
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Movimiento Celular , Factores de Intercambio de Guanina Nucleótido/metabolismo , Transducción de Señal , Factor de Crecimiento Transformador beta/metabolismo , Proteínas ras/metabolismo , Línea Celular Tumoral , Endocitosis , Receptores ErbB/metabolismo , Femenino , Genes Reporteros , Factores de Intercambio de Guanina Nucleótido/análisis , Humanos , Péptidos y Proteínas de Señalización Intracelular/química , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Modelos Biológicos , Mutación , Estructura Terciaria de Proteína , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Transfección , Factor de Crecimiento Transformador beta/genéticaRESUMEN
The human RIN1 gene was first identified as a cDNA fragment that interfered with RAS-induced phenotypes in the yeast Saccharomyces cerevisiae. Subsequent analysis of full-length RIN1 clones showed that the protein product of this gene is a downstream effector of RAS and binds with high affinity and specificity to activated HRAS. Two downstream RIN1 effector pathways have been described. The first involves direct activation of RAB5-mediated endocytosis. The second involves direct activation of ABL tyrosine kinase activity. Importantly, each of these distinct RIN1 functions is enhanced by activated RAS, suggesting that RIN1 represents a unique class of RAS effector connected to two independent signaling pathways. In this chapter, we summarize our assays and approaches for evaluating the biochemistry and biology of RIN1.
Asunto(s)
Péptidos y Proteínas de Señalización Intracelular/metabolismo , Animales , Endocitosis/fisiología , Evolución Molecular , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Proteínas de Unión al GTP rab5/metabolismoRESUMEN
BACKGROUND: ABL tyrosine kinases control actin remodeling in development and in response to environmental stimuli. These changes affect cell adhesion, cell migration, and cell-cell contact. Little is known, however, about upstream mechanisms regulating ABL protein activation. RESULTS: We report that the RAS effector RIN1 is an activator of ABL tyrosine kinases. RIN1 expression in fibroblasts promotes the formation of membrane spikes; similar effects have been reported for ABL overexpression. RIN1 binds to the ABL SH3 and SH2 domains, and these interactions stimulate ABL2 catalytic activity. This leads to increased phosphorylation of CRK and CRKL, inhibiting these cytoskeletal regulators by promoting intramolecular over intermolecular associations. Activated RAS participates in a stable RAS-RIN1-ABL2 complex and stimulates the tyrosine kinase-activation function of RIN1. Deletion of the RAS binding domain (RBD) strongly stimulated the ABL2 activation function of RIN1, suggesting that RAS activation results from the relief of RIN1 autoinhibition. The ABL binding domain of RIN1 (RIN1-ABD) increased the activity of ABL2 immune complexes and purified RIN1-ABD-stimulated ABL2 kinase activity toward CRK. Mammary epithelial cells (MECs) from Rin1-/- mice showed accelerated cell adhesion and increased motility in comparison to wild-type cells. Knockdown of RIN1 in epithelial-cell lines blocked the induction of CRKL phosphorylation, confirming that RIN1 normally functions as an inhibitor of cell motility. CONCLUSIONS: RIN1 is a directly binding ABL tyrosine kinase activator in cells as well as in a defined-component assay. In response to environmental changes, this novel signal pathway mediates actin remodeling associated with adhesion and migration of epithelial cells.