RESUMO
Before fertilization, spermatozoa must undergo calcium-regulated acrosome exocytosis in response to physiological stimuli such as progesterone and zona pellucida. Our laboratory has elucidated the signaling cascades accomplished by different sphingolipids during human sperm acrosomal exocytosis. Recently, we established that ceramide increases intracellular calcium by activating various channels and stimulating the acrosome reaction. However, whether ceramide induces exocytosis on its own, activation of the ceramide kinase/ceramide 1-phosphate (CERK/C1P) pathway or both is still an unsolved issue. Here, we demonstrate that C1P addition induces exocytosis in intact, capacitated human sperm. Real-time imaging in single-cell and calcium measurements in sperm population showed that C1P needs extracellular calcium to induce [Ca2+]i increase. The sphingolipid triggered the cation influx through voltage-operated calcium (VOC) and store-operated calcium (SOC) channels. However, it requires calcium efflux from internal stores through inositol 3-phosphate receptors (IP3R) and ryanodine receptors (RyR) to achieve calcium rise and the acrosome reaction. We report the presence of the CERK in human spermatozoa, the enzyme that catalyzes C1P synthesis. Furthermore, CERK exhibited calcium-stimulated enzymatic activity during the acrosome reaction. Exocytosis assays using a CERK inhibitor demonstrated that ceramide induces acrosomal exocytosis, mainly due to C1P synthesis. Strikingly, progesterone required CERK activity to induce intracellular calcium increase and acrosome exocytosis. This is the first report, implicating the bioactive sphingolipid C1P in the physiological progesterone pathway leading to the sperm acrosome reaction.
RESUMO
BACKGROUND: During embryogenesis lateral symmetry is broken, giving rise to Left/Right (L/R) breast tissues with distinct identity. L/R-sided breast tumors exhibit consistently-biased incidence, gene expression, and DNA methylation. We postulate that a differential L/R tumor-microenvironment crosstalk generates different tumorigenesis mechanisms. METHODS: We performed in-silico analyses on breast tumors of public datasets, developed xenografted tumors, and conditioned MDA-MB-231 cells with L/R mammary extracts. RESULTS: We found L/R differential DNA methylation involved in embryogenic and neuron-like functions. Focusing on ion-channels, we discovered significant L/R epigenetic and bioelectric differences. Specifically, L-sided cells presented increased methylation of hyperpolarizing ion channel genes and increased Ca2+ concentration and depolarized membrane potential, compared to R-ones. Functional consequences were associated with increased proliferation in left tumors, assessed by KI67 expression and mitotic count. CONCLUSIONS: Our findings reveal considerable L/R asymmetry in cancer processes, and suggest specific L/R epigenetic and bioelectric differences as future targets for cancer therapeutic approaches in the breast and many other paired organs.
Assuntos
Impedância Elétrica , Epigênese Genética , Neoplasias Unilaterais da Mama/genética , Neoplasias Unilaterais da Mama/patologia , Animais , Linhagem Celular Tumoral , Biologia Computacional , Metilação de DNA , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Transcriptoma , Microambiente TumoralRESUMO
Regional Symposium on Emergency Preparedness and Chemical Disasters: a Challenge for the XXI Century
Simposio Regional sobre Preparativos para Emergencias y Desastres Químicos: un Reto para el Siglo XXI. Organización Panamericana de la Salud; 30 oct. -1 nov. 1996
Assuntos
Vazamento de Resíduos Químicos , Planejamento em Desastres , Emergências em Desastres , Alerta em Desastres , Sistemas de Informação , Cooperação Internacional , Estrutura dos ServiçosRESUMO
Se realiza el estudio de los 86 nacimientos ocurridos en el Hospital Maternoinfantil "Leopoldito Martínez" de San José de las Lajas" en el período comprendido entre el 1 de julio de 1982 y el 30 de junio de 1983. Se consideró como recién nacido de bajo peso lo propuesto por Batlagia y Lubchenco. Se analizaron un conjunto de factores que estuvieron presentes antes o durante el embarazo de los nacidos bajo peso. Se determinó el estado al nacer y las enfermedades más frecuentes. La mayor frecuencia de Apgar bajo ocurrió en los productos de embarazo con menos de 36 semanas. Las enfermedades más frecuentes en el bajo de peso fueron en orden descendente la hiperbilirrubinemia, la plétora sanguínea, el ictero fisiológico, la hipoglicemia, la sepsis urinaria, el distress respiratorio y la bronconeumonia congénita. Se concluye que es importante por parte del personal de Enfermería que labora en la Sala de neonatología aplicar los cuidados específicos a este recién nacido