Browsing by Author "Nualart, Francisco"
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- ItemA characterization of cancer vasculogenic mimicry: Extracellular matrix induced cellular signaling to lumen formation.(AMER ASSOC CANCER RESEARCH, 2021) Mingo, Gabriel; Valdivia, Andres; Aldana, Varina; Pradenas, Javiera; Babbitt, Nicole; Gonzalez, Pamela; Nualart, Francisco; Diaz, Jorge; Leyton, Lisette; Bertocchi, Cristina; Owen, Gareth
- ItemDynamic expression of the sodium-vitamin C co-transporters, SVCT1 and SVCT2, during perinatal kidney development(2013) Nualart, Francisco; Castro, Tamara; Low, Marcela; Henríquez, Juan Pablo; Oyarce, Karina; Cisternas, Pedro; García, Andra; Yañez, Alejandro J.; Bertinat, Romina; Montecinos Acuña, Viviana; García Robles, María Angeles
- ItemFact or Fiction, It Is Time for a Verdict on Vasculogenic Mimicry?(2019) Valdivia Román, Andrés Felipe; Mingo Orsini, Gabriel Antonio; Aldana, Varina; Pinto, Mauricio P.; Ramírez, Marco; Retamal, Claudio; González, Alfonso; Nualart, Francisco; Corválan, Alejandro H.; Owen, Gareth Ivor
- ItemGlucose increases intracellular free Ca2+ in tanycytes via ATP released through connexin 43 hemichannels(Wiley Periodicals, Inc., 2012) Orellana Roca, Juan Andrés; Sáez Pedraza, Pablo José; Cortés-Campos, Christian; Elizondo, Roberto J.; Shoji Sánchez, Kenji Fabricio; Contreras Duarte, Susana de las Mercedes; Figueroa, Vania; Velarde Aliaga, María Victoria; Jiang, Jean X.; Nualart, Francisco; Sáez, Juan Carlos; García, María A.The ventromedial hypothalamus is involved in regulating feeding and satiety behavior, and its neurons interact with specialized ependymal-glial cells, termed tanycytes. The latter express glucose-sensing proteins, including glucose transporter 2, glucokinase, and ATP-sensitive K+ (KATP) channels, suggesting their involvement in hypothalamic glucosensing. Here, the transduction mechanism involved in the glucose-induced rise of intracellular free Ca2+ concentration ([Ca2+]i) in cultured beta-tanycytes was examined. Fura-2AM time-lapse fluorescence images revealed that glucose increases the intracellular Ca2+ signal in a concentration-dependent manner. Glucose transportation, primarily via glucose transporters, and metabolism via anaerobic glycolysis increased connexin 43 (Cx43) hemichannel activity, evaluated by ethidium uptake and whole cell patch clamp recordings, through a KATP channel-dependent pathway. Consequently, ATP export to the extracellular milieu was enhanced, resulting in activation of purinergic P2Y1 receptors followed by inositol trisphosphate receptor activation and Ca2+ release from intracellular stores. The present study identifies the mechanism by which glucose increases [Ca2+]i in tanycytes. It also establishes that Cx43 hemichannels can be rapidly activated under physiological conditions by the sequential activation of glucosensing proteins in normal tanycytes
- ItemOver-expression of muscle glycogen synthase in human diabetic nephropathy(2015) Gatica, Rodrigo; Bertinat, Romina; Silva, Pamela; Kairath, Pamela; Slebe, Felipe; Pardo, Fabian; Ramirez, Maria J.; Slebe, Juan C.; Campistol, Jose M.; Nualart, Francisco; Caelles, Carme; Yanez, Alejandro J.Diabetic nephropathy (DN) is a major complication of diabetic patients and the leading cause of end-stage renal disease. Glomerular dysfunction plays a critical role in DN, but deterioration of renal function also correlates with tubular alterations. Human DN is characterized by glycogen accumulation in tubules. Although this pathological feature has long been recognized, little information exists about the triggering mechanism. In this study, we detected over-expression of muscle glycogen synthase (MGS) in diabetic human kidney. This enhanced expression suggests the participation of MGS in renal metabolic changes associated with diabetes. HK2 human renal cell line exhibited an intrinsic ability to synthesize glycogen, which was enhanced after over-expression of protein targeting to glycogen. A correlation between increased glycogen amount and cell death was observed. Based on a previous transcriptome study on human diabetic kidney disease, significant differences in the expression of genes involved in glycogen metabolism were analyzed. We propose that glucose, but not insulin, is the main modulator of MGS activity in HK2 cells, suggesting that blood glucose control is the best approach to modulate renal glycogen-induced damage during long-term diabetes.
- ItemRegulation of GLUT3 and glucose uptake by the cAMP signalling pathway in the breast cancer cell line ZR-75(2008) Meneses, Ana Maria; Medina, Rodolfo A.; Kato, Sumie; Pinto, Mauricio; Jaque, Maria Paz; Lizama, Isabel; Garcia, Maria De Los Angeles; Nualart, Francisco; Owen, Gareth I.Increased glucose uptake as a principal energy source is a requirement for the continued survival of tumour cells. Facilitative glucose transporter-1 (GLUT 1) and -3(GLUTS) have been previously shown to be present and regulated in breast cancer cells and are associated with poor patient prognosis. In cancer cells, the cAMP secondary messenger pathway is known to potentiate described glucose transporter activators and regulate cell fate. However, no regulation of the glucose transporters in breast cancer cells by cAMP has previously been examined. Herein, we determined in the well-characterized breast cancer cell line ZR-75, if the cAMP analogue 8-br-cAMP was capable of regulating GLUT I and GLUTS expression and thus glucose uptake. We demonstrated that 8-br-cAMP transiently up-regulates GLUTS mRNA levels. The use of actinomycin-D and the cloning of 1,200 by upstream of the human GLUTS promoter demonstrated that this regulation was transcriptional. Immunocytochemistry and Western blotting confirmed that the increase in mRNA was reflected by an increase in protein levels. No notable regulation of GLUT I in the presence of 8-br-cAMP was detected. Finally, we determined using the non-metabolizable glucose analogue 2-DOG if this up-regulation in GLUTS increased glucose uptake. We observed the presence of two uptake components, one corresponding to the Km of GLUT 1/4 and the other to GLUTS. A doubling in the uptake velocity was observed only at the Km corresponding to GLUTS. In conclusion, we demonstrate and characterize for the first time, an upregulation of GLUTS mRNA, protein and glucose uptake by the cAMP pathway in breast cancer cells.
- ItemThe Differential Paracrine Role of the Endothelium in Prostate Cancer Cells(2022) Torres-Estay, Veronica; Mastri, Michalis; Rosario, Spencer; Fuenzalida, Patricia; Echeverria, Carolina E.; Flores, Emilia; Watts, Anica; Cerda-Infante, Javier; Montecinos, Viviana P.; Sotomayor, Paula C.; Amigo, Julio; Escudero, Carlos; Nualart, Francisco; Ebos, John M. L.; Smiraglia, Dominic J.; Godoy, Alejandro S.Simple Summary A growing body of literature supports the concept that a tumor mass is under the strict control of the microvascular endothelium and that the perfusion of oxygen and nutrients by capillary vessels to the tumor mass is reinforced by potent paracrine activity from the vascular endothelial cells. In our study, we investigate the biological and molecular implications of the paracrine crosstalk between vascular endothelial cells and prostate cancer cells. Our results indicate that the endothelial cells were able to secrete molecular signals that promote the proliferation and growth of low and highly aggressive prostate cancer cells and selectively increased the migration, invasion and metastatic potential of highly aggressive prostate cancer cells. The molecular analyses indicated that endothelial cells induced a differential effect on gene expression profile when comparing low versus highly aggressive prostate cancer cells, causing an enrichment of epigenetic changes in migratory pathways in highly aggressive prostate cancer cells. In conclusion, our results indicate that endothelial cells release signals that favor tumor growth and aggressiveness and that this interaction may play an important role in the progression of prostate cancer. The survival of patients with solid tumors, such as prostate cancer (PCa), has been limited and fleeting with anti-angiogenic therapies. It was previously thought that the mechanism by which the vasculature regulates tumor growth was driven by a passive movement of oxygen and nutrients to the tumor tissue. However, previous evidence suggests that endothelial cells have an alternative role in changing the behavior of tumor cells and contributing to cancer progression. Determining the impact of molecular signals/growth factors released by endothelial cells (ECs) on established PCa cell lines in vitro and in vivo could help to explain the mechanism by which ECs regulate tumor growth. Using cell-conditioned media collected from HUVEC (HUVEC-CM), our data show the stimulated proliferation of all the PCa cell lines tested. However, in more aggressive PCa cell lines, HUVEC-CM selectively promoted migration and invasion in vitro and in vivo. Using a PCa-cell-line-derived xenograft model co-injected with HUVEC or preincubated with HUVEC-CM, our results are consistent with the in vitro data, showing enhanced tumor growth, increased tumor microvasculature and promoted metastasis. Gene set enrichment analyses from RNA-Seq gene expression profiles showed that HUVEC-CM induced a differential effect on gene expression when comparing low versus highly aggressive PCa cell lines, demonstrating epigenetic and migratory pathway enrichments in highly aggressive PCa cells. In summary, paracrine stimulation by HUVEC increased PCa cell proliferation and tumor growth and selectively promoted migration and metastatic potential in more aggressive PCa cell lines.