Claudia Araya
Pontifical Catholic University of Chile
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Publication
Featured researches published by Claudia Araya.
Molecular Neurodegeneration | 2007
Rodrigo A. Fuentealba; María Inés Barría; Jiyeon Lee; Judy A. Cam; Claudia Araya; Claudia A. Escudero; Nibaldo C. Inestrosa; Francisca C. Bronfman; Guojun Bu; María Paz Marzolo
BackgroundThe generation of the amyloid-β peptide (Aβ) through the proteolytic processing of the amyloid precursor protein (APP) is a central event in the pathogenesis of Alzheimers disease (AD). Recent studies highlight APP endocytosis and localization to lipid rafts as important events favoring amyloidogenic processing. However, the precise mechanisms underlying these events are poorly understood. ApoER2 is a member of the low density lipoprotein receptor (LDL-R) family exhibiting slow endocytosis rate and a significant association with lipid rafts. Despite the important neurophysiological roles described for ApoER2, little is known regarding how ApoER2 regulates APP trafficking and processing.ResultsHere, we demonstrate that ApoER2 physically interacts and co-localizes with APP. Remarkably, we found that ApoER2 increases cell surface APP levels and APP association with lipid rafts. The increase of cell surface APP requires the presence of ApoER2 cytoplasmic domain and is a result of decreased APP internalization rate. Unexpectedly, ApoER2 expression correlated with a significant increase in Aβ production and reduced levels of APP-CTFs. The increased Aβ production was dependent on the integrity of the NPxY endocytosis motif of ApoER2. We also found that expression of ApoER2 increased APP association with lipid rafts and increased γ-secretase activity, both of which might contribute to increased Aβ production.ConclusionThese findings show that ApoER2 negatively affects APP internalization. However, ApoER2 expression stimulates Aβ production by shifting the proportion of APP from the non-rafts to the raft membrane domains, thereby promoting β-secretase and γ-secretase mediated amyloidogenic processing and also by incrementing the activity of γ-secretase.
Journal of Cellular Biochemistry | 2009
Andrés Toro; Claudia Araya; Gonzalo Córdova; Cristian Arredondo; Hugo Cardenas; Regina E. Moreno; Alejandro Venegas; Cecilia S. Koenig; Jorge Cancino; Alfonso González; Manuel J. Santos
The mechanisms of peroxisomal biogenesis remain incompletely understood, specially regarding the role of the endoplasmic reticulum (ER) in human cells, where genetic disorders of peroxisome biogenesis lead to Zellweger syndrome (ZS). The Pex3p peroxisomal membrane protein (PMP) required for early steps of peroxisome biogenesis has been detected in the ER in yeast but not in mammalian cells. Here, we show that Pex3p‐GFP expressed in a new ZS cell line (MR), which lacks peroxisomes due to a mutation in the PEX3 gene, localizes first in the ER and subsequently in newly formed peroxisomes. Pex3p bearing an artificial N‐glycosylation site shows an electrophoretic shift indicative of ER targeting while en route to preformed peroxisomes in normal fibroblast. A signal peptide that forces its entry into the ER does not eliminate its capability to drive peroxisome biogenesis in ZS cells. Thus, Pex3p is able to drive peroxisome biogenesis from the ER and its ER pathway is not privative of ZS cells. Cross‐expression experiments of Pex3p in GM623 cells lacking Pex16p or Pex16p in MR cells lacking Pex3p, showed evidence that Pex3p requires Pex16p for ER location but is dispensable for the ER location of Pex16p. These results indicate that Pex3p follows the ER‐to‐peroxisomal route in mammalian cells and provides new clues to understand its function. J. Cell. Biochem. 107: 1083–1096, 2009.
Journal of Chemical Ecology | 1999
Christian Figueroa; Cecilia S. Koenig; Claudia Araya; Manuel J. Santos; Hermann M. Niemeyer
Abstract2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a hydroxamic acid involved in the resistance of cereals to aphids, was administered to adult individuals of the aphid Sitobion avenae in artificial diets. Effects on the cellular metabolism were inferred from the evaluation of several organelle marker enzymes. Catalase from peroxisomes and cytochrome c oxidase from mitochondria increased their activities about twofold when aphids were fed with 2 mM DIMBOA. The role of these enzymes in the metabolizing of xenobiotics by aphids is discussed. Biochemical and cytochemical evidences for the presence of peroxisomes in aphids are reported here for the first time.
Journal of Histochemistry and Cytochemistry | 2002
Cecilia S. Koenig; Claudia Araya; Cetna Skorin; Claudio Valencia; Andrés Toro; Federico Leighton; Manuel J. Santos
We demonstrated a neutral Mg-ATPase activity in human peroxisomal membranes. To establish the precise experimental conditions for detection of this ATPase, both cytochemical and biochemical characterizations were first carried out in liver peroxisomes from control and cipofibrate-treated rats. The results demonstrated an Mg-ATPase reaction in both normal and proliferated peroxisomes. The nucleotidase activity, with marked preference for ATP, was sensitive to the inhibitors N-ethylmaleimide and 7-chloro-4-nitrobenzo-2-oxadiazole (NBDCl). An ultrastructural cytochemical analysis was developed to evaluate the peroxisomal localization, which localized the reaction product to the peroxisomal membrane. These characteristics can help to differentiate the peroxisomal ATPase from the activity found in mitochondria and endoplasmic reticulum. The conditions established for detecting the rat peroxisomal ATPase were then applied to human peroxisomes isolated from liver and skin fibroblasts in culture. A similar Mg-ATPase activity was readily shown, both cytochemically and biochemically, in the membranes of human peroxisomes. These results, together with previous evidence, strongly support the presence of a specific ATPase in the human peroxisomal membrane. This ATPase may play a crucial role in peroxisome biogenesis.
Psicologia Em Estudo | 2011
Dariela Sharim; Claudia Araya; Mariela Carmona; Paula Riquelme
Important changes in the realm of intimacy have been described in light of the processes of social individualization. In this context, this research enquires the meanings and subjective experience regarding couple relationships, focusing in the psychological dimension of intimacy. Life histories from Chilean adult men and women who narrated their couple’s history were collected. The results call into question the assumption that this relationship is particularly representative of the domain of intimacy. When talking about couples the interviewees did not talk about intimacy. Instead, they conveyed a sense of fear or threaten, and the avoidance of the other in that realm. Their narratives show that the ideals regarding the couple are -paradoxicallyconstructed at an individual level, and this results in a way of being in a couple’s relationship that we have called “collective monologue”.
Psicologia Em Estudo | 2011
Dariela Sharim; Claudia Araya; Mariela Carmona; Paula Riquelme
Important changes in the realm of intimacy have been described in light of the processes of social individualization. In this context, this research enquires the meanings and subjective experience regarding couple relationships, focusing in the psychological dimension of intimacy. Life histories from Chilean adult men and women who narrated their couple’s history were collected. The results call into question the assumption that this relationship is particularly representative of the domain of intimacy. When talking about couples the interviewees did not talk about intimacy. Instead, they conveyed a sense of fear or threaten, and the avoidance of the other in that realm. Their narratives show that the ideals regarding the couple are -paradoxicallyconstructed at an individual level, and this results in a way of being in a couple’s relationship that we have called “collective monologue”.
Psicologia Em Estudo | 2011
Dariela Sharim; Claudia Araya; Mariela Carmona; Paula Riquelme
Important changes in the realm of intimacy have been described in light of the processes of social individualization. In this context, this research enquires the meanings and subjective experience regarding couple relationships, focusing in the psychological dimension of intimacy. Life histories from Chilean adult men and women who narrated their couple’s history were collected. The results call into question the assumption that this relationship is particularly representative of the domain of intimacy. When talking about couples the interviewees did not talk about intimacy. Instead, they conveyed a sense of fear or threaten, and the avoidance of the other in that realm. Their narratives show that the ideals regarding the couple are -paradoxicallyconstructed at an individual level, and this results in a way of being in a couple’s relationship that we have called “collective monologue”.
Convegno su "Cultura e Diritto nelle Costituzioni Europee" | 2001
Carolina Bernal; Claudia Araya; Verónica Palma; Miguel Bronfman
The subventricular zone (SVZ) is one of the main niches of neural stem cells in the adult mammalian brain. Stem and precursor cells in this region are the source for neurogenesis and oligodendrogesis, mainly in the olfactory bulb and corpus callosum, respectively. The identification of the molecular components regulating the decision of these cells to differentiate or maintain an undifferentiated state is important in order to understand the modulation of neurogenic processes in physiological and pathological conditions. PPARs are a group of transcription factors, activated by lipid ligands, with important functions in cellular differentiation and proliferation in several tissues. In this work, we demonstrate that mouse adult neural precursor cells (NPCs), in situ and in vitro, express PPARβ/δ and PPARγ. Pharmacological activation of both PPARs isoforms induces proliferation and maintenance of the undifferentiated phenotype. Congruently, inhibition of PPARβ/δ and PPARγ results in a decrease of proliferation and loss of the undifferentiated phenotype. Interestingly, PPARγ regulates the level of EGFR in adult NPCs, concurrent with it is function described in embryonic NPCs. Furthermore, we describe for the first time that PPARβ/δ regulates SOX2 level in adult NPCs, probably through a direct transcriptional regulation, as we identified two putative PPAR response elements in the promoter region of Sox2. EGFR and SOX2 are key players in neural stem/precursor cells self-renewal. Finally, rosiglitazone, a PPARγ ligand, increases PPARβ/δ level, suggesting a possible cooperation between these two PPARs in the control of cell fate behavior. Our work contributes to the understanding of the molecular mechanisms associated to neural cell fate decision and places PPARβ/δ and PPARγ as interesting new targets of modulation of mammalian brain homeostasis.
Biological Research | 2007
Andrés Toro; Cristian Arredondo; Gonzalo Córdova; Claudia Araya; José Luis Palacios; Alejandro Venegas; Masashi Morita; Tsuneo Imanaka; Manuel J. Santos
Psykhe (santiago) | 2017
Andrea Rihm; Dariela Sharim; Jaime Barrientos; Claudia Araya; Margarita Larraín