Browsing by Author "Rivera, Patricia"

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    A single bout of resistance exercise triggers mitophagy, potentially involving the ejection of mitochondria in human skeletal muscle
    (2024) Diaz-Castro, Francisco; Tunon-Suarez, Mauro; Rivera, Patricia; Botella, Javier; Cancino, Jorge; Figueroa, Ana Maria; Gutierrez, Juan; Cantin, Claudette; Deldicque, Louise; Zbinden-Foncea, Hermann; Nielsen, Joachim; Henriquez-Olguin, Carlos; Morselli, Eugenia; Castro-Sepulveda, Mauricio
    AimThe present study aimed to investigate the effects of a single bout of resistance exercise on mitophagy in human skeletal muscle (SkM).MethodsEight healthy men were recruited to complete an acute bout of one-leg resistance exercise. SkM biopsies were obtained one hour after exercise in the resting leg (Rest-leg) and the contracting leg (Ex-leg). Mitophagy was assessed using protein-related abundance, transmission electron microscopy (TEM), and fluorescence microscopy.ResultsOur results show that acute resistance exercise increased pro-fission protein phosphorylation (DRP1Ser616) and decreased mitophagy markers such as PARKIN and BNIP3L/NIX protein abundance in the Ex-leg. Additionally, mitochondrial complex IV decreased in the Ex-leg when compared to the Rest-leg. In the Ex-leg, TEM and immunofluorescence images showed mitochondrial cristae abnormalities, a mitochondrial fission phenotype, and increased mitophagosome-like structures in both subsarcolemmal and intermyofibrillar mitochondria. We also observed increased mitophagosome-like structures on the subsarcolemmal cleft and mitochondria in the extracellular space of SkM in the Ex-leg. We stimulated human primary myotubes with CCCP, which mimics mitophagy induction in the Ex-leg, and found that BNIP3L/NIX protein abundance decreased independently of lysosomal degradation. Finally, in another human cohort, we found a negative association between BNIP3L/NIX protein abundance with both mitophagosome-like structures and mitochondrial cristae density in the SkM.ConclusionThe findings suggest that a single bout of resistance exercise can initiate mitophagy, potentially involving mitochondrial ejection, in human skeletal muscle. BNIP3L/NIX is proposed as a sensitive marker for assessing mitophagy flux in SkM.
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    Palmitic acid control of ciliogenesis modulates insulin signaling in hypothalamic neurons through an autophagy-dependent mechanism
    (SPRINGERNATURE, 2022) Avalos, Yenniffer; Paz Hernandez-Caceres, Maria; Lagos, Pablo; Pinto-Nunez, Daniela; Rivera, Patricia; Burgos, Paulina; Diaz-Castro, Francisco; Joy-Immediato, Michelle; Venegas-Zamora, Leslye; Lopez-Gallardo, Erik; Kretschmar, Catalina; Batista-Gonzalez, Ana; Cifuentes-Araneda, Flavia; Toledo-Valenzuela, Lilian; Rodriguez-Pena, Marcelo; Espinoza-Caicedo, Jasson; Perez-Leighton, Claudio; Bertocchi, Cristina; Cerda, Mauricio; Troncoso, Rodrigo; Parra, Valentina; Budini, Mauricio; Burgos, Patricia, V; Criollo, Alfredo; Morselli, Eugenia
    Palmitic acid (PA) is significantly increased in the hypothalamus of mice, when fed chronically with a high-fat diet (HFD). PA impairs insulin signaling in hypothalamic neurons, by a mechanism dependent on autophagy, a process of lysosomal-mediated degradation of cytoplasmic material. In addition, previous work shows a crosstalk between autophagy and the primary cilium (hereafter cilium), an antenna-like structure on the cell surface that acts as a signaling platform for the cell. Ciliopathies, human diseases characterized by cilia dysfunction, manifest, type 2 diabetes, among other features, suggesting a role of the cilium in insulin signaling. Cilium depletion in hypothalamic pro-opiomelanocortin (POMC) neurons triggers obesity and insulin resistance in mice, the same phenotype as mice deficient in autophagy in POMC neurons. Here we investigated the effect of chronic consumption of HFD on cilia; and our results indicate that chronic feeding with HFD reduces the percentage of cilia in hypothalamic POMC neurons. This effect may be due to an increased amount of PA, as treatment with this saturated fatty acid in vitro reduces the percentage of ciliated cells and cilia length in hypothalamic neurons. Importantly, the same effect of cilia depletion was obtained following chemical and genetic inhibition of autophagy, indicating autophagy is required for ciliogenesis. We further demonstrate a role for the cilium in insulin sensitivity, as cilium loss in hypothalamic neuronal cells disrupts insulin signaling and insulin-dependent glucose uptake, an effect that correlates with the ciliary localization of the insulin receptor (IR). Consistently, increased percentage of ciliated hypothalamic neuronal cells promotes insulin signaling, even when cells are exposed to PA. Altogether, our results indicate that, in hypothalamic neurons, impairment of autophagy, either by PA exposure, chemical or genetic manipulation, cause cilia loss that impairs insulin sensitivity.
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    The autophagy process and oxidized LDL independently modulate the invasion and differentiation of extravillous trophoblastic cells to an endothelial-like phenotype in normoxia
    (2024) Carvajal, Lorena; Escalona, Rodrigo; Rivera, Patricia; Aguilera-Olguin, Macarena; Hernandez-Caceres, Maria Paz; Gutierrez, Jaime; Morselli, Eugenia; Leiva, Andrea
    Introduction: The mechanisms leading to proper placentation are not fully understood. Extravillous trophoblasts (EVTs) are crucial for placentation through invasion and vascular remodeling, which, when impaired, promote a poor placentation. How autophagy could regulate EVTs function and the study of regulators of these processes, such as oxidized low-density lipoproteins (ox-LDL), could contribute to better understand events associated with pregnancy complications related to abnormal placental development, such as preeclampsia (PE). Aim: To investigate the role of autophagy and oxidized LDL (ox-LDL) in invasion and endothelial-like phenotype acquisition of a model of EVTs, as well as to determine the levels of autophagy flux markers in control and PE placentas. Methods: Invasion and endothelial-like phenotype acquisition assays were performed in a cell line model of first trimester EVTs: HTR-8/SVneo cultured in normoxia (oxygen concentration of 20 %), in the absence or the presence of the autophagy inhibitor bafilomycin or/and ox-LDL. Markers of autophagic flux were evaluated in human term placentas. Results: Autophagy is essential for EVTs to acquire an endothelial-like phenotype but does not affect invasion. Conversely, ox-LDL decreases invasion and reticular structures formation, independent of autophagy. At pregnancy term, the levels of the autophagy markers LC3 and p62 are deregulated in the trophoblast cells of PE placentas. Conclusion: Autophagy is necessary for proper endothelial-like phenotype acquisition in HTR-8/SVneo cultured in normoxia, and ox-LDL impairs this process as well as the invasion of EVTs by a mechanism independent of autophagy. Changes in autophagy and/or in the concentration of ox-LDL could affect placental vascular remodeling.