Browsing by Author "Carrasco, Hector"
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- ItemEarly requirement of Hyaluronan for tail regeneration in Xenopus tadpoles(COMPANY OF BIOLOGISTS LTD, 2009) Contreras, Esteban G.; Gaete, Marcia; Sanchez, Natalia; Carrasco, Hector; Larrain, JuanTail regeneration in Xenopus tadpoles is a favorable model system to understand the molecular and cellular basis of tissue regeneration. Although turnover of the extracellular matrix (ECM) is a key event during tissue injury and repair, no functional studies to evaluate its role in appendage regeneration have been performed. Studying the role of Hyaluronan (HA), an ECM component, is particularly attractive because it can activate intracellular signaling cascades after tissue injury. Here we studied the function of HA and components of the HA pathway in Xenopus tadpole tail regeneration. We found that transcripts for components of this pathway, including Hyaluronan synthase2 (HAS2), Hyaluronidase2 and its receptors CD44 and RHAMM, were transiently upregulated in the regenerative bud after tail amputation. Concomitantly, an increase in HA levels was observed. Functional experiments using 4-methylumbelliferone, a specific HAS inhibitor that blocked the increase in HA levels after tail amputation, and transgenesis demonstrated that the HA pathway is required during the early phases of tail regeneration. Proper levels of HA are required to sustain proliferation of mesenchymal cells in the regenerative bud. Pharmacological and genetic inhibition of GSK3 beta was sufficient to rescue proliferation and tail regeneration when HA synthesis was blocked, suggesting that GSK3 beta is downstream of the HA pathway. We have demonstrated that HA is an early component of the regenerative pathway and is required for cell proliferation during the early phases of Xenopus tail regeneration. In addition, a crosstalk between HA and GSK3 beta signaling during tail regeneration was demonstrated.
- ItemInfluence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures(2024) Aravena, Paulo; Cea-Klapp, Esteban; Gajardo-Parra, Nicolas F.; Olea, Andres F.; Carrasco, Hector; Matias Garrido, Jose; Canales, Roberto I.One of the environmental concerns in the chemical industry is using organic solvents that are not environmentally friendly. Eutectic mixtures, also called deep eutectic solvents (DESs), have emerged as their substitutes due to favorable properties, including biodegradability, tunability, and low cost, among others. DESs show applications in extractions, biocatalysis, etc. To expand their uses, it is crucial to characterize their properties and understand their interactions with other solvents. In this study, the surface tension of DESs between 30 and 60 degrees C at 101.3 kPa was measured. The DESs were prepared using choline chloride or betaine as the hydrogen bond acceptor (HBA) and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, or 1,4-butanediol) as the hydrogen bond donor (HBD) in different molar ratios. The surface tension of DESs + water mixtures was measured over the entire range of compositions. To assess the effect of temperature, HBD chain length, and water content, PC-SAFT coupled with the density gradient theory was used to model the surface tension. Furthermore, molecular dynamics simulations were conducted to gain a molecular understanding of the components at the interface. The molecular insights obtained from these simulations and the experimental data can help reduce the number of experiments when designing DESs for chemical processes.
- ItemNatural history of the relict marsupial Monito del Monte at the most extreme altitudinal and latitudinal location(2021) Mejias, Carlos; Castro-Pastene, Carlos A.; Carrasco, Hector; Quintero-Galvis, Julian F.; Soto-Gamboa, Mauricio; Bozinovic, Francisco; Nespolo, Roberto F.Until a few years ago, the "monito del monte" (Dromiciops gliroides) was considered the sole surviving species of Microbiotheria, the sister group of Australidelphia (Australian marsupials). However, the recent identification of a new species relegated to the northern range (Dromiciops bozinovici) and newly discovered populations of Dromiciops beyond the known limits for the geographic range demands for new studies in extreme locations. In this report, we describe the northernmost population of D. bozinovici at a high Andean location (Reserva Nacional Altos de Lircay [RNAL], which represents a record of Dromiciops distribution both in latitude [35 degrees S] and in altitude [1696 m a.s.l.]). We live-trapped individuals, performed behavioral observations, and extracted mtDNA (Cytb) for analyzing phylogenetic affinities. Together with confirming the phylogenetic position of RNAL within the D. bozinovici clade, interesting aspects of this isolated population arose, such as the sympatry with a didelphid marsupial (Thylamys elegans), and phylogenetic closeness with populations 300 km southward coastal. Our trapping effort yielded approximately 9.3 individuals/ha, which is relatively high compared with other small mammal populations, but typical for Dromiciops. Using in situ thermographic imaging during a night transect, we detected free-ranging animals running vertically at similar to 3.6 km/h through the logs of mature trees (Nothofagus pumilio), which is fast compared with other small runners (e.g., cursorial rodents), and also compared with Dromiciops from other locations. We compared the critical time to escape, of RNAL individuals which resulted significantly higher than Dromiciops from Nahuelbuta and Valdivia, suggesting that animals from RNAL are more tolerant to human presence than other populations, which is probably due to the high level of isolation of this population. According to the IUCN the northernmost distribution of Dromiciops reaches Cauquenes, thus this report extends the distribution in 120 km to the North East. Interesting aspects, such as hibernation at freezing temperatures and the existence of a viable D. bozinovici population northward of RNAL, warrant further research on this interesting location.
- ItemNon-canonical Wnt Signaling Induces Ubiquitination and Degradation of Syndecan(AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2010) Carvallo, Loreto; Munoz, Rosana; Bustos, Francisco; Escobedo, Noelia; Carrasco, Hector; Olivares, Gonzalo; Larrain, JuanDynamic regulation of cell adhesion receptors is required for proper cell migration in embryogenesis, tissue repair, and cancer. Integrins and Syndecan4 (SDC4) are the main cell adhesion receptors involved in focal adhesion formation and are required for cell migration. SDC4 interacts biochemically and functionally with components of the Wnt pathway such as Frizzled7 and Dishevelled. Non-canonical Wnt signaling, particularly components of the planar cell polarity branch, controls cell adhesion and migration in embryogenesis and metastasic events. Here, we evaluate the effect of this pathway on SDC4. We have found that Wnt5a reduces cell surface levels and promotes ubiquitination and degradation of SDC4 in cell lines and dorsal mesodermal cells from Xenopus gastrulae. Gain-and loss-of-function experiments demonstrate that Dsh plays a key role in regulating SDC4 steady-state levels. Moreover, a SDC4 deletion construct that interacts inefficiently with Dsh is resistant to Wnt5a-induced degradation. Non-canonical Wnt signaling promotes monoubiquitination of the variable region of SDC4 cytoplasmic domain. Mutation of these specific residues abrogates ubiquitination and results in increased SDC4 steady-state levels. This is the first example of a cell surface protein ubiquitinated and degraded in a Wnt/Dsh-dependent manner.
- ItemSyndecan-1 regulates BMP signaling and dorso-ventral patterning of the ectoderm during early Xenopus development(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009) Olivares, Gonzalo H.; Carrasco, Hector; Aroca, Francisco; Carvallo, Loreto; Segovia, Fabian; Larrain, JuanExtracellular regulation of growth factor signaling is a key event for embryonic patterning. Heparan sulfate proteoglycans (HSPG) are among the molecules that regulate this signaling during embryonic development. Here we study the function of syndecan1 (Syn1), a cell-surface HSPG expressed in the non-neural ectoderm during early development of Xenopus embryos. Overexpression of Xenopus Syn1 (xSyn1) mRNA is Sufficient to reduce BMP signaling, induce chordin expression and rescue dorso-ventral patterning in ventrailized embryos. Experiments using chordin morpholinos established that xSyn1 mRNA can inhibit BM P signaling in the absence of chordin. Knockdown of xSyn1 resulted in a reduction of BMP signaling and expansion of the neural plate with the concomitant reduction of the non-neural ectoderm. Overexpression of xSyn1 mRNA in xSyn1 morphant embryos resulted in a biphasic effect, with BMP being inhibited at high concentrations and activated at low concentrations of xSyn1. Interestingly, the function of xSyn1 on dorso-ventral patterning and BMP signaling is specific for this HSPG. In summary, we report that xSyn1 regulates dorso-ventral patterning of the ectoderm through modulation of BMP signaling. (C) 2009 Elsevier Inc. All rights reserved.
- ItemSyndecan-4 inhibits Wnt/β-catenin signaling through regulation of low-density-lipoprotein receptor-related protein (LRP6) and R-spondin 3(2014) Astudillo, Pablo; Carrasco, Hector; Larrain, JuanRegulation of Wnt signaling is crucial for embryonic development and adult homeostasis. Here we study the role of Syndecan-4 (SDC4), a cell-surface heparan sulphate proteoglycan, and Fibronectin (FN), in Wnt/beta-catenin signaling. Gain- and loss-of-function experiments in mammalian cell lines and Xenopus embryos demonstrate that SDC4 and FN inhibit Wnt/beta-catenin signaling. Epistatic and biochemical experiments show that this inhibition occurs at the cell membrane level through regulation of LRP6. R-spondin 3, a ligand that promotes canonical and non-canonical Wnt signaling, is more prone to potentiate Wnt/beta-catenin signaling when SDC4 levels are reduced, suggesting a model whereby SDC4 tunes the ability of R-spondin to modulate the different Wnt signaling pathways. Since SDC4 has been previously related to non-canonical Wnt signaling, our results also suggest that this proteoglycan can be a key component in the regulation of Wnt signaling. (C) 2013 Elsevier Ltd. All rights reserved.