Vicerrectoría de Investigación, Innovación y Postgrado

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Serine–Arginine Protein Kinase SRPK2 Modulates the Assembly of the Active Zone Sca olding Protein CAST1/ERC2
(2019) Duxan Arancibia; Matias Lira; Yocelin Cruz; Daniela P. Barrera; Carolina Montenegro Venegas; Juan A. Godoy; Craig C. Garner; Nibaldo C. Inestrosa; Eckart D. Gundelfinger; Pedro Zamorano; VivianaI.Torres
Neurons release neurotransmitters at a specialized region of the presynaptic membrane, the active zone (AZ), where a complex meshwork of proteins organizes the release apparatus. The formation of this proteinaceous cytomatrix at the AZ (CAZ) depends on precise homo- and hetero-oligomerizations of distinct CAZ proteins. The CAZ protein CAST1/ERC2 contains four coiled-coil (CC) domains that interact with other CAZ proteins, but also promote self-assembly, which is an essential step for its integration during AZ formation. The self-assembly and synaptic recruitmentoftheDrosophilaproteinBruchpilot(BRP),apartialhomologofCAST1/ERC2,ismodulated by the serine-arginine protein kinase (SRPK79D). Here, we demonstrate that overexpression of the vertebrate SRPK2 regulates the self-assembly of CAST1/ERC2 in HEK293T, SH-SY5Y and HT-22 cells and the CC1 and CC4 domains are involved in this process. Moreover, the isoform SRPK2 forms a complex with CAST1/ERC2 when co-expressed in HEK293T and SH-SY5Y cells. More importantly, SRPK2 is present in brain synaptic fractions and synapses, suggesting that this protein kinase might control the level of self-aggregation of CAST1/ERC2 in synapses, and thereby modulate presynaptic assembly.
The activation of the chymotrypsin-like activity of the proteasome is regulated by soluble adenyl cyclase/cAMP/protein kinase A pathway and required for human sperm capacitation
(2019) Héctor Zapata Carmona; Lina Barón; Lidia M.Zuñiga; Emilce Silvina Díaz; Milene Kong; Erma Z.Drobnis; Peter Sutovsky; Patricio Morales
Determining the Potential of Haematococcus pluvialis Oleoresin as a Rich Source of Antioxidants
(2019) Mari Carmen Ruiz Domínguez; Carolina Espinosa; Adrián Paredes; Jenifer Palma; Carolina Jaime; Carlos Vílchez; Pedro Cerezal
Haematococcus pluvialis is known to be a natural source of antioxidants for numerous applications. In this study, an oleoresin rich in carotenoids extracted by supercritical CO2 treatment of H. pluvialis was extensively characterized for its antioxidant capacity. Carotenoid content, fatty acid profile, total phenol content, antioxidant capacity, and viscosity of the oleoresin were determined with the aim of ascertaining the potential of the oleoresin in terms of its antioxidant content for food applications. The oleoresin contained 96.22 mg/g of total astaxanthin (which includes free astaxanthin and astaxanthin esters) and mostly included unsaturated fatty acids (~78% of total fatty acids). High total phenol content and ferric reducing antioxidant potential indicated high antioxidant capacity, but oxygen radical absorbance capacity was lower compared to the oleoresin samples obtained from other species. The oleoresin was a non-Newtonian fluid since it had shear-thinning (pseudoplastic) and shear-thickening (dilatant) flow. Therefore, the H. pluvialis oleoresin is a potential alternative in developing functional ingredients for designing healthy food products. To the best of our knowledge, this is the first study that has reported an extensive characterization of the antioxidant properties of a microalgal oleoresin obtained by means of supercritical CO2 fluid extraction.
Glutamatergic Receptor Trafficking and Delivery: Role of the Exocyst Complex
(2020) Matías Lira; Rodrigo G. Mira; Francisco J. Carvajal; Pedro Zamorano; Nibaldo C. Inestrosa; Waldo Cerpa
Cells comprise several intracellular membrane compartments that allow them to function properly. One of these functions is cargo movement, typically proteins and membranes within cells. These cargoes ride microtubules through vesicles from Golgi and recycling endosomes to the plasma membrane in order to be delivered and exocytosed. In neurons, synaptic functions employ this cargo tra cking to maintain inter-neuronal communication optimally. One of the complexes that oversee vesicle tra cking and tethering is the exocyst. The exocyst is a protein complex containing eight subunits first identified in yeast and then characterized in multicellular organisms. This complex is related to several cellular processes, including cellular growth, division, migration, and morphogenesis, among others. It has been associated with glutamatergic receptor tracking and tethering into the synapse, providing the molecular machinery to deliver receptor-containing vesicles into the plasma membrane in a constitutive manner. In this review, we discuss the evidence so far published regarding receptor tracking and the exocyst complex in both basal and stimulated levels, comparing constitutive tracking and long-term potentiation-related tracking.
Exo70 intracellular redistribution after repeated mild traumatic brain injury
(2021) Matías Lira; Pedro Zamorano; Waldo Cerpa
Exo70 is a subunit of the greater exocyst complex, a collection of proteins that oversees cellular membrane addition and polarized exocytosis by acting as a tethering intermediate between the plasma membrane and newly synthesized secretory vesicles. Although Exo70 function has been implicated in several developmental events including cytokinesis and the establishment of cell polarity, its role in neuropathologies is poorly understood. On the other hand, traumatic brain injury is the result of mechanical external force including contusion, fast acceleration, and expansive waves that produce temporal or permanent cognitive damage and triggers physical and psychosocial alterations including headache, memory problems, attention deficits, difficulty thinking, mood swings, and frustration. Traumatic brain injury is a critical health problem on a global scale, constituting a major cause of deaths and disability among young adults. Trauma-related cellular damage includes redistribution of N-methyl-D-aspartate receptors outside of the synaptic compartment triggering detrimental effects to neurons. The exocyst has been related to glutamate receptor constitutive trafficking/delivery towards synapse as well. This work examines whether the exocyst complex subunit Exo70 participates in traumatic brain injury and if it is redistributed among subcellular compartments Results: Our analysis shows that Exo70 expression is not altered upon injury induction. By using subcellular fractionation, we determined that Exo70 is redistributed from microsomes fraction into the synaptic compartment after brain trauma. In the synaptic compartment, we also show that the exocyst complex assembly and its interaction with GluN2B are increased. Finally, we show that the Exo70 pool that is redistributed comes from the plasma membrane. Conclusions: The present findings position Exo70 in the group of proteins that could modulate GluN2B synaptic availability in acute neuropathology like a traumatic brain injury. By acting as a nucleator factor, Exo70 is capable of redirecting the ensembled complex into the synapse. We suggest that this redistribution is part of a compensatory mechanism by which Exo70 is able to maintain GluN2B partially on synapses. Hence, reducing the detrimental effects associated with TBI pathophysiology.
Climate variability in a 3.8 Ma old sedimentary record from the hyperarid Atacama Desert
(2024) Felix L. Arens; Jenny Feige; Alessandro Airo; Christof Sager; Lutz Hecht; Lucas Horstmann; Felix E.D. Kaufmann; Johannes Lachner; Thomas Neumann; Norbert Nowaczyk; Ferry Schiperski; Peter Steier; Alexandra Stoll; Ulrich Struck; Bernardita Valenzuela; Friedhelm von Blanckenburg; Hella Wittmann; Lukas Wacker; Dirk Wagner; Pedro Zamorano; Dirk Schulze Makuch
The hyperarid Atacama Desert is one of the driest and oldest deserts on Earth, rendering it a valuable climate archive. However, unraveling its past climate is particularly challenging and the few studied paleoclimate records of the region reveal strong temporal and spatial variabilities. To enhance our understanding of these dynamics we investigated a sedimentary record in the Yungay valley located in the southern hyperarid Atacama Desert. We employed paleomagnetic and radiocarbon dating, and for the first time for Atacama Desert sediments, a meteoric 10Be/9Be based method for determining the depositional age. The respective 4.20 m deep profile comprises a lower alluvial fan deposit with a maximum age of 3.8 ± 0.8 Ma, and an upper 1.84 m thick clay pan deposit that has accumulated over the last 19 ka. Different proxies including grain size, salt concentration, and elemental composition indicate an aridity increase around 2.3 Ma ago and repeated dry and wet phases during the late Pleistocene and the Holocene. The latter climatic shifts can be assigned to variabilities of the South American Summer Monsoon and El Niño Southern Oscillation with moisture sources from the Atlantic and the Pacific Ocean, respectively. This study provides deeper insights into the heterogeneous climate of the hyperarid Atacama Desert and underlines the importance of interdisciplinary investigations to decipher climate systems and their effect on potential habitable regions in such an extreme environment.
Isolation of Thermophilic Bacteria from Extreme Environments in Northern Chile
(2024) Bernardita Valenzuela; Francisco Solís Cornejo; Rubén Araya; Pedro Zamorano
The northern region of Chile boasts unique geographical features that support the emergence of geothermal effluents, salt lagoons, and coastal creeks. These extreme climate conditions create polyextreme habitats for microorganisms, particularly adapted to survive these harsh environments. These extremophilic microorganisms hold immense potential as a source of hydrolytic enzymes, among other biotechnological applications. In this study, we isolated 15 strains of aerobic thermophilic bacteria (45–70 ◦C) from sediment samples collected at five different ecological sites, including hot springs, geothermal fields, and lagoons in the Atacama Desert and Andes high planes. Analyses of the 16S rRNA gene sequences of the isolates showed a close genetic similarity (98–100%) with microorganisms of the genera Parageobacillus, Geobacillus, Anoxybacillus, and Aeribacillus. Notably, these thermophiles exhibited significant hydrolytic enzyme activity, particularly amylases, lipases, and proteases. These findings underscore the potential of using these thermophilic bacterial strains as an invaluable source of thermozymes with wide-ranging applications in diverse industries, such as detergent formulations, pharmaceutical processing, and food technology. This research highlights the ecological significance of these extreme environments in the Atacama Desert and Andes high plains, which serve as vital ecological niches housing extremophilic bacteria as a genetic source of relevant thermozymes, promising great potential for innovation in the biotechnology industry.
Microbial response to deliquescence of nitrate-rich soils in the hyperarid Atacama Desert
(2024) Felix L. Arens; Alessandro Airo; Christof Sager; Hans Peter Grossart; Kai Mangelsdorf; Rainer U. Meckenstock; Mark Pannekens; Philippe Schmitt Kopplin; Jenny Uhl; Bernardita Valenzuela; Pedro Zamorano; Luca Zoccarato; Dirk Schulze-Makuch
Life in hyperarid regions has adapted to extreme water scarcity through mechanisms like salt deliquescence. While halite (NaCl) crusts have been intensively studied and identified as one of the last habitats under hyperarid conditions, other less common hygroscopic salt crusts remain unexplored. Here, we investigated newly discovered deliquescent soil surfaces in the Atacama Desert, containing substantial amounts of nitrates, to evaluate their habitability for microorganisms. We characterized the environment with respect to water availability and biogeochemistry. Microbial abundances and composition were determined by cell cultivation experiments, 16S rRNA gene sequencing, and membrane phospholipid fatty acid (PLFA) analysis, while microbial activity was assessed by analyzing adenosine triphosphate (ATP) and the molecular composition of organic matter. Our findings reveal that, while the studied hygroscopic salts provide temporary water, microbial abundances and activity are lower in the studied soil surfaces than in non-deliquescent soil surfaces. Intriguingly, the deliquescent crusts are enriched in geochemically degraded organic matter, indicated by the molecular composition. We conclude that high nitrate concentrations in the hyperarid soils suppress microbial activity but preserve eolian-derived biomolecules. These insights are important for assessing the habitability and searching for life in hyperarid environments on Earth and beyond.

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