Browsing by Subject "Secretion"
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- PublicationOpen AccessControl of morphology and virulence by ADP-ribosylation factors (Arf) in Mucor circinelloides(Springer Nature, 2017-12-20) Patiño-Medina, Jose Alberto; Maldonado-Herrera, Guadalupe; Pérez Arques, Carlos; Alejandre-Castañeda, Viridiana; Reyes-Mares, Nancy Yadira; Valle-Maldonado, Marco I.; Campos-García, Jesus; Ortiz-Alvarado, Rafael; Jácome-Galarza, Irvin E.; Ramírez-Díaz, Martha I.; Garre Mula, Victoriano; Meza-Carmen, Victor; Genética y Microbiología; Facultades de la UMU::Facultad de BiologíaMucor circinelloides is a dimorphic fungus used to study cell differentiation that has emerged as a model to characterize mucormycosis. In this work, we identified four ADP-ribosylation factor (Arf)-encoding genes (arf1-arf4) and study their role in the morphogenesis and virulence. Arfs are key regulators of the vesicular trafficking process and are associated with both growth and virulence in fungi. Arf1 and Arf2 share 96% identity and Arf3 and Arf4 share 89% identity, which suggests that the genes arose through gene-duplication events in M. circinelloides. Transcription analysis revealed that certain arf genes are affected by dimorphism of M. circinelloides, such as the arf2 transcript, which was accumulated during yeast development. Therefore, we created knockout mutants of four arf genes to evaluate their function in dimorphism and virulence. We found that both arf1 and arf2 are required for sporulation, but these genes also perform distinct functions; arf2 participates in yeast development, whereas arf1 is involved in aerobic growth. Conversely, arf3 and arf4 play only minor roles during aerobic growth. Moreover, we observed that all single arf-mutant strains are more virulent than the wild-type strain in mouse and nematode models, with the arf3 mutant being most virulent. Lastly, arf1/arf2 and arf3/arf4 double mutations produced heterokaryon strains that did not reach the homokaryotic state, indicating that these genes participate in essential and redundant functions. Overall, this work reveals that Arfs proteins regulate important cellular processes in M. circinelloides such as morphogenesis and virulence, laying the foundation to characterize the molecular networks underlying this regulation.
- PublicationOpen AccessCorrelated color temperature and light intensity: complementary features in non-visual light field(Public Library of Science (PLoS), 2021-07-12) Arguelles Prieto, Raquel; Madrid, Juan Antonio; Rol de Lama, María de los Ángeles; Bonmatí Carrión, María de los Ángeles; FisiologíaAn appropriate exposure to the light-dark cycle, with high irradiances during the day and darkness during the night is essential to keep our physiology on time. However, considering the increasing exposure to artificial light at night and its potential harmful effects on health (i.e. chronodisruption and associated health conditions), it is essential to understand the non-visual effects of light in humans. Melatonin suppression is considered the gold standard for nocturnal light effects, and the activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) through the assessment of pupillary light reflex (PLR) has been recently gaining attention. Also, some theoretical models for melatonin suppression and retinal photoreceptors activation have been proposed. Our aim in this study was to determine the influence of correlated color temperature (CCT) on melatonin suppression and PLR, considering two commercial light sources, as well as to explore the possible correlation between both processes. Also, the contribution of irradiance (associated to CCT) was explored through mathematical modelling on a wider range of light sources. For that, melatonin suppression and PLR were experimentally assessed on 16 healthy and young volunteers under two light conditions (warmer, CCT 3000 K; and cooler, CCT 5700 K, at ~5·1018 photons/cm2/sec). Our experimental results yielded greater post-stimulus constriction under the cooler (5700 K, 13.3 ± 1.9%) than under the warmer light (3000 K, 8.7 ± 1.2%) (p < 0.01), although no significant differences were found between both conditions in terms of melatonin suppression. Interestingly, we failed to demonstrate correlation between PLR and melatonin suppression. Although methodological limitations cannot be discarded, this could be due to the existence of different subpopulations of Type 1 ipRGCs differentially contributing to PLR and melatonin suppression, which opens the way for further research on ipRGCs projection in humans. The application of theoretical modelling suggested that CCT should not be considered separately from irradiance when designing nocturnal/diurnal illumination systems. Further experimental studies on wider ranges of CCTs and light intensities are needed to confirm these conclusions.
- PublicationOpen AccessDifferent expression of the catalytic alpha subunits of the AMP activated protein kinase - an immunohistochemical study in human tissue(Murcia: F. Hernández, 2011) Quentin, Thomas; Kitz, Julia; Steinmetz, Michael; Poppe, Andrea; Bär, Karin; Krätzner, RalphSummary. AMPK is an ubiquitously distributed multienzyme complex. It is an important energy sensor and regulator of cellular metabolic activity. In this study we analyzed for the first time the cellular distribution of the catalytically active subunits AMPKα1 and α2 in different human tissues by immunohistochemistry. We found different expression patterns for both isoforms. AMPKα2 expression clearly dominates in skeletal myocytes and cardiomyocytes, whereas AMPKα1 dominates in a number of secreting cells, like mammary glands, islets of langerhans and cells of the colon crypts.
- PublicationOpen AccessProsaposin: a protein with differential sorting and multiple functions(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) Carvelli, L.; Libin, Yuan; Morales, C.R.In eukaryotes the delivery of newly synthesized proteins to their final destination is dependent on a series of functionally distinct compartments, including the endoplasmic reticulum and the Golgi apparatus, which plays a role in posttranslational modification, sorting and distribution of proteins. Most cargo is sorted within, and exits from, the trans-Golgi network (TGN). Proteins delivered to lysosomes include hydrolytic enzymes and nonenzymic activator proteins. They are directed away from the cell surface by their binding to mannose-6-phosphate receptors (MPR). However, in I-cell disease, in which the MPR pathway is disrupted, the nonenzymic sphingolipid activator protein, prosaposin, continue to traffic to lysosomes. This observation led to discovery of a new lysosomal sorting receptor, sortilin. The targeting prosaposin to the lysosomes results from the interaction of its C-terminus with sortilin. Deletion of the Cterminus did not interfere with its secretion, but abolished its transport to the lysosomes. Mutational analysis revealed that the first half of the prosaposin Cterminus contains a motif required for its binding to sortilin and its transport to the lysosomes. Prosaposin can be also secreted to the extracellular space as oligomers. Extracellular prosaposin showed to exert a variety of responses in nervous tissues including the activation of G protein-coupled receptors and ERK phosphorylation. Lastly, prosaposin has been found to be expressed in other fluids of the body such as pancreaticjuice, bile, cerebrospinal fluid, milk and seminal fluid, indicating that prosaposin is not only a house keeping lysosomal protein but an essential factor in the development and maintenance of the nervous systems and other systems of the body.