Publications by authors named "Milton Osmar Aguilera"

5 Publications

  • Page 1 of 1

The cAMP effectors, Rap2b and EPAC, are involved in the regulation of the development of the Coxiella burnetii containing vacuole by altering the fusogenic capacity of the vacuole.

PLoS One 2019 14;14(2):e0212202. Epub 2019 Feb 14.

Laboratorio de Biología Celular y Molecular- Instituto de Histología y Embriología (IHEM)-Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina.

Cyclic Adenosine 3',5'-monophosphate (cAMP) is a key second messenger known to directly regulate not only the protein kinase A (PKA) activity but also other important molecules such as the exchange protein activated by cAMP (EPAC), which is as a guanine nucleotide exchange factor (GEF) of the low molecular weight GTPase, Rap2. Coxiella burnetii is a Gram negative bacterium that survives and grows in a large Coxiella replicative vacuole (CRV), which displays lysosomal and autophagic features. In this report, we present evidence that both, EPAC and its downstream effector Rap2b, were recruited to the CRV. The transient over-expression of the Rap2b wt protein, but not its inactive mutant Rap2b ΔAAX, markedly inhibited the development of the large CRV. Additionally, Rap2b wtinhibited the fusion of early Coxiella phagosomes with the fully developed CRV, indicating that homotypic fusion events are altered in the presence of high levels of Rap2b wt. Likewise, the fusion of endosome/lysosomal compartments (heterotypic fusions) with the large CRV was also affected by the over-expression of this GTPase. Interestingly, cell overexpression of Rap2b wt markedly decreased the levels of the v-SNARE, Vamp7, suggesting that this down-regulation impairs the homotypic and heterotypic fusions events of the Coxiella vacuole.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212202PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6375611PMC
November 2019

Autophagy response: manipulating the mTOR-controlled machinery by amino acids and pathogens.

Amino Acids 2015 Oct 19;47(10):2101-12. Epub 2014 Sep 19.

Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM)-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 56, Centro Universitario, Parque General San Martín, (5500), Mendoza, Argentina.

Macroautophagy is a self-degradative process that normally maintains cellular homeostasis via a lysosomal pathway. It is induced by different stress signals, including nutrients and growth factors' restriction as well as pathogen invasions. These stimuli are modulated by the serine/threonine protein kinase mammalian target of rapamycin (mTOR) which control not only autophagy but also protein translation and gene expression. This review focuses on the important role of mTOR as a master regulator of cell growth and the autophagy pathway. Here, we have discussed the role of intracellular amino acid availability and intracellular pH in the redistribution of autophagic structures, which may contribute to mammalian target of rapamycin complex 1 (mTORC1) activity regulation. We have also discussed that mTORC1 complex and components of the autophagy machinery are localized at the lysosomal surface, representing a fascinating mechanism to control the metabolism, cellular clearance and also to restrain invading intracellular pathogens.
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http://dx.doi.org/10.1007/s00726-014-1835-7DOI Listing
October 2015

ATP is released from autophagic vesicles to the extracellular space in a VAMP7-dependent manner.

Autophagy 2012 Dec 5;8(12):1741-56. Epub 2012 Sep 5.

Laboratorio de Biología Celular y Molecular-Instituto de Histología y Embriología (IHEM), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo-CONICET, Mendoza, Argentina.

Autophagy is a normal degradative pathway that involves the sequestration of cytoplasmic components and organelles in a vacuole called autophagosome. SNAREs proteins are key molecules of the vesicle fusion machinery. Our results indicate that in a mammalian tumor cell line a subset of VAMP7 (V-SNARE)-positive vacuoles colocalize with LC3 at the cell periphery (focal adhesions) upon starvation. The re-distribution of VAMP7 positive structures is a microtubule-dependent event, with the participation of the motor protein KIF5 and the RAB7 effector RILP. Interestingly, most of the VAMP7-labeled vesicles were loaded with ATP. Moreover, in cells subjected to starvation, these structures fuse with the plasma membrane to release the nucleotide to the extracellular medium. Summarizing, our results show the molecular components involved in the release of ATP to extracellular space, which is recognized as an important autocrine/paracrine signal molecule that participates in the regulation of several cellular functions such as immunogenicity of cancer cell death or inflammation.
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http://dx.doi.org/10.4161/auto.21858DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3541285PMC
December 2012

The actin cytoskeleton participates in the early events of autophagosome formation upon starvation induced autophagy.

Autophagy 2012 Nov 6;8(11):1590-603. Epub 2012 Aug 6.

Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo-CONICET, Mendoza, Argentina.

Autophagy is a process by which cytoplasmic material is sequestered in a double-membrane vesicle destined for degradation. Nutrient deprivation stimulates the pathway and the number of autophagosomes in the cell increases in response to such stimulus. In the current report we have demonstrated that actin is necessary for starvation-mediated autophagy. When the actin cytoskeleton is depolymerized, the increase in autophagic vacuoles in response to the starvation stimulus was abolished without affecting maturation of remaining autophagosomes. In addition, actin filaments colocalized with ATG14, BECN1/Beclin1 and PtdIns3P-rich structures, and some of them have a typical omegasome shape stained with the double FYVE domain or ZFYVE1/DFCP1. In contrast, no major colocalization between actin and ULK1, ULK2, ATG5 or MAP1LC3/LC3 was observed. Taken together, our data indicate that actin has a role at very early stages of autophagosome formation linked to the PtdIns3P generation step. In addition, we have found that two members of the Rho family of proteins, RHOA and RAC1 have a regulatory function on starvation-mediated autophagy, but with opposite roles. Indeed, RHOA has an activatory role whereas Rac has an inhibitory one. We have also found that inhibition of the RHOA effector ROCK impaired the starvation-mediated autophagic response. We propose that actin participates in the initial membrane remodeling stage when cells require an enhanced rate of autophagosome formation, and this actin function would be tightly regulated by different members of the Rho family.
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http://dx.doi.org/10.4161/auto.21459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494589PMC
November 2012

Prevalence and characterization of Clostridium perfringens from spices in Argentina.

Anaerobe 2005 Dec 7;11(6):327-34. Epub 2005 Jul 7.

General Microbiology, Department of Biochemistry and Biological Sciences, Faculty of Chemistry, Biochemistry and Pharmacy, San Luis National University, Chacabuco y Pedernera, 5700-San Luis, Argentina.

Spices can present high microbial counts and Clostridium perfringens, Bacillus cereus, Salmonella and Shigella, among others have been isolated from spices. C. perfringens is an important pathogen agent causing, among other diseases, enteritis in humans caused by C. perfringens enterotoxin (CPE) which causes human food poisoning and enterotoxemia in domestic animals. The aims of the present work were (i) to establish the hygienic sanitary quality of some spices in San Luis, Argentina; (ii) to determine the presence of C. perfringens in these spices by means of the most probable number (MPN) and count on plate methods; (iii) to characterize the enterotoxigenic strains of C. perfringens by PCR and immunological methods such as reverse passive latex agglutination (RPLA) and (iv) to type by PCR C. perfringens strains isolated. A total of 115 samples of spices, 67 of which were purchased in local retail stores and 48 domestically collected were analysed. Total aerobe counts on tryptone glucose yeast extract agar medium of the 115 samples were between <10 and 10(6) CFU/g. The colifecal counts using Mac Conkey broth of the 115 samples were <4-10(3)CFU/g, with 28 samples (24.34%) exceeding the limit established by the Spanish Alimentary Code (10 CFU/g) while 2 samples (1.73%) had a sulfite reducing anaerobe load above standard limits. A total of 14 C. perfringens strains (12.17%) were isolated and characterized from 115 samples by the standard biochemical tests. Four of which (28.60%) turned out to be enterotoxigenic by PCR and RPLA. In order to type C. perfringens strains based on their main toxins, the 14 strains were analysed by PCR. All strains belonged to type A. All RPLA positive strains were cpe(+) by PCR. The percentage of enterotoxigenic strains was more elevated that those reported in other studies for this type of sample. These results indicate that sanitary conditions in different production stages of species must be improved to reduce health hazards. The high percentage (24.34%) of samples with colifecal values above standard limits is an indication of deficient sanitary conditions. These results suggest the need to provide legislation on the sanitary and hygienic quality of spices in our country.
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http://dx.doi.org/10.1016/j.anaerobe.2005.05.003DOI Listing
December 2005
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