Protein family review: The mitochondrial uncoupling proteins

9 páginas, 5 figuras -- PAGS nros. 3015.1-3015.9The uncoupling proteins (UCPs) are transporters, present in the mitochondrial inner membrane, that mediate a regulated discharge of the proton gradient that is generated by the respiratory chain. This energy-dissipatory mechanism can serve functions such as thermogenesis, maintenance of the redox balance, or reduction in the production of reactive oxygen species. Some UCP homologs may not act as true uncouplers, however, and their activity has yet to be defined. The UCPs are integral membrane proteins, each with a molecular mass of 31-34 kDa and a tripartite structure in which a region of around 100 residues is repeated three times; each repeat codes for two transmembrane segments and a long hydrophilic loop. The functional carrier unit is a homodimer. So far, 45 genes encoding members of the UCP family have been described, and they can be grouped into six families. Most of the described genes are from mammals, but UCP genes have also been found in fish, birds and plants, and there is also functional evidence to suggest their presence in fungi and protozoa. UCPs are encoded in their mature form by nuclear genes and, unlike many nuclear-encoded mitochondrial proteins, they lack a cleavable mitochondrial import signal. The information for mitochondrial targeting resides in the first loop that protrudes into the mitochondrial matrix; the second matrix loop is essential for insertion of the protein into the inner mitochondrial membrane. UCPs are regulated at both the transcriptional level and by activation and inhibition in the mitochondrionThis work has been supported by a grant from the Spanish Ministry of Science and Technology (BIO99-0870). A.L. is supported by a grant from the Comunidad de MadridPeer reviewe

Metástasis en cuero cabelludo de mesotelioma pleural maligno tras quimioterapia: caso clínico y revisión de la literatura

12 p.-3 fig.-2 tab.[EN]Malignant pleural mesothelioma is a neoplasm involving mesothelial cells of the pleura. Both local and distant metastases may develop, although the latter are less common and it is extremely rare for cutaneous metastases to appear as a solitary lesion on the scalp. We present the case of a 54-year-old woman with a 2-year history of unresectable left pleural mesothelioma treated with chemotherapy, who had developed a painful lump on the scalp one month prior to consultation. Skin metastases of mesothelioma must be differentiated from primary neoplasms, and immunohistochemistry is fundamental to determine the origin of such lesions, which can be correctly identified through the use of a panel of markers.[ES]El mesotelioma pleural maligno es una neoplasia que afecta a las células mesoteliales de la pleura. Durante el curso de la enfermedad pueden desarrollarse metástasis locales y a distancia, aunque estas últimas son más infrecuentes. Por ello, es raro que aparezcan metástasis cutáneas como lesión solitaria en el cuero cabelludo. Presentamos el caso de una mujer de 54 años con historia de mesotelioma pleural izquierdo no extirpable desde hacía 2 años, tratada con quimioterapia, que desarrolló una protuberancia dolorosa en el cuero cabelludo un mes antes de acudir a consulta. Las metástasis cutáneas del mesotelioma deben diferenciarse de las neoplasias primarias, siendo fundamental la inmunohistoquímica para determinar el origen de dichas lesiones, que pueden identificarse correctamente utilizando un panel de marcadores.Peer reviewe

Tyrosine aminotransferase from Leishmania infantum: A new drug target candidate

8 p.-5 fig. Moreno, Miguel A. et alt.Leishmania infantum is the etiological agent of zoonotic visceral leishmaniasis in the Mediterranean basin. The disease is fatal without treatment, which has been based on antimonial pentavalents for more than 60 years. Due to resistances, relapses and toxicity to current treatment, the development of new drugs is required. The structure of the L. infantum tyrosine aminotransferase (LiTAT) has been recently solved showing important differences with the mammalian orthologue. The characterization of LiTAT is reported herein. This enzyme is cytoplasmic and is over-expressed in the more infective stages and nitric oxide resistant parasites. Unlike the mammalian TAT, LiTAT is able to use ketomethiobutyrate as co-substrate. The pharmacophore model of LiTAT with this specific co-substrate is described herein. This may allow the identification of new inhibitors present in the databases. All the data obtained support that LiTAT is a good target candidate for the development of new anti-leishmanial drugs.This research was funded under Federal Contract No. HHSN272201200025C from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services. The project was also funded by grant AGL 2010-21806-C02-01 of the Spanish Ministry of Economy and Competitiveness and by a contract No. 050204100014 by Fundación Ramón Areces.Peer reviewe

Differential gene expression analysis by RNA-seq reveals the importance of actin cytoskeletal proteins in erythroleukemia cells

20 p.-8 fig.-1 tab.Development of drug resistance limits the effectiveness of anticancer treatments. Understanding the molecular mechanisms triggering this event in tumor cells may lead to improved therapeutic strategies. Here we used RNA-seq to compare the transcriptomes of a murine erythroleukemia cell line (MEL) and a derived cell line with induced resistance to differentiation (MEL-R). RNA-seq analysis identified a total of 596 genes (Benjamini-Hochberg adjusted p-value < 0.05) that were differentially expressed by more than two-fold, of which 81.5% (486/596) of genes were up-regulated in MEL cells and 110 up-regulated in MEL-R cells. These observations revealed that for some genes the relative expression of mRNA amount in the MEL cell line has decreased as the cells acquired the resistant phenotype. Clustering analysis of a group of genes showing the highest differential expression allowed identification of a sub-group among genes up-regulated in MEL cells. These genes are related to the organization of the actin cytoskeleton network. Moreover, the majority of these genes are preferentially expressed in the hematopoietic lineage and at least three of them, Was (Wiskott Aldrich syndrome), Btk (Bruton's tyrosine kinase) and Rac2, when mutated in humans, give rise to severe hematopoietic deficiencies. Among the group of genes that were up-regulated in MEL-R cells, 16% of genes code for histone proteins, both canonical and variants. A potential implication of these results on the blockade of differentiation in resistant cells is discussed.This work was supported by grant BFU2014 to JBS, PH and DBK from the Ministerio de Economía y Competitividad of Spain.Peer reviewe

Characterization of a pathogenesis-related protein 4 (PR-4) induced in Capsicum chinense L3 plants with dual RNase and DNase activities

Resistance conferred by the L3 gene is active against most of the tobamoviruses, including the Spanish strain (PMMoV-S), a P1,2 pathotype, but not against certain strains of pepper mild mottle virus (PMMoV), termed as P1,2,3 pathotype, such as the Italian strain (PMMoV-I). PMMoV-S induces a hypersensitive reaction (HR) in C. chinense PI159236 plant leaves with the formation of necrotic local lesions and restriction of the virus at the primary infection sites. In this paper, a C. chinense PR-4 protein induced during both the compatible and the incompatible interactions has been identified. It was strongly associated with HR induction and to a lesser extent with the compatible interaction, but only in the later stages of infection. Moreover, it was found to accumulate during the necrogenic reaction induced by Potato virus X. The C. chinense PR-4 protein belongs to the PR-4 protein subgroup II, based on the absence of a hevein domain. Furthermore, it is shown that the purified protein does not have chitinase activity, as previously proposed for PR-4 proteins. Instead, it has both RNase and DNase activity, although its contribution to the bulk activity of nucleases in infected plants is very low.This work was supported by grants from the CICYT (AGF95-0696, BIO2007-67874-C02-01 and AGL2008-00450) and CAM (07B/0034/97). MAG was a recipient of a post-doctoral fellowship from Caja Madrid. We would like to thank to Dr MJ Martínez and J Varela (CIB.CSIC) by their help in protein purification

Caracterización de una proteína relacionada con la patogénesis PR-4 de Capsicum chinense L3 L3 con actividad RNasa y DNasa

Resumen del trabajo presentado en el XV Congreso de la Sociedad Española de Fitopatología, celebrado en Vitoria del 27 de septiembre al 1 de octubre de 2010La resistencia conferida por el gen L3 de Capsicum spp. es activa frente a la mayoría de los tobamovirus, incluyendo la cepa española del virus del moteado suave del pimiento, (PMMoV-S), pero no es activa frente a los patotipos P1,2,3,tales como la cepa italiana de dicho virus, o el patotipo P1,2,3,4. PMMoV-S induce una reacción hipersensible en las hojas inoculadas de las plantas de C. chinense PI159236 que se manifiesta por la producción de lesiones locales necróticas y la restricción del virus a los lugares de infección primarios. Hemos identificado una proteína PR-4 de C. chinense que se induce en ambas interacciones, compatible e incompatible; si bien su expresión se incrementa notablemente durante la inducción de la HR, y sólo se detecta en la reacción compatible en los estadios tardíos de la infección. Hemos observado también que su expresión se asocia a la respuesta necrogénica inducida por el virus X de la patata (PVX) en las hojas sistémicas de C. chinense. La proteína pertenece al subgrupo II de las PR-4 por cuanto que carece del dominio heveina. Hemos determinado que la proteína PR-4 de C. chinense no tiene actividad quitinasa, pero que posee tanto actividad DNAsa como RNAsa, siendo la primera vez que se detecta la actividad DNAsa para una proteína PR. Mediante análisis en gel de dichas actividades, hemos podido establecer que su contribución al total de ambas actividades en la planta es baja

Modelling the transmembrane arrangement of the uncoupling protein UCP1 and topological considerations of the nucleotide binding site

14 páginas, 6 figuras -- PAGS nros. 473-486The uncoupling protein from brown adipose tissue (UCP1) is a mitochondrial proton transporter whose activity is inhibited by purine nucleotides. UCP1, like the other members of the mitochondrial transporter superfamily, is an homodimer and each subunit contains six transmembrane segments. In an attempt to understand the structural elements that are important for nucleotide binding, a model for the transmembrane arrangement of UCP1 has been built by computational methods. Biochemical and sequence analysis considerations are taken as constraints. The main features of the model include the following: (i) the six transmembrane α-helices (TMHs) associate to form an antiparallel helix bundle; (ii) TMHs have an amphiphilic nature and thus the hydrophobic and variable residues face the lipid bilayer; (iii) matrix loops do not penetrate in the core of the bundle; and (iv) the polar core constitutes the translocation pathway. Photoaffinity labeling and mutagenesis studies have identified several UCP1 regions that interact with the nucleotide. We present a model where the nucleotide binds deep inside the bundle core. The purine ring interacts with the matrix loops while the polyphosphate chain is stabilized through interactions with essential Arg residues in the TMH and whose side chains face the core of the helix bundleThis work has been supported by a grant from the Spanish Ministry of Science and Technology 8BIO99-0870). AL is supported by a grant from the Comunidad de MadridPeer reviewe

Caracterización de una proteína relacionada con la patogénesis 4 (PR-4) en plantas de Capsicum chinense L3 con actividad dual de RNasa y DNasa

Resumen del póster presentado en la X Reunión de Biología Molecular de Plantas, celebrada en Valencia (España) del 8 al 10 de Julio de 2010.La resistencia conferida por el gen L3 de Capsicum spp. es activa frente a la mayoría de los tobamovirus, incluyendo la cepa española del virus del moteado suave del pimiento, (PMMoV-S), la más prevalente en los cultivos españoles, pero no es activa frente a los patotipos P1,2,3, tales como la cepa italiana de dicho virus, o el patotipo P1,2,3,4. PMMoV-S induce una reacción hipersensible en las hojas inoculadas de las plantas de C. chinense PI159236 que se manifiesta por la producción de lesiones locales necróticas y la restricción del virus a los lugares de infección primarios. Hemos identificado una proteína PR‑4 de C.chinense que se induce en ambas interacciones, compatible e incompatible; si bien su expresión se incrementa notablemente durante la inducción de la HR, y sólo se detecta en la reacción compatible en los estadios tardíos de la infección. Hemos observado también que su expresión se asocia a la respuesta necrogénica inducida por el virus X de la patata (PVX) en las hojas sistémicas de C. chinense. La proteína pertenece al subgrupo II de las PR-4 por cuanto que carece del dominio heveina. Hemos determinado que la proteína PR-4 de C. chinense no tiene actividad quitinasa, pero que posee tanto actividad DNAsa como RNAsa, siendo la primera vez que se detecta la actividad DNAsa para una proteína PR. Mediante análisis en gel de dichas actividades, hemos podido establecer que su contribución al total de ambas actividades en la planta es baja