Nuestros investigadores

Juan José Martínez Irujo

Departamento
Bioquímica y Genética
Facultad de Ciencias. Universidad de Navarra
Líneas de investigación
Drug interaction: synergy, antagonism, isobologram, interaction index, combined therapy., HIV-1 reverse transcriptase, HIV-1 RT inhibition, NNRTI, AZT, AZT-resistance, phosphorolysis, synergistic inhibition of HIV-1 RT, Antitumoral agents, endotelium, lymphatic, hypoxia, tumoral angiogenesis, apoptosis, flavonoids, lung cancer, metastasis, Hepatic fibrosis, antifibrotic agents, Hepatic stellate cells, non-phagocitic NADPH oxidases (Nox), Nox5

Publicaciones científicas más recientes (desde 2010)

Autores: López, María Jesús; Martinez-Irujo, Juan J; et al.
Revista: BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
ISSN 0167-4889  Vol. 1866  Nº 4  2019  págs. 673 - 685
Liver damage induces hepatic stellate cells (HSC) activation, characterised by a fibrogenic, proliferative and migratory phenotype. Activated HSC are mainly regulated by transforming growth factor ß 1 (TGFß1), which increases the production of extracellular matrix proteins (e.g. collagen-I) promoting the progression of hepatic fibrosis. AGAP2 (ArfGAP with GTPase domain, ankyrin repeat and PH domain 2) is a GTPase/GTP-activating protein involved in the actin remodelling system and receptor recycling. In the present work the role of AGAP2 in human HSC in response to TGFß1 was investigated. LX-2 HSC were transfected with AGAP2 siRNA and treated with TGFß1. AGAP2 knockdown prevented to some extent the proliferative and migratory TGFß1-induced capacities of LX-2 cells. An array focused on human fibrosis revealed that AGAP2 knockdown partially prevented TGFß1-mediated gene expression of the fibrogenic genes ACTA2, COL1A2, EDN1, INHBE, LOX, PDGFB, TGF¿12, while favored the expression of CXCR4, IL1A, MMP1, MMP3 and MMP9 genes. Furthermore, TGFß1 induced AGAP2 promoter activation and its protein expression in LX-2. Moreover, AGAP2 protein levels were significantly increased in liver samples from rats with thioacetamide-induced fibrosis. In addition, AGAP2 silencing affected TGFß1-receptor 2 (TGFR2) trafficking in U2OS cells, blocking its effective recycling to the membrane. AGAP2 silencing in LX-2 cells prevented the TGFß1-induced increase of collagen-I protein levels, while its overexpression enhanced collagen-I protein expression in the presence or absence of the cytokine. AGAP2 overexpression also increased focal adhesion kinase (FAK) phosphorylated levels in LX-2 cells. FAK and MEK1 inhibitors prevented the increase of collagen-I expression caused by TGFß1 in LX-2 overexpressing AGAP2. In summary, the present work shows for the first time, that AGAP2 is a potential new target involved in TGFß1 signalling, contributing to the progression of hepatic fibrosis.
Autores: Solas, Maite; Pejenaute, Álvaro; et al.
Revista: FREE RADICAL BIOLOGY AND MEDICINE
ISSN 0891-5849  Vol. 139  Nº S1  2019  págs. S17 - S17
Autores:  Garde, N.; et al.
Revista: FREE RADICAL BIOLOGY AND MEDICINE
ISSN 0891-5849  Vol. 126  2018  págs. 15 - 26
NADPH oxidase (Nox) variants Nox1, Nox2 and Nox4 are implicated in the progression of liver fibrosis. However, the role of Nox5 is not yet known, mainly due to the lack of this enzyme in rat and mouse genomes. Here we describe the expression and functional relevance of Nox5 in the human cell line of hepatic stellate cells (HSC) LX-2. Under basal conditions, three long (Nox5-L: Nox5 alpha, -beta, and -delta) and a short (Nox5-S or Nox5 epsilon) splice variants were detected, which were silenced with specific siRNAs for Nox5. The most abundant isoform was Nox5-S, accounting for more than 90% of Nox5 protein. Overexpression of Nox5 beta generated reactive oxygen species (ROS) in the presence of calcium, as judged by the production of hydrogen peroxide, L-012 luminescence and cytochrome c reduction. Nox5 epsilon did not generated ROS under these conditions, and a reduced ROS production was observed when co-expressed with Nox5 beta. In contrast, dihydroethidium oxidation was increased by Nox5 beta or Nox5 epsilon, suggesting that Nox5 epsilon induced intracellular oxidative stress by an unknown mechanism. Functional studies showed that both Nox5 beta and Nox5 epsilon stimulated the proliferation of LX-2 cells and the collagen type I levels, while Nox5 siRNAs inhibited these effects. Interestingly, TGF-beta and angiotensin II upregulated Nox5 expression, which was reduced in cells pre-incubated with catalase. Further studies silencing Nox5 in TGF-beta-treated cells resulted in a reduction of collagen levels via p38 MAPK. Collectively, these results show for the first time that Nox5 can play a relevant role in the proliferation and fibrosis on human HSC.
Autores:  Garde, N. ; et al.
Revista: FREE RADICAL BIOLOGY AND MEDICINE
ISSN 0891-5849  Vol. 120  2018  págs. S86 - S86
NADPH oxidase (Nox) variants Nox1, Nox2 and Nox4 have been implicated in the progression of liver fibrosis. However, the role of Nox5 is unknown, mainly due to the lack of this enzyme in rat and mouse genomes. Here we describe the expression and functional relevance of Nox5 in the human cell line of hepatic stellate cells (HSC), LX-2. Under basal conditions, these cells expressed a long (Nox5L) and a short (Nox5S) variant which were silenced with specific siRNAs for Nox5. Overexpression of Nox5L generated ROS in the presence of calcium, as judged by the production of extracellular hydrogen peroxide, L-012 luminescence and cytochrome c reduction, while Nox5S did not generated ROS under these conditions. In contrast, dihydroethidium oxidation was increased when either Nox5L or Nox5S were overexpressed. Functional studies revealed that both Nox5L and Nox5S stimulated the proliferation of LX-2 cells and the synthesis of type I collagen, while Nox5 siRNAs inhibited these effects. Interestingly, TGF-beta and angiotensin II induced Nox5, and silencing Nox5 reduced collagen production stimulated by TGF-beta. Collectively, these results suggest for the first time that Nox5 can play a relevant role in HSC proliferation and fibrogenesis.
Autores: Aragón, Tomás; Martínez-Velez, N.; et al.
Revista: NEURO-ONCOLOGY
ISSN 1522-8517  Vol. 18  Nº 8  2016  págs. 1109-1119
These findings provide a strong rationale for combining temozolomide with ER stress-inducing drugs as an alternative therapeutic strategy for glioblastoma.
Autores: Navarro, A.; Ansorena, Eduardo; et al.
Revista: BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
ISSN 0167-4889  Vol. 1863  Nº 8  2016  págs. 2115 - 2123
Unfolded protein response (UPR) triggered as a consequence of ER stress has been shown to be involved in the development of different pathologies, including fibrotic disorders. In the present paper we explore the role played by UPR on a key fibrogenic parameter in the liver: collagen type I levels in activated hepatic stellate cells (HSC). Using Brefeldin A (BFA) as an ER stress inducer we found that UPR correlated with enhanced mRNA and protein levels of collagen type I in a cell line of immortalized non-tumoral rat HSC. Analysis of the three branches of UPR revealed the activation of IRE1¿, PERK and ATF6 in response to BFA, although PERK activation was shown not to be involved in the fibrogenic action of BFA. BFA also activated p38 MAPK in an IRE1¿-dependent way and the p38 MAPK inhibitor SB203580 prevented the increase in collagen type I mRNA and protein levels caused by BFA, suggesting the involvement of this kinase on this effect. Analysis of Smad activation showed that phosphorylated nuclear levels of Smad2 and 3 were increased in response to BFA treatment. Inhibition of Smad3 phosphorylation by SIS3 prevented the enhancement of collagen type I levels caused by BFA. Pretreatment with IRE1¿ and p38 MAPK inhibitors also prevented the increased p-Smad3 accumulation in the nucleus, suggesting an IRE1¿-p38 MAPK-Smad pathway to be responsible for the fibrogenic action of BFA on HSC.
Autores: González, María Soledad; Martinez-Irujo, Juan J; et al.
Revista: ONCOTARGET
ISSN 1949-2553  Vol. 7  Nº 21  2016  págs. 30626-30641
Glioblastoma is the most frequent malignant brain tumor. Even with aggressive treatment, prognosis for patients is poor. One characteristic of glioblastoma cells is its intrinsic resistance to apoptosis. Therefore, drugs that induce alternative cell deaths could be interesting to evaluate as alternative therapeutic candidates for glioblastoma. Salinomycin (SLM) was identified through a chemical screening as a promising anticancer drug, but its mechanism of cell death remains unclear. In the present work we set out to elucidate how SLM causes cell death in glioblastoma cell lines (both established cell lines and brain tumor stem cell lines), aiming to find a potential antitumor candidate. In addition, we sought to determine the mechanism of action of SLM so that this mechanism can be can be exploited in the fight against cancer. Our data showed that SLM induces a potent endoplasmic reticulum (ER) stress followed by the trigger of the unfolded protein response (UPR) and an aberrant autophagic flux that culminated in necrosis due to mitochondria and lysosomal alterations. Of importance, the aberrant autophagic flux was orchestrated by the production of Reactive Oxygen Species (ROS). Alleviation of ROS production restored the autophagic flux. Altogether our data suggest that in our system the oxidative stress blocks the autophagic flux through lipid oxidation. Importantly, oxidative stress could be instructing the type of cell death in SLM-treated cells, suggesting that cell deat
Autores: Andueza, A.; Ruiz de Galarreta, M.; et al.
Revista: FREE RADICAL BIOLOGY AND MEDICINE
ISSN 0891-5849  Vol. 87  2015  págs. 169 - 180
Apigenin, a natural flavone, is emerging as a promising compound for the treatment of several diseases. One of the hallmarks of apigenin is the generation of intracellular reactive oxygen species (ROS), as judged by the oxidation of reduced dichlorofluorescein derivatives seen in many cell types. This study aimed to reveal some mechanisms by which apigenin can be oxidized and how apigenin-derived radicals affect the oxidation of 5-(and-6)-chloromethyl-2',7'-dichloroclihydrolluorescein (H2DCF), a probe usually employed to detect intracellular ROS. Apigenin induced a rapid oxidation of H2DCF in two different immortalized cell lines derived from rat and human hepatic stellate cells. However, apigenin did not generate ROS in these cells, as judged by dihydroethidium oxidation and extracellular hydrogen peroxide production. In cell -free experiments we found that oxidation of apigenin leads to the generation of a phenoxyl radical, which directly oxidizes H2DCF with catalytic amounts of hydrogen peroxide. The net balance of the reaction was the oxidation of the probe by molecular oxygen due to redox cycling of apigenin. This flavonoid was also able to deplete NADH and glutathione by a similar mechanism. InLeresLingly, H2DCF oxidation was significantly accelerated by apigenin in the presence of horseradish peroxidase and xarahine oxidase, but not with other enzymes showing peroxiclase-like activity, such as cylochrome c or calalase. We conclude that in cells treated with apigenin oxidation of reduced clichlorofluorescein derivatives does not measure intracellular ROS and that pro- and antioxidant effects of flavonoids deduced from these experiments are inconclusive and must be confirmed by other techniques.
Autores:  et al.
Revista: JOURNAL OF CELLULAR PHYSIOLOGY
ISSN 0021-9541  Vol. 230  Nº 3  2015  págs. 546 - 553
The turnover of extracellular matrix (ECM) components can generate signals that regulate several cellular functions such as proliferation, differentiation, and apoptosis. During liver injury, matrix metalloproteases (MMPs) production is enhanced and increased levels of peptides derived from extracellular matrix proteins can be generated. Synthetic peptides with sequences present in extracellular matrix proteins were previously found to induce both stimulating and apoptotic effects on several cell types including the inflammatory cells monocytes/macrophages. Therefore, in inflammatory liver diseases, locally accumulated peptides could be also important in regulating hepatic fibrosis by inducing apoptosis of hepatic stellate cells (HSC), the primary cellular source of extracellular matrix components. Here, we describe the apoptotic effect of fibronectin peptides on the cell line of human hepatic stellate cells LX-2 based on oligonucleosomal DNA fragmentation, caspase-3 and -9 activation, Bcl-2 depletion, and accumulation of Bax protein. We also found that these peptides trigger the activation of Src kinase, which in turn mediated the increase of JNK and p38 activities. By the use of specific inhibitors we demonstrated the involvement of Src, JNK, and p38 in apoptosis induced by fibronectin peptides on HSC. Moreover, fibronectin peptides increased iNOS expression in human HSC, and specific inhibition of iNOS significantly reduced the sustained activity of JNK and the programmed
Autores: Plano, Daniel; et al.
Revista: CHEMICAL RESEARCH IN TOXICOLOGY
ISSN 0893-228X  Vol. 25  Nº 11  2012  págs. 2479-2489
In the search for new molecules with potential antiangiogenic activity, we found that several imidoselenocarbamate derivatives effectively suppressed the expression of vascular endothelial growth factor (VEGF) induced by hypoxia in NCI-H157 tumor cells. Mechanistic studies indicated that these compounds inhibited STAT3 phosphorylation triggered by hypoxia, suggesting that inhibition of STAT3 function may play a role in VEGF inhibition. Moreover, these molecules showed interesting proapoptotic and antiproliferative effects. Both the presence of selenium, but not sulfur, and the nature of the radical substituents were important for activity. Interestingly, under hypoxic conditions, several methyl imidoselenocarbamate derivatives released methylselenol, a highly reactive and cytotoxic gas, which was responsible for their biological activities. The kinetics of the release of methylselenol by these molecules was highly dependent on the nature of the substituent radicals and correlated with their early proapoptotic activity. Our results support the notion that pharmacological activities reported for methyl imidoselenocarbamate derivatives are dependent on the release of methylselenol. Given the well-known antitumor activities of this compound, imidoselenocarbamate derivatives represent a promising approach to develop new drugs that release methylselenol in a controlled way.
Autores: Font, María ; et al.
Revista: Bioorganic & Medicinal Chemistry
ISSN 0968-0896  Vol. 20  Nº 17  2012  págs. 5110 - 5116
In the search for molecules with potential antiangiogenic activity we found that several imidoselenocarbamate derivatives, which have pro-apoptotic and antiproliferative activities, under hypoxic conditions release methylselenol, a volatile and highly reactive gas that was considered to be responsible for the observed biological activity. The kinetic for the liberation of methylselenol is highly dependent on the nature of the overall structure and correlate with their proven pro-apoptotic activity in lung cancer cell line H157. The preliminary structure-activity relationships allow us to select as the basic structural element a scaffold constructed with an imidoselenocarbamate fragment decorated with a methyl residue on the Se central atom and two heteroaromatic lateral rings. These imidoselenocarbamate derivatives may be of interest both for their antitumoral activities and because they have a structure that can be considered as a template for the design of new derivatives with apoptotic activity. This activity is related to the controlled delivery of methylselenol and makes this an interesting approach to develop new antitumoral agents.
Autores:  et al.
Revista: FEBS JOURNAL
ISSN 1742-464X  Vol. 279  Nº Supl. 1  2012  págs. 317 - 318
Autores:  et al.
Revista: Biochemical Pharmacology
ISSN 0006-2952  Vol. 79  Nº 11  2010  págs. 1600 - 1609