1. Investigación

Macrophage activation is a complex process with multiple control elements that ensures an adequate response to the aggressor pathogens and, on the other hand, avoids an excess of inflammatory activity that could cause tissue damage. In this study, we have identified RND3, a small GTP-binding protein, as a new element in the complex signaling process that leads to macrophage activation. We show that RND3 expression is transiently induced in macrophages activated through Toll receptors and potentiated by IFN-γ. We also demonstrate that RND3 increases NOTCH signaling in macrophages by favoring NOTCH1 expression and its nuclear activity; however, Rnd3 expression seems to be inhibited by NOTCH signaling, setting up a negative regulatory feedback loop. Moreover, increased RND3 protein levels seem to potentiate NFκB and STAT1 transcriptional activity resulting in increased expression of proinflammatory genes, such as Tnf-α, Irf-1, or Cxcl-10. Altogether, our results indicate that RND3 seems to be a new regulatory element which could control the activation of macrophages, able to fine tune the inflammatory response through NOTCH.

The lens proteome undergoes dramatic composition changes during development and maturation. A defective developmental process leads to congenital cataracts that account for about 30% of cases of childhood blindness. Gene mutations are associated with approximately 50% of early-onset forms of lens opacity, with the remainder being of unknown etiology. To gain a better understanding of cataractogenesis, we utilized a transgenic mouse model expressing a mutant ubiquitin protein in the lens (K6W-Ub) that recapitulates most of the early pathological changes seen in human congenital cataracts. We performed mass spectrometry-based tandem-mass-tag quantitative proteomics in E15, P1, and P30 control or K6W-Ub lenses. Our analysis identified targets that are required for early normal differentiation steps and altered in cataractous lenses, particularly metabolic pathways involving glutathione and amino acids. Computational molecular phenotyping revealed that glutathione and taurine were spatially altered in the K6W-Ub cataractous lens. High-performance liquid chromatography revealed that both taurine and the ratio of reduced glutathione to oxidized glutathione, two indicators of redox status, were differentially compromised in lens biology. In sum, our research documents that dynamic proteome changes in a mouse model of congenital cataracts impact redox biology in lens. Our findings shed light on the molecular mechanisms associated with congenital cataracts and point out that unbalanced redox status due to reduced levels of taurine and glutathione, metabolites already linked to age-related cataract, could be a major underlying mechanism behind lens opacities that appear early in life.

Glucose uptake into the mammalian nervous system is mediated by the family of facilitative glucose transporter proteins (GLUT). In this work we investigate how the expression of the main neuronal glucose transporters (GLUT3, GLUT4 and GLUT8) is modified during cerebellar cortex maturation. Our results reveal that the levels of the three transporters increase during the postnatal development of the cerebellum. GLUT3 localizes in the growing molecular layer and in the internal granule cell layer. However, the external granule cell layer, Purkinje cell cytoplasm and cytoplasm of the other cerebellar cells lack GLUT3 expression. GLUT4 and GLUT8 have partially overlapping patterns, which are detected in the cytoplasm and dendrites of Purkinje cells, and also in the internal granule cell layer where GLUT8 displays a more diffuse pattern. The differential localization of the transporters suggests that they play different roles in the cerebellum, although GLUT4 and GLUT8 could also perform some compensatory or redundant functions. In addition, the increase in the levels and the area expressing the three transporters suggests that these roles become more important as development advances. Interestingly, the external granule cells, which have been shown to express the monocarboxylate transporter MCT2, express none of the three main neuronal GLUTs. However, when these cells migrate inwardly to differentiate in the internal granule cells, they begin to produce GLUT3, GLUT4 and GLUT8, suggesting that the maturation of the cerebellar granule cells involves a switch in their metabolism in such a way that they start using glucose as they mature.