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Lopez-Fernandez, S.

Publications and source records attributed to Lopez-Fernandez, S..

3 recordsLinked to original sources

A curated collection of Klebsiella metabolic models reveals variable substrate usage and gene essentiality

The Klebsiella pneumoniae species complex (KpSC) is a set of seven Klebsiella taxa which are found in a variety of niches, and are an important cause of opportunistic healthcare-associated infections in humans. Due to increasing rates of multi-drug resistance within the KpSC, there is a growing interest in better understanding the biology and metabolism of these organisms to inform novel control strategies. We collated 37 sequenced KpSC isolates isolated from a variety of niches, representing all seven taxa. We generated strain-specific genome scale metabolic models (GEMs) for all 37 isolates and simulated growth phenotypes on 511 distinct carbon, nitrogen, sulphur and phosphorus substrates. Models were curated and their accuracy assessed using matched phenotypic growth data for 94 substrates (median accuracy of 96%). We explored species-specific growth capabilities and examined the impact of all possible single gene deletions on growth in 145 core carbon substrates. These analyses revealed multiple strain-specific differences, within and between species and highlight the importance of selecting a diverse range of strains when exploring KpSC metabolism. This diverse set of highly accurate GEMs could be used to inform novel drug design, enhance genomic analyses, and identify novel virulence and resistance determinants. We envisage that these 37 curated strain-specific GEMs, covering all seven taxa of the KpSC, provide a valuable resource to the Klebsiella research community.

microbiology

Low dose AKT inhibitor miransertib cures PI3K-related vascular malformations in preclinical models of human disease

Low-flow vascular malformations are congenital overgrowths composed by abnormal blood vessels potentially causing pain, bleeding, and obstruction of different organs. These diseases are caused by oncogenic mutations in the endothelium which result in overactivation of the PI3K/AKT pathway. Lack of robust in vivo preclinical data has prevented the development and translation into clinical trials of specific molecular therapies for these diseases. Here, we describe a new reproducible preclinical in vivo model of PI3K-driven vascular malformations using the postnatal mouse retina. This model reproduces human disease with Pik3ca activating mutations expressed in a mosaic pattern and vascular malformations formed in veins and capillaries. We show that active angiogenesis is required for the pathogenesis of vascular malformations caused by activating Pik3ca mutations. Using this model, we demonstrate that low doses of the AKT inhibitor miransertib both prevents and induces the regression of PI3K-driven vascular malformations. We confirmed miransertib efficacy in isolated human endothelial cells with genotypes spanning most of human low-flow vascular malformations. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=69 SRC="FIGDIR/small/452617v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@15b29b6org.highwire.dtl.DTLVardef@fa9f8org.highwire.dtl.DTLVardef@6001d8org.highwire.dtl.DTLVardef@11926c5_HPS_FORMAT_FIGEXP M_FIG C_FIG Low-flow vascular malformations are caused by PI3K signalling overactivation in endothelial cells. We have generated an optimised and robust preclinical system of PI3K-driven vascular malformations by inducing the mosaic expression of Pik3caH1047R in the retinal angiogenic endothelium. This preclinical model displays traits constituting the main hallmarks of the pathogenesis of low-flow blood vascular malformations: overactivation of PI3K signalling (high phospho-S6), vascular compartment specificity, loss of pericyte coverage, and endothelial cell hyperproliferation. Using this preclinical model we report that low dose AKT inhibitor miransertib prevents and regress PI3K-driven vascular malformations.

molecular biology

RhoA/ROCK2 signalling is enhanced by PDGF-AA in fibro-adipogenic progenitor cells in DMD

The lack of dystrophin expression in Duchenne muscular dystrophy (DMD) leads to muscle necrosis and replacement of muscle tissue by fibro-adipose tissue. Although the role of some growth factors in the process of fibrogenesis has been previously studied, the pathways that are activated by PDGF-AA in muscular dystrophies have not been described so far. Herein we report the effects of PDGF-AA on the fibrotic process in muscular dystrophies by performing a quantitative proteomic study in DMD isolated fibro-adipogenic precursor cells (FAPs) treated with PDGF-AA. In vitro studies showed that RhoA/ROCK2 pathway is activated by PDGF-AA and induces the activation of FAPs. The inhibition of RhoA/ROCK signalling pathway by C3-exoenzyme or fasudil attenuated the effects of PDGF-AA. The blocking effects of RhoA/ROCK pathway were analysed in the dba/2J-mdx murine model with fasudil. Grip strength test showed an improvement in the muscle function and histological studies demonstrated reduction of the fibrotic area. Our results suggest that blockade of RhoA/ROCK could attenuate the activation of FAPs and could be considered a potential therapeutic approach for muscular dystrophies.

molecular biology