Publications by authors named "Lionel Host"

ShcA is an adaptor protein that binds to the cytoplasmic tail of receptor tyrosine kinases and of the Low Density Lipoprotein-related receptor 1 (LRP1), a trans-membrane receptor that protects against atherosclerosis. Here, we examined the role of endothelial ShcA in atherosclerotic lesion formation. We found that atherosclerosis progression was markedly attenuated in mice deleted for ShcA in endothelial cells, that macrophage content was reduced at the sites of lesions, and that adhesion molecules such as the intercellular adhesion molecule-1 (ICAM-1) were severely reduced.

View Article and Find Full Text PDF

The low density lipoprotein receptor-related protein 1 (LRP1) is a ubiquitously expressed cell surface receptor that protects from intracellular cholesterol accumulation. However, the underlying mechanisms are unknown. Here we show that the extracellular (α) chain of LRP1 mediates TGFβ-induced enhancement of Wnt5a, which limits intracellular cholesterol accumulation by inhibiting cholesterol biosynthesis and by promoting cholesterol export.

View Article and Find Full Text PDF

Src homology and collagen A (ShcA) is an adaptor protein that binds to tyrosine kinase receptors. Its germ line deletion is embryonic lethal with abnormal cardiovascular system formation, and its role in cardiovascular development is unknown. To investigate its functional role in cardiovascular development in mice, ShcA was deleted in cardiomyocytes and vascular smooth muscle cells by crossing ShcA flox mice with SM22a-Cre transgenic mice.

View Article and Find Full Text PDF

Drug addiction is a chronic brain disease characterized by a persistent risk of relapse, even after a long period of abstinence. A current hypothesis states that relapse results from lasting neuroadaptations that are induced in response to repeated drug administration. The adaptations require gene expression, some of which being under the control of stable epigenetic regulations.

View Article and Find Full Text PDF

Recent evidence suggests that epigenetic mechanisms play a role in psychiatric diseases. In this study, we considered rats with neonatal ventral hippocampal lesions (NVHL) that are currently used for modeling neurodevelopmental aspects of schizophrenia. Contribution of epigenetic regulation to the effects of the lesion was investigated, using a histone deacetylase (HDAC) inhibitor.

View Article and Find Full Text PDF

Epigenetic mechanisms have recently been shown to be involved in the long-term effects of drugs of abuse. A well described epigenetic mechanism modulating transcriptional activity consists in the binding to DNA of methyl-CpG binding proteins, such as MeCP2, recruiting histone deacetylases (HDACs). Nicotine causes long-term changes in the brain, but little is known concerning the mechanisms involved in nicotine-preference.

View Article and Find Full Text PDF

Rett syndrome and its "early-onset seizure" variant are severe neurodevelopmental disorders associated with mutations within the MECP2 and the CDKL5 genes. Antidepressants and drugs of abuse induce the expression of the epigenetic factor MeCP2, thereby influencing chromatin remodeling. We show that increased MeCP2 levels resulted in the repression of Cdkl5 in rat brain structures in response to cocaine, as well as in cells exposed to serotonin, or overexpressing MeCP2.

View Article and Find Full Text PDF

Injection of the histone deacetylase inhibitor trichostatin A (TsA) to rats has been shown to decrease their motivation to self-administer cocaine. In the present study, we investigated alterations in gene expression patterns in the anterior cingulate cortex and nucleus accumbens of rats self-administering cocaine and treated with TsA. Using oligonucleotide microarrays, we identified 722 probe sets in the cortex and 136 probe sets in the nucleus accumbens that were differentially expressed between vehicle and TsA-treated rats that self-administered cocaine.

View Article and Find Full Text PDF

Injection of the histone deacetylases inhibitor trichostatin A to rats has been shown to decrease the reinforcing properties of cocaine. In the present study, we investigated alterations in gene expression patterns in the anterior cingulate cortex, caudate-putamen and nucleus accumbens of rats self-administering cocaine and treated with trichostatin A. As recent studies highlighted the importance of chromatin remodelling in the regulation of gene transcription in neurons, we studied the expression of Mecp2 and of several histone deacetylases.

View Article and Find Full Text PDF

Regulation of gene expression is known to contribute to the long-term adaptations taking place in response to drugs of abuse. Recent studies highlighted the regulation of gene transcription in neurons by chromatin remodeling, a process in which posttranslational modifications of histones play a major role. To test the involvement of epigenetic regulation on drug-reinforcing properties, we submitted rats to the cocaine operant self-administration paradigm.

View Article and Find Full Text PDF