Molecular and Therapeutic Potential and Toxicity of Valproic Acid

Valproic acid (VPA), a branched short-chain fatty acid, is widely used as an antiepileptic drug and a mood stabilizer. Antiepileptic properties have been attributed to inhibition of Gamma Amino Butyrate (GABA) transaminobutyrate and of ion channels. VPA was recently classified among the Histone Deacetylase Inhibitors, acting directly at the level of gene transcription by inhibiting histone deacetylation and making transcription sites more accessible. VPA is a widely used drug, particularly for children suffering from epilepsy. Due to the increasing number of clinical trials involving VPA, and interesting results obtained, this molecule will be implicated in an increasing number of therapies. However side effects of VPA are substantially described in the literature whereas they are poorly discussed in articles focusing on its therapeutic use. This paper aims to give an overview of the different clinical-trials involving VPA and its side effects encountered during treatment as well as its molecular properties

Caractérisation des cellules souches mesenchymateuses multipotentes stromales des deux principaux sites de l'hématopoïese (foie foetal et moelle osseuse)

Using cell lines obtain from the fetal liver and the bone marrow, we established a molecular signature of these stromales multipotential mesenchymal stem cells (MSC). This signature is based on the characterization of the lines by a study of differentiation in the mesodermic lineage generally studied (osteoblastic, adipocygenic, chondrogenic and vascular smooth muscle) and by their capacity to support the hematopoiesis. Starting from these cellular studies it could be highlighted a molecular signature based on the common gene expression only in the MSC lines. This signature shows a possible implication of cytoskeleton and proteins related to the DNA, in the inhibition of the phenomena of differentiation and proliferation of cells. In the second time we carried out a preliminary study of the differentiation capacity of MSC at the clonal level, in the mesodermic and neurœctodermic lineageNous avons établis, à partir de lignés cellulaires originaires du foie fœtal et de la moelle osseuse, une signature moléculaire des cellules souches mésenchymateuses (CSM) stromales multipotentielle. Cette signature repose sur la caractérisation des lignées par une étude de différenciation dans les voies mésodermiques usuellement étudiées (ostéoblastique, adipocytaire, chondrocytaire et vasculaire musculaire lisse) et par leur capacité de soutien de l'hématopoïèse après 3 et 5 semaines. A partir de ces e tudes cellulaires il a put être mis en évidence une signature moléculaire réalisée à partir de la expression commune dans les lignées de types CSM, et montrant une possible relation entre le cytosquelette et les protéines liées à l'ADN, dans l'inhibition des phénomènes de différenciation et prolifération des cellules. Dans un second temps nous avons réalisé une étude préliminaire de la capacité de différenciation des CSM à l'échelon clonale, au travers des voies mésodermiques et neurœctodermique.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Long and Short Non-Coding RNAs as Regulators of Hematopoietic Differentiation

Abstract: Genomic analyses estimated that the proportion of the genome encoding proteins corresponds to approximately 1.5%, while at least 66 % are transcribed, suggesting that many non-coding DNA-regions generate non-coding RNAs (ncRNAs). The relevance of these ncRNAs in biological, physiological as well as in pathological processes increased over the last two decades with the understanding of their implication in complex regulatory networks. This review particularly focuses on the involvement of two large families of ncRNAs, namely microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of hematopoiesis. To date, miRNAs have been widely studied, leading to a wealth of data about processing, regulation and mechanisms of action and more specifically, their involvement in hematopoietic differentiation. Notably, the interaction of miRNAs with the regulatory network of transcription factors is well documented whereas roles, regulation and mechanisms of lncRNAs remain largely unexplored in hematopoiesis; this review gathers current data about lncRNAs as well as both potential and confirmed roles in normal and pathological hematopoiesis. Int. J. Mol. Sci. 2013, 14 1474

Eurycomanone and Eurycomanol from Eurycoma longifolia Jack as Regulators of Signaling Pathways Involved in Proliferation, Cell Death and Inflammation

Eurycomanone and eurycomanol are two quassinoids from the roots of Eurycoma longifolia Jack. The aim of this study was to assess the bioactivity of these compounds in Jurkat and K562 human leukemia cell models compared to peripheral blood mononuclear cells from healthy donors. Both eurycomanone and eurycomanol inhibited Jurkat and K562 cell viability and proliferation without affecting healthy cells. Interestingly, eurycomanone inhibited NF-κB signaling through inhibition of IκBα phosphorylation and upstream mitogen activated protein kinase (MAPK) signaling, but not eurycomanol. In conclusion, both quassinoids present differential toxicity towards leukemia cells, and the presence of the α,β-unsaturated ketone in eurycomanone could be prerequisite for the NF-κB inhibition

Sphingolipid-mediated inflammatory signaling leading to autophagy inhibition converts erythropoiesis to myelopoiesis in human hematopoietic stem/progenitor cells

Elevated levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) inhibit erythropoiesis and cause anemia in patients with cancer and chronic inflammatory diseases. TNFα is also a potent activator of the sphingomyelinase (SMase)/ceramide pathway leading to ceramide synthesis and regulating cell differentiation, proliferation, apoptosis, senescence, and autophagy. Here we evaluated the implication of the TNFα/SMase/ceramide pathway on inhibition of erythropoiesis in human CD34+ hematopoietic stem/progenitor cells (CD34/HSPCs) from healthy donors. Exogenous synthetic C2- and C6-ceramide as well as bacterial SMase inhibited erythroid differentiation in erythropoietin-induced (Epo)CD34/HSPCs shown by the analysis of various erythroid markers. The neutral SMase inhibitor GW4869 as well as the genetic inhibition of nSMase with small interfering RNA (siRNA) against sphingomyelin phosphodiesterase 3 (SMPD3) prevented the inhibition by TNFα, but not the acid SMase inhibitor desipramine. Moreover, sphingosine-1-phosphate (S1P), a ceramide metabolite, restored erythroid differentiation, whereas TNFα inhibited sphingosine kinase-1, required for S1P synthesis. Analysis of cell morphology and colony formation demonstrated that erythropoiesis impairment was concomitant with a granulomonocytic differentiation in TNFα- and ceramide-treated EpoCD34/HSPCs. Inhibition of erythropoiesis and induction of granulomonocytic differentiation were correlated to modulation of hematopoietic transcription factors (TFs) GATA-1, GATA-2, and PU.1. Moreover, the expression of microRNAs (miR)-144/451, miR-146a, miR-155, and miR-223 was also modulated by TNFα and ceramide treatments, in line with cellular observations. Autophagy plays an essential role during erythropoiesis and our results demonstrate that the TNFα/neutral SMase/ceramide pathway inhibits autophagy in EpoCD34/HSPCs. TNFα- and ceramide-induced phosphorylation of mTORS2448 and ULK1S758, inhibited Atg13S355 phosphorylation, and blocked autophagosome formation as shown by transmission electron microscopy and GFP-LC3 punctae formation. Moreover, rapamycin prevented the inhibitory effect of TNFα and ceramides on erythropoiesis while inhibiting induction of myelopoiesis. In contrast, bafilomycin A1, but not siRNA against Atg5, induced myeloid differentiation, while both impaired erythropoiesis. We demonstrate here that the TNFα/neutral SMase/ceramide pathway inhibits erythropoiesis to induce myelopoiesis via modulation of a hematopoietic TF/miR network and inhibition of late steps of autophagy. Altogether, our results reveal an essential role of autophagy in erythroid vs. myeloid differentiation