RARβ2-dependent signaling represses neuronal differentiation in mouse ES cells

Abstract

Embryonic Stem (ES) cells are pluripotent cells that can be induced to differentiate into cells of all three lineages: mesoderm, endoderm, and ectoderm. In culture, ES cells can be differentiated into mature neurons by treatment with Retinoic Acid (RA) and this effect is mediated mainly through the activation of the RA nuclear receptors (RAR α, β, and γ), and their isoforms. However, little is known about the role played by specific RAR types on ES cell differentiation. Here, we found that treatment of ES cells with AC55649, an RARβ2 agonist, increased endodermal marker gene expression. On the other hand, we found that the inhibition of RARβ with 5 μM LE135, together with RA treatment, increased the efficiency of mouse ES cell differentiation into neurons by more than 4-fold as compared to cells treated with RA only. Finally, we performed proteomic analyses on ES cells treated with RA vs RA plus AC55649 in order to identify the signaling pathways activated by the RARβ agonist. Our proteomic analyses using antibody microarrays indicated that proteins such as p38 and AKT were upregulated in cells treated with RA plus the agonist, as compared to cells treated with RA alone. Our results indicate that RARβ may function as a repressor of neuronal differentiation through the activation of major cell signaling pathways, and that the pharmacological inhibition of this nuclear receptor may constitute a novel method to increase the efficiency of ES to neuronal differentiation in culture.

Dietary Vitamin E as a Protective Factor for Parkinson's Disease: Clinical and Experimental Evidence

“…Effects of Vitamin E (alpha-tocopherol and the water-soluble analog Trolox) were assessed in comparison to other antioxidant agents of alimentary origin, in order to test their action specificity. In particular, for our experiments we specifically selected: beta-carotene (21, 22), lycopene (22, 23), lutein (24), folic acid (25), ascorbic acid/Vitamin C (26), retinol/Vitamin A (27), Vitamin K1/phylloquinone, and Vitamin K2/menaquinones (28, 29).…”

“…For acute treatment, a single slice was incubated, from 40 min before HFS induction and for the duration of the whole experiment (about 1 h), in a bath solution containing the drug dissolved in Krebs' solution. Selected compounds were used in bath at the respective dose of: alpha-tocopherol = 100 μM and Trolox = 100 μM (9); beta-carotene = 100 μM (30); lutein = 20 μM (24); lycopene = 5 μM (22, 23); folic acid = 100 μM (25); Vitamin A = 1 μM (27); Vitamin C = 1–3 mM (26); Vitamin K1 = 20 μM, and Vitamin K2 = 10 μM (28, 29).…”