Discovery and characterization of 2-(cyclopropanesulfonamido)-N-(2-ethoxyphenyl)benzamide, ML382: a potent and selective positive allosteric modulator of MrgX1.

Previous studies have shown that the activation of mouse MrgC11, a G-protein-coupled receptor, by its peptide ligand BAM8-22 can inhibit chronic pain. A large-scale screen has been carried out to isolate small-molecule allosteric agonists of MrgX1, the human homologue of MrgC11. The goal of this study is to improve the efficacy and potency of positive allosteric modulators (PAMs) with therapeutic implications in combating chronic pain. Herein we report an iterative parallel synthesis effort and a structure-activity relationship study of a series of arylsulfonamides which led to the discovery of the first PAM of MrgX1, ML382.

Spontaneous differentiation of adult rat marrow stromal cells in a long-term culture.

It is well recognized that bone marrow stromal cells (MSCs) can differentiate into neuron-like cells when supplemented with growth factors and/or chemical treatments. We demonstrated that primary MSCs obtained from adult rats could spontaneously differentiate into neural precursor cells after long-term culture. During the outset of in vitro culture, less than 0.1% of adult rat primary MSCs expressed nestin, the common protein of neural precursors. These MSCs didn't show neuronal morphology nor express neuronal antigens. In contrast, after continuous maintenance for 6 weeks, a significant subpopulation of MSCs formed cellular clumps and expressed nestin (32.3 +/- 6.3%). Less than 0.1% of cells expressing immature neuron marker betaIII-tubulin could be detected in these prolonged cultured MSCs. After serum deprivation and growth factor supplement, these nestin-positive cells could express neuron-like morphology and neuron-specific markers NF-H, betaIII-tubulin, tau, and neurotransmitter GABA. In contrast, the MSCs without prolonged culture didn't show neuronal morphology nor neuronal markers even after serum withdrawal and growth factors stimulation. These results demonstrated that neural precursors could be obtained from long-term cultured MSCs, and suggested that MSCs should be useful as a potential source for treatment of neurological disease.