Inhibition of amyloid fibril formation by molecular chaperone proteins, such as the small heat-shock protein alpha B-crystallin, may play a protective role in preventing the toxicity associated with this form of protein misfolding. Reduced and carboxymethylated kappa-casein (RCM kappa-CN), a protein derived from milk, readily Selleckchem Stem Cell Compound Library and reproducibly forms fibrils at physiological temperature and pH. We investigated the toxicity of fibril formation by RCM kappa-CN using neuronal model PC12 cells and determined whether the inhibition of fibril formation altered its cell toxicity. To resolve ambiguities in the literature, we also investigated whether fibril formation

by amyloid-beta 1-40 (A beta(1-40)), the peptide associated with Alzheimer’s disease, was inhibited by alpha B-crystallin and if this affected the toxicity of A beta. To this end, either RCM kappa-CN or A beta(1-40) was incubated at neutral pH to induce fibril formation before treating PC12 cells and assessing cell

viability. Incubated (fibrillar) RCM kappa-CN was more toxic to PC12 cells than native RCM kappa-CN with the highest level of toxicity being associated with mature fibrils and protofibrils. Furthermore, the toxicity of RCM kappa-CN was attenuated when its fibril formation was inhibited, either through the chaperone action of alpha B-crystallin or when it interacted with its natural binding partners in milk, alpha(S)- and beta-casein. Likewise, incubating A beta(1-40) 17DMAG with alpha B-crystallin inhibited both A beta(1-40) fibril formation and the associated cell toxicity. Importantly, see more by inhibiting fibril formation, alpha B-crystallin prevents the cell toxicity associated with protein misfolding.”
“Mesenchymal stem cells (MSCs) residing within the bone marrow (BM) differentiate into multiple lineages, including fat, bone, and cartilage. Because MSCs are multipotent and have a great capacity to be expanded in vitro, these cells are an attractive candidate for clinical applications to repair or regenerate damaged tissues of mesenchymal

origin. However, application of MSCs to muscle degenerative diseases has been hampered by the poor differentiation of MSCs into the muscle lineage. To date most methods require the presence of strong non-physiological agents, such as azacytidine. In the present study we explored the potential of Pax3, the master regulator of the embryonic myogenic program, to promote myogenic differentiation from MSCs. Our results clearly demonstrate that Pax3 promotes the differentiation of MSCs towards the myogenic lineage, which occurs at the expense of other mesenchymal lineages including fat, bone, and cartilage. This effect is cell type-selective since Pax3 overexpression in endothelial cells fails to promote myogenesis. These results highlight the potential of regulating transcriptional pathways to direct differentiation of adult stem cells. (C) 2008 Elsevier Inc. All rights reserved.