Huntington’s disease (HD) is an incurable hereditary neurodegenerative disorder, which manifests itself as a loss of GABAergic medium spiny (GABA MS) neurons in the striatum and caused by an expansion of the CAG repeat in exon 1 of the huntingtin gene. There is no cure for HD, existing pharmaceutical can only relieve its symptoms. Here, induced pluripotent stem cells were established from patients with low CAG repeat expansion in the huntingtin gene, and were then efficiently differentiated into GABA MS-like neurons (GMSLNs) under defined culture conditions. The generated HD GMSLNs recapitulated disease pathology in vitro, as evidenced by mutant huntingtin protein aggregation, increased number of lysosomes/autophagosomes, nuclear indentations, and enhanced neuronal death during cell aging. Moreover, store-operated channel (SOC) currents were detected in the differentiated neurons, and enhanced calcium entry was reproducibly demonstrated in all HD GMSLNs genotypes. Additionally, the quinazoline derivative, EVP4593, reduced the number of lysosomes/autophagosomes and SOC currents in HD GMSLNs and exerted neuroprotective effects during cell aging. Our data is the first to demonstrate the direct link of nuclear morphology and SOC calcium deregulation to mutant huntingtin protein expression in iPSCs-derived neurons with disease-mimetic hallmarks, providing a valuable tool for identification of candidate anti-HD drugs. Our experiments demonstrated that EVP4593 may be a promising anti-HD drug.

Autoantibody-mediated tissue destruction is among the main features of organ-specific autoimmunity. This report describes “an antibody enzyme” (abzyme) contribution to the site-specific degradation of a neural antigen. We detected proteolytic activity toward myelin basic protein (MBP) in the fraction of antibodies purified from the sera of humans with multiple sclerosis (MS) and mice with induced experimental allergic encephalomyelitis. Chromatography and zymography data demonstrated that the proteolytic activity of this preparation was exclusively associated with the antibodies. No activity was found in the IgG fraction of healthy donors. The human and murine abzymes efficiently cleaved MBP but not other protein substrates tested. The sites of MBP cleavage determined by mass spectrometry were localized within immunodominant regions of MBP. The abzymes could also cleave recombinant substrates containing encephalytogenic MBP_85-101peptide. An established MS therapeutic Copaxone appeared to be a specific abzyme inhibitor. Thus, the discovered epitope-specific antibody-mediated degradation of MBP suggests a mechanistic explanation of the slow development of neurodegeneration associated with MS.

(2010). Induction of pluripotency in human endothelial cells resets epigenetic profile on genome scale. Cell Cycle: Vol. 9, No. 5, pp. 937-946.

The peptidoglycan recognition protein Tag7 is shown to form a stable 1:1 complex with the major stress protein Hsp70. Neither protein is cytotoxic by itself, but their complex induces apoptotic death in several tumor-derived cell lines even at subnanomolar concentrations. The minimal part of Hsp70 needed to evoke cytotoxicity is residues 450-463 of its peptide-binding domain, but full cytotoxicity requires its ATPase activity; remarkably, Tag7 liberated from the complex at high ATP is not cytotoxic. The Tag7-Hsp70 complex is produced by tag7-transfected cells and by lymphokine-activated killers, being assembled within the cell and released into the medium through the Golgi apparatus by a mechanism different from the commonly known granule exocytosis. Thus, we demonstrate how a heat shock protein may perform functions clearly distinct from chaperoning or cell rescue and how peptidoglycan recognition proteins may be involved in innate immunity and anti-cancer defense.