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Huntington's disease (HD) is a progressive and fatal neurodegenerative disease, and the most common inherited CAG repeat disorder. A polyglutamine expansion in the N-terminus of the huntingtin protein (HTT) leads to protein misfolding and downstream pathogenic processes culminating in widespread functional impairment and neurodegeneration in the striatum, cortex and other brain areas. To date, only symptomatic treatments are available that address motor, psychiatric and cognitive deficits. Here we review recent strategies for developing disease-modifying therapies designed to limit or abolish the pathogenic activities of the primary molecular target in HD, the mutant HTT protein itself., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Huntington's disease (HD) is a rare neurodegenerative disorder that progressively destroys the mental capacity and motor control of patients. This loss of motor control results in abnormal body movements (chorea) - the hallmark of HD. Given that no disease-modifying therapy for HD exists and that available symptomatic treatments are not highly efficacious, the medical need for this 'orphan' disease remains high. The number of compounds that are undergoing discovery and development for the treatment of HD has increased significantly in recent years, spurred by legislative incentives for orphan drug development and by support from non-profit foundations. Thus, hope exists for patients with HD that efficacious medicines will become available.

Recognition of some of the limitations of target-based drug discovery has recently led to the renaissance of a more holistic approach in which complex biological systems are investigated for phenotypic changes upon exposure to small molecules. The subsequent identification of the molecular targets that underlie an observed phenotypic response--termed target deconvolution--is an important aspect of current drug discovery, as knowledge of the molecular targets will greatly aid drug development. Here, the broad panel of experimental strategies that can be applied to target deconvolution is critically reviewed.

The recent sequencing of the human genome has created comprehensive information of all potential drug targets. Based on current estimations for the total number of genes, around 400 poreforming ion channel genes can be expected corresponding to about 1.3% of the human genome. Since many ion channels are involved in diseases and the currently marketed drugs act only on a small fraction of these pore-forming membrane proteins, there is a big opportunity for innovative ion channel drug discovery. In fact, recent advances in the development of functional ion channel assays are currently enabling a more systematic exploitation of this important target class. In particular, fluorescence-based methods, automated electrophysiology, and ion flux assays are most important in this regard. This article will briefly describe these methods focusing on the nonradioactive Rb(+) efflux assay that I developed in the early 1990s since it has found widespread application in drug discovery and development and greatly displaced (86)Rb(+) assays for the analysis of K(+) and nonselective cation channels in the pharmaceutical industry.

Abstract: The patch-clamp technique was used to investigate the effects of bis-benzylisoquinoline alkaloids on two of the major neuronal nicotinic acetylcholine receptors (nAChRs), the α3-containing nAChR (α3*nAChR) endogenously expressed in PC12 cells and the rat α7-nAChR heterologously expressed in GH4C1 cells. Tetrandrine and hernandezine reversibly inhibited both receptors displaying half-maximal inhibitory concentrations (IC50) of 8.1μM and 5.8μM for α3*nAChR and 407.4nM and 372.2nM, respectively, for α7-nAChR. E6-berbamine completely inhibited the α3*nAChR with an IC50 of 5.1μM, but only partially inhibited the α7-nAChR at concentrations up to 30μM. Tetrandrine inhibition of α3*nAChR was functionally non-competitive. All three compounds displaced radiolabelled methyllycaconitine ([3H]-MLA) binding to α7-nAChR providing some evidence of competitive antagonism. The results demonstrate that these alkaloids are nAChRs antagonists, with tetrandrine and hernandezine displaying selectivity for one of the major neuronal subtype, the α7 nAChR. The different potencies and multiple modes of action on nAChRs may help to better understand the pharmacology of these receptors and to aid in novel drug design. [Copyright &y& Elsevier]