Selective positive modulator of calcium-activated potassium channels exerts beneficial effects in a mouse model of spinocerebellar ataxia type 2.

Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder caused by a polyglutamine expansion within the Ataxin-2 (Atxn2) protein. Purkinje cells (PC) of the cerebellum fire irregularly and eventually die in SCA2. We show here that the type 2 small conductance calcium-activated potassium channel (SK2) play a key role in control of normal PC activity.

Evidence for a common pharmacological interaction site on K(Ca)2 channels providing both selective activation and selective inhibition of the human K(Ca)2.1 subtype.

We have previously identified Ser293 in transmembrane segment 5 as a determinant for selective K(Ca)2.1 channel activation by GW542573X (4-(2-methoxyphenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester). Now we show that Ser293 mediates both activation and inhibition of K(Ca)2.

Selective activation of the SK1 subtype of human small-conductance Ca2+-activated K+ channels by 4-(2-methoxyphenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X) is dependent on serine 293 in the S5 segment.

A new small molecule, 4-(2-methoxy-phenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X), is presented as an activator of small-conductance Ca(2+)-activated K(+) (SK, K(Ca)2) channels and distinguished from previously published positive modulators of SK channels, such as 1-ethyl-2-benzimidazolinone (1-EBIO) and cyclohexyl-[2-(3,5-dimethylpyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA), in several aspects. GW542573X is the first SK1-selective compound described: an EC(50) value of 8.2 +/- 0.

Novel 1-hydroxyazole bioisosteres of glutamic acid. Synthesis, protolytic properties, and pharmacology.

A number of 1-hydroxyazole derivatives were synthesized as bioisosteres of (S)-glutamic acid (Glu) and as analogues of the AMPA receptor agonist (R,S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA, 3b). All compounds were subjected to in vitro pharmacological studies, including a series of Glu receptor binding assays, uptake studies on native as well as cloned Glu uptake systems, and the electrophysiological rat cortical slice model. Compounds 7a,b, analogues of AMPA bearing a 1-hydroxy-5-pyrazolyl moiety as the distal carboxylic functionality, showed only moderate affinity for [3H]AMPA receptor binding sites (IC(50) = 2.

Synthesis of 2-Substituted 1-Hydroxyimidazoles through Directed Lithiation.

Benzylation of 3-hydroxyimidazole 1-oxide gave 3-(benzyloxy)imidazole 1-oxide, which was deoxygenated with phosphorous trichloride to produce 1-(benzyloxy)imidazole. 1-(Benzyloxy)imidazole was deprotonated selectively at C-2 by n-butyllithium. The anion formed was reacted with electrophiles to give 1-(benzyloxy)imidazoles with carbon, halogen, silicon, or sulfur substituents at the 2-position.