Anti-diabetic drugs inhibit obesity-linked phosphorylation of PPAR gamma by Cdk5

Obesity induced in mice by high-fat feeding activates the protein kinase Cdk5 (cyclin-dependent kinase 5) in adipose tissues. This results in phosphorylation of the nuclear receptor PPAR?? 3 (peroxisome proliferator-activated receptor ?? 3), a dominant regulator of adipogenesis and fat cell gene expression, at serine 273. This modification of PPAR?? 3 does not alter its adipogenic capacity, but leads to dysregulation of a large number of genes whose expression is altered in obesity, including a reduction in the expression of the insulin-sensitizing adipokine, adiponectin. The phosphorylation of PPAR?? 3 by Cdk5 is blocked by anti-diabetic PPAR?? 3 ligands, such as rosiglitazone and MRL24. This inhibition works both in vivo and in vitro, and is completely independent of classical receptor transcriptional agonism. Similarly, inhibition of PPAR?? 3 phosphorylation in obese patients by rosiglitazone is very tightly associated with the anti-diabetic effects of this drug. All these findings strongly suggest that Cdk5-mediated phosphorylation of PPAR?? 3 may be involved in the pathogenesis of insulin-resistance, and present an opportunity for development of an improved generation of anti-diabetic drugs through PPAR?? 3.close24724

A systematic review of calcium channel antagonists in bipolar disorder and some considerations for their future development

L-type calcium channel (LTCC) antagonists have been used in bipolar disorder for over 30 years, without becoming an established therapeutic approach. Interest in this class of drugs has been rekindled by the discovery that LTCC genes are part of the genetic aetiology of bipolar disorder and related phenotypes. We have therefore conducted a systematic review of LTCC antagonists in the treatment and prophylaxis of bipolar disorder. We identified 23 eligible studies, with six randomised, double-blind, controlled clinical trials, all of which investigated verapamil in acute mania, and finding no evidence that it is effective. Data for other LTCC antagonists (diltiazem, nimodipine, nifedipine, methyoxyverapamil and isradipine) and for other phases of the illness are limited to observational studies, and therefore no robust conclusions can be drawn. Given the increasingly strong evidence for calcium signalling dysfunction in bipolar disorder, the therapeutic candidacy of this class of drugs has become stronger, and hence we also discuss issues relevant to their future development and evaluation. In particular, we consider how genetic, molecular and pharmacological data can be used to improve the selectivity, efficacy and tolerability of LTCC antagonists. We suggest that a renewed focus on LTCCs as targets, and the development of ”brain-selective” LTCC ligands, could be one fruitful approach to innovative pharmacotherapy for bipolar disorder and related phenotypes

Targeting voltage-gated calcium channels in neurological and psychiatric diseases

Voltage-gated calcium channels are important regulators of brain, heart and muscle functions, and their dysfunction can give rise to pathophysiological conditions ranging from cardiovascular disorders to neurological and psychiatric conditions such as epilepsy, pain and autism. In the nervous system, calcium channel blockers have been used successfully to treat absence seizures, and are emerging as potential therapeutic avenues for pathologies such as pain, Parkinson disease, addiction and anxiety. This Review provides an overview of calcium channels as drug targets for nervous system disorders, and discusses potential challenges and opportunities for the development of new clinically effective calcium channel inhibitors