Summary PGC1α is a key transcriptional coregulator of oxidative metabolism and thermogenesis. Through a high throughput chemical screen, we found that molecules antagonizing the TRPVs (Transient Receptor Potential Vanilloid), a family of ion channels, induced PGC1α expression in adipocytes. In particular, TRPV4 negatively regulated the expression of PGC1α, UCP1 and cellular respiration. Additionally, it potently controlled the expression of multiple proinflammatory genes involved in the development of insulin resistance. Mice with a null mutation for TRPV4 or wild-type mice treated with a TRPV4 antagonist showed elevated thermogenesis in adipose tissues and were protected from diet-induced obesity, adipose inflammation and insulin resistance. This role of TRPV4 as a cell-autonomous mediator for both the thermogenic and proinflammatory programs in adipocytes could offer a new target for treating obesity and related metabolic diseases.

Given the significant body of data supporting an essential role for c-jun-N-terminal kinase (JNK) in neurodegenerative disorders, we set out to develop highly selective JNK inhibitors, with good cell potency, and good brain penetration properties. The structure activity relationships (SAR) around a series of aminopyrimidines was evaluated utilizing biochemical and cell- based assays to measure JNK inhibition, and brain penetration in mice. Microsomal stability in three species, P450 inhibition, inhibition of generation of reactive oxygen species (ROS), and pharmacokinetics in rats were also measured. Compounds 9g, 9i, 9j, and 9l had greater than 135-fold selectivity over p38, and cell-based IC50 values < 100 nM. Moreover, compound 9l showed an IC50= 0.8 nM for inhibition of ROS and had good pharmacokinetic properties in rat, along with a brain-to-plasma ratio of 0.75. These results suggest that biaryl substituted aminopyrimidines represented by compound 9l may serve as the first small molecule inhibitors to test efficacy of JNK inhibitors in neurodegenerative disorders.

c-Jun N-terminal kinase 3␣1 (JNK3␣1) is a mitogen-activated protein kinase family member expressed primarily in the brain that phosphorylates protein transcription factors, including c-Jun and activating transcription factor-2 (ATF-2) upon activation by a variety of stress-based stimuli. In this study, we set out to design JNK3-selective inhibitors that had >1000-fold selectivity over p38, another closely related mitogen-activated protein kinase family member. To do this we employed traditional medicinal chemistry principles coupled with structurebased drug design. Inhibitors from the aminopyrazole class, such as SR-3576, were found to be very potent JNK3 inhibitors (IC 50 ‫؍‬ 7 nM) with >2800-fold selectivity over p38 (p38 IC 50 > 20 M) and had cell-based potency of ϳ1 M. In contrast, indazole-based inhibitors exemplified by SR-3737 were potent inhibitors of both JNK3 (IC 50 ‫؍‬ 12 nM) and p38 (IC 50 ‫؍‬ 3 nM). These selectivity differences between the indazole class and the aminopyrazole class came despite nearly identical binding (root mean square deviation ‫؍‬ 0.33 Å ) of these two compound classes to JNK3. The structural features within the compounds giving rise to the selectivity in the aminopyrazole class include the highly planar nature of the pyrazole, N-linked phenyl structures, which better occupied the smaller active site of JNK3 compared with the larger active site of p38.Because the initial reports on the discovery of p38 (1) and c-Jun N-terminal kinase (JNK) 2 (2-6) these mitogen-activated protein kinase family members have generated great interest as drug targets. p38 especially has garnered considerable interest, particularly for the treatment of rheumatoid arthritis and Crohn disease, and numerous compounds have entered clinical trials for these indications (7-11). Because most of the p38 inhibitors are competitive versus ATP (12-17), and there are 518 kinases in the genome, it was crucial to develop compounds that are selective against a broad panel of kinases so that compounds could be advanced to clinical development. The molecular basis that gives rise to selective p38 inhibitors from numerous structural classes has been reported (18 -20) and is centered on amino acid differences at the so-called "gatekeeper" Thr-106 residue in p38 (Met in all of the JNK isoforms and Gln in extracellular regulated kinase, the other mitogenactivated protein kinase family member). Many compounds have been synthesized that take advantage of this deeper hydrophobic pocket in p38, compared with JNK3, and the structures of the compounds have included trifluoromethyl and other large moieties, which all contribute to p38 selectivity (21). In contrast to p38, there have been fewer reports for selective JNK inhibitors, and the clinical development of JNK inhibitors also lags that of p38. Despite the paucity of highly selective JNK inhibitors that have advanced to clinical development, numerous recent reports have begun to emerge that show compounds from various structural classes (benzothiazole pyrimidines, aminopyr...

There are currently no drugs to treat neurodegeneration in Parkinson’s disease (PD) and all existing medications only treat symptoms, lose efficacy over time, and produce untoward side effects. In the current work, we report the first highly selective, orally bioavailable, c-jun-N-terminal kinase (JNK) inhibitor for protection of dopaminergic neurons in vitro and in vivo. At 300 nM this compound showed statistically significant protection of primary dopaminergic neurons exposed to 1-methyl-4-phenylpyridinium (MPP+), had pharmacokinetic properties in rodents consistent with twice daily (b.i.d.) dosing, and was orally efficacious at 30 mg/kg in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson’s disease. Moreover, a dose-dependent target modulation of c-jun phosphorylation served as a biomarker for demonstrating on-target inhibition of JNK as the mechanism of action for this compound. Collectively these results suggest that this JNK inhibitor could be a promising therapeutic neuroprotective agent in the treatment of Parkinson’s disease.

No abstract