GSK 2193874

GSK2193874 is an orally active, potent, and selective TRPV4 antagonist with IC50 of 2 nM and 40 nM for rTRPV4 and hTRPV4.

In Vitro:GSK2193874 is profiled against TRP channels and is selective against TRPV1, TRPA1, TRPC3, TRPC6, and TRPM8 (IC50>25 μM)[1]. GSK2193874 is a selective, orally active TRPV4 blocker that inhibits Ca2+ influx through recombinant TRPV4 channels and native endothelial TRPV4 currents. In whole-cell patch-clamp studies, GSK2193874 inhibits activation of recombinant TRPV4 currents when applied to the extracellular solution at 3 nM and above but is ineffective at up to 10 μM when applied to the inside of the cell by inclusion in the intracellular pipette solution[2].

In Vivo:The pharmacokinetic (PK) properties for GSK2193874 are evaluated in both rat and dog and found to have half-lives and oral exposure suitable for oral dosing in chronic animal models (Rat PK: iv CL=7.3 mL/min/kg, po t1/2=10 h, %F=31. Dog PK: iv CL=6.9 mL/min/kg, po t1/2=31 h, %F=53). In addition, GSK2193874 shows no blood pressure or heart rate effect in rats when dose up to 30 mg/kg. GSK2193874 is the first-in-class orally bioavailable TRPV4 inhibitor that demonstrated ability to improve pulmonary functions in a number of heart failure models[1]. GSK2193874 shows low clearance (7.3 mL/min/kg) and good rat oral bioavailability (31%)[2].

References:
[1]. Cheung M, et al. Discovery of GSK2193874: An Orally Active, Potent, and Selective Blocker of Transient Receptor Potential Vanilloid 4. ACS Med Chem Lett. 2017 Mar 20;8(5):549-554. [2]. Thorneloe KS, et al. An orally active TRPV4 channel blocker prevents and resolves pulmonary edema induced by heart failure. Sci Transl Med. 2012 Nov 7;4(159):159ra148.

Activation of Ras-ERK Signaling and GSK-3 by Amyloid Precursor Protein and Amyloid Beta Facilitates Neurodegeneration in Alzheimer's Disease.[Pubmed:28374012]

eNeuro. 2017 Mar 27;4(2). pii: eN-NWR-0149-16.

It is widely accepted that amyloid beta (Abeta) generated from amyloid precursor protein (APP) oligomerizes and fibrillizes to form neuritic plaques in Alzheimer's disease (AD), yet little is known about the contribution of APP to intracellular signaling events preceding AD pathogenesis. The data presented here demonstrate that APP expression and neuronal exposure to oligomeric Abeta42 enhance Ras/ERK signaling cascade and glycogen synthase kinase 3 (GSK-3) activation. We find that RNA interference (RNAi)-directed knockdown of APP in B103 rat neuroblastoma cells expressing APP inhibits Ras-ERK signaling and GSK-3 activation, indicating that APP acts upstream of these signal transduction events. Both ERK and GSK-3 are known to induce hyperphosphorylation of tau and APP at Thr668, and our findings suggest that aberrant signaling by APP facilitates these events. Supporting this notion, analysis of human AD brain samples showed increased expression of Ras, activation of GSK-3, and phosphorylation of APP and tau, which correlated with Abeta levels in the AD brains. Furthermore, treatment of primary rat neurons with Abeta recapitulated these events and showed enhanced Ras-ERK signaling, GSK-3 activation, upregulation of cyclin D1, and phosphorylation of APP and tau. The finding that Abeta induces Thr668 phosphorylation on APP, which enhances APP proteolysis and Abeta generation, denotes a vicious feedforward mechanism by which APP and Abeta promote tau hyperphosphorylation and neurodegeneration in AD. Based on these results, we hypothesize that aberrant proliferative signaling by APP plays a fundamental role in AD neurodegeneration and that inhibition of this would impede cell cycle deregulation and neurodegeneration observed in AD.

Transient Cerebral Ischemia Alters GSK-3beta and p-GSK-3beta Immunoreactivity in Pyramidal Neurons and Induces p-GSK-3beta Expression in Astrocytes in the Gerbil Hippocampal CA1 Area.[Pubmed:28349361]

Neurochem Res. 2017 Aug;42(8):2305-2313.

Glycogen synthase kinase 3beta (GSK-3beta) is a key downstream protein in the PI3K/Akt pathway. Phosphorylation of serine 9 of GSK-3beta (GSK-3beta activity inhibition) promotes cell survival. In this study, we examined changes in expressions of GSK-3beta and phosphorylation of GSK-3beta (p-GSK-3beta) in the gerbil hippocampal CA1 area after 5 min of transient cerebral ischemia. GSK-3beta immunoreactivity in the CA1 area was increased in pyramidal cells at 6 h after ischemia-reperfusion. It was decreased in CA1 pyramidal cells from 12 h after ischemia-reperfusion, and hardly detected in the CA1 pyramidal cells at 5 days after ischemia-reperfusion. p-GSK-3beta immunoreactivity was slightly decreased in CA1 pyramidal cells at 6 and 12 h after ischemia-reperfusion. It was significantly increased in these cells at 1 and 2 days after ischemia-reperfusion. Five days after ischemia-reperfusion, p-GSK-3beta immunoreactivity was hardly found in CA1 pyramidal cells. However, p-GSK-3beta immunoreactivity was strongly expressed in astrocytes primarily distributed in strata oriens and radiatum. In conclusion, GSK-3beta and p-GSK-3beta were significantly changed in pyramidal cells and/or astrocytes in the gerbil hippocampal CA1 area following 5 min of transient cerebral ischemia. This finding indicates that GSK-3beta and p-GSK-3beta are closely related to delayed neuronal death.

GSK-3-mediated phosphorylation couples ER-Golgi transport and nuclear stabilization of the CREB-H transcription factor to mediate apolipoprotein secretion.[Pubmed:28381424]

Mol Biol Cell. 2017 Jun 1;28(11):1565-1579.

CREB-H, an ER-anchored transcription factor, plays a key role in regulating secretion in metabolic pathways, particularly triglyceride homeostasis. It controls the production both of secretory pathway components and cargoes, including apolipoproteins ApoA-IV and ApoC-II, contributing to VLDL/HDL distribution and lipolysis. The key mechanism controlling CREB-H activity involves its ER retention and forward transport to the Golgi, where it is cleaved by Golgi-resident proteases, releasing the N-terminal product, which traffics to the nucleus to effect transcriptional responses. Here we show that a serine-rich motif termed the P-motif, located in the N-terminus between serines 73 and 90, controls release of the precursor transmembrane form from the ER and its forward transport to the Golgi. This motif is subject to GSK-3 phosphorylation, promoting ER retention, while mutation of target serines and drug inhibition of GSK-3 activity coordinately induce both forward transport of the precursor and cleavage, resulting in nuclear import. We previously showed that for the nuclear product, the P-motif is subject to multiple phosphorylations, which regulate stability by targeting the protein to the SCF(Fbw1a) E3 ubiquitin ligase. Thus phosphorylation at the P-motif provides integrated control of CREB-H function, coupling intercompartmental transport in the cytoplasm with stabilization of the active form in the nucleus.

SLM, a novel carbazole-based fluorophore attenuates okadaic acid-induced tau hyperphosphorylation via down-regulating GSK-3beta activity in SH-SY5Y cells.[Pubmed:28359686]

Eur J Pharm Sci. 2017 Dec 15;110:101-108.

Phosphorylated tau dissociates from microtubules and aggregates to form neurofibrillary tangles resulting in neuronal toxicity and cognitive deficits. Attenuating tau hyperphosphorylation is considered as an effective therapeutic approach for Alzheimer's disease (AD). From our previous study, SLM, a carbazole-based fluorophore prevents Abeta aggregation, reduced glycogen synthase kinase-3beta (GSK-3beta) activity and tau hyperphosphorylation in triple transgenic mouse model of AD. However, the mechanism by which SLM attenuates tau hyperphosphorylation warrants further investigation. In the current study, we intend to evaluate the effects of SLM against okadaic acid (OA)-induced tau hyperphosphorylation and microtubules instability in human neuroblastoma (SH-SY5Y) cells. The results showed that, SLM reduced the OA-induced cell neurotoxicity and tau hyperphosphorylation in SH-SY5Y cells. SLM treatment down-regulated GSK-3beta activity. However, in the presence of GSK-3beta inhibitor (SB216763, 10muM), SLM treatment could not reduce GSK-3beta activity and tau hyperphosphorylation as compared with SB216763 treatment alone. Furthermore, SLM treatment also ameliorated OA-induced microtubules instability and cytoskeleton damage. Collectively, SLM attenuated OA-induced tau hyperphosphorylation via down-regulating GSK-3beta activity in SH-SY5Y cells. Therefore, this study supports SLM as a potential compound for AD and other tau pathology-related neurodegenerative disorders.

An orally active TRPV4 channel blocker prevents and resolves pulmonary edema induced by heart failure.[Pubmed:23136043]

Sci Transl Med. 2012 Nov 7;4(159):159ra148.

Pulmonary edema resulting from high pulmonary venous pressure (PVP) is a major cause of morbidity and mortality in heart failure (HF) patients, but current treatment options demonstrate substantial limitations. Recent evidence from rodent lungs suggests that PVP-induced edema is driven by activation of pulmonary capillary endothelial transient receptor potential vanilloid 4 (TRPV4) channels. To examine the therapeutic potential of this mechanism, we evaluated TRPV4 expression in human congestive HF lungs and developed small-molecule TRPV4 channel blockers for testing in animal models of HF. TRPV4 immunolabeling of human lung sections demonstrated expression of TRPV4 in the pulmonary vasculature that was enhanced in sections from HF patients compared to controls. GSK2193874 was identified as a selective, orally active TRPV4 blocker that inhibits Ca(2+) influx through recombinant TRPV4 channels and native endothelial TRPV4 currents. In isolated rodent and canine lungs, TRPV4 blockade prevented the increased vascular permeability and resultant pulmonary edema associated with elevated PVP. Furthermore, in both acute and chronic HF models, GSK2193874 pretreatment inhibited the formation of pulmonary edema and enhanced arterial oxygenation. Finally, GSK2193874 treatment resolved pulmonary edema already established by myocardial infarction in mice. These findings identify a crucial role for TRPV4 in the formation of HF-induced pulmonary edema and suggest that TRPV4 blockade is a potential therapeutic strategy for HF patients.