Discovery and Structure-Activity Relationship of a Ryanodine Receptor 2 Inhibitor.

Ryanodine receptor 2 (RyR2) is a large Ca-release channel in the sarcoplasmic reticulum (SR) of cardiac muscle cells. It serves to release Ca from the SR into the cytosol to initiate muscle contraction. RyR2 overactivation is associated with arrhythmogenic cardiac disease, but few specific inhibitors have been reported so far.

Anti-Inflammatory Effects of a Novel Nuclear Factor-B Inhibitory Derivative Derived from Pyrazolo[3,4-]Pyrimidine in Three Inflammation Models.

Nuclear factor-B (NF-B) plays a central role in inflammatory responses, and its physiologic functions are essential for cell survival and proliferation. Currently, drugs targeting NF-B inhibition have not yet been applied in clinical practice. We investigated the physiologic effect of a novel NF-B inhibitory compound, 1-pyrazolo[3,4-]pyrimidin-4-amine derivative (INH #1), on three inflammatory animal models.

A potent and selective cis-amide inhibitor of ryanodine receptor 2 as a candidate for cardiac arrhythmia treatment.

Ryanodine receptor 2 (RyR2) is a Ca release channel mainly located on the sarcoplasmic reticulum (SR) membrane of heart muscle cells and regulates the concentration of Ca in the cytosol. RyR2 overactivation causes potentially lethal cardiac arrhythmias, but no specific inhibitor is yet available. Herein we developed the first highly potent and selective RyR2 inhibitor, TMDJ-035, containing 3,5-difluoro substituents on the A ring and a 4-fluoro substituent on the B ring, based on a comprehensive structure-activity relationship (SAR) study of tetrazole compound 1.

Screening for Novel Type 2 Ryanodine Receptor Inhibitors by Endoplasmic Reticulum Ca Monitoring.

Type 2 ryanodine receptor (RyR2) is a Ca release channel on the endoplasmic (ER)/sarcoplasmic reticulum that plays a central role in the excitation-contraction coupling in the heart. Hyperactivity of RyR2 has been linked to ventricular arrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia and heart failure, where spontaneous Ca release via hyperactivated RyR2 depolarizes diastolic membrane potential to induce triggered activity. In such cases, drugs that suppress RyR2 activity are expected to prevent the arrhythmias, but there is no clinically available RyR2 inhibitors at present.

Solvent-Dependent Conformational Switching of N-Methyl-N,N'-diarylsquaramide.

,'-Diarylsquaramide and ,'-dialkylsquaramide are conformationally stable linkers with extended (trans, trans) and folded (cis, cis) structures, respectively, independently of external conditions. Here, we show that -monomethylated ,'-diarylsquaramides generally take a (trans, cis) structure in the crystal but show a solvent-dependent conformational equilibrium in solution. In particular, the stable conformer of -methyl-,'-bis(1-naphthyl)squaramide () changes depending upon the solvent.

An N-Cyanoamide Derivative of Lithocholic Acid Co-Operates with Lysophosphatidic Acid to Promote Human Osteoblast (MG63) Differentiation.

Less-calcaemic vitamin D receptor (VDR) agonists have the potential to promote osteoblast maturation in a bone regenerative setting. The emergence of lithocholic acid (LCA) as a bona fide VDR agonist holds promise as an adjunct for arthroplasty following reports that it was less calcaemic than calcitriol (1,25D). However, LCA and some earlier derivatives, e.

Acyclic retinoid peretinoin reduces hemorrhage-associated brain injury in vitro and in vivo.

Peretinoin is an acyclic retinoid that stimulates retinoic acid receptors (NR1Bs) and produces therapeutic effects on hepatocellular cancer. We have previously shown that NR1B agonists such as Am80 and all trans-retinoic acid suppress pathogenic events in intracerebral hemorrhage. The present study addressed the actions of peretinoin and Am80 against cytotoxicity of a blood protease thrombin on cortico-striatal slice cultures obtained from neonatal rat brains.

Targeting transglutaminase 2 mediated exostosin glycosyltransferase 1 signaling in liver cancer stem cells with acyclic retinoid.

Transglutaminase 2 (TG2) is a multifunctional protein that promotes or suppresses tumorigenesis, depending on intracellular location and conformational structure. Acyclic retinoid (ACR) is an orally administered vitamin A derivative that prevents hepatocellular carcinoma (HCC) recurrence by targeting liver cancer stem cells (CSCs). In this study, we examined the subcellular location-dependent effects of ACR on TG2 activity at a structural level and characterized the functional role of TG2 and its downstream molecular mechanism in the selective depletion of liver CSCs.

[Development of Bioactive Molecules Bearing Hexacoordinated Sulfur Fluoride].

Hexa-coordinated sulfur fluoride compounds have a regular octahedral structure and exhibit distinctive chemical properties. This review describes the application of two hexa-coordinated sulfur fluoride groups as substructures of bioactive compounds. One of them, the pentafluorosulfanyl (SF) group, also called a "super-trifluoromethyl group" has attracted considerable attention in recent years because of its strong electron-withdrawing character, high hydrophobicity, and bulky structure.

Targeting Cellular Retinoic Acid Binding Protein 1 with Retinoic Acid-like Compounds to Mitigate Motor Neuron Degeneration.

All-trans-retinoic Acid (atRA) is the principal active metabolite of Vitamin A, essential for various biological processes. The activities of atRA are mediated by nuclear RA receptors (RARs) to alter gene expression (canonical activities) or by cellular retinoic acid binding protein 1 (CRABP1) to rapidly (minutes) modulate cytosolic kinase signaling, including calcium calmodulin-activated kinase 2 (CaMKII) (non-canonical activities). Clinically, atRA-like compounds have been extensively studied for therapeutic applications; however, RAR-mediated toxicity severely hindered the progress.

Drug development for the treatment of RyR1-related skeletal muscle diseases.

Type 1 ryanodine receptor (RyR1) is an intracellular Ca release channel on the sarcoplasmic reticulum of skeletal muscle, and it plays a central role in excitation-contraction (E-C) coupling. Mutations in RyR1 are implicated in various muscle diseases including malignant hyperthermia, central core disease, and myopathies. Currently, no specific treatment exists for most of these diseases.

A Novel Lithocholic Acid Derivative Upregulates Detoxification-Related Genes in Human Induced Pluripotent Stem Cell-Derived Intestinal Organoids.

Vitamin D is a fat-soluble micronutrient that plays essential roles in a range of biological processes, including cell proliferation, inflammation, and metabolism. In this study, we investigated the effects of a novel synthetic lithocholic acid derivative with vitamin D activity (Dcha-20) on pharmacokinetic gene expression in human induced pluripotent stem cell-derived intestinal organoids. Compared with vitamin D treatment, Dcha-20 was found to upregulate the expression and enzyme activity of the drug-metabolizing enzyme CYP3A4, an indicator of intestinal functional maturation.

A reconstituted depolarization-induced Ca2+ release platform for validation of skeletal muscle disease mutations and drug discovery.

In skeletal muscle excitation-contraction (E-C) coupling, depolarization of the plasma membrane triggers Ca2+ release from the sarcoplasmic reticulum (SR), referred to as depolarization-induced Ca2+ release (DICR). DICR occurs through the type 1 ryanodine receptor (RyR1), which physically interacts with the dihydropyridine receptor Cav1.1 subunit in specific machinery formed with additional essential components including β1a, Stac3 adaptor protein, and junctophilins.

Development of a water-soluble ryanodine receptor 1 inhibitor.

Ryanodine receptor 1 (RyR1) is a Ca-release channel expressed on the sarcoplasmic reticulum (SR) membrane. RyR1 mediates release of Ca from the SR to the cytoplasm to induce muscle contraction, and mutations associated with overactivation of RyR1 cause lethal muscle diseases. Dantrolene sodium salt (dantrolene Na) is the only approved RyR inhibitor to treat malignant hyperthermia patients with RyR1 mutations, but is poorly water-soluble.

Mice with R2509C-RYR1 mutation exhibit dysfunctional Ca2+ dynamics in primary skeletal myocytes.

Type 1 ryanodine receptor (RYR1) is a Ca2+ release channel in the sarcoplasmic reticulum (SR) of the skeletal muscle and plays a critical role in excitation-contraction coupling. Mutations in RYR1 cause severe muscle diseases, such as malignant hyperthermia, a disorder of Ca2+-induced Ca2+ release (CICR) through RYR1 from the SR. We recently reported that volatile anesthetics induce malignant hyperthermia (MH)-like episodes through enhanced CICR in heterozygous R2509C-RYR1 mice.

Conformational Properties of Aromatic Amides Bearing Imidazole Ring and Acid-Induced - Amide Switching.

Aromatic amides bearing secondary amide bond exist in trans conformation both in the crystal and in solution, whereas the conformation of the -methylated derivatives is cis in the crystal and predominantly cis in various solvents. The cis conformational preference of -alkylated benzanilide provides access to aromatic foldamers such as oligo(-alkyl--benzamide)s, which adopt dynamic helical structures. Here, the conformational properties of imidazole-substituted amide in the crystal and in solution were examined.

LRBA is essential for urinary concentration and body water homeostasis.

Protein kinase A (PKA) directly phosphorylates aquaporin-2 (AQP2) water channels in renal collecting ducts to reabsorb water from urine for the maintenance of systemic water homeostasis. More than 50 functionally distinct PKA-anchoring proteins (AKAPs) respectively create compartmentalized PKA signaling to determine the substrate specificity of PKA. Identification of an AKAP responsible for AQP2 phosphorylation is an essential step toward elucidating the molecular mechanisms of urinary concentration.

Structural Development of Silicon-Containing Retinoids: Structure-Activity Relationship Study of the Hydrophobic Pharmacophore of Retinobenzoic Acids Using Silyl Functionalities.

We designed and synthesized a series of retinobenzoic acids bearing various silyl functionalities in order to explore in detail the structure-activity relationship (SAR) at the hydrophobic moiety of retinoids. Among the synthesized compounds, 24 c bearing a t-butyldimethylsilyl (TBS) group at the hydrophobic site exhibited potent retinoid activity comparable to that of the lead compound Am555S (4). Compound 24 c exhibited transcription-promoting activity towards all three subtypes of retinoic acid receptor (RAR), but showed the highest activity towards RARγ, in contrast to the high RARα-selectivity of Am80 (3) and Am555S (4).

Lithocholic Acid Amides as Potent Vitamin D Receptor Agonists.

1α,25-Dihydroxyvitamin D [1α,25(OH)D, ] is an active form of vitamin D and regulates various biological phenomena, including calcium and phosphate homeostasis, bone metabolism, and immune response via binding to and activation of vitamin D receptor (VDR). Lithocholic acid (LCA, ) was identified as a second endogenous agonist of VDR, though its potency is very low. However, the lithocholic acid derivative () is a more potent agonist than 1α,25(OH)D, (), and its carboxyl group has similar interactions to the 1,3-dihydroxyl groups of with amino acid residues in the VDR ligand-binding pocket.

ASKA technology-based pull-down method reveals a suppressive effect of ASK1 on the inflammatory NOD-RIPK2 pathway in brown adipocytes.

Recent studies have shown that adipose tissue is an immunological organ. While inflammation in energy-storing white adipose tissues has been the focus of intense research, the regulatory mechanisms of inflammation in heat-producing brown adipose tissues remain largely unknown. We previously identified apoptosis signal-regulating kinase 1 (ASK1) as a critical regulator of brown adipocyte maturation; the PKA-ASK1-p38 axis facilitates uncoupling protein 1 (UCP1) induction cell-autonomously.

Identification of a KLF5-dependent program and drug development for skeletal muscle atrophy.

Skeletal muscle atrophy is caused by various conditions, including aging, disuse related to a sedentary lifestyle and lack of physical activity, and cachexia. Our insufficient understanding of the molecular mechanism underlying muscle atrophy limits the targets for the development of effective pharmacologic treatments and preventions. Here, we identified Krüppel-like factor 5 (KLF5), a zinc-finger transcription factor, as a key mediator of the early muscle atrophy program.

A novel RyR1-selective inhibitor prevents and rescues sudden death in mouse models of malignant hyperthermia and heat stroke.

Mutations in the type 1 ryanodine receptor (RyR1), a Ca release channel in skeletal muscle, hyperactivate the channel to cause malignant hyperthermia (MH) and are implicated in severe heat stroke. Dantrolene, the only approved drug for MH, has the disadvantages of having very poor water solubility and long plasma half-life. We show here that an oxolinic acid-derivative RyR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (Compound 1, Cpd1), effectively prevents and treats MH and heat stroke in several mouse models relevant to MH.

Structural Development of Salicylanilide-Based SPAK Inhibitors as Candidate Antihypertensive Agents.

Hypertension is an important target for drug discovery. We have focused on the with-no-lysine kinase (WNK)-oxidative stress-responsive 1 (OSR1) and STE20/SPS1-related proline-alanine-rich protein kinase (SPAK)-NaCl cotransporter (NCC) signal cascade as a potential target, and we previously developed a screening system for inhibitors of WNK-OSR1/SPAK-NCC signaling. Herein we used this system to examine the structure-activity relationship (SAR) of salicylanilide derivatives as SPAK kinase inhibitors.

CSE1L promotes nuclear accumulation of transcriptional coactivator TAZ and enhances invasiveness of human cancer cells.

The transcriptional coactivator with PDZ-binding motif (TAZ) (WWTR1) induces epithelial-mesenchymal transition and enhances drug resistance in multiple cancers. TAZ has been shown to interact with transcription factors in the nucleus, but when phosphorylated, translocates to the cytoplasm and is degraded through proteasomes. Here, we identified a compound TAZ inhibitor 4 (TI-4) that shifted TAZ localization to the cytoplasm independently of its phosphorylation.