Relevance of ceramide 1-phosphate domain formation in activation of cytosolic phospholipase A.

Ceramide 1-phosphate (C1P), as a lipid mediator, specifically binds and activates cytosolic phospholipase Aα (cPLAα). Previous findings revealed that modification of the specific hydrophobic moiety decreases the affinity with cPLAα. However, the possible biological role of the temporal C1P-enriched domains formed in biomembranes for the molecular recognition of cPLAα has not been fully elucidated.

Design, synthesis of ceramide 1-phosphate analogs and their affinity for cytosolic phospholipase A as evidenced by surface plasmon resonance.

Ceramide 1-phosphate (C1P) is a lipid mediator that specifically binds and activates cytosolic phospholipase Aα (cPLAα). To elucidate the structure-activity relationship of the affinity of C1P for cPLAα in lipid environments, we prepared a series of C1P analogs containing structural modifications in the hydrophilic parts and subjected them to surface plasmon resonance (SPR). The results suggested the presence of a specific binding site for cPLAα on the amide, 3-OH and phosphate groups in C1P structure.

SYNTHESIS OF PROBE MOLECULES, 6-(DIMETHYLAMINO)-2-PHENYLISOINDOLIN-1-ONES, FOR MECHANISTIC STUDIES OF FIREFLY LUCIFERASE INHIBITION.

Firefly luciferase is used in high-throughput screening based on the detection of chemiluminescence. It catalyzes an esterification reaction of luciferin with adenosine 5'-triphosphate (ATP) followed by decarbonylation with oxygen and concomitance of light. Previously, we reported that firefly luciferase also possesses acyl-CoA synthetase activity and catalyzes an aromatic carboxylic acid group of F-53, using ATP, Mg and coenzyme A (CoA), to produce F-53 covalently attached to active-site lysine-529 residue of firefly luciferase through the formation of an amide group.

Endocrine disrupting chemicals, 4-nonylphenol, bisphenol A and butyl benzyl phthalate, impair metabolism of estradiol in male and female rats as assessed by levels of 15α-hydroxyestrogens and catechol estrogens in urine.

Bisphenol A (BPA), 4-nonylphenol (NP) and butyl benzyl phthalate (BBP), termed endocrine-disrupting chemicals, are known to mimic estrogen activity. The effects of these chemicals on 17β-estradiol (E ) metabolism in vivo in rats were examined. Male and female rats were given NP (250 mg kg  day ), BPA (250 μg kg  day ) or BBP (500 mg kg  day ) by gavage for 14 days, followed by a single intraperitoneal injection of E (5 mg kg ) on the final day.

Alpha-1 antichymotrypsin is involved in astrocyte injury in concert with arginine-vasopressin during the development of acute hepatic encephalopathy.

Background And Aims: We developed a bio-artificial liver (BAL) using a radial-flow bioreactor and rescued mini-pig models with lethal acute liver failure (ALF). The point of the rescue is the recovery from hepatic encephalopathy (HE). HE on ALF has sometimes resulted in brain death following brain edema with astrocyte swelling.

Determination of urinary 15α-hydroxyestrogen levels via immunoaffinity extraction.

15α-Hydroxyestrogens (15α-OHEs) are metabolites of the female hormone estradiol. In this study, to discover physiological markers that can be utilized for monitoring fetal conditions and estrogen-induced cancers, we established a method for quantifying 15α-OHEs in rat urine via immunoaffinity column extraction and HPLC-electrochemical detection, and detected 15α-OHEs in urine obtained male rats treated with estradiol. Notably, the standard curves for quantification obtained using the column were linear over a range of 0.

Cooperative therapeutic action of retinoic acid receptor and retinoid x receptor agonists in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative process involving amyloid-β (Aβ) peptide deposition, neuroinflammation, and progressive memory loss. Here, we evaluated whether oral administration of retinoic acid receptor (RAR)α,β agonist Am80 (tamibarotene) or specific retinoid X receptor (RXR) pan agonist HX630 or their combination could improve deficits in an AD model, 8.5-month-old amyloid-β protein precursor 23 (AβPP23) mice.

Structure-activity relationship-guided development of retinoic acid receptor-related orphan receptor gamma (RORγ)-selective inverse agonists with a phenanthridin-6(5H)-one skeleton from a liver X receptor ligand.

Retinoic acid receptor-related orphan receptors (RORs), which belong to the nuclear receptor superfamily, regulate many physiological processes, including hepatic gluconeogenesis, lipid metabolism, immune function and circadian rhythm. Since RORs resemble liver X receptors (LXRs) in the fold structure of their ligand-binding domains, we speculated that ROR-mediated transcription might be modulated by LXR ligands, in line with the multi-template hypothesis. Therefore, we screened our LXR ligand library for compounds with ROR ligand activity and identified a novel ROR ligand with a phenanthridin-6(5H)-one skeleton.

Development of novel silicon-containing inverse agonists of retinoic acid receptor-related orphan receptors.

Retinoic acid receptor (RAR)-related orphan receptors (RORs) regulate a variety of physiological processes, including hepatic gluconeogenesis, lipid metabolism, circadian rhythm and immune function. The RAR agonist: all-trans retinoic acid was reported to be an RORβ inverse agonist, but no information is available regarding ROR activity of its synthetic analogue Am580. Therefore, we screened Am580 and some related tetramethyltetrahydronaphthalene derivatives and carried out structural development studies, including substitution of carbon atoms with silicon, with the aim of creating a potent ROR transcriptional inhibitor.

A novel aromatic carboxylic acid inactivates luciferase by acylation of an enzymatically active regulatory lysine residue.

Firefly luciferase (Luc) is widely used as a reporter enzyme in cell-based assays for gene expression. A novel aromatic carboxylic acid, F-53, reported here for the first time, substantially inhibited the enzymatic activity of Luc in a Luc reporter screening. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry (MS/MS) analyses showed that F-53 modifies Luc at lysine-529 via amidation of the F-53 carboxyl group.

Design, synthesis and evaluation of retinoids with novel bulky hydrophobic partial structures.

Many synthetic retinoids contain an aromatic structure with a bulky hydrophobic fragment. In order to obtain retinoids with therapeutic potential that do not bind to or activate retinoic acid X receptors (RXRs), we focused on the introduction of novel hydrophobic moieties, that is, metacyclophane, phenalene and benzoheptalene derivatives. The designed compounds were synthesized and their agonistic activities towards RARs and RXRs were evaluated.

The retinoic acid receptor agonist Am80 increases hippocampal ADAM10 in aged SAMP8 mice.

The retinoic acid (RA, a vitamin A metabolite) receptor (RAR) is a transcription factor. Vitamin A/RA administration improves the Alzheimer's disease (AD)- and age-related attenuation of memory/learning in mouse models. Recently, a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) was identified as a key molecule in RA-mediated anti-AD mechanisms.

Synthetic retinoid Am80 results in improved exploratory and emotional behavior in the P8 substrain of senescence-accelerated mice.

Am80 is a synthetic retinoid that has been used clinically for patients with acute promyelocytic leukemia and has been reported to affect the brain and its neurons. We investigated the influence of Am80 on anti-anxiety-like behavior, which is a characteristic of age-associated emotional disorder, in the P8 strain of senescence-accelerated mice (SAMP8). Am80 at a concentration of 2 mg/kg/day was administered to the mice in their feed for 1.

Tamibarotene: a candidate retinoid drug for Alzheimer's disease.

Tamibarotene (Am80), a synthetic retinoid approved in Japan for treatment of acute promyelocytic leukemia (APL), is a retinoic acid receptor (RAR) agonist with high specificity for RARα and RARβ over RARγ. Temporarily and spatially specific expression of RARs suggests their pivotal roles in the adult brain. Am80 is considered to be a promising candidate drug for treatment of Alzheimer's disease (AD) because of its transcriptional controls of multiple target genes involved in etiology and pathology of AD.

Retinoic acid receptor antagonist LE540 attenuates wakefulness via the dopamine D1 receptor in mice.

Vitamin A is a common lipophilic vitamin, and its function is mainly mediated by the binding of its metabolite retinoic acid to retinoic acid receptors (RARs) and retinoid X receptors. Recently, it was reported that the expression of the RARb (an RAR subtype) gene determines the contribution of the delta oscillation in the sleep electroencephalogram (EEG) patterns in mice. We also reported that 4-week dietary deficiency of vitamin A (VAD) causes the attenuation of delta power in sleep and spontaneous activity in mice.

Oral administration of synthetic retinoid Am80 (Tamibarotene) decreases brain beta-amyloid peptides in APP23 mice.

The purpose of this study is to investigate whether a synthetic retinoid Am80 (tamibarotene) exhibits any improving effects on amyloid precursor protein (APP)23 mice, a model of Alzheimer's disease. Am80 was orally administered in feed to 20-week (5-month)-old APP23 mice at a dose of 0 (control) or 0.5 mg/kg/d for 14 weeks.

Repressive domain of unliganded human estrogen receptor alpha associates with Hsc70.

Estrogen receptor (ER) is a hormone-inducible transcription factor as a member of the nuclear receptor gene superfamily. Unliganded ER is transcriptionally silent and capable of DNA binding; however, it is unable to suppress the basal activity of the target gene promoters, unlike non-steroid hormone receptors that associate with corepressors in the absence of their cognate ligands. To study the molecular basis of how unliganded human ERalpha is maintained silent in gene regulation upon the target gene promoters, we biochemically searched interactants for hERalpha, and identified heat shock protein 70 (Hsc70).

Intrauterine position and postnatal growth in Sprague-Dawley rats and ICR mice.

In rodents, steroid hormones are thought to be transported between adjacent fetuses, and male or female fetuses that develop in utero between female fetuses may have higher serum levels of estradiol, and lower serum levels of testosterone, relative to siblings of the same sex that develop between two male fetuses. The consequence in the variation of postnatal growth, development, and function in the intrauterine position, using various parameters such as anogenital distance, preputial separation and vaginal opening, estrous cycle, locomotor activity, and growth of reproductive organs, were examined in Sprague-Dawley rats. ICR mice were treated with 17beta-estradiol before copulation and during pregnancy to address the interaction with endogenous estradiol during pregnancy.

Nuclear receptor function requires a TFTC-type histone acetyl transferase complex.

Nuclear receptors (NRs) regulate transcription in a ligand-dependent way through two types of coactivator complexes: the p160/CBP histone acetyl transferase (HAT) complex and the DRIP/TRAP/SMCC complex without HAT activity. Here we identified a large human (h) coactivator complex necessary for the estrogen receptor alpha (ERalpha) transactivation. This complex contains the GCN5 HAT, the c-Myc interacting protein TRRAP/PAF400, TAF(II)30, and other subunits.