Impeding the interaction between Nur77 and p38 reduces LPS-induced inflammation.

Sepsis, a hyperinflammatory response that can result in multiple organ dysfunctions, is a leading cause of mortality from infection. Here, we show that orphan nuclear receptor Nur77 (also known as TR3) can enhance resistance to lipopolysaccharide (LPS)-induced sepsis in mice by inhibiting NF-κB activity and suppressing aberrant cytokine production. Nur77 directly associates with p65 to block its binding to the κB element. However, this function of Nur77 is countered by the LPS-activated p38α phosphorylation of Nur77. Dampening the interaction between Nur77 and p38α would favor Nur77 suppression of the hyperinflammatory response. A compound, n-pentyl 2-[3,5-dihydroxy-2-(1-nonanoyl) phenyl]acetate, screened from a Nur77-biased library, blocked the Nur77-p38α interaction by targeting the ligand-binding domain of Nur77 and restored the suppression of the hyperinflammatory response through Nur77 inhibition of NF-κB. This study associates the nuclear receptor with immune homeostasis and implicates a new therapeutic strategy to treat hyperinflammatory responses by targeting a p38α substrate to modulate p38α-regulated functions.

Orphan nuclear receptor TR3 acts in autophagic cell death via mitochondrial signaling pathway.

Autophagy is linked to cell death, yet the associated mechanisms are largely undercharacterized. We discovered that melanoma, which is generally resistant to drug-induced apoptosis, can undergo autophagic cell death with the participation of orphan nuclear receptor TR3. A sequence of molecular events leading to cellular demise is launched by a specific chemical compound, 1-(3,4,5-trihydroxyphenyl)nonan-1-one, newly acquired from screening a library of TR3-targeting compounds. The autophagic cascade comprises TR3 translocation to mitochondria through interaction with the mitochondrial outer membrane protein Nix, crossing into the mitochondrial inner membrane through Tom40 and Tom70 channel proteins, dissipation of mitochondrial membrane potential by the permeability transition pore complex ANT1-VDAC1 and induction of autophagy. This process leads to excessive mitochondria clearance and irreversible cell death. It implicates a new approach to melanoma therapy through activation of a mitochondrial signaling pathway that integrates a nuclear receptor with autophagy for cell death.

The orphan nuclear receptor Nur77 regulates LKB1 localization and activates AMPK.

Liver kinase B1 (LKB1) has important roles in governing energy homeostasis by regulating the activity of the energy sensor kinase AMP-activated protein kinase (AMPK). The regulation of LKB1 function, however, is still poorly understood. Here we demonstrate that the orphan nuclear receptor Nur77 binds and sequesters LKB1 in the nucleus, thereby attenuating AMPK activation. This Nur77 function is antagonized by the chemical compound ethyl 2-[2,3,4-trimethoxy-6-(1-octanoyl)phenyl]acetate (TMPA), which interacts with Nur77 with high affinity and at specific sites. TMPA binding of Nur77 results in the release and shuttling of LKB1 to the cytoplasm to phosphorylate AMPKα. Moreover, TMPA effectively reduces blood glucose and alleviates insulin resistance in type II db/db and high-fat diet- and streptozotocin-induced diabetic mice but not in diabetic littermates with the Nur77 gene knocked out. This study attains a mechanistic understanding of the regulation of LKB1-AMPK axis and implicates Nur77 as a new and amenable target for the design and development of therapeutics to treat metabolic diseases.

Enantioselective total syntheses of (-)-FR901483 and (+)-8-epi-FR901483.

The enantioselective total syntheses of the potent immunosuppressant FR901483 (1) and its 8-epimer (47) have been accomplished. Our approach features the use of building block 6 as the chiron, the application of the one-pot amide reductive bis-alkylation method to construct the chiral aza-quaternary center (dr = 9:1), regio- and diastereoselective intramolecular aldol reaction to build the bridged ring, and RCM to form the 3-pyrrolin-2-one ring.

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A.

A concise enantioselective synthesis of the advanced intermediate 5 for the synthesis of pumiliotoxins (Gallagher's intermediate) is described. The synthesis started from the regio- and trans-diastereoselective (dr = 98:2) reductive 3-butenylation of (R)-3-(tert-butyldimethylsilyloxy)glutarimide 14. After O-desilylation and Dess-Martin oxidation, the resulting keto-lactam 10 was subjected to a highly trans-stereoselective addition of the methylmagnesium iodide to give carbinol 11 as sole diastereomer. An efficient ring closure procedure consisting of ozonolysis and reductive dehydroxylation provided the indolizidine derivative 5, which completed the formal enantioselective total synthesis of pumiliotoxins 251D and 237A.

Calcium dobesilate-induced hyperpyrexia: A case report.

RATIONALE: Calcium dobesilate, a vasoprotective and antioxidant agent, is gradually being used for the treatment of chronic kidney disease. Calcium dobesilate-induced hyperpyrexia is a rare clinical event, and few studies have reported it. PATIENT CONCERNS: The patient took calcium dobesilate, which caused high fever. After stopping calcium dobesilate, his body temperature returned to normal. DIAGNOSES: Based on the medical history, symptoms and signs, the patient was diagnosed with drug fever caused by calcium dobesilate. INTERVENTIONS: Calcium dobesilate was stopped, and supportive treatment was given at the same time. OUTCOMES: The present case was initially misdiagnosed as a fever caused by a bacterial infection, but treatment with the antibiotic moxifloxacin was ineffective. Based on the patient's medical history, laboratory and examination results, body temperature changes, and Naranjo Advanced Drug Response Scale, calcium dobesilate-induced hyperpyrexia was diagnosed. After discontinuation of calcium dobesilate, the patient's body temperature normalized, and no additional episode of fever was observed at follow-up. LESSON: Moreover, misdiagnosis and mistreatment of this condition can deteriorate the patient's condition. Herein, we report a case of calcium dobesilate-induced hyperpyrexia that occurred during the treatment of chronic renal insufficiency. Subsequently, a systematic analysis of the patient's diagnosis and treatment was reviewed. If unexplained high fever develops during the use of calcium dobesilate, calcium dobesilate-induced hyperpyrexia should be considered. Accordingly, calcium dobesilate should be discontinued.

4-Bromo-2-chloro-aniline.

The title compound, C(6)H(5)BrClN, is almost planar (r.m.s. deviation = 0.018 Å). In the crystal, mol-ecules are linked by inter-molecular N-H⋯N and weak N-H⋯Br hydrogen bonds, generating sheets.

A formal enantioselective total synthesis of FR901483.

A formal enantioselective total synthesis of the potent immunosuppressant FR901483 (1) has been accomplished. Our approach features the use of chiron 6 as the starting material, the application of the one-pot amide reductive bisalkylation method to construct the chiral aza-quaternary center (dr = 9:1), regio- and diastereoselective intramolecular aldol reaction to build the bridged ring, and ring closing metathesis to form the 3-pyrrolin-2-one ring.

Enantioselective syntheses of rigidiusculamides A and B: revision of the relative stereochemistry of rigidiusculamide A.

The first enantioselective synthesis of cytotoxic natural products rigidiusculamides A (ent-21) and B (8) has been achieved by two synthetic routes. The first one is convergent based on the common intermediate 11, obtained through a high yielding SmI(2) -mediated Reformatsky-type reaction. A highly diastereoselective one-pot Dess-Martin periodinane-mediated bis-oxidation allowed the direct conversion of the diastereomeric mixture of 11 into rigidiusculamide B (8). Isolation of minor diastereomer 21, in combination with computational work, allowed us to suggest the structure of the natural rigidiusculamide A to be ent-21, as synthesized by the second route. Four diastereomers (7, ent-7, 22a, and 22b) and an enantiomer (21) of rigidiusculamide A (ent-21) have been synthesized. On the basis of literature precedents and computational work, a biosynthetic pathway for rigidiusculamides A and B was proposed to account for the opposite configuration at C-5 of those two congeners.

A unique pharmacophore for activation of the nuclear orphan receptor Nur77 in vivo and in vitro.

Nur77 is a steroid orphan receptor that plays a critical role in regulating proliferation, differentiation, and apoptosis, including acting as a switch for Bcl-2 function. We previously reported that the octaketide cytosporone B (Csn-B) is a natural agonist for Nur77. In this study, we synthesized a series of Csn-B analogues and performed a structure-activity analysis that suggested criteria for the development of a unique pharmacophore to activate Nur77. The components of the pharmacophore necessary for binding Nur77 included the benzene ring, the phenolic hydroxyl group, and the acyl chain of the Csn-B scaffold, whereas the key feature for activating the biological function of Nur77 was the ester group. Csn-B analogues that bound Nur77 tightly not only stimulated its transactivation activity but also initiated mitochondrial apoptosis by means of novel cross-talk between Nur77 and BRE, an antiapoptotic protein regulated at the transcriptional level. Notably, the derivative n-amyl 2-[3,5-dihydroxy-2-(1-nonanoyl)phenyl]acetate exhibited greater antitumor activity in vivo than its parent compounds, highlighting particular interest in this compound. Our findings describe a pathway for rational design of Csn-B-derived Nur77 agonists as a new class of potent and effective antitumor agents.

A ratiometric fluorescent sensor for Ag(I) with high selectivity and sensitivity.

A bicyclic cycloadduct 1 bearing a pyrenyl moiety has been synthesized and investigated as a ratiometric fluorescent sensor for AgI. In an aqueous ethanol solution of 1, the presence of silver ion induces the formation of a 1:2 metal-ligand complex, which exhibits a strong intensity enhancement of the pyrene excimer emission at the expense of the emission of monomeric pyrene.