1.Treatment with TO901317, a synthetic liver X receptor agonist, reduces brain damage and attenuates neuroinflammation in experimental intracerebral hemorrhage.
Wu CH1,2, Chen CC3, Lai CY1,2, Hung TH4, Lin CC3, Chao M5, Chen SF6,7. J Neuroinflammation. 2016 Mar 11;13(1):62. doi: 10.1186/s12974-016-0524-8.
BACKGROUND: Intracerebral hemorrhage (ICH) induces a series of inflammatory processes that contribute to neuronal damage and neurological deterioration. Liver X receptors (LXRs) are nuclear receptors that negatively regulate transcriptional processes involved in inflammatory responses, but their role in the pathology following ICH remains unclear. The present study investigated the neuroprotective effects and anti-inflammatory actions of TO901317, a synthetic LXR agonist, in a model of collagenase-induced ICH and in microglial cultures.
2.Thrombin Augments LPS-Induced Human Endometrial Endothelial Cell Inflammation via PAR1 Activation.
Mhatre MV1, Potter JA1, Lockwood CJ2, Krikun G1, Abrahams VM1. Am J Reprod Immunol. 2016 Apr 24. doi: 10.1111/aji.12517. [Epub ahead of print]
PROBLEM: Risk factors for preterm birth include placental abruption, giving rise to excessive decidual thrombin, and intrauterine bacterial infection. Human endometrial endothelial cells (HEECs) express Toll-like receptors (TLRs), and infection-derived agonists trigger HEECs to generate specific inflammatory responses. As thrombin, in addition to inducing coagulation, can contribute to inflammation, its effect on HEEC inflammatory responses to the TLR4 agonist, bacterial lipopolysaccharide (LPS), was investigated.
3.Allosteric Partial Inhibition of Monomeric Proteases. Sulfated Coumarins Induce Regulation, not just Inhibition, of Thrombin.
Verespy Iii S1,2, Mehta AY1,3, Afosah D1,3, Al-Horani RA1,3, Desai UR1,3. Sci Rep. 2016 Apr 7;6:24043. doi: 10.1038/srep24043.
Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated coumarins to discover two agents that display sub-maximal efficacy (~50%), high potency (<500 nM) and high selectivity for thrombin (>150-fold). Michaelis-Menten, competitive inhibition, and site-directed mutagenesis studies identified exosite 2 as the site of binding for the most potent sulfated coumarin. Stern-Volmer quenching of active site-labeled fluorophore suggested that the allosteric regulators induce intermediate structural changes in the active site as compared to those that display ~80-100% efficacy.
4.Featured Article: Differential regulation of endothelial nitric oxide synthase phosphorylation by protease-activated receptors in adult human endothelial cells.
Tillery LC1, Epperson TA2, Eguchi S3, Motley ED4. Exp Biol Med (Maywood). 2016 Mar;241(6):569-80. doi: 10.1177/1535370215622584. Epub 2016 Jan 4.
Protease-activated receptors have been shown to regulate endothelial nitric oxide synthase through the phosphorylation of specific sites on the enzyme. It has been established that PAR-2 activation phosphorylates eNOS-Ser-1177 and leads to the production of the potent vasodilator nitric oxide, while PAR-1 activation phosphorylates eNOS-Thr-495 and decreases nitric oxide production in human umbilical vein endothelial cells. In this study, we hypothesize a differential coupling of protease-activated receptors to the signaling pathways that regulates endothelial nitric oxide synthase and nitric oxide production in primary adult human coronary artery endothelial cells. Using Western Blot analysis, we showed that thrombin and the PAR-1 activating peptide, TFLLR, lead to the phosphorylation of eNOS-Ser-1177 in human coronary artery endothelial cells, which was blocked by SCH-79797 (SCH), a PAR-1 inhibitor. Using the nitrate/nitrite assay, we also demonstrated that the thrombin- and TFLLR-induced production of nitric oxide was inhibited by SCH and L-NAME, a NOS inhibitor.
