SphK (sphingosine kinase) is the major source of the bioactive lipid and GPCR (G-protein-coupled receptor) agonist S1P (sphingosine 1-phosphate). S1P promotes cell growth, survival and migration, and is a key regulator of lymphocyte trafficking. Inhibition of S1P signalling has been proposed as a strategy for treatment of inflammatory diseases and cancer. In the present paper we describe the discovery and characterization of PF-543, a novel cell-permeant inhibitor of SphK1. PF-543 inhibits SphK1 with a K(i) of 3.6 nM, is sphingosine-competitive and is more than 100-fold selective for SphK1 over the SphK2 isoform. In 1483 head and neck carcinoma cells, which are characterized by high levels of SphK1 expression and an unusually high rate of S1P production, PF-543 decreased the level of endogenous S1P 10-fold with a proportional increase in the level of sphingosine. In contrast with past reports that show that the growth of many cancer cell lines is SphK1-dependent, specific inhibition of SphK1 had no effect on the proliferation and survival of 1483 cells, despite a dramatic change in the cellular S1P/sphingosine ratio. PF-543 was effective as a potent inhibitor of S1P formation in whole blood, indicating that the SphK1 isoform of sphingosine kinase is the major source of S1P in human blood. PF-543 is the most potent inhibitor of SphK1 described to date and it will be useful for dissecting specific roles of SphK1-driven S1P signalling.

Supplementary key words cholesterol • diagnostic tools • liquid chromatography/tandem mass spectrometry • Niemann-Pick disease • oxysterols • neurodegenerationNiemann-Pick type C (NPC) disease is a rare, primarily pediatric disorder characterized by accumulation of cholesterol and other lipids in the viscera and central nervous system. Approximately 95% of NPC cases are caused by mutations of the NPC1 gene, whereas the remaining 5% are caused by mutations in the NPC2 gene ( 1, 2 ). Affected individuals typically present in early childhood with ataxia and progressive impairment of motor and intellectual function and usually die in adolescence. There are currently no FDA-approved therapies for this progressively fatal neurodegenerative disorder. However, a recent controlled study and a series of case reports suggests effi cacy for miglustat ( 3 ), an inhibitor of glycosphingolipid biosynthesis that is now licensed for use as a disease modifying therapy in multiple countries, including the European Union, Russia, Brazil, Australia, Canada, and Taiwan.Abstract Niemann-Pick type C1 (NPC1) disease is a rare, progressively fatal neurodegenerative disease for which there are no FDA-approved therapies. A major barrier to developing new therapies for this disorder has been the lack of a sensitive and noninvasive diagnostic test. Recently, we demonstrated that two cholesterol oxidation products, specifi cally cholestane-3 ␤ ,5 ␣ ,6 ␤ -triol (3 ␤ ,5 ␣ ,6 ␤ -triol) and 7-ketocholesterol (7-KC), were markedly increased in the plasma of human NPC1 subjects, suggesting a role for these oxysterols in diagnosis of NPC1 disease and evaluation of therapeutics in clinical trials. In the present study, we describe the development of a sensitive and specifi c LC-MS/ MS method for quantifying 3 ␤ ,5 ␣ ,6 ␤ -triol and 7-KC human plasma after derivatization with N,N-dimethylglycine. We show that dimethylglycine derivatization successfully enhanced the ionization and fragmentation of 3 ␤ ,5 ␣ ,6 ␤ -triol and 7-KC for mass spectrometric detection of the oxysterol species in human plasma. The oxysterol dimethylglycinates were resolved with high sensitivity and selectivity, and enabled accurate quantifi cation of 3 ␤ ,5 ␣ ,6 ␤ -triol and 7-KC concentrations in human plasma. The LC-MS/MS assay was able to discriminate with high sensitivity and specifi city between control and NPC1 subjects, and offers for the fi rst time a noninvasive, rapid, and highly sensitive method for diagnosis of NPC1

In the gibberellin (GA) biosynthesis pathway, 20-oxidase catalyzes the oxidation and elimination of carbon-20 to give rise to C 19 -GAs. All bioactive GAs are C 19 -GAs. We have overexpressed a cDNA encoding 20-oxidase isolated from Arabidopsis seedlings in transgenic Arabidopsis plants. These transgenic plants display a phenotype that may be attributed to the overproduction of GA. The phenotype includes a longer hypocotyl, lighter-green leaves, increased stem elongation, earlier flowering, and decreased seed dormancy. However, the fertility of the transgenic plants is not affected. Increased levels of endogenous GA 1 , GA 9 , and GA 20 were detected in seedlings of the transgenic line examined. GA 4 , which is thought to be the predominantly active GA in Arabidopsis, was not present at increased levels in this line. These results suggest that the overexpression of this 20-oxidase increases the levels of some endogenous GAs in transgenic seedlings, which causes the GAoverproduction phenotype.

Among the known genetic risk factors for Parkinson disease, mutations in GBA1, the gene responsible for the lysosomal disorder Gaucher disease, are the most common. This genetic link has directed attention to the role of the lysosome in the pathogenesis of parkinsonism. To study how glucocerebrosidase impacts parkinsonism and to evaluate new therapeutics, we generated induced human pluripotent stem cells from four patients with Type 1 (non-neuronopathic) Gaucher disease, two with and two without parkinsonism, and one patient with Type 2 (acute neuronopathic) Gaucher disease, and differentiated them into macrophages and dopaminergic neurons. These cells exhibited decreased glucocerebrosidase activity and stored the glycolipid substrates glucosylceramide and glucosylsphingosine, demonstrating their similarity to patients with Gaucher disease. Dopaminergic neurons from patients with Type 2 and Type 1 Gaucher disease with parkinsonism had reduced dopamine storage and dopamine transporter reuptake. Levels of ␣-synuclein, a protein present as aggregates in Parkinson disease and related synucleinopathies, were selectively elevated in neurons from the patients with parkinsonism or Type 2 Gaucher disease. The cells were then treated with NCGC607, a small-molecule noninhibitory chaperone of glucocerebrosidase identified by high-throughput screening and medicinal chemistry structure optimization. This compound successfully chaperoned the mutant enzyme, restored glucocerebrosidase activity and protein levels, and reduced glycolipid storage in both iPSC-derived macrophages and dopaminergic neurons, indicating its potential for treating neuronopathic Gaucher disease. In addition, NCGC607 reduced ␣-synuclein levels in dopaminergic neurons from the patients with parkinsonism, suggesting that noninhibitory small-molecule chaperones of glucocerebrosidase may prove useful for the treatment of Parkinson disease. Key words: ␣-synuclein; dopaminergic neurons; glucocerebrosidase; induced pluripotent stem cells; parkinsonism; pharmacological chaperone Significance StatementBecause GBA1 mutations are the most common genetic risk factor for Parkinson disease, dopaminergic neurons were generated from iPSC lines derived from patients with Gaucher disease with and without parkinsonism. These cells exhibit deficient enzymatic activity, reduced lysosomal glucocerebrosidase levels, and storage of glucosylceramide and glucosylsphingosine. Lines generated from the patients with parkinsonism demonstrated elevated levels of ␣-synuclein. To reverse the observed phenotype, the neurons were treated with a novel noninhibitory glucocerebrosidase chaperone, which successfully restored glucocerebrosidase activity and protein levels and reduced glycolipid storage. In addition, the small-molecule chaperone reduced ␣-synuclein levels in dopaminergic neurons, indicating that chaperoning glucocerebrosidase to the lysosome may provide a novel therapeutic strategy for both Parkinson disease and neuronopathic forms of Gaucher disease.

Diseases of the liver related to metabolic syndrome have emerged as the most common and undertreated hepatic ailments. The cause of nonalcoholic fatty liver disease (NAFLD) is the aberrant accumulation of lipid in hepatocytes, though the mechanisms whereby this leads to hepatocyte dysfunction, death, and hepatic fibrosis are still unclear. Insulin-sensitizing thiazolidinediones have shown efficacy in treating nonalcoholic steatohepatitis (NASH), but their widespread use is constrained by dose-limiting side effects thought to be due to activation of the peroxisome proliferator-activated receptor γ (PPARγ). We sought to determine whether a next-generation thiazolidinedione with markedly diminished ability to activate PPARγ (MSDC-0602) would retain its efficacy for treating NASH in a rodent model. We also determined whether some or all of these beneficial effects would be mediated via an inhibitory interaction with the mitochondrial pyruvate carrier 2 (MPC2), which was recently identified as a mitochondrial binding site for thiazolidinediones, including MSDC-0602. We found that MSDC-0602 prevented and reversed liver fibrosis and suppressed expression of markers of stellate cell activation in livers of mice fed a diet rich in trans-fatty acids, fructose, and cholesterol. Moreover, mice with liver-specific deletion of MPC2 were protected from development of NASH on this diet. Finally, MSDC-0602 directly reduced hepatic stellate cell activation in vitro, and MSDC-0602 treatment or hepatocyte MPC2 deletion also limited stellate cell activation indirectly by affecting secretion of exosomes from hepatocytes. Conclusion Collectively, these data demonstrate the effectiveness of MSDC-0602 for attenuating NASH in a rodent model and suggest that targeting hepatic MPC2 may be an effective strategy for pharmacologic development.

Niemann-Pick Type C1 (NPC1) disease is a rare neurovisceral, cholesterol-sphingolipid lysosomal storage disorder characterized by ataxia, motor impairment, progressive intellectual decline, and dementia. The most prevalent mutation, NPC1I1061T , encodes a misfolded protein with a reduced half-life caused by ER-associated degradation. Therapies directed at stabilization of the mutant NPC1 protein reduce cholesterol storage in fibroblasts but have not been tested in vivo because of lack of a suitable animal model. Whereas the prominent features of human NPC1 disease are replicated in the null Npc1 Ϫ/Ϫ mouse, this model is not amenable to examining proteostatic therapies. The objective of the present study was to develop an NPC1 I1061T knock-in mouse in which to test proteostatic therapies. Compared with the Npc1Ϫ/Ϫ mouse, this Npc1 tm(I1061T)Dso model displays a less severe, delayed form of NPC1 disease with respect to weight loss, decreased motor coordination, Purkinje cell death, lipid storage, and premature death. The murine NPC1I1061T protein has a reduced half-life in vivo, consistent with protein misfolding and rapid ER-associated degradation, and can be stabilized by histone deacetylase inhibition. This novel mouse model faithfully recapitulates human NPC1 disease and provides a powerful tool for preclinical evaluation of therapies targeting NPC1 protein variants with compromised stability.

Excess circulating uric acid, a product of hepatic glycolysis and purine metabolism, often accompanies metabolic syndrome. However, whether hyperuricemia contributes to development of metabolic syndrome or is merely a by-product of other processes that cause this disorder has not been resolved. Additionally, how uric acid is cleared from the circulation is incompletely understood. Here, we present a genetic model of spontaneous, early-onset metabolic syndrome in mice lacking the enterocyte urate transporter Glut9 (encoded by the SLC2A9 gene). Glut9-deficient mice develop impaired enterocyte uric acid transport kinetics, hyperuricemia, hyperuricosuria, spontaneous hypertension, dyslipidemia, and elevated body fat. Allopurinol, a xanthine oxidase inhibitor, can reverse the hypertension and hypercholesterolemia. These data provide evidence that hyperuricemia per se could have deleterious metabolic sequelae. Moreover, these findings suggest that enterocytes may regulate whole-body metabolism, and that enterocyte urate metabolism could potentially be targeted to modulate or prevent metabolic syndrome.

Background: Ceramide is a critical lipid mediator of cellular stress responses relating to inflammation and insulin resistance. Results: Palmitate and LPS synergistically induce macrophage de novo ceramide biosynthesis. Conclusion: TLR4 signaling via TRIF and MyD88 in combination with palmitate up-regulates ceramide synthesis through a non-transcriptional mechanism. Significance: Understanding how lipid excess intersects with inflammatory signaling may provide insights into the pathogenesis of metabolic disease.