Activation of lipid-burning pathways in the fat-storing white adipose tissue (WAT) is a promising strategy to improve metabolic health and reduce obesity, insulin resistance, and type II diabetes. For unknown reasons, bilirubin levels are negatively associated with obesity and diabetes. Here, using mice and an array of approaches, including MRI to assess body composition, biochemical assays to measure bilirubin and fatty acids, MitoTracker-based mitochondrial analysis, immunofluorescence, and high-throughput coregulator analysis, we show that bilirubin functions as a molecular switch for the nuclear receptor transcription factor peroxisome proliferator–activated receptor α (PPARα). Bilirubin exerted its effects by recruiting and dissociating specific coregulators in WAT, driving the expression of PPARα target genes such as uncoupling protein 1 (Ucp1) and adrenoreceptor β 3 (Adrb3). We also found that bilirubin is a selective ligand for PPARα and does not affect the activities of the related proteins PPARγ and PPARδ. We further found that diet-induced obese mice with mild hyperbilirubinemia have reduced WAT size and an increased number of mitochondria, associated with a restructuring of PPARα-binding coregulators. We conclude that bilirubin strongly affects organismal body weight by reshaping the PPARα coregulator profile, remodeling WAT to improve metabolic function, and reducing fat accumulation.

A 14-step biomimetic synthetic route to glyceollin I (1.5% overall yield) was developed and deployed to produce the natural enantiomeric form in soy, its unnatural stereoisomer, and a racemic mixture. Enantiomeric excess was assessed by asymmetric NMR shift reagents and chiral HPLC. Antiproliferative effects were measured in human breast, ovarian, and prostate cancer cell lines, with all three chiral forms exhibiting growth inhibition (GI) in the low to mid μM range for all cells. The natural enantiomer, and in some cases the racemate, gave significantly greater GI than the unnatural stereoisomer for estrogen receptor positive (ER(+)) versus ER(-) breast/ovarian cell lines as well as for androgen receptor positive (AR(+)) versus AR(-) prostate cancer cells. Surprisingly, differences between ER(+) and ER(-) cell lines were not altered by media estrogen conditions. These results suggest the antiproliferative mechanism of glyceollin I stereoisomers may be more complicated than strictly ER interactions.

BackgroundSynthetic indolyl- pyridinyl- propenones (IPPs) induce methuosis, a form of non-apoptotic cell death, in glioblastoma and other cancer cell lines. Methuosis is characterized by accumulation of cytoplasmic vacuoles derived from macropinosomes and late endosomes, followed by metabolic failure and rupture of the plasma membrane. However, not all IPPs that cause vacuolization are cytotoxic. The main goals of the present study were to identify key signaling pathways that contribute to methuosis induced by cytotoxic IPPs and to evaluate the anti-tumor potential of a prototype IPP in vivo.MethodsWe utilized metabolic flux analysis, glucose uptake, immunoblotting, and selective pharmacological inhibitors to compare the effects of closely related cytotoxic and non-cytotoxic IPPs in cultured glioblastoma cells. To determine whether the use of methuosis-inducing IPPs might be feasible in a therapeutic context, we quantified the distribution of our lead IPP compound, MOMIPP, in mouse plasma and brain, and tested its ability to inhibit tumor growth in an intracerebral glioblastoma xenograft model.ResultsThe cytotoxic IPP compound, MOMIPP, causes early disruptions of glucose uptake and glycolytic metabolism. Coincident with these metabolic changes, MOMIPP selectively activates the JNK1/2 stress kinase pathway, resulting in phosphorylation of c-Jun, Bcl-2 and Bcl-xL. At the same concentration, the non-cytotoxic analog, MOPIPP, does not activate these pathways. Pharmacologic inhibition of JNK activity promotes survival, even when cells are extensively vacuolated, but suppression of c-Jun transcriptional activity offers no protection. MOMIPP readily penetrates the blood-brain barrier and is moderately effective in suppressing progression of intracerebral glioblastoma xenografts.ConclusionsThe results suggest that interference with glucose uptake and induction of JNK-mediated phosphorylation of pro-survival members of the Bcl-2 family represent key events in the methuosis death process. In addition to providing new insights into the underlying molecular mechanism of methuosis, the results indicate that compounds of the cytotoxic IPP class may have potential for further development as therapeutic agents for brain tumors.Electronic supplementary materialThe online version of this article (10.1186/s12885-019-5288-y) contains supplementary material, which is available to authorized users.

The ab initio MP2 and DFT/B3LYP quantum chemical methods applying the 6-311++G** basis set are equally useful for the conformational analysis of simple esters and thioesters. Calculated equilibrium geometric values were close to the experimental ones for the cis methyl acetate and methyl thioformate. Barriers to the OC−X−C rotation in methyl acetate (X = O) and methyl thioacetate (X = S) were calculated at 11−13 kcal/mol with both methods. Both oxo- and thioesters favor the OC−X−C cis, planar form. Solvent effects were estimated by using the polarizable continuum dielectric method (PCM). The cis form was found as the prevailing conformation for both the oxo- and thioesters in chloroform, acetone, acetonitrile, and water. The trans CH3−CH2−CO structure (with cis OC−X−C ester moiety) is a transition state both in methyl propanoate and methyl thiopropanoate, and a basically cis arrangement is preferred for both esters as revealed from B3LYP/6-311++G** calculations. The potential curve for the rotation of the methyl-group of ethyl acetate shows double minima at φ = 87° and φ = 180°. Only the gauche methyl position (φ = 85°) corresponds to an energy minimum structure in ethyl thioacetate. Using the results of the conformational analyses, stretching, bending, torsion, and improper torsion (out-of-plane) parameters were derived for the −CH2−CH2−C(O)−S−CH2−CH2− thioester moiety. In compliance with parameters in the GROMACS force field and by accepting the united CH3 and CH2 atom models with zero net-charge for these groups, the derived parameters are useful in molecular modeling of unusual proteins containing an acylated cysteine side chain.

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