Background:Ghrelin O-acyltransferase (GOAT) is a membrane protein that is responsible for octanoylating the metabolism-regulating peptide hormone ghrelin. Results: We have used a combination of approaches to determine the topology of GOAT. Conclusion:We have shown that GOAT has 11 transmembrane-spanning domains and one reentrant loop. Significance: These findings serve as a reference for other membrane-bound O-acyltransferase family members.

Lysine-specific demethylase 1 (LSD1) is an epigenetic enzyme that oxidatively cleaves methyl groups from monomethyl and dimethyl Lys4 of histone H3 (H3K4Me1, H3K4Me2) and can contribute to gene silencing. This study describes the design and synthesis of analogues of a monoamine oxidase antidepressant, phenelzine, and their LSD1 inhibitory properties. A novel phenelzine analogue (bizine) containing a phenyl-butyrylamide appendage was shown to be a potent LSD1 inhibitor in vitro and was selective versus monoamine oxidases A/B and the LSD1 homologue, LSD2. Bizine was found to be effective at modulating bulk histone methylation in cancer cells, and ChIP-seq experiments revealed a statistically significant overlap in the H3K4 methylation pattern of genes affected by bizine and those altered in LSD1–/– cells. Treatment of two cancer cell lines, LNCaP and H460, with bizine conferred a reduction in proliferation rate, and bizine showed additive to synergistic effects on cell growth when used in combination with two out of five HDAC inhibitors tested. Moreover, neurons exposed to oxidative stress were protected by the presence of bizine, suggesting potential applications in neurodegenerative disease.

Ghrelin O-acyltransferase (GOAT) is responsible for catalyzing the attachment of the eight-carbon fatty acid octanoyl to the Ser3 side chain of the peptide ghrelin to generate the active form of this metabolic hormone. As such, GOAT is viewed as a potential therapeutic target for the treatment of obesity and diabetes mellitus. Here, we review recent progress in the development of cell and in vitro assays to measure GOAT action and the identification of several synthetic GOAT inhibitors. In particular, we discuss the design, synthesis, and characterization of the bisubstrate analog GO-CoA-Tat and its ability to modulate weight and blood glucose in mice. We also highlight current challenges and future research directions in our biomedical understanding of this fascinating ghrelin processing enzyme.

The adenosine A2A receptor (A2AR) is expressed in immune cells as well as heart and lung tissue and has been intensively studied as a therapeutic target for multiple disease indications. Inhibitors of the A2AR have the potential for stimulating immune response which could be valuable for cancer immune surveillance and mounting a response against pathogens. One well-established potent and selective small-molecule A2AR antagonist, ZM-241385 (ZM), has a short pharmacokinetic half-life and has the potential for systemic toxicity due to A2AR effects in the brain and the heart. In this study, we designed an analog of ZM for tethering to the Fc domain of the immunoglobulin IgG3 using expressed protein ligation. The resulting protein-small molecule conjugate, Fc-ZM, retained high affinity for both the FcγRI and the neonatal Fc receptor (FcRn). In addition, Fc-ZM was a potent A2AR antagonist as measured in a cell-based cAMP assay. Cell-based assays also revealed that Fc-ZM could stimulate interferon γ production in splenocytes in a fashion that was dependent on the presence of A2AR. We found that Fc-ZM compared with the small molecule ZM was a superior A2AR antagonist in mice, consistent with the possibility that Fc attachment can improve pharmacokinetic and/or pharmacodynamic properties of the small molecule.