Pillar[6]arene acts as a biosensor for quantitative detection of a vitamin metabolite in crude biological samples

ビタミン代謝物を迅速定量できる超分子バイオセンサーを開発. 京都大学プレスリリース. 2020-12-09.Metabolic syndrome is associated with obesity, hypertension, and dyslipidemia, and increased cardiovascular risk. Therefore, quick and accurate measurements of specific metabolites are critical for diagnosis; however, detection methods are limited. Here we describe the synthesis of pillar[n]arenes to target 1-methylnicotinamide (1-MNA), which is one metabolite of vitamin B3 (nicotinamide) produced by the cancer-associated nicotinamide N-methyltransferase (NNMT). We found that water-soluble pillar[5]arene (P5A) forms host–guest complexes with both 1-MNA and nicotinamide, and water-soluble pillar[6]arene (P6A) selectively binds to 1-MNA at the micromolar level. P6A can be used as a “turn-off sensor” by photoinduced electron transfer (detection limit is 4.38 × 10−6 M). In our cell-free reaction, P6A is used to quantitatively monitor the activity of NNMT. Moreover, studies using NNMT-deficient mice reveal that P6A exclusively binds to 1-MNA in crude urinary samples. Our findings demonstrate that P6A can be used as a biosensor to quantify 1-MNA in crude biological samples

Reactivation of hyperglycemia-induced hypocretin (<i>HCRT)</i> gene silencing by <i>N</i>-acetyl-d-mannosamine in the orexin neurons derived from human iPS cells

<p>Orexin neurons regulate critical brain activities for controlling sleep, eating, emotions, and metabolism, and impaired orexin neuron function results in several neurologic disorders. Therefore, restoring normal orexin function and understanding the mechanisms of loss or impairment of orexin neurons represent important goals. As a step toward that end, we generated human orexin neurons from induced pluripotent stem cells (hiPSCs) by treatment with <i>N</i>-acetyl-d-mannosamine (ManNAc) and its derivatives. The generation of orexin neurons was associated with DNA hypomethylation, histone H3/H4 hyperacetylation, and hypo-<i>O</i>-GlcNAcylation on the <i>HCRT</i> gene locus, and, thereby, the treatment of inhibitors of SIRT1 and OGT were effective at inducing orexin neurons from hiPSCs. The prolonged exposure of orexin neurons to high glucose in culture caused irreversible silencing of the <i>HCRT</i> gene, which was characterized by H3/H4 hypoacetylation and hyper-<i>O</i>-GlcNAcylation. The DNA hypomethylation status, once established in orexin neurogenesis, was maintained in the <i>HCRT</i>-silenced orexin neurons, indicating that histone modifications, but not DNA methylation, were responsible for the <i>HCRT</i> silencing. Thus, the epigenetic status of the <i>HCRT</i> gene is unique to the hyperglycemia-induced silencing. Intriguingly, treatment of ManNAc and its derivatives reactivated <i>HCRT</i> gene expression, while inhibitors SIRT1 and the OGT did not. The present study revealed that the <i>HCRT</i> gene was silenced by the hyperglycemia condition, and ManNAc and its derivatives were useful for restoring the orexin neurons.</p