Departments of Medicine and Physiology/Biophysics, University of California, Irvine, CA, 92697, USA.
VA Medical Center, Long Beach, CA, 90822, USA.
Dig Dis Sci. 2019 Jan;64(1):84-92. doi: 10.1007/s10620-018-5305-z. Epub 2018 Oct 1.
Uptake of riboflavin (RF) by intestinal epithelial cells occurs via a specific carrier-mediated process that involves the apically localized RF transporter-3 (RFVT3). Previous studies have shown that sodium butyrate (NaB) affects intestinal uptake of other substrates and expression of their membrane transporters, but its effect on intestinal uptake of RF and expression of RFVT3 has not been examined.
To investigate the effect of NaB on intestinal RF uptake process and expression of the RFVT3.
Two experimental models were used in this study: Human-derived intestinal epithelial Caco-2 cells and ex vivo mouse colonoids. H-RF uptake assay, Western blot, RT-qPCR, and chromatin immunoprecipitation assay were performed.
Treating Caco-2 cells with NaB led to a significant increase in carrier-mediated RF uptake. This increase was associated with a significant induction in the level of expression of the hRFVT3 protein, mRNA, and heterogenous nuclear RNA (hnRNA). Similarly, treating mouse colonoids with NaB led to a marked increase in the level of expression of the mRFVT3 protein, mRNA, and hnRNA. NaB did not affect hRFVT3 mRNA stability, rather it caused significant epigenetic changes (histone modifications) in the SLC52A3 gene where an increase in H3Ac and a reduction in H3K27me3 levels were observed in the NaB-treated Caco-2 cells compared to untreated controls.
These findings demonstrate that NaB up-regulates intestinal RF uptake and that the effect appears to be mediated, at least in part, at the level of transcription of the SLC52A3 gene and may involve epigenetic mechanism(s).
肠道上皮细胞通过特定的载体介导过程摄取核黄素（RF），该过程涉及定位于顶端的 RF 转运蛋白 3（RFVT3）。先前的研究表明，丁酸钠（NaB）会影响其他底物的肠道摄取及其膜转运蛋白的表达，但尚未研究其对肠道 RF 摄取和 RFVT3 表达的影响。
研究 NaB 对肠道 RF 摄取过程和 RFVT3 表达的影响。
本研究使用了两种实验模型：人源肠道上皮细胞 Caco-2 和离体小鼠结肠类器官。进行了 H-RF 摄取测定、Western blot、RT-qPCR 和染色质免疫沉淀测定。
用 NaB 处理 Caco-2 细胞可显著增加载体介导的 RF 摄取。这种增加与 hRFVT3 蛋白、mRNA 和异质核 RNA（hnRNA）水平的显著诱导相关。同样，用 NaB 处理小鼠结肠类器官也导致 mRFVT3 蛋白、mRNA 和 hnRNA 的表达水平显著增加。NaB 不影响 hRFVT3 mRNA 的稳定性，而是在 SLC52A3 基因中引起明显的表观遗传变化（组蛋白修饰），与未处理的对照相比，在 NaB 处理的 Caco-2 细胞中观察到 H3Ac 增加和 H3K27me3 水平降低。
这些发现表明 NaB 上调肠道 RF 摄取，其作用似乎至少部分通过 SLC52A3 基因的转录水平介导，并且可能涉及表观遗传机制。
