Regulation of intestinal serotonin transporter expression via epigenetic mechanisms: role of HDAC2
Regulation of intestinal serotonin transporter expression via epigenetic mechanisms: role of HDAC2
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DOI：
10.1152/ajpcell.00361.2012
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发表时间：
2013-02-01
影响因子：
5.5
通讯作者：
Saksena, Seema
中科院分区：
文献类型：
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作者：
Gill, Ravinder K.;Kumar, Anoop;Saksena, Seema
Gill RK，Kumar A，Malhotra P，Maher D，Singh V，Dudeja PK，Alrefai W，Saksena S.通过表观遗传机制调节肠道5-羟色胺转运蛋白表达：HDAC 2的作用。Am J Physiol Cell Physiol 304：C334-C341，2013.首次发表于2012年11月28日; doi：10.1152/ajpcell.00361.2012.- 5-羟色胺转运蛋白（SERT）通过摄取和内化促进细胞外5-羟色胺的清除。SERT的表达减少和随之而来的高5-HT水平已经与各种神经系统疾病有关。因此，适当调节SERT对于维持健康和疾病中的5-HT稳态至关重要。研究表明SERT是通过转录后和翻译后机制调控的。然而，表观遗传机制在SERT调控中的作用尚不清楚。目前的研究探讨了组蛋白去乙酰化酶（HDAC）抑制对SERT表达的影响，并阐明了其机制。用泛HDAC抑制剂丁酸盐（5 mM）和阿司他丁（TSA，1 μ M）处理Caco-2细胞降低SERT mRNA和蛋白水平。丁酸或TSA诱导的SERT降低与人SERT（hSERT）启动子1（外显子1a上游）的活性降低相关，但与hSERT启动子2（外显子2上游）无关。丁酸+ TSA没有显示出对SERT表达的累加效应，表明可能涉及组蛋白超乙酰化的机制。染色质免疫沉淀分析表明hSERT启动子1（侧翼nt-250/+2）富集有四乙酰化的组蛋白H3或H4，其被丁酸盐增加（类似于3倍）。有趣的是，利用小干扰RNA特异性抑制HDAC 2（而不是HDAC 1）降低了SERT mRNA和蛋白水平。在体内模型中重现了HDAC抑制引起的SERT表达降低。与喂食无纤维饮食的对照组相比，喂食果胶的小鼠回肠和结肠中的SERT mRNA水平降低（丁酸盐的可用性增加）（类似于50-60%）。我们的研究结果确定了HDAC 2作为肠上皮细胞中SERT基因表达的调节剂的新作用。
Gill RK, Kumar A, Malhotra P, Maher D, Singh V, Dudeja PK, Alrefai W, Saksena S. Regulation of intestinal serotonin transporter expression via epigenetic mechanisms: role of HDAC2. Am J Physiol Cell Physiol 304: C334-C341, 2013. First published November 28, 2012; doi:10.1152/ajpcell.00361.2012.-The serotonin (5-HT) transporter (SERT) facilitates clearance of extracellular 5-HT by its uptake and internalization. Decreased expression of SERT and consequent high 5-HT levels have been implicated in various diarrheal disorders. Thus, appropriate regulation of SERT is critical for maintenance of 5-HT homeostasis in health and disease. Previous studies demonstrated that SERT is regulated via posttranslational and transcriptional mechanisms. However, the role of epigenetic mechanisms in SERT regulation is not known. Current studies investigated the effects of histone deacetylase (HDAC) inhibition on SERT expression and delineated the mechanisms. Treatment of Caco-2 cells with the pan-HDAC inhibitors butyrate (5 mM) and trichostatin (TSA, 1 mu M) decreased SERT mRNA and protein levels. Butyrate-or TSA-induced decrease in SERT was associated with decreased activity of human SERT (hSERT) promoter 1 (upstream of exon 1a), but not hSERT promoter 2 (upstream of exon 2). Butyrate + TSA did not show an additive effect on SERT expression, indicating that mechanisms involving histone hyperacetylation may be involved. Chromatin immunoprecipitation assays demonstrated enrichment of the hSERT promoter 1 (flanking nt -250/+2) with tetra-acetylated histone H3 or H4, which was increased (similar to 3-fold) by butyrate. Interestingly, specific inhibition of HDAC2 (but not HDAC1) utilizing small interfering RNA decreased SERT mRNA and protein levels. The decrease in SERT expression by HDAC inhibition was recapitulated in an in vivo model. SERT mRNA levels were decreased in the ileum and colon of mice fed pectin (increased availability of butyrate) compared with controls fed a fiber-free diet (similar to 50-60%). Our results identify a novel role of HDAC2 as a regulator of SERT gene expression in intestinal epithelial cells.