APOB48 downregulation is the causing factor in mediating iAs-induced lipid accumulation in enterocytes

摘要 在胎儿和新生儿发育期间早期暴露于砷是加速毒性的先决条件 和延迟的健康后果。人类通过受污染的饮用水和食物摄入砷 肠道是砷吸收的主要部位。终生接触砷 在世界范围内发生，关于砷对肠道的影响的数据有限，特别是在 早期发展阶段。我们的实验室已经证明，口服砷治疗 肠组织中的氧化应激，改变了显着的整体基因表达。最近，我们 观察到，口服无机砷（iAs）的新生小鼠显着加速 肠干细胞（ISC）增殖和肠上皮细胞（IEC）分化。组织学 检查和生化分析表明，iAs暴露导致脂质急剧积累， 肠上皮细胞当我们用母乳中富含的油酸处理新生小鼠时， 治疗模拟了我们在小肠中观察到的iAs诱导的病理生理学变化。因此，在本发明中， iAs暴露引起的脂质蓄积可能介导iAs诱导的肠道效应。的功能性 消化道的功能主要由小肠决定，通过改变上皮功能， 早期生活中的iAs暴露可能会产生无数的健康挑战，这些挑战可能使个体易患 更大的疾病脆弱性。因此，了解iAs如何影响肠道脂质代谢将有助于 成为我们研究的重点。我们已经确定了载脂蛋白B48（APOB 48），结构 乳糜微粒合成和分泌的组成部分在iAs暴露后显著下调。我们 将检验下调的APOB48是介导iAs诱导的脂质过氧化的原因这一假设。 在肠细胞中蓄积。在本提案中，我们将确定APOB48的功能结果 通过测量血浆样品中的脂质含量来下调，包括脂质谱分析、脂溶性蛋白水平、脂质水平、脂质水平和脂质水平。 维生素和必需脂肪酸。我们将确定iAs后小鼠的脂肪吸收能力 暴露（目标1）。我们还将确定是否在肠上皮细胞中过表达组成型活性APOB48， 在转基因小鼠中进行实验，组织计数器iAs诱导肠上皮细胞脂质蓄积 携带绒毛蛋白启动子驱动的人APOB cDNA（Aim 2）。我们认为这些实验将 为理解iAs诱导肠道脂质的潜在机制奠定基础 在新生小鼠中的累积，我们预测这一事件可能使小鼠易于加速生理性 生活中的变化和疾病。

ABSTRACT Early life exposure to arsenic during fetal and neonatal development is a prerequisite to accelerated toxicity and delayed health consequences. Humans ingest arsenic through contaminated drinking water and foods with the intestinal tract being the primary site for arsenic absorption. With whole life exposure to arsenic occurring worldwide, there is limited data available on arsenic’s effects on the intestinal tract, especially during the early developmental stage. Our laboratory has demonstrated that oral arsenic treatment induces oxidative stress in the intestinal tissues, altering significant overall gene expression. Most recently, we observed that oral administration of inorganic arsenic (iAs) to neonatal mice dramatically accelerates intestinal stem cell (ISC) proliferation and intestinal epithelial cell (IEC) differentiation. Histological examination and biochemical analysis have revealed that iAs exposure leads to drastic lipid accumulation in intestinal enterocytes. When we treated neonatal mice with oleic acid, which is abundant in breast milk, this treatment mimics what we observed with iAs-induced pathophysiological changes in the small intestine. Thus, it is likely that lipid accumulation from iAs exposure mediates iAs-induced intestinal effects. As the functionality of the digestive tract is determined primarily by the small intestine, through altering the epithelium function, early life iAs exposure may generate a myriad of health challenges that could predispose individuals to a greater disease vulnerability. Therefore, understanding how iAs impacts on intestinal lipid metabolism will be the focus of our studies. We have identified that apolipoprotein B48 (APOB48), the structural component of chylomicron synthesis and secretion, is dramatically downregulated following iAs exposure. We will test the hypothesis that downregulated APOB48 is the causing factor in mediating iAs-induced lipid accumulation in enterocytes. In this proposal, we will determine the functional outcomes of APOB48 downregulation by measuring lipid content in plasma samples, including lipid profiling, levels of fat-soluble vitamins, and essential fatty acids. We will determine the fat absorption capability in mice following iAs exposure (Aim 1). We will also determine if overexpression of the constitutive active APOB48 in intestinal tissue counters iAs induced enterocyte lipid accumulation by conducting experiments in transgenic mice carrying a villin-promoter driven human APOB cDNA (Aim 2). We contend that these experiments will lay the foundation for an understanding of the underlying mechanisms leading to iAs induced intestinal lipid accumulation in neonatal mice, an event that we predict may predispose mice to accelerated physiological changes and diseases later in life.