Reduction of Fe(III) is required for uptake of nonheme iron by Caco-2 cells.
Reduction of Fe(III) is required for uptake of nonheme iron by Caco-2 cells.
复制标题
Caco-2 细胞摄取非血红素铁需要还原 Fe(III)。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
J. C. Smith
中科院分区：
文献类型：
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作者：
Okhee Han;M. Failla;A. Hill;Eugene R. Morris;J. C. Smith
Caco-2人结肠细胞的分化培养物被用来检查减少非血红素三价铁，Fe（III），跨刷状缘表面运输的重要性。培养物积累约100 pmol铁/（h.mg蛋白质）时，10 μ mol铁（III）作为氨三乙酸络合物（1Fe：2NTA）被添加到顶端室。抗坏血酸以剂量依赖性方式增强细胞对铁的获取，低至8 μ mol/L抗坏血酸盐的浓度可使铁摄取增加50%。同样，铁转运率从顶端到基底侧室增加5.6和30倍时，100和1000 μ mol/L的抗坏血酸，分别存在于顶室。抗坏血酸介导的刺激铁的吸收是温度依赖性的，需要还原的Fe（III）的Fe（II），因为它被抑制抗坏血酸氧化酶和螯合剂的Fe（II）。此外，Caco-2细胞将脱氢抗坏血酸再循环为抗坏血酸。铁氰化物和Fe（II）螯合剂也部分抑制铁的吸收，从介质中没有抗坏血酸。完整的Caco-2细胞表现出铁还原酶活性的顶端表面上，占大多数的铁积累的细胞培养在不存在外源性还原剂。这些数据表明，腔体内或细胞表面的Fe（III）还原是这种必需微量营养素穿过肠道刷状缘表面转移所必需的。
Differentiated cultures of Caco-2 human colonic cells were used to examine the importance of reduction of nonheme ferric iron, Fe(III), for transport across the brush border surface. Cultures accumulated approximately 100 pmol Fe/(h.mg protein) when 10 mumol Fe(III) as the nitrilotriacetic acid complex (1Fe:2NTA) was added to the apical compartment. Ascorbic acid enhanced cellular acquisition of iron in a dose-dependent manner, with a concentration as low as 8 mumol/L ascorbate increasing iron uptake by 50%. Similarly, the rate of iron transport from the apical to the basolateral compartment increased 5.6- and 30-fold when 100 and 1000 mumol/L ascorbic acid, respectively, were present in the apical chamber. Ascorbate-mediated stimulation of iron uptake was temperature dependent and required the reduction of Fe(III) to Fe(II), because it was inhibited by ascorbate oxidase and chelators of Fe(II). Moreover, Caco-2 cells recycled dehydroascorbic acid to ascorbic acid. Ferricyanide and Fe(II) chelators also partially inhibited iron uptake from a medium devoid of ascorbic acid. Intact Caco-2 cells exhibited a ferrireductase activity on the apical surface that accounted for the majority of iron accumulated by cells incubated in the absence of exogenous reductant. These data suggest that reduction of Fe(III) within the lumen or at the cell surface is required for transfer of this essential micronutrient across the intestinal brush border surface.