Iron handling and gene expression of the divalent metal transporter, DMT1, in the kidney of the anemic Belgrade (b) rat
Iron handling and gene expression of the divalent metal transporter, DMT1, in the kidney of the anemic Belgrade (b) rat
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DOI：
10.1046/j.1523-1755.2003.00274.x
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发表时间：
2003-11-01
影响因子：
19.6
通讯作者：
Riccardi, D
中科院分区：
文献类型：
--
作者：
Ferguson, CJ;Wareing, M;Riccardi, D
背景。我们之前的研究表明，大鼠肾脏以代谢方式重新吸收大量的铁，并表达二价金属转运蛋白1 DMT1。贝尔格莱德(b)大鼠携带DMT1基因突变，由于肠铁吸收和铁从转铁蛋白周期内体转运受损，导致低色性小细胞贫血。b/b大鼠十二指肠DMT1 mRNA和蛋白的表达增加，提示其受铁储备的反馈调节。本研究的目的是研究铁处理和DMT1在贝尔格莱德大鼠肾脏中的表达。实验动物饲喂含185 mg/kg铁（FeSO4）的合成饲料3周后，分析雄性杂合子（+/b）和纯合子（b/b）大鼠（每组N = 4 ~ 6只）的功能和分子参数。b/b组大鼠血清铁浓度明显高于+/b组大鼠，而b/b组大鼠尿铁排泄率与+/b组大鼠相比没有变化。使用大鼠DMT1探针的Northern分析显示+/b和b/b动物之间的mRNA水平相当。Western分析和免疫荧光显微镜对大鼠DMT1的多克隆抗体显示，与+/b动物相比，b/b大鼠肾脏中几乎没有DMT1特异性免疫反应性。我们的研究结果表明，DMT1的G185R突变导致b/b大鼠肾脏蛋白质不稳定。考虑到+/b和b/b大鼠的铁排泄量相当，DMT1蛋白的缺乏可以通过另一种尚未确定的机制来补偿。
Background. We have previously shown that the rat kidney reabsorbs metabolically significant amounts of iron and that it expresses the divalent metal transporter 1, DMT1. The Belgrade (b) rat carries a mutation in DMT1 gene, which causes hypochromic, microcytic anemia due to impaired intestinal iron absorption and transport of iron out of the transferrin cycle endosome. In the duodenum of b/b rats, expression of DMT1 mRNA and protein is increased, suggesting a feedback regulation by iron stores. The aim of this study was to investigate iron handling and DMT1 expression in the kidneys of Belgrade rats.Methods. Animals were maintained for 3 weeks on a synthetic diet containing 185 mg/kg iron (FeSO4), after which functional and molecular parameters were analyzed in male heterozygous (+/b) and homozygous (b/b) rats (N = 4 to 6 for each group).Results. Serum iron concentration was significantly higher in b/b compared to +/b rats while urinary iron excretion rates were unchanged in b/b compared to +/b rats. Northern analysis using a rat DMT1 probe showed comparable mRNA levels between +/b and b/b animals. Western analysis and immunofluorescence microscopy performed using a polyclonal antibody against rat DMT1 showed that DMT1-specific immunoreactivity was almost absent in the kidneys of b/b rats compared to that seen in +/b animals.Conclusion. Our results indicate that the G185R mutation of DMT1 causes protein instability in the kidneys of b/b rats. Given that +/b and b/b rats excrete comparable amounts of iron, the lack of DMT1 protein is compensated by an alternative, yet to be identified, mechanism.