Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Pflugers Arch. 2013 Oct;465(10):1409-21. doi: 10.1007/s00424-013-1275-3. Epub 2013 May 1.
Introduction of zebrafish as a model for human diseases with symptomatic hypomagnesemia urges to identify the regulatory transport genes involved in zebrafish Mg(2+) physiology. In humans, mutations related to hypomagnesemia are located in the genes TRPM6 and CNNM2, encoding for a Mg(2+) channel and transporter, respectively; EGF (epidermal growth factor); SLC12A3, which encodes for the Na(+)-Cl(-) co-transporter NCC; KCNA1 and KCNJ10, encoding for the K(+) channels Kv1.1 and Kir4.1, respectively; and FXYD2, which encodes for the γ-subunit of the Na(+),K(+)-ATPase. Orthologues of these genes were found in the zebrafish genome. For cnnm2, kcna1 and kcnj10, two conserved paralogues were retrieved. Except for fxyd2, kcna1b and kcnj10 duplicates, transcripts of orthologues were detected in ionoregulatory organs such as the gills, kidney and gut. Gene expression analyses in zebrafish acclimated to a Mg(2+)-deficient (0 mM Mg(2+)) or a Mg(2+)-enriched (2 mM Mg(2+)) water showed that branchial trpm6, gut cnnm2b and renal slc12a3 responded to ambient Mg(2+). When changing the Mg(2+) composition of the diet (the main source for Mg(2+) in fish) to a Mg(2+)-deficient (0.01 % (w/w) Mg) or a Mg(2+)-enriched diet (0.7 % (w/w) Mg), mRNA expression of branchial trpm6, gut trpm6 and cnnm2 duplicates, and renal trpm6, egf, cnnm2a and slc12a3 was the highest in fish fed the Mg(2+)-deficient diet. The gene regulation patterns were in line with compensatory mechanisms to cope with Mg(2+)-deficiency or surplus. Our findings suggest that trpm6, egf, cnnm2 paralogues and slc12a3 are involved in the in vivo regulation of Mg(2+) transport in ionoregulatory organs of the zebrafish model.
介绍斑马鱼作为一种具有症状性低镁血症的人类疾病模型，促使我们鉴定参与斑马鱼 Mg(2+)生理学的调节性转运基因。在人类中，与低镁血症相关的突变位于编码 Mg(2+)通道和转运体的 TRPM6 和 CNNM2 基因中；EGF（表皮生长因子）；SLC12A3，编码 Na(+)-Cl(-)共转运体 NCC；KCNA1 和 KCNJ10，分别编码 K(+)通道 Kv1.1 和 Kir4.1；以及 FXYD2，编码 Na(+)、K(+) -ATPase 的 γ-亚基。这些基因的同源基因在斑马鱼基因组中被发现。对于 cnnm2、kcna1 和 kcnj10，检索到两个保守的旁系同源物。除了 fxyd2、kcna1b 和 kcnj10 副本外，在离子调节器官（如鳃、肾脏和肠道）中检测到同源物的转录本。在适应低镁（0 mM Mg(2+)）或高镁（2 mM Mg(2+)）水的斑马鱼中进行基因表达分析表明，鳃 TRPM6、肠道 CNNM2B 和肾脏 SLC12A3 对环境 Mg(2+)有反应。当改变饮食中的 Mg(2+)组成（鱼类中 Mg(2+)的主要来源）为低镁（0.01%（w/w）Mg）或高镁饮食（0.7%（w/w）Mg）时，鳃 TRPM6、肠道 TRPM6 和 CNNM2 副本，以及肾脏 TRPM6、EGF、CNNM2A 和 SLC12A3 的 mRNA 表达在低镁饮食组的鱼中最高。基因调控模式与应对镁缺乏或过剩的补偿机制一致。我们的发现表明，TRPM6、EGF、CNNM2 旁系同源物和 SLC12A3 参与了斑马鱼模型离子调节器官中 Mg(2+)转运的体内调节。
