Identification and lateral membrane localization of cyclin M3, likely to be involved in renal Mg2+ handling in seawater fish
Identification and lateral membrane localization of cyclin M3, likely to be involved in renal Mg2+ handling in seawater fish
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DOI：
10.1152/ajpregu.00032.2014
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发表时间：
2014-09-01
影响因子：
2.8
通讯作者：
Kato, Akira
中科院分区：
文献类型：
--
作者：
Islam, Zinia;Hayashi, Naoko;Kato, Akira
海洋硬骨鱼的肾脏是Mg2+排泄的主要部位，产生高浓度的Mg2+尿液。然而，参与Mg2+排泄的转运蛋白却知之甚少。细胞周期蛋白M （Cnnm，也被称为古保守结构域蛋白）家族包括与细菌Mg2+和Co2+外排蛋白CorC同源的膜蛋白。为了了解海洋硬骨鱼体内Mg2+稳态的分子机制，我们分析了Cnnm家族基因在海水河豚（SW）， torafugu （Takifugu rubripes）和与其密切相关的泛盐物种mefugu （Takifugu obscurus）中的表达。数据库挖掘和系统发育分析表明，东方鲀基因组包含6个Cnnm家族成员：Cnnm1的2个直系同源，Cnnm2的1个，Cnnm3的1个，Cnnm4的2个。RT-PCR分析表明，Cnnm2、Cnnm3和Cnnm4a主要在肾脏中表达，而其他成员主要在脑中表达。在淡水（FW）河豚中，Cnnm2的肾脏表达上调，而在淡水（SW）河豚中，Cnnm2的肾脏表达上调。Cnnm4a在SW和FW河豚肾脏的表达无显著差异。原位杂交和免疫组化分析显示，Cnnm3在近端肾小管中表达，其产物定位于侧膜。Cnnm3在非洲爪蟾卵母细胞中表达后，全细胞Mg2+含量和胞内游离Mg2+活性显著降低。这些结果表明Cnnm3参与了海洋硬骨鱼体液Mg2+的稳态。
The kidney of marine teleosts is the major site of Mg2+ excretion and produces urine with a high Mg2+ concentration. However, the transporters involved in Mg2+ excretion are poorly understood. The cyclin M (Cnnm; also known as ancient conserved domain protein) family comprises membrane proteins homologous to the bacterial Mg2+ and Co2+ efflux protein, CorC. To understand the molecular mechanism of Mg2+ homeostasis in marine teleosts, we analyzed the expression of the Cnnm family genes in the seawater (SW) pufferfish, torafugu (Takifugu rubripes), and the closely related euryhaline species, mefugu (Takifugu obscurus). Database mining and phylogenetic analysis indicated that the Takifugu genome contains six members of the Cnnm family: two orthologs of Cnnm1, one of Cnnm2, one of Cnnm3, and two of Cnnm4. RT-PCR analyses indicated that Cnnm2, Cnnm3, and Cnnm4a are expressed in the kidney, whereas other members are mainly expressed in the brain. Renal expression of Cnnm3 was upregulated in SW mefugu, whereas renal expression of Cnnm2 was upregulated in freshwater (FW) mefugu. No significant difference was observed in renal expression of Cnnm4a between SW and FW mefugu. In situ hybridization and immunohistochemical analyses of the SW mefugu kidney revealed that Cnnm3 is expressed in the proximal tubule, and its product localizes to the lateral membrane. When Cnnm3 was expressed in Xenopus laevis oocytes, whole cellular Mg2+ content and free intracellular Mg2+ activity significantly decreased. These results suggest that Cnnm3 is involved in body fluid Mg2+ homeostasis in marine teleosts.