Mg2+ Extrusion from Intestinal Epithelia by CNNM Proteins Is Essential for Gonadogenesis via AMPK-TORC1 Signaling in Caenorhabditis elegans.
Mg2+ Extrusion from Intestinal Epithelia by CNNM Proteins Is Essential for Gonadogenesis via AMPK-TORC1 Signaling in Caenorhabditis elegans.
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DOI：
10.1371/journal.pgen.1006276
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发表时间：
2016-08
期刊：
影响因子：
4.5
通讯作者：
Miki H
中科院分区：
文献类型：
--
作者：
Ishii T;Funato Y;Hashizume O;Yamazaki D;Hirata Y;Nishiwaki K;Kono N;Arai H;Miki H
Mg2+是许多酶的重要辅助因子，其水平受到各种Mg2+转运体的严格调节。在这里，我们分析了携带编码细胞周期蛋白M (CNNM) Mg2+转运体基因突变的秀丽隐杆线虫菌株。我们分离了秀丽隐杆线虫cnnm家族基因（cnnm-1至cnnm-5）的灭活突变体。cnnm-1;cnnm-3双突变体蠕虫表现出多种表型，其中在培养基中添加Mg2+恢复了不育表型。这种不育是由生殖细胞增殖严重减弱的性腺发育缺陷引起的。以这种促性腺功能缺陷为指标，我们进行了全基因组RNAi筛选，以寻找与这种表型相关的基因。结果显示，rnai介导的几种基因失活可恢复性腺伸长，包括编码amp活化蛋白激酶（AMPK）催化亚基的aak-2。然后，我们为cnnm-1生成了三重突变蠕虫；cnnm-3;证实了Aak-2突变也抑制了cnnm-1的性腺伸长缺陷；Cnnm-3突变蠕虫。AMPK在低能量条件下被激活，在调节细胞代谢以适应细胞的能量状态中起核心作用。因此，我们提供了通过AMPK将Mg2+稳态与能量代谢联系起来的遗传证据。Mg2+是细胞中第二丰富的阳离子，是许多酶的重要辅助因子。为了避免其短缺，细胞和机体的Mg2+水平受到各种Mg2+转运体和通道的协同作用的严格调节。在这项研究中，我们分析了携带Mg2+转运体编码基因突变的秀丽隐杆线虫菌株，发现这些突变破坏了Mg2+的稳态。此外，这些蠕虫是不育的，因为生殖腺发育缺陷，生殖细胞增殖严重减弱。这些异常可以通过向培养基中补充额外的Mg2+来挽救，因此被认为是由于Mg2+缺乏。我们研究了这种与Mg2+相关的性腺发育衰减的机制，发现amp活化蛋白激酶（AMPK）功能的破坏可以恢复性腺伸长。众所周知，AMPK在低能量条件下被激活，在调节细胞代谢以适应细胞的能量状态中起核心作用。因此，我们证明了Mg2+稳态通过AMPK与能量代谢密切相关。
Mg2+ serves as an essential cofactor for numerous enzymes and its levels are tightly regulated by various Mg2+ transporters. Here, we analyzed Caenorhabditis elegans strains carrying mutations in genes encoding cyclin M (CNNM) Mg2+ transporters. We isolated inactivating mutants for each of the five Caenorhabditis elegans cnnm family genes, cnnm-1 through cnnm-5. cnnm-1; cnnm-3 double mutant worms showed various phenotypes, among which the sterile phenotype was rescued by supplementing the media with Mg2+. This sterility was caused by a gonadogenesis defect with severely attenuated proliferation of germ cells. Using this gonadogenesis defect as an indicator, we performed genome-wide RNAi screening, to search for genes associated with this phenotype. The results revealed that RNAi-mediated inactivation of several genes restores gonad elongation, including aak-2, which encodes the catalytic subunit of AMP-activated protein kinase (AMPK). We then generated triple mutant worms for cnnm-1; cnnm-3; aak-2 and confirmed that the aak-2 mutation also suppressed the defective gonadal elongation in cnnm-1; cnnm-3 mutant worms. AMPK is activated under low-energy conditions and plays a central role in regulating cellular metabolism to adapt to the energy status of cells. Thus, we provide genetic evidence linking Mg2+ homeostasis to energy metabolism via AMPK. Mg2+ is the second most abundant cation in cells and serves as an essential cofactor for numerous enzymes. To avoid its shortage, cellular and organismal levels of Mg2+ are tightly regulated by the concerted actions of various Mg2+ transporters and channels. In this study, we analyzed Caenorhabditis elegans strains carrying mutations in genes encoding Mg2+ transporters and found that the mutations abrogated Mg2+ homeostasis. Additionally, these worms were sterile because of a developmental defect in the gonads with severely attenuated proliferation of germ cells. These abnormalities were rescued by additional Mg2+ supplementation to the medium, and thus were considered to be due to Mg2+ shortage. We investigated the mechanism of this Mg2+-associated attenuation of gonadal development, and found that disrupting of the function of AMP-activated protein kinase (AMPK) restored gonad elongation. It is well-known that AMPK is activated under low-energy conditions and plays a central role in regulating cellular metabolism to adapt to the energy status of cells. Thus, we demonstrated that Mg2+ homeostasis is intimately connected to energy metabolism via AMPK.
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