Transmembrane mucins Hkr1 and Msb2 are putative osmosensors in the SHO1 branch of yeast HOG pathway
Transmembrane mucins Hkr1 and Msb2 are putative osmosensors in the SHO1 branch of yeast HOG pathway
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DOI：
10.1038/sj.emboj.7601796
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发表时间：
2007-08-08
期刊：
影响因子：
11.4
通讯作者：
Saito, Haruo
中科院分区：
文献类型：
--
作者：
Tatebayashi, Kazuo;Tanaka, Keiichiro;Saito, Haruo
为了应对危及生命的高渗透压，酵母激活高渗透压甘油（HOG）信号通路，其核心元件是Hog1 MAP激酶级联。活化的Hog1调控细胞周期、蛋白翻译和基因表达。HOG通路的上游是功能冗余的SLN1和SHO1信号分支。然而，无论是渗透传感器还是SHO1分支的信号发生器都没有明确的定义。在这里，我们发现粘蛋白样跨膜蛋白Hkr1和Msb2是SHO1分支的潜在渗透传感器。过度活跃的Hkr1和Msb2只有在Sho1存在的情况下才能激活HOG通路，而过度活跃的Sho1突变体在Hkr1和Msb2都不存在的情况下激活HOG通路，这表明Hkr1和Msb2是迄今为止已知的Sho1分支中最上游的元件。Hkr1和Msb2分别与Sho1形成复合物，并且在高外部渗透压胁迫下，似乎诱导Sho1产生细胞内信号。此外，Msb2也能以不依赖于sho1的方式产生胞内信号，而Hkr1则不能。
To cope with life-threatening high osmolarity, yeast activates the high-osmolarity glycerol ( HOG) signaling pathway, whose core element is the Hog1 MAP kinase cascade. Activated Hog1 regulates the cell cycle, protein translation, and gene expression. Upstream of the HOG pathway are functionally redundant SLN1 and SHO1 signaling branches. However, neither the osmosensor nor the signal generator of the SHO1 branch has been clearly defined. Here, we show that the mucin-like transmembrane proteins Hkr1 and Msb2 are the potential osmosensors for the SHO1 branch. Hyperactive forms of Hkr1 and Msb2 can activate the HOG pathway only in the presence of Sho1, whereas a hyperactive Sho1 mutant activates the HOG pathway in the absence of both Hkr1 and Msb2, indicating that Hkr1 and Msb2 are the most upstream elements known so far in the SHO1 branch. Hkr1 and Msb2 individually form a complex with Sho1, and, upon high external osmolarity stress, appear to induce Sho1 to generate an intracellular signal. Furthermore, Msb2, but not Hkr1, can also generate an intracellular signal in a Sho1-independent manner.