Missense mutations in Otopetrin 1 affect subcellular localization and inhibition of purinergic signaling in vestibular supporting cells
Missense mutations in Otopetrin 1 affect subcellular localization and inhibition of purinergic signaling in vestibular supporting cells
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DOI：
10.1016/j.mcn.2011.01.005
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发表时间：
2011-03-01
影响因子：
3.5
通讯作者：
Ornitz, David M.
中科院分区：
文献类型：
--
作者：
Kim, Euysoo;Hyrc, Krzysztof L.;Ornitz, David M.
耳垂蛋白1 （Otop1）编码一种对耳垂发育至关重要的蛋白质。耳石是细胞外含有晶体的碳酸钙，对前庭机械感觉的线性运动和重力传导很重要。小鼠Otop1有两个突变等位基因，分别名为（tit）和mergulhador (mlh)，导致非综合征性耳鸣发育和随之而来的平衡缺陷。生物化学方面，Otop1已被证明可以调节前庭支持细胞内钙的嘌呤能控制，这可能是Otop1参与耳郭矿化的机制之一。为了了解tit和mlh突变如何影响Otop1的生化功能，我们检测了表达突变Otop1蛋白的COS7细胞的嘌呤能反应，并分离了tit和mlh小鼠的感觉上皮细胞。我们还检测了Otop1在tit和mlh小鼠整个感觉上皮中的亚细胞定位。在这里，我们发现tit和mlh突变解除了Otop1对P2Y受体功能的抑制。虽然Otop1突变蛋白的体外生化功能是正常的，但在体内它们表现为零等位基因。我们发现，在支持细胞中，突变体Otop1蛋白的顶膜定位丢失。这些数据表明，tit和mlh突变主要影响Otop1的定位，从而干扰其与其他对其细胞和生化功能重要的蛋白质相互作用的能力。(C) 2011爱思唯尔公司版权所有。
Otopetrin 1 (Otop1) encodes a protein that is essential for the development of otoconia. Otoconia are the extracellular calcium carbonate containing crystals that are important for vestibular mechanosensory transduction of linear motion and gravity. There are two mutant alleles of Otop1 in mice, titled (tit) and mergulhador (mlh), which result in non-syndromic otoconia agenesis and a consequent balance defect. Biochemically, Otop1 has been shown to modulate purinergic control of intracellular calcium in vestibular supporting cells, which could be one of the mechanisms by which Otop1 participates in the mineralization of otoconia. To understand how tit and mlh mutations affect the biochemical function of Otop1, we examined the purinergic response of COS7 cells expressing mutant Otop1 proteins, and dissociated sensory epithelial cells from tit and mlh mice. We also examined the subcellular localization of Otop1 in whole sensory epithelia from tit and mlh mice. Here we show that tit and mlh mutations uncouple Otop1 from inhibition of P2Y receptor function. Although the in vitro biochemical function of the Otop1 mutant proteins is normal, in vivo they behave as null alleles. We show that in supporting cells the apical membrane localization of the mutant Otop1 proteins is lost. These data suggest that the tit and mlh mutations primarily affect the localization of Otop1, which interferes with its ability to interact with other proteins that are important for its cellular and biochemical function. (C) 2011 Elsevier Inc. All rights reserved.