Abnormal differentiation of dopaminergic neurons in zebrafish trpm7 mutant larvae impairs development of the motor pattern.
Abnormal differentiation of dopaminergic neurons in zebrafish trpm7 mutant larvae impairs development of the motor pattern.
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DOI：
10.1016/j.ydbio.2013.11.015
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发表时间：
2014-02-15
影响因子：
2.7
通讯作者：
Cornell RA
中科院分区：
文献类型：
--
作者：
Decker AR;McNeill MS;Lambert AM;Overton JD;Chen YC;Lorca RA;Johnson NA;Brockerhoff SE;Mohapatra DP;MacArthur H;Panula P;Masino MA;Runnels LW;Cornell RA
瞬时受体电位，melastatin-like 7 （Trpm7）是一个离子通道和激酶的组合，与许多细胞类型的分化或功能有关。缺乏相应基因的小鼠和青蛙的早期致命性阻碍了对这种蛋白质功能的研究，特别是在发育的后期。相比之下，斑马鱼trpm7突变体的幼虫在早期形态发生正常，因此没有这种限制。突变的幼虫具有多种缺陷，包括黑素细胞死亡、短暂性瘫痪和导致肾结石的离子失衡。在这里，我们报道了体内多巴胺能神经元的分化或功能需要Trpm7。首先，trpm7突变体的幼虫运动能力低下，不能在游动长度上实现多巴胺依赖的发育转变。这两种缺陷都可以通过左旋多巴或多巴胺的应用得到部分补救。其次，组织学分析显示，在trpm7突变体中，相当一部分多巴胺能神经元缺乏酪氨酸羟化酶的表达，酪氨酸羟化酶是多巴胺合成的限速酶。第三，trpm7突变体对神经毒素1-甲基-4-苯基吡啶（一种氧化应激源）异常敏感，它们的运动能力可以通过使用铁螯合剂去铁胺（一种抗氧化剂）部分恢复。最后，在模拟人类多巴胺能神经元的SH-SY5Y细胞中，TRPM7通道死亡变体的强制表达会导致细胞死亡。总之，斑马鱼的正向遗传筛选表明，黑素细胞和多巴胺能神经元都依赖于离子通道Trpm7。这种依赖性的机制基础需要进一步研究。
Transient receptor potential, melastatin-like 7 (Trpm7) is a combined ion channel and kinase implicated in the differentiation or function of many cell types. Early lethality in mice and frogs depleted of the corresponding gene impedes investigation of the functions of this protein particularly during later stages of development. By contrast, zebrafish trpm7 mutant larvae undergo early morphogenesis normally and thus do not have this limitation. The mutant larvae are characterized by multiple defects including melanocyte cell death, transient paralysis, and an ion imbalance that leads to the development of kidney stones. Here we report a requirement for Trpm7 in differentiation or function of dopaminergic neurons in vivo. First, trpm7 mutant larvae are hypomotile and fail to make a dopamine-dependent developmental transition in swim-bout length. Both of these deficits are partially rescued by the application of levodopa or dopamine. Second, histological analysis reveals that in trpm7 mutants a significant fraction of dopaminergic neurons lack expression of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Third, trpm7 mutants are unusually sensitive to the neurotoxin 1-methyl-4-phenylpyridinium, an oxidative stressor, and their motility is partially rescued by application of the iron chelator deferoxamine, an anti-oxidant. Finally, in SH-SY5Y cells, which model aspects of human dopaminergic neurons, forced expression of a channel-dead variant of TRPM7 causes cell death. In summary, a forward genetic screen in zebrafish has revealed that both melanocytes and dopaminergic neurons depend on the ion channel Trpm7. The mechanistic underpinning of this dependence requires further investigation.