Role of TRPM7 and TRPM2 Channels in Neuronal Development and Regeneration

神经元是形成脑回路基本功能单位的高度特化的细胞，神经元结构和回路的正常发育对大脑的正常功能至关重要。我们建议研究瞬时受体电位（TRP）通道在神经元发育和再生中的作用，特别关注TRPM7及其密切相关的TRPM2通道。TRPM7和TRPM2是Ca2+可渗透的非选择性阳离子通道，在细胞存活和增殖等多种生理功能中发挥重要作用。TRPM7敲除（KO）是胚胎致死的。然而，我们已经证明TRPM7通道在大脑中表达，抑制这些通道可以增加神经元在体外和体内缺氧（Sun lab, Mol brain 2015, 8:11）和缺血（Sun et al., Nat Neurosci 2009; 12:1300-7）下的存活。矛盾的是，TRPM7的表达是胚胎发育所必需的，但抑制或抑制TRPM7可防止新生儿缺氧诱导的神经元细胞死亡和成人缺血诱导的神经元细胞死亡。这导致我们假设TRPM7在正常和缺氧条件下通过差异调节Ca2+稳态在神经元发育和再生中起关键作用。然而，TRPM7如何参与神经元的发育和再生尚未得到充分的研究。因为神经元的发育和再生依赖于一个关键的Ca2+窗口，我假设TRPM7通道是调节Ca2+水平的重要蛋白质，而Ca2+水平反过来又需要在正常和缺氧条件下通过不同的下游信号通路进行神经元的发育和再生。相反，抑制TRPM7可能促进神经元细胞增殖、存活、生长和再生。必要的合适的工具和试剂包括选择性TRPM7和TRPM2抑制剂，siRNA, CRISPR （TRPM7构建），抗体，TRPM2敲除（KO）小鼠（活的），TRPM7激酶KO，以及TRPM7和TRPM2的诱导KO小鼠（正在开发中），我的实验室可用。结合我在TRPM7的丰富经验，我们在未来五年内提出以下三个短期项目和一个长期项目：

Neurons are highly specialized cells that form the basic functional units in brain circuitry, and proper development of neuronal structure and circuitry is essential for normal function of the brain. We propose to investigate the role of Transient Receptor Potential (TRP) channels in neuronal development and regeneration with specific interest in TRPM7 and its closely related TRPM2 channels. TRPM7 and TRPM2 are non-selective cation channels permeable to Ca2+ and play an important role in various physiological functions, including cell survival and proliferation. TRPM7 knockout (KO) is embryonic lethal. However, we have shown that TRPM7 channels are expressed in the brain, and inhibiting these channels increases neuronal survival to hypoxia (Sun lab, Mol Brain 2015, 8:11) and ischemia (Sun et al., Nat Neurosci 2009; 12:1300-7), both in vitro and in vivo. The paradox is that expression of TRPM7 is required for embryonic development, but inhibition or suppression of TRPM7 prevents hypoxia-induced neuronal cell death in neonates and ischemia-induced neuronal cell death in adults. This leads to our postulating that TRPM7 plays a critical role in neuronal development and regeneration by differentially regulating Ca2+ homeostasis under normoxic and hypoxic conditions. However, how TRPM7 is involved in neuronal development and regeneration has not been fully investigated. Because neuronal development and regeneration depends on a critical Ca2+ window, I hypothesize that the TRPM7 channel is an essential protein regulating Ca2+ levels that are, in turn, needed for neuronal development and regeneration under normal and hypoxic conditions via differential downstream signal pathways. Conversely, inhibition of TRPM7 may promote neuronal cell proliferation, survival, outgrowth and regeneration. The requisite suitable tools and reagents include selective TRPM7 and TRPM2 inhibitors, siRNA, CRISPR (TRPM7 construct), antibodies, TRPM2 knockout (KO) mice (viable), and TRPM7 kinase KO, as well as inducible KO mice for both TRPM7 and TRPM2 (under development) available to my lab. Together with my extensive experience in TRPM7, we propose the following three short-term projects and one long-term project over the next five years: 1) Explore the role of TRPM7 and TRPM2 in neuronal outgrowth, maturation and synapse formation in normoxic and hypoxic conditions. 2) Determine the signal pathways involved in the TRPM7 and TRPM2 channels mediated neuronal development and maturation in brain neurons in normoxic and hypoxic conditions. 3) Evaluate the role of TRPM7 and TRPM2 in neuronal regeneration in vitro and in vivo. Our long-term project is to evaluate the role of TRPM7 and TRPM2 in neuronal regeneration. Significance: This work will contribute to our knowledge of the TRP channels in the field of neuronal development and regeneration, and our research will have tangible benefits for HQP development.