Seizures Epileptogenesis and TrkB Transactivation

描述（由申请人提供）：神经营养因子受体TrkB在神经元存活和分化以及突触结构、功能和可塑性中起着关键作用。TrkB信号也与多种精神和神经疾病有关。值得注意的是，TrkB在边缘癫痫发生过程中被激活，并且是边缘癫痫发生所必需的。了解TrkB被激活的机制将有助于了解其在健康和疾病中的多效性功能。反激活是指一个给定受体及其下游信号被一个不直接与受体相互作用的刺激激活的过程，这一机制与神经营养因子如BDNF激活TrkB的机制不同。我们最近发现，二价阳离子锌可以通过活性依赖和神经营养因子独立的机制反激活培养神经元中的TrkB。锌是否在体内激活TrkB，如果是，其生理和病理后果尚不清楚。这一应用主要集中在假设的TrkB在体内和体外切片中被锌活化。将评估三个分析水平：膜和组织中pTrkB和TrkB的生化和免疫组织化学测量；离体切片海马苔藓纤维- ca3锥体突触的增强；以及在体内点燃和匹罗卡品模型中的癫痫发生。我们将确定囊泡锌是否在体内激活TrkB；苔藓纤维- ca3锥体突触的LTP是否需要囊泡锌；以及体内边缘癫痫发生是否需要水疱锌。这项工作的成功完成将阐明锌在体内TrkB转激活中的作用，从而阐明神经营养因子和非神经营养因子配体对TrkB的激活。了解TrkB如何被激活是很重要的，因为TrkB信号在哺乳动物神经系统的发育和成年以及健康和疾病中都具有重要作用。

DESCRIPTION (provided by applicant): The neurotrophin receptor, TrkB, serves a pivotal role in neuronal survival and differentiation as well as in synaptic structure, function, and plasticity. TrkB signaling has also been implicated in diverse psychiatric and neurological disorders. Notably, TrkB is activated during and is required for limbic epileptogenesis. Understanding the mechanisms by which TrkB is activated will provide insight into its pleiotropic functions in health and disease. Transactivation refers to the process whereby a given receptor and its downstream signaling is activated by a stimulus that does not interact directly with the receptor, a mechanism distinct from activation of TrkB by neurotrophins such as BDNF. We recently discovered that the divalent cation, zinc, can transactivate TrkB in cultured neurons by an activity dependent and neurotrophin independent mechanism. Whether zinc transactivates TrkB in vivo and, if so, it's physiological and pathological consequences are unknown. This application centers on the hypothesized transactivation of TrkB by zinc, both in vivo and in slices ex vivo. Three levels of analysis will be assessed: biochemical and immunohistochemical measures of pTrkB and TrkB in membranes and tissue ex vivo; potentiation of the hippocampal mossy fiber-CA3 pyramid synapse in slices ex vivo; and epileptogenesis in the kindling and pilocarpine models in vivo. We will determine whether vesicular zinc transactivates TrkB in vivo; whether vesicular zinc is required for LTP of the mossy fiber-CA3 pyramid synapse; and whether vesicular zinc is required for limbic epileptogenesis in vivo. Successful completion of the proposed work will clarify the role of zinc in transactivation of TrkB in vivo and thereby shed light on the activation of TrkB by both neurotrophin and non-neurotrophin ligands. Understanding how TrkB is activated is important because of the seminal role of TrkB signaling in the mammalian nervous system in development and adulthood and in both health and disease.