Axonal alterations in demyelinating diseases

我们假设在正常的有髓鞘PNS轴突中，Kv1.1、Kv1.2、KCNQ 2和KCNQ 3的组合可能与PNS轴突中Kv1.1、Kv1.2、KCNQ 2和KCNQ 3的表达有关。 KCNQ 3是复极化所必需的，Kv 3.1 B的错误表达对复极化有有害影响。 脱髓鞘/再生轴突的轴突传导。在未发表的工作中，我们发现了 Na，K-ATPase是唯一一个明确定位于轴突的，它（令人惊讶地）被排除在节点之外， 并且似乎由于脱髓鞘而局部减少。因此，我们也假设， α可能有助于脱髓鞘/再髓鞘轴突的去极化。拟议的实验建立在这些基础上 研究结果的中心主题是阐明K+稳态如何在正常和脱髓鞘/再生髓鞘中发挥作用 轴突 目的#1：Kv3.1b通道是否有助于脱髓鞘疾病的传导失败？ 我们将通过比较DTX-I和4-AP的效果来调查KvS.lb是否是4-AP敏感的频道。 AP对TremblerJ小鼠轴突传导的影响KvS.lb-null（Kcncl-/-）与Kcnc 1 +/+背景。 目的#2：KCNQ 2在有髓轴突中的作用是什么？ 由于Kcnq 2基因缺失的小鼠在出生时就死亡了，在髓鞘形成和节点形成之前，我们将产生一个新的基因。 条件性Kcnq 2基因敲除小鼠，分析有髓轴突的结构和功能，包括 KCNQ 3的表达。 目的#3：有髓轴突和脱髓轴突表达什么样的Na，K-ATP酶亚型？ 我们将通过免疫电子显微镜定位α 1 -3在CM和PNS的有髓轴突中，沿着它们的 β亚单位

We hypothesize that in normal myelinated PNS axons, the combination of Kv1.1, Kv1.2, KCNQ2, and KCNQ3 is necessary for repolarization, and that the misexpression of Kv3.1 b has a deleterious effect on axonal conduction of de/remyelinated axons. In unpublished work, we have found the alphas isoform of Na,K-ATPase is the only one that is clearly localized to axons, that it is (surprisingly) excluded from nodes, and appears to be focally diminished by demyelination. Thus, we also hypothesize that the misexpression of alphas may contribute to depolarization of de/remyelinated axons. The proposed experiments build on these findings, with the central theme of illuminating how K+ homeostasis works in normal and de/remyelinated axons. Aim #1: Do Kv3.1b channels contribute to conduction failure in demyelinating diseases? We will investigate whether KvS.lb is the 4-AP-sensitive channel by comparing the effects of DTX-I and 4- AP on axonal conduction in TremblerJ mice on a KvS.lb -null (Kcncl-/-) versus Kcnc1+/+ background. Aim #2: What is the role of KCNQ2 in myelinated axons? Because Kcnq2-null mice die at birth, before myelination and the formation of nodes, we will generate a conditional Kcnq2-null mouse and analyze the structure and function of myelinated axons, including the expression of KCNQ3. Aim #3: What Na,K-ATPase isoforms are expressed by myelinated axons and demyelinated axons? we will localize alpha1-3 by immunoelectron microscopy in CMSand PNS myelinated axons, along with their beta subunits.