NEUROBIOLOGY OF MARCKS--A MACS MUTANT MOUSE MODEL

Marcks(肉豆蔻酰化丙氨酸富C激酶底物)是最多的 大脑中蛋白激酶C的显著磷蛋白底物。 越来越多的数据表明，Marcks在转换过程中发挥了作用 肌动蛋白-膜可塑性调节的细胞外信号 和细胞过程与细胞的动态调节有关 神经元细胞骨架和突触重构，例如脑 发育和神经递质信号。补充证据来自 我们的实验室已经证明了Marcks在海马体中的作用 这是慢性锂在大脑中长期作用的目标。使用 最近建立了Macs基因的突变小鼠模型，该模型具有 现已回交到C57BL/6背景的第八代， 马克斯已被证明在大脑发育中起着关键作用。 我们实验室的最新数据首次证明了 MARCKS基因在脑内的分布优先 在大脑的边缘和边缘相关区域表达，具有 大鼠和小鼠海马区特异性细胞分布 大脑。在初步数据中，我们还证明了马克是 成人MACs Null/+以基因剂量依赖性方式表达 杂合子，Marcks大约50%的减少 表达与海马苔藓纤维增生有关，AS 以及加强空间学习(C.8b和C.9节)。这些 鉴于我们目前的额外研究，这些发现具有进一步的意义 数据显示，DBA/2小鼠表现出海马苔藓 纤维发育不全和显著的空间学习障碍，也显示 与C57BL/6相比，海马区Marcks显著升高 老鼠。这份提案概述了一项为期三年的跨学科研究 战略，与哺乳动物遗传学中心合作，以 创建表达Marcks水平从50%(Mac)变化的小鼠 空/+)到260%(Marcks Tg+/+)的野生型表达 老鼠。在这些小鼠中，我们将研究 MARCKS在海马苔藓纤维上的低表达和高表达 发育、海马LTP电生理学和空间学习。 此外，我们还将评估这种中间菌株的遗传基础。 Marcks基因表达的变异及其定位 控制回交MARCKS表达的数量性状基因座 和/或DBA/2与C57BL/6的F2杂交后代。 这种变异的基础是显而易见的，我们将确定是否相同的基因座 与苔藓纤维锥体下部投射的长度共分离 杂交后代的空间学习表现为最高与最低 马克。概述的一系列研究旨在检查直接 MARCKS在脑内与海马区相关的神经再生事件中的作用 发展和学习/记忆，并评估这些因素的程度 复杂的表型性状与macs基因本身和/或 互动式基因修饰物。

MARCKS (Myristoylated Alanine Rich C Kinase Substrate) is the most prominent phosphoprotein substrate for protein kinase C in brain. Accumulating data have indicated a role for MARCKS in transducing extracellular signals for the regulation of actin-membrane plasticity and cellular processes associated with dynamic regulation of the neuronal cytoskeleton and synaptic restructuring, e.g., brain development and neurotransmitter signaling. Additional evidence from our laboratory has demonstrated a role for MARCKS in the hippocampus as a target for the long-term action of chronic lithium in the brain. With the recent creation of a mutant mouse model for the Macs gene which has now been backcrossed onto a C57BL/6 background to the eighth generation, MARCKS has been shown to play a critical role in brain development. Recent data from our laboratory have demonstrated for the first time that the distribution of MARCKS mRNA in brain is preferentially expressed in limbic and limbic-related regions of the brain, with a specific cellular distribution in hippocampus of both rat and mouse brain. In preliminary data, we have also demonstrated that MARCKS is expressed in a gene-dose dependent fashion in adult Macs null/+ heterozygotes, and that the approximately 50 percent reduction of MARCKS expression is associated with hippocampal mossy fiber hyperplasia, as well as enhanced spatial learning (Sections C.8b and C.9). These findings take on further significance in light of our current additional data demonstrating that DBA/2 mice which demonstrate hippocampal mossy fiber hypoplasia and significant spatial learning deficits, also show a significant elevation in hippocampal MARCKS as compared to C57BL/6 mice. This proposal outlines a three year interdisciplinary research strategy, in conjunction with the Center for Mammalian Genetics, to create mice expressing levels of MARCKS varying from 50 percent (Macs null/+) to 260 percent (MARCKS Tg+/+) of that expressed by wild-type mice. In these mice we will investigate the functional consequences of both under and over-expression of MARCKS on hippocampal mossy fiber development, hippocampal LTP electrophysiology, and spatial learning. In addition, we will assess the genetic basis of this interstrain variation in MARCKS expression and identify the positions of quantitative trait loci controlling MARCKS expression among backcross and/or F2 intercross progeny of DBA/2 and C57BL/6. Once the genetic basis of this variation is evident, we will determine if the same loci cosegregate with the length of the mossy fiber infrapyramidal projection and spatial learning in hybrid progeny expressing highest vs. lowest MARCKS. The outlined series of studies are designed to examine a direct role for MARCKS in neuroplastic events in brain related to hippocampal development and learning/memory, and assess the extent to which these complex phenotypic traits are linked to the Macs gene itself and/or interactive gene modifiers.