Analysis of the detrimental effects of Cnr1-/- mice in an Alzheimer's mouse model and of the interplay between CB1 receptor function and amyloid precursor protein processing

为了研究内源性大麻素系统与阿尔茨海默病(AD)之间的相互作用，我们建立了一种新的转基因小鼠模型。在第一个资助期，在一个著名的AD小鼠(APP23)中发现了CB1。与APP23/Cnr1-/+和APP23/Cnr1+/+小鼠相比，APP23/Cnr1-/-小鼠的出生率和体重较低，死亡率较高。Cnr1的缺失会影响APP的生物化学，导致淀粉样斑块负荷减少和炎症减少。尽管如此，APP23/Cnr1-/-小鼠的学习和记忆能力却有所下降。我们现在将分析CB1受体在幼年动物和存活的老年动物中对APP生化的调节作用，并利用体外模型来研究信号转导。为了解决APP23/Cnr1-/-小鼠在没有明确原因的情况下意外的高死亡率，我们的目标是通过关注潜在的关键角色和细胞死亡的机制来破译早期死亡的原因，包括髓鞘形成缺陷、氧化应激和宏观自噬途径。因此，我们将研究髓鞘碱性蛋白、髓鞘少突胶质细胞糖蛋白和2‘，3’-环核苷酸3‘-磷酸二酯酶在幼年APP23/Cnr1-/-小鼠中的表达。此外，我们还将比较所有基因类型的幼年和成年动物的宏自噬和蛋白质降解(如LC3、p62、WIPI1、泛素)和蛋白质动态平衡的途径。此外，我们计划对过早死亡的动物进行详细的解剖学分析，以确定潜在的病理异常，表明死亡原因。

To study the interplay between the endocannabinoid system and Alzheimer’s disease (AD), we established a novel transgenic mouse model, a k.o. of CB1 in a well-known AD mouse (APP23) in the first funding period. APP23/Cnr1-/- mice showed lower birth rate and body weight and a highly increased mortality compared to APP23/Cnr1-/+ and APP23/Cnr1+/+ mice. Deletion of Cnr1 affects APP biochemistry, leading to a reduced amyloid plaque load and reduced inflammation. Despite that, APP23/Cnr1-/- mice displayed decreased learning and memory abilities. We will now analyze the regulatory role of CB1 receptors on the APP biochemistry in young and in the surviving old animals and employ in vitro models to study the signal transduction. To address the unexpected high mortality of the APP23/Cnr1-/- mice without an overt reason, we aim to decipher the cause of early death by focusing on potential key players and mechanisms of cell death including deficits in myelination, oxidative stress and the macroautophagy pathway. Therefore, we will investigate the expression of myelin basic protein as well as of myelin oligodendrocyte glycoprotein and 2',3'-cyclic nucleotide 3'- phosphodiesterase in young APP23/Cnr1-/- mice. In addition, we will compare the pathways of macroautophagy and protein degradation (e.g. LC3, p62, WIPI1, ubiquitin) and protein homeostasis in young and adult animals of all genotypes. In addition, we plan a detailed anatomical analysis of the animals, which have died prematurely in order to identify potential pathological abnormalities that indicate the cause of death.