Model for SorCS1-mediated Diabetes with Dementia

摘要 2型糖尿病(T2D或T2 DM)会增加患阿尔茨海默病(AD)的风险，而SORCS1是 基因上与T2D和AD有关。我们已经进行了一项关于SorCS1在 阿尔茨海默病淀粉样前体蛋白(APP)的代谢，以定义分子 这种机制与这两种疾病的遗传联系相协调。SorCS1c？-myc的过表达 导致世代减少(p=0.002)(Lane等人，2010年)。内源性小鼠 雌性动物大脑中A？40和A？42水平升高(A？40，p=0.044；A？42，p=0.007)。 低形态的小鼠，可能与遗传特征的性二型性平行 SORCS1与阿尔茨海默病和糖尿病的相关性自SORL1以来，另一种与AD相关的Vps10结构域蛋白直接 与VPS35相互作用调节APP代谢，我们调查了SorCS1c？-myc可能 与APP、SORL1和/或VPS35交互。我们很容易地恢复了SorCS1：App、SorCS1：SORL1和 SorCS1：来自非转基因小鼠脑的VPS35复合体。值得注意的是，总的VPS35蛋白水平是 大脑中SORL1总蛋白水平下降了29%(p=0.003)，下降了49%(p=0.009) 雌性Sorcs1-/-小鼠。我们推测，SorCS1功能障碍可能与APP/？ 阿尔茨海默病的潜在障碍和糖尿病的胰岛素/葡萄糖代谢障碍。为了测试 在这一假设的基础上，我们提出了以下具体目标：具体目标1.评估重要性 SorCS1蛋白相互作用基序和SorCS1/SORL1/APP复合体的形成对APP代谢的影响：(A) 鉴定APP在过表达SorCS1的培养细胞中的代谢；(B)测试 SorCS1胞质和胞外区蛋白相互作用基序的突变 三方SorCS1/SORL1/APP复合体的形成和APP代谢；(C)检测A 可能致病的SorCS1多态形成三方SorCS1/SORL1/APP复合体 和APP代谢；(D)确认目标1aii和1aiii中确定的功能结构域的重要性 病毒基因转移到原代培养物中。具体目的2.使用Sorcs1亚形和斑块- 人瑞典APP/PS双基因小鼠与Sorcs1亚型小鼠杂交的研究 研究：(I)内源性APP代谢；(Ii)海马形态计量学、树突分枝和脊椎 结构；(C)学习行为。老化(3个月、6个月、12个月)的影响也将被研究。具体目标3.至 对Sorcs1-/-小鼠进行标准的葡萄糖和胰岛素耐量试验及代谢谱表型分析 和斑块形成“人瑞典APP/PS共转基因小鼠与Sorcs1-/-小鼠杂交。

SUMMARY Type 2 diabetes mellitus (T2D or T2DM) increases the risk for Alzheimer's disease (AD), and SORCS1 is genetically linked to both T2D and AD. We have undertaken a study of the possible role(s) for SorCS1 in metabolism of the Alzheimer's amyloid-¿ (¿¿) precursor protein (APP), in order to define the molecular mechanisms underlying this coordinate genetic linkage to both diseases. Overexpression of SorCS1c¿-myc in cultured cells caused a reduction (p=0.002) in ¿¿ generation (Lane et al., 2010). Endogenous murine A¿40 and ¿¿42 levels were increased (A¿40, p=0.044; A¿42, p=0.007) in the brains of female Sorcs1 hypomorphic mice, possibly paralleling the sexual dimorphism that is characteristic of the genetic associations of SORCS1 with AD and DM. Since SorL1, another AD-linked Vps10-domain protein, directly interacts with Vps35 to modulate APP metabolism, we investigated the possibility that SorCS1c¿-myc might interact with APP, SorL1, and/or Vps35. We readily recovered SorCS1:APP, SorCS1:SorL1, and SorCS1:Vps35 complexes from nontransgenic mouse brain. Notably, total Vps35 protein levels were decreased by 49% (p=0.009) and total SorL1 protein levels were decreased by 29% (p=0.003) in the brains of female Sorcs1-/- mice. We hypothesize that dysfunction of SorCS1 may contribute to both the APP/¿¿ disturbance underlying AD and the insulin/glucose metabolism disturbance underlying DM. In order to test this hypothesis further, we propose the following specific aims: Specific Aim 1. To evaluate the importance of SorCS1 protein interaction motifs and SorCS1/SorL1/APP complex formation on APP metabolism by: (a) Characterizing APP metabolism in cultured cells overexpressing SorCS1; (b) Testing the effects of mutations of protein-protein interacting motifs in the cytoplasmic and ectodomains of SorCS1 on both the formation of tripartite SorCS1/SorL1/APP complexes and APP metabolism; (c) Testing the effect of a putative pathogenic SorCS1 polymorphism on both the formation of tripartite SorCS1/SorL1/APP complexes and APP metabolism; (d) Confirming the importance of functional domains identified in Aim 1aii and 1aiii by viral gene transfer into primary cultures. Specific Aim 2. To employ Sorcs1 hypomorphic and plaque- forming human Swedish APP/PS bigenic mice crossed with Sorcs1 hypomorphic mice for characterization of: (i) endogenous APP metabolism; (ii) hippocampal morphometry, dendritic arborization, and spine structure; (c) learning behavior. Aging (3 mo, 6 mo, 12 mo) effects will also be studied. Specific Aim 3. To perform standard glucose and insulin tolerance tests and metabolic profile phenotyping of Sorcs1-/- mice and plaque-forming" human Swedish APP/PS co-transgenic mice crossed with Sorcs1 -/- mice.