Model for SorCS1-mediated Diabetes with Dementia

总结 2型糖尿病（T2 D或T2 DM）增加阿尔茨海默病（AD）的风险，SORCS 1是 与T2 D和AD都有遗传联系。我们已经对SorCS 1在以下方面可能发挥的作用进行了研究： 阿尔茨海默氏症淀粉样蛋白前体蛋白（APP）的代谢，以确定分子 这两种疾病的协调遗传联系的潜在机制。SorCS 1c-myc的过表达 在培养的细胞中，引起第二代的减少（p=0.002）（Lane等人，2010年）。内源鼠 在雌性Sorcs的大脑中，A <$40和A <$42水平增加（A <$40，p=0.044; A <$42，p=0.007）1 亚型小鼠，可能与遗传特征的性二型性平行。 SORCS 1与AD和DM的相关性。由于SorL 1，另一个AD连接的Vps 10结构域蛋白，直接 与Vps 35相互作用以调节APP代谢，我们研究了SorCS 1c <$-myc可能 与APP、SorL 1和/或Vps 35交互。我们很容易地回收了SorCS 1：APP，SorCS 1：SorL 1， 来自非转基因小鼠脑的SorCS 1：Vps 35复合物。值得注意的是，总Vps 35蛋白水平为 降低49%（p=0.009），大脑中总SorL 1蛋白水平降低29%（p=0.003 雌性Sorcs 1-/-小鼠的死亡率。我们假设SorCS 1的功能障碍可能导致APP/APP 1/APP 2的表达。 AD基础的胰岛素/葡萄糖代谢紊乱和DM基础的胰岛素/葡萄糖代谢紊乱。为了测试 根据这一假设，我们提出了以下具体目标：具体目标1。为了评估 SorCS 1蛋白相互作用基序和SorCS 1/SorL 1/APP复合物形成对APP代谢的影响： 表征过表达SorCS 1的培养细胞中的APP代谢;（B）测试 SorCS 1的胞质和胞外域中蛋白质-蛋白质相互作用基序的突变， 三重SorCS 1/SorL 1/APP复合物的形成和APP代谢;（c）测试 推定的致病性SorCS 1多态性对SorCS 1/SorL 1/APP三元复合物的形成均具有影响 和APP代谢;（d）通过以下方式重申目标1aii和1aiii中鉴定的功能结构域的重要性： 将病毒基因转移到原代培养物中。具体目标2。使用半变形巫师和噬斑巫师- 形成人瑞典APP/PS双基因小鼠与Sorcs 1亚型小鼠杂交用于表征 （i）内源性APP代谢;（ii）海马形态学，树突状分支和棘 （3）学习行为。还将研究老化（3个月、6个月、12个月）的影响。具体目标3。到 对Sorcs 1-/-小鼠进行标准葡萄糖和胰岛素耐量试验和代谢谱表型分析 以及与Sorcs 1-/-小鼠杂交的“噬斑形成”人瑞典APP/PS共转基因小鼠。

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.