LRAD3, a novel low-density lipoprotein receptor family member that modulates amyloid precursor protein trafficking.
LRAD3, a novel low-density lipoprotein receptor family member that modulates amyloid precursor protein trafficking.
复制标题
DOI：
10.1523/jneurosci.5065-10.2011
复制
发表时间：
2011-07-27
期刊：
影响因子：
--
通讯作者：
Strickland DK
中科院分区：
文献类型：
--
作者：
Ranganathan S;Noyes NC;Migliorini M;Winkles JA;Battey FD;Hyman BT;Smith E;Yepes M;Mikhailenko I;Strickland DK
我们已经确定了一个新的LDL受体家族成员，称为LDL受体A类结构域包含3（LRAD 3），这是在神经元中表达。LRAD 3基因编码约50 kDa的I型跨膜受体，其具有包含三个LDLa重复的胞外域、跨膜结构域和包含保守的双亮氨酸内化基序和两个聚脯氨酸基序的胞质结构域，所述胞质结构域具有与包含WW结构域的蛋白质相互作用的潜力。小鼠脑的免疫组织化学分析揭示了LRAD 3在皮质和海马中的表达。在小鼠海马衍生细胞系HT 22中，LRAD 3与淀粉样前体蛋白（APP）部分共定位，并与APP相互作用，如免疫共沉淀实验所揭示的。为了鉴定与LRAD 3相互作用的APP部分，我们采用固相结合试验，该试验证明LRAD 3不能与α-分泌酶切割后释放的可溶性APP片段（sAPPα）结合。相比之下，C99（保持细胞缔合的β-分泌酶产物）与LRAD 3共沉淀，证实APP的该部分内的区域对于与LRAD 3缔合是重要的。LRAD 3与APP的结合增加了APP加工的淀粉样蛋白生成途径，导致sAPPα产生减少和Aβ肽产生增加。脉冲追踪实验证实，LRAD 3的表达显着降低了成熟APP的细胞半衰期。这些结果表明，LRAD 3影响APP的加工，并提出了可能性，LRAD 3改变APP功能的神经元，包括其下游信号。
We have identified a novel LDL receptor family member, termed LDL receptor class A domain containing 3 (LRAD3), which is expressed in neurons. The LRAD3 gene encodes an approximately 50 kDa type I transmembrane receptor with an ectodomain containing three LDLa repeats, a transmembrane domain and a cytoplasmic domain containing a conserved dileucine internalization motif and two polyproline motifs with potential to interact with WW domain containing proteins. Immunohistochemical analysis of mouse brain reveals LRAD3 expression in the cortex and hippocampus. In the mouse hippocampal derived cell line, HT22, LRAD3 partially co-localizes with amyloid precursor protein (APP), and interacts with APP as revealed by co-immunoprecipitation experiments. To identify the portion of APP that interacts with LRAD3, we employed solid phase binding assays which demonstrated that LRAD3 failed to bind to a soluble APP fragment (sAPPα) released following α-secretase cleavage. In contrast, C99, the β-secretase product that remains cell associated, co-precipitated with LRAD3, confirming that regions within this portion of APP are important for associating with LRAD3. The association of LRAD3 with APP increases the amyloidogenic pathway of APP processing, resulting in a decrease in sAPPα production and increased Aβ peptide production. Pulse-chase experiments confirm that LRAD3 expression significantly decreases the cellular half-live of mature APP. These results reveal that LRAD3 influences APP processing and raises the possibility that LRAD3 alters APP function in neurons including its downstream signaling.