Caspr1 Facilitates sAPP alpha Production by Regulating alpha-Secretase ADAM9 in Brain Endothelial Cells
Caspr1 Facilitates sAPP alpha Production by Regulating alpha-Secretase ADAM9 in Brain Endothelial Cells
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Caspr1 通过调节脑内皮细胞中的 α-分泌酶 ADAM9 促进 sAPPα 的产生
DOI：
10.3389/fnmol.2020.00023
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发表时间：
2020
影响因子：
4.8
通讯作者：
Chen YH
中科院分区：
文献类型：
--
作者：
Tang SY;Liu DX;Li Y;Wang KJ;Wang XF;Su ZK;Fang WG;Qin XX;Wei JY;Zhao WD;Chen YH
接触素相关蛋白1（Caspr 1）在脑微血管内皮细胞（BMEC）中的表达是近年来发现的。然而，Caspr 1在BMEC中的生理作用仍不清楚。我们先前报道了人骨髓基质细胞（HBMEC）中淀粉样蛋白前体（APP）通路的非淀粉样加工。在这项研究中，我们发现Caspr 1缺失降低了HBMEC上清液中可溶性淀粉样蛋白前体α（sAPPα）的水平，这可以通过全长Caspr 1的表达来挽救。我们进一步的结果表明，在Caspr 1缺失的HBMEC中，ADAM 9（APP加工产生sAPPα所必需的α-分泌酶）减少。在Caspr 1缺失的HBMEC中，sAPPα分泌减少可通过外源性ADAM 9的表达恢复。随后，我们确定Caspr 1通过核因子-κB（NF-κB）信号通路在转录水平特异性调控ADAM 9的表达，而不调控ADAM 10和ADAM 17的表达。Caspr 1基因敲除可抑制NF-κB的活化，抑制p65的核转位，而全长Caspr 1的表达可逆转这一作用。NF-κB激动剂可有效恢复Caspr 1耗尽后sAPPα产生和ADAM 9表达的减少。荧光素酶分析结果表明，NF-κB结合位点位于ADAM 9启动子的−859 bp至−571 bp之间。综上所述，我们的结果表明，Caspr 1通过转录调节脑内皮细胞中的α-分泌酶ADAM 9促进sAPPα的产生。
The expression of contactin-associated protein 1 (Caspr1) in brain microvascular endothelial cells (BMECs), one of the major cellular components of the neurovascular unit (NVU), has been revealed recently. However, the physiological role of Caspr1 in BMECs remains unclear. We previously reported the nonamyloidogenic processing of amyloid protein precursor (APP) pathway in the human BMECs (HBMECs). In this study, we found Caspr1 depletion reduced the levels of soluble amyloid protein precursor α (sAPPα) in the supernatant of HBMECs, which could be rescued by expression of full-length Caspr1. Our further results showed that ADAM9, the α-secretase essential for processing of APP to generate sAPPα, was decreased in Caspr1-depleted HBMECs. The reduced sAPPα secretion in Caspr1-depleted HBMECs was recovered by expression of exogenous ADAM9. Then, we identified that Caspr1 specifically regulates the expression of ADAM9, but not ADAM10 and ADAM17, at transcriptional level by nuclear factor-κB (NF-κB) signaling pathway. Caspr1 knockout attenuated the activation of NF-κB and prevented the nuclear translocation of p65 in brain endothelial cells, which was reversed by expression of full-length Caspr1. The reduced sAPPα production and ADAM9 expression upon Caspr1 depletion were effectively recovered by NF-κB agonist. The results of luciferase assays indicated that the NF-κB binding sites are located at −859 bp to −571 bp of ADAM9 promoter. Taken together, our results demonstrated that Caspr1 facilitates sAPPα production by transcriptional regulation of α-secretase ADAM9 in brain endothelial cells.