Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada.
Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.
J Neurochem. 2021 Jun;157(6):2195-2209. doi: 10.1111/jnc.15167. Epub 2020 Sep 21.
Heme oxygenase-1 (HO-1), a highly inducible stress protein that degrades heme to biliverdin, carbon monoxide, and free ferrous iron, is increased in blood and other biofluids of subjects with various systemic and neurological disorders. HO-1 does not contain an N-terminal signal peptide and the mechanism responsible for its secretion remains unknown. Extracellular vesicles (EVs) are membrane-bound inclusions that transport microRNAs, messenger RNAs, lipids, and proteins among diverse cellular and extracellular compartments. The objective of the current study was to determine whether EVs in human biofluids contain HO-1, and whether the latter may be transported in EVs from brain to periphery. Total, L1 cell adhesion molecule protein (L1CAM)-enriched (neuron-derived), and glutamate aspartate transporter 1 (GLAST)-enriched (astrocyte-derived) EVs were purified from five different human biofluids (saliva [n = 40], plasma [n = 14], serum [n = 10], urine [n = 10], and cerebrospinal fluid [n = 11]) using polymer precipitation and immuno-affinity-based capture methods. L1CAM-enriched, GLAST-enriched, and L1CAM/GLAST-depleted (LGD) EV, along with EV-depleted (EVD), fractions were validated by nanoparticle tracking analysis, enzyme-linked immunosorbent assay (ELISA), and western blot. HO-1 was assayed in all fractions using ELISA and western blot. The majority of HO-1 protein was localized to LGD, L1CAM-enriched, and GLAST-enriched EVs of all human biofluids surveyed after adjusting for age and sex, with little HO-1 protein detected in EVD fractions. HO-1 protein in human biofluids is predominantly localized to EV compartments. A substantial proportion of EV HO-1 in peripheral human biofluids is derived from the central nervous system and may contribute to the systemic manifestations of various neurological conditions.
血红素加氧酶-1（HO-1）是一种高度诱导的应激蛋白，可将血红素降解为胆绿素、一氧化碳和游离亚铁，在患有各种系统性和神经疾病的患者的血液和其他生物液中增加。HO-1 不含 N 端信号肽，其分泌的机制尚不清楚。细胞外囊泡（EVs）是一种膜结合的内含物，可在不同的细胞和细胞外隔室之间运输 microRNAs、信使 RNA、脂质和蛋白质。本研究的目的是确定人生物液中的 EV 是否含有 HO-1，以及后者是否可以通过 EV 从脑转移到外周。使用聚合物沉淀和免疫亲和捕获方法从五种不同的人生物液（唾液[ n = 40]、血浆[ n = 14]、血清[ n = 10]、尿液[ n = 10]和脑脊液[ n = 11]）中纯化总、L1 细胞黏附分子蛋白（L1CAM）富集（神经元衍生）和谷氨酸天冬氨酸转运蛋白 1（GLAST）富集（星形胶质细胞衍生）EV。使用纳米颗粒跟踪分析、酶联免疫吸附测定（ELISA）和 Western blot 验证 L1CAM 富集、GLAST 富集和 L1CAM/GLAST 耗尽（LGD）EV 以及 EV 耗尽（EVD）级分。使用 ELISA 和 Western blot 测定所有级分中的 HO-1。在调整年龄和性别后，所有调查的人生物液中的 LGD、L1CAM 富集和 GLAST 富集 EV 中大多数 HO-1 蛋白被定位，而 EVD 级分中检测到的 HO-1 蛋白很少。HO-1 蛋白主要位于人生物液的 EV 隔室中。外周人生物液中相当一部分 EV HO-1 源自中枢神经系统，可能有助于各种神经状况的全身表现。
