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Mol Neurobiol. 2017 May;54(4):2595-2610. doi: 10.1007/s12035-016-9856-8. Epub 2016 Mar 19.

MicroRNA-27a Promotes Inefficient Lysosomal Clearance in the Hippocampi of Rats Following Chronic Brain Hypoperfusion.

Author information

1
Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), No.157 Baojian Road, Nangang District, Harbin, Heilongjiang Province, 150086, China.
2
Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, 150001, China.
3
Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), No.157 Baojian Road, Nangang District, Harbin, Heilongjiang Province, 150086, China. azhrbmu@126.com.

Abstract

Chronic brain hypoperfusion (CBH) induces the accumulation of abnormal cellular proteins, accompanied by cognitive decline, and the autophagic-lysosomal system is abnormal in dementia. Whether CBH accounts for autophagic-lysosomal neuropathology remains unknown. Here, we show that CBH significantly increased the number of autophagic vacuoles (AVs) with high LC3-II levels, but decreased SQSTM1 and cathepsin D levels in the hippocampi of rats following bilateral common carotid artery occlusion (2VO) for 2 weeks. Further studies showed that microRNA-27a (Mir27a) was upregulated at 2 weeks compared with the sham group. Additionally, LAMP-2 proteins were downregulated by Mir27a overexpression, upregulated by Mir27a inhibition, and unchanged by binding-site mutations or miR-masks, indicating that lamp-2 is the target of Mir27a. Knockdown of endogenous Mir27a prevented the reduction of LAMP-2 protein expression as well as the accumulation of AVs in the hippocampi of 2VO rats. Overexpression of Mir27a induced, while the knockdown of Mir27a reduced, the accumulation of AVs and the LC3-II level in cultured neonatal rat neurons. The results revealed that CBH in rats at 2 weeks could induce inefficient lysosomal clearance, which is regulated by the Mir27a-mediated downregulation of LAMP-2 protein expression. These findings provide an insight into a novel molecular mechanism of autophagy at the miRNA level.

KEYWORDS:

Autophagy; Chronic brain hypoperfusion; LAMP-2; Lysosome; Mir27a

PMID:
26993299
DOI:
10.1007/s12035-016-9856-8
[Indexed for MEDLINE]

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