title: Geniposide reduces α-synuclein by blocking microRNA-21/lysosome-associated membrane protein 2A interaction in Parkinson disease models.
abstract: This study aimed to explore whether the regulatory effect of miR-21 on α-synuclein expression in neurons is a potential mechanism by which geniopside (GP) protects the central nervous system from Parkinson disease (PD).
  
  
  
  The human neuroblastoma cell line SH-SY5Y was induced to differentiate in vitro and treated with dimethyl sulfoxide (DMSO), N-methyl-4-phenylpyridinium iodide (MPP(+)), and MPP(+) together with GP. To identify the role of miR-21 in the regulation of lysosome-associated membrane protein 2 (LAMP2A) and α-synuclein, SH-SY5Y cells pretreated with MPP(+) were transfected with miR-21 mimic and miR-21 inhibitor. To identify whether GP could reduce the level of α-synuclein through miR-21/LAMP2A, SHSY5Y cells pretreated with GP were treated with miR-21 mimic or miR-21 inhibitor; meanwhile, a luciferase reporter assay was performed to confirm the direct target of miR-21. LAMP2A was overexpressed using a pCMV6-XL5-LAMP2A vector to confirm the role of LAMP2A in the regulation of α-synuclein by miR-21. In these in vitro experiments, the RNA and/or protein expressions of miR-21, LAMP2A, and α-synuclein in SH-SY5Y cells were determined by quantitative real-time polymerase chain reaction and/or western blotting, respectively. An in vivo PD mouse model was established through intraperitoneal injection with N-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP). The mice were treated with saline, MPTP, MPTP+GP, and MPTP+GP+miR-21 agomir. The numbers of TH(+) cells in the substantia nigra in different groups of mice were compared. The RNA and/or protein expressions of miR-21, LAMP2A, and α-synuclein were also determined.
  
  
  
  The level of miR-21 in the cells or mice models was significantly higher than that in normal cells or normal mice, respectively, and GP significantly downregulated miR-21. GP also raised the protein and mRNA expressions of LAMP2A and reduced the protein level of α-synuclein in PD models. MiR-21 upregulated the expression of α-synuclein by directly targeting 3' UTR of LAMP2A. LAMP2A overexpression abolished the upregulating effect of miR-21 mimic on α-synuclein. MiR-21 mimics/agomir reversed the GP-induced downregulation of α-synuclein; miR-21 inhibitor effectively increased the downregulation of α-synuclein caused by GP.
  
  
  
  GP exhibits neuroprotective properties by inhibiting α-synuclein expression in PD models through the miR-21/LAMP2A axis.
authors.affiliation: Department of Neurology, Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, Henan Province, China.
authors.forename: Chunhe
authors.initials: C
authors.lastname: Su
authors.affiliation: Department of Neurology, Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, Henan Province, China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Neurology, Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, Henan Province, China. Electronic address: loujiy@126.com.
authors.forename: Jiyu
authors.initials: J
authors.lastname: Lou
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D039823:Iridoids / Q000008:administration & dosage*; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism*; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000008:administration & dosage*; D010300:Parkinson Disease / Q000378:metabolism / Q000517:prevention & control; D020734:Parkinsonian Disorders / Q000378:metabolism*; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D051844:alpha-Synuclein / Q000378:metabolism*
chemical_list: D039823:Iridoids; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D018696:Neuroprotective Agents; D051844:alpha-Synuclein; C007835:geniposide; D014446:Tyrosine 3-Monooxygenase
keywords: Geniposide; LAMP2A; MiR-21; Parkinson disease; α-synuclein