Cell-specific post-transcriptional regulation of γ-synuclein gene by micro-RNAs

PLoS One. 2013 Sep 11;8(9):e73786. doi: 10.1371/journal.pone.0073786. eCollection 2013.

Abstract

γ-Synuclein is a member of the synucleins family of small proteins, which consists of three members:α, β- and γ-synuclein. γ-Synuclein is abnormally expressed in a high percentage of advanced and metastatic tumors, but not in normal or benign tissues. Furthermore, γ-synuclein expression is strongly correlated with disease progression, and can stimulate proliferation, induce invasion and metastasis of cancer cells. γ-Synuclein transcription is regulated basically through the binding of AP-1 to specific sequences in intron 1. Here we show that γ-synuclein expression may be also regulated by micro RNAs (miRs) on post-transcriptional level. According to prediction by several methods, the 3'-untranslated region (UTR) of γ-synuclein gene contains targets for miRs. Insertion of γ-synuclein 3'-UTR downstream of the reporter luciferase (LUC) gene causes a 51% reduction of LUC activity after transfection into SKBR3 and Y79 cells, confirming the presence of efficient targets for miRs in this fragment. Expression of miR-4437 and miR-4674 for which putative targets in 3'-UTR were predicted caused a 61.2% and 60.1% reduction of endogenous γ-synuclein expression confirming their role in gene expression regulation. On the other hand, in cells overexpressing γ-synuclein no significant effect of miRs on γ-synuclein expression was found suggesting that miRs exert their regulatory effect only at low or moderate, but not at high level of γ-synuclein expression. Elevated level of γ-synuclein differentially changes the level of several miRs expression, upregulating the level of some miRs and downregulating the level of others. Three miRs upregulated as a result of γ-synuclein overexpression, i.e., miR-885-3p, miR-138 and miR-497 have putative targets in 3'-UTR of the γ-synuclein gene. Some of miRs differentially regulated by γ-synuclein may modulate signaling pathways and cancer related gene expression. This study demonstrates that miRs might provide cell-specific regulation of γ-synuclein expression and set the stage to further evaluate their role in pathophysiological processes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 3' Untranslated Regions / genetics*
  • Base Sequence
  • Blotting, Western
  • Cell Line, Tumor
  • Cluster Analysis
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Luciferases* / genetics
  • Luciferases* / metabolism
  • MicroRNAs / genetics*
  • Models, Genetic
  • Molecular Sequence Data
  • Oligonucleotide Array Sequence Analysis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / genetics
  • Transcriptome
  • gamma-Synuclein / genetics*
  • gamma-Synuclein / metabolism

Substances

  • 3' Untranslated Regions
  • MIRN-4437 microRNA, human
  • MIRN138 microRNA, human
  • MIRN4674 microRNA, human
  • MIRN497 microRNA, human
  • MIRN885 microRNA, human
  • MicroRNAs
  • gamma-Synuclein
  • Luciferases

Grants and funding

This work was supported by VA Merit review grant and the Glaucoma Foundation grant. VA merit Review grant is a federal funding, the Glaucoma foundation is a private funding agency. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.