Reciprocal regulation of γ-globin expression by exo-miRNAs: Relevance to γ-globin silencing in β-thalassemia major

Sci Rep. 2017 Mar 16;7(1):202. doi: 10.1038/s41598-017-00150-7.

Abstract

Induction of fetal hemoglobin (HbF) is a promising strategy in the treatment of β-thalassemia major (β-TM). The present study shows that plasma exosomal miRNAs (exo-miRs) are involved in γ-globin regulation. Exosomes shuttle miRNAs and mediate cell-cell communication. MiRNAs are regulators of biological processes through post-transcriptional targeting. Compared to HD (Healthy Donor), β-TM patients showed increased levels of plasma exosomes and the majority of exosomes had cellular origin from CD34+ cells. Further, HD and β-TM exosomes showed differential miRNA expressions. Among them, deregulated miR-223-3p and miR-138-5p in β-TM exosomes and HD had specific targets for γ-globin regulator and repressor respectively. Functional studies in K562 cells showed that HD exosomes and miR-138-5p regulated γ-globin expression by targeting BCL11A. β-TM exosomes and miR-223-3p down regulated γ-globin expression through LMO2 targeting. Importantly, miR-223-3p targeting through sponge repression resulted in γ-globin activation. Further, hnRNPA1 bound to stem-loop structure of pre-miR-223 and we found that hnRNPA1 knockdown or mutagenesis at miR-223-3p stem-loop sequence resulted in less mature exo-miR-223-3p levels. Altogether, the study shows for the first time on the important clinical evidence that differentially expressed exo-miRNAs reciprocally control γ-globin expressions. Further, the hnRNPA1-exo-miR-223-LMO2 axis may be critical to γ-globin silencing in β-TM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adolescent
  • Adult
  • Carrier Proteins / genetics
  • Cell Communication
  • Down-Regulation*
  • Exosomes / genetics*
  • Female
  • Heterogeneous Nuclear Ribonucleoprotein A1 / genetics
  • Humans
  • K562 Cells
  • LIM Domain Proteins / genetics
  • Male
  • MicroRNAs / genetics*
  • Nuclear Proteins / genetics
  • Proto-Oncogene Proteins / genetics
  • Repressor Proteins
  • Young Adult
  • beta-Thalassemia / genetics*
  • gamma-Globins / genetics*

Substances

  • Adaptor Proteins, Signal Transducing
  • BCL11A protein, human
  • Carrier Proteins
  • Heterogeneous Nuclear Ribonucleoprotein A1
  • LIM Domain Proteins
  • LMO2 protein, human
  • MIRN138 microRNA, human
  • MIRN223 microRNA, human
  • MicroRNAs
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Repressor Proteins
  • gamma-Globins
  • hnRNPA1 protein, human