Altered A-to-I RNA editing in human embryogenesis

PLoS One. 2012;7(7):e41576. doi: 10.1371/journal.pone.0041576. Epub 2012 Jul 31.


Post-transcriptional events play an important role in human development. The question arises as to whether Adenosine to Inosine RNA editing, catalyzed by the ADAR (Adenosine Deaminase acting on RNA) enzymes, differs in human embryogenesis and in adulthood. We tested the editing of various target genes in coding (FLNA, BLCAP, CYFIP2) and non-coding sequences at their Alu elements (BRCA1, CARD11, RBBP9, MDM4, FNACC), as well as the transcriptional levels of the ADAR1 enzymes. This analysis was performed on five fetal and adult human tissues: brain, heart, liver, kidney, and spleen, as well as on human embryonic stem cells (hESCs), which represent the blastocyst stage in early human development. Our results show substantially greater editing activity for most adult tissue samples relative to fetal ones, in six of the eight genes tested. To test the effect of reduced A-to-I RNA editing activity in early human development we used human embryonic stem cells (hESCs) as a model and tried to generate hESC clones that overexpress the ADAR1-p110 isoform. We were unable to achieve overexpression of ADAR1-p110 by either transfection or lentiviral infection, though we easily generated hESC clones that expressed the GFP transgene and overexpressed ADAR1-p110 in 293T cells and in primary human foreskin fibroblast (HFF) cells. Moreover, in contrast to the expected overexpression of ADAR1-p110 protein following its introduction into hESCs, the expression levels of this protein decreased dramatically 24-48 hr post infection. Similar results were obtained when we tried to overexpress ADAR1-p110 in pluripotent embryonal carcinoma cells. This suggests that ADAR1 protein is substantially regulated in undifferentiated pluripotent hESCs. Overall, our data suggest that A-to-I RNA editing plays a critical role during early human development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adenosine / genetics
  • Adenosine / metabolism
  • Adenosine Deaminase / genetics
  • Adenosine Deaminase / metabolism
  • Alu Elements
  • BRCA1 Protein / genetics
  • CARD Signaling Adaptor Proteins / genetics
  • Cell Cycle Proteins / genetics
  • Cells, Cultured
  • Contractile Proteins / genetics
  • Embryonal Carcinoma Stem Cells
  • Embryonic Development*
  • Embryonic Stem Cells
  • Fanconi Anemia Complementation Group C Protein / genetics
  • Filamins
  • Gene Expression
  • Gene Expression Regulation, Developmental
  • Guanylate Cyclase / genetics
  • Humans
  • Inosine / genetics
  • Inosine / metabolism
  • Intracellular Signaling Peptides and Proteins / genetics
  • Microfilament Proteins / genetics
  • Neoplasm Proteins / genetics
  • Nuclear Proteins / genetics
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Proto-Oncogene Proteins / genetics
  • RNA Editing*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins


  • Adaptor Proteins, Signal Transducing
  • BLCAP protein, human
  • BRCA1 Protein
  • BRCA1 protein, human
  • CARD Signaling Adaptor Proteins
  • CYFIP2 protein, human
  • Cell Cycle Proteins
  • Contractile Proteins
  • FANCC protein, human
  • Fanconi Anemia Complementation Group C Protein
  • Filamins
  • Intracellular Signaling Peptides and Proteins
  • MDM4 protein, human
  • Microfilament Proteins
  • Neoplasm Proteins
  • Nuclear Proteins
  • Protein Isoforms
  • Proto-Oncogene Proteins
  • RBBP9 protein, human
  • RNA, Messenger
  • RNA-Binding Proteins
  • Inosine
  • ADARB1 protein, human
  • Adenosine Deaminase
  • CARD11 protein, human
  • Guanylate Cyclase
  • Adenosine

Grants and funding

This study was supported by Technion Research and Development Foundation Ltd., which is fully own by the Technion - Israel Institute of Technology - a non-for-profit organization. This work was also supported in part by grants from Bio-Med Morasha ISF and The Israel Ministry for Science and Technology (Scientific Infrastructure Program). The funders have no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.