TGF-β contamination of purified recombinant GDF15

PLoS One. 2017 Nov 21;12(11):e0187349. doi: 10.1371/journal.pone.0187349. eCollection 2017.

Abstract

Purified recombinant proteins for use in biomedical research are invaluable to investigate protein function. However, purity varies in protein batches made in mammalian expression systems, such as CHO-cells or HEK293-cells. This study points to caution while investigating effects of proteins related to the transforming growth factor (TGF)-β superfamily. TGF-β itself is a very potent cytokine and has effects on cells in the femtomolar range. Thus, even very small amounts of contaminating TGF-β in purified protein batches may influence the experimental results given that receptors for TGF-β are present. When we attempted to characterize possible receptors for the TGF-β superfamily ligand GDF15, striking similarities between GDF15-induced activities and known TGF-β activities were found. However, differences between batches of GDF15 were a concern and finally led us to the conclusion that the measured effects were caused by TGF-β and not by GDF15. Our results emphasize that purified recombinant proteins must be used with caution and warrant proper controls. Notably, some conclusions made about GDF15 in already published papers may not be supported by the results shown. Awareness about this issue in the scientific community may prevent spreading of false positive results.

MeSH terms

  • Animals
  • CHO Cells
  • Cell Differentiation / genetics
  • Cell Line, Tumor
  • Cricetulus
  • Gene Expression / genetics
  • Growth Differentiation Factor 15 / genetics
  • Growth Differentiation Factor 15 / isolation & purification*
  • Humans
  • Phosphorylation
  • RNA, Small Interfering / genetics
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification*
  • Signal Transduction
  • Smad Proteins / genetics
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / isolation & purification*

Substances

  • GDF15 protein, human
  • Growth Differentiation Factor 15
  • RNA, Small Interfering
  • Recombinant Proteins
  • Smad Proteins
  • Transforming Growth Factor beta

Grants and funding

The work was supported by a grant from Kreftforeningen (NO)(https://kreftforeningen.no), Project number: 5793765. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.