Transgene-associated human growth hormone expression in pancreatic β-cells impairs identification of sex-based gene expression differences

Am J Physiol Endocrinol Metab. 2019 Feb 1;316(2):E196-E209. doi: 10.1152/ajpendo.00229.2018. Epub 2018 Dec 11.

Abstract

Fluorescent protein reporter genes are widely used to identify and sort murine pancreatic β-cells. In this study, we compared use of the MIP-GFP transgene, which exhibits aberrant expression of human growth hormone (hGH), with a newly derived Ins2Apple allele that lacks hGH expression on the expression of sex-specific genes. β-Cells from MIP-GFP transgenic mice exhibit changes in the expression of 7,733 genes, or greater than half of their transcriptome, compared with β-cells from Ins2Apple/+ mice. To determine how these differences might affect a typical differential gene expression study, we analyzed the effect of sex on gene expression using both reporter lines. Six hundred fifty-seven differentially expressed genes were identified between male and female β-cells containing the Ins2Apple allele. Female β-cells exhibit higher expression of Xist, Tmed9, Arpc3, Eml2, and several islet-enriched transcription factors, including Nkx2-2 and Hnf4a, whereas male β-cells exhibited a generally higher expression of genes involved in cell cycle regulation. In marked contrast, the same male vs. female comparison of β-cells containing the MIP-GFP transgene revealed only 115 differentially expressed genes, and comparison of the 2 lists of differentially expressed genes revealed only 17 that were common to both analyses. These results indicate that 1) male and female β-cells differ in their expression of key transcription factors and cell cycle regulators and 2) the MIP-GFP transgene may attenuate sex-specific differences that distinguish male and female β-cells, thereby impairing the identification of sex-specific variations.

Keywords: RNA-Seq; gene expression; growth hormone; pancreatic β-cells; sex.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Female
  • Gene Expression
  • Genes, Reporter / genetics
  • Green Fluorescent Proteins / genetics*
  • Green Fluorescent Proteins / metabolism
  • Human Growth Hormone / genetics*
  • Human Growth Hormone / metabolism
  • Humans
  • Insulin / genetics*
  • Insulin-Secreting Cells / metabolism*
  • Male
  • Mice
  • Mice, Transgenic
  • Promoter Regions, Genetic
  • RNA, Messenger / metabolism
  • Sex Factors
  • Transgenes

Substances

  • Ins1 protein, mouse
  • Ins2 protein, mouse
  • Insulin
  • RNA, Messenger
  • Human Growth Hormone
  • Green Fluorescent Proteins