Tnfaip8 Is an Essential Gene for the Regulation of Glucocorticoid-Mediated Apoptosis of Thymocytes

Cell Death Differ. 2010 Feb;17(2):316-23. doi: 10.1038/cdd.2009.125. Epub 2009 Sep 4.

Abstract

Glucocorticoids have significant immunoregulatory actions on thymocytes and T cells and act by binding and activating cytosolic glucocorticoid receptors, which translocate to the nucleus and control gene expression through binding to specific response elements in target genes. Glucocorticoids promote cell death by activating an apoptotic program that requires transcriptional regulation. We set out to identify genes that are crucial to the process of glucocorticoid-mediated thymocyte apoptosis. Freshly isolated murine primary thymocytes were treated with dexamethasone, mRNA isolated and used to screen DNA microarrays. A set of candidate genes with upregulated expression was identified and selected members assayed in reconstituted fetal thymic organ culture (FTOC). Fetal liver-derived hematopoietic progenitor cells (HPCs) were infected with retroviruses expressing individual genes then used to repopulate depleted fetal thymic lobes. Reconstituted FTOCs expressing the gene Tnfaip8 were treated with dexamethasone and shown to be greatly sensitized to dexamethasone. Retrovirus-mediated RNA interference was applied to knock down Tnfaip8 expression in HPCs and these were used to reconstitute FTOCs. We observed that downregulating the expression of Tnfaip8 alone was sufficient to effectively protect thymocytes against glucocorticoid-induced apoptosis. We propose that Tnfaip8 is crucial in regulating glucocorticoid-mediated apoptosis of thymocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Apoptosis Regulatory Proteins / genetics*
  • Apoptosis Regulatory Proteins / metabolism*
  • Dexamethasone / metabolism*
  • Dexamethasone / pharmacology
  • Glucocorticoids / metabolism*
  • Glucocorticoids / pharmacology
  • Mice
  • Organ Culture Techniques
  • RNA Interference
  • Retroviridae / genetics
  • Stromal Cells / cytology
  • Stromal Cells / drug effects
  • Stromal Cells / physiology
  • T-Lymphocytes / cytology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / physiology
  • Thymus Gland / cytology*
  • Thymus Gland / physiology*
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / immunology
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Apoptosis Regulatory Proteins
  • Glucocorticoids
  • TNFAIP8 protein, mouse
  • Tumor Necrosis Factor-alpha
  • Dexamethasone