The Majority of the Serine/Threonine Phosphorylation Sites in Bcl11b Protein Are Dispensable for the Differentiation of T Cells

J Immunol. 2023 Jun 1;210(11):1728-1739. doi: 10.4049/jimmunol.2200101.

Abstract

Posttranslational modification, such as phosphorylation, is an important biological event that modulates and diversifies protein function. Bcl11b protein is a zinc-finger transcription factor that plays a crucial role in early T cell development and the segregation of T cell subsets. Bcl11b possesses at least 25 serine/threonine (S/T) residues that can be phosphorylated upon TCR stimulation. To understand the physiological relevance of the phosphorylation on Bcl11b protein, we replaced S/T residues with alanine (A) by targeting murine Bcl11b gene in embryonic stem cells. By combinational targeting of exons 2 and 4 in the Bcl11b gene, we generated a mouse strain, Bcl11b-phosphorylation site mutation mice, in which 23 S/T residues were replaced with A residues. Such extensive manipulation left only five putative phosphorylated residues, two of which were specific for mutant protein, and resulted in reduced amounts of Bcl11b protein. However, primary T cell development in the thymus, as well as the maintenance of peripheral T cells, remained intact even after loss of major physiological phosphorylation. In addition, in vitro differentiation of CD4+ naive T cells into effector Th cell subsets-Th1, Th2, Th17, and regulatory T-was comparable between wild-type and Bcl11b-phosphorylation site mutation mice. These findings indicate that the physiological phosphorylation on major 23 S/T residues in Bcl11b is dispensable for Bcl11b functions in early T cell development and effector Th cell differentiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Mice
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Repressor Proteins* / genetics
  • Serine / genetics
  • Serine / metabolism
  • Threonine / genetics
  • Threonine / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Tumor Suppressor Proteins* / metabolism

Substances

  • Repressor Proteins
  • Tumor Suppressor Proteins
  • Transcription Factors
  • Serine
  • Threonine
  • Bcl11b protein, mouse