An IRF4-MYC-mTORC1 Integrated Pathway Controls Cell Growth and the Proliferative Capacity of Activated B Cells during B Cell Differentiation In Vivo

J Immunol. 2021 Oct 1;207(7):1798-1811. doi: 10.4049/jimmunol.2100440. Epub 2021 Sep 1.


Cell division is an essential component of B cell differentiation to Ab-secreting plasma cells, with critical reprogramming occurring during the initial stages of B cell activation. However, a complete understanding of the factors that coordinate early reprogramming events in vivo remain to be determined. In this study, we examined the initial reprogramming by IRF4 in activated B cells using an adoptive transfer system and mice with a B cell-specific deletion of IRF4. IRF4-deficient B cells responding to influenza, 4-hydroxy-3-nitrophenylacetyl-Ficoll, and LPS divided but stalled during the proliferative response. Gene expression profiling of IRF4-deficient B cells at discrete divisions revealed IRF4 was critical for inducing MYC target genes, oxidative phosphorylation, and glycolysis. Moreover, IRF4-deficient B cells maintained an inflammatory gene expression signature. Complementary chromatin accessibility analyses established a hierarchy of IRF4 activity and identified networks of dysregulated transcription factor families in IRF4-deficient B cells, including E-box binding bHLH family members. Indeed, B cells lacking IRF4 failed to fully induce Myc after stimulation and displayed aberrant cell cycle distribution. Furthermore, IRF4-deficient B cells showed reduced mTORC1 activity and failed to initiate the B cell activation unfolded protein response and grow in cell size. Myc overexpression in IRF4-deficient cells was sufficient to overcome the cell growth defect. Together, these data reveal an IRF4-MYC-mTORC1 relationship critical for controlling cell growth and the proliferative response during B cell differentiation.

Publication types

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

MeSH terms

  • Animals
  • B-Lymphocytes* / metabolism
  • Cell Cycle
  • Cell Differentiation
  • Cell Proliferation
  • Interferon Regulatory Factors* / genetics
  • Interferon Regulatory Factors* / metabolism
  • Mechanistic Target of Rapamycin Complex 1
  • Mice


  • Interferon Regulatory Factors
  • Mechanistic Target of Rapamycin Complex 1