KLF4 is a FOXO target gene that suppresses B cell proliferation.

Department of Molecular Biology and Biochemistry, University of California-Irvine, Irvine, CA, USA.
International Immunology (Impact Factor: 3.18). 06/2008; 20(5):671-81. DOI: 10.1093/intimm/dxn024
Source: PubMed

ABSTRACT Lymphocytes circulate in a quiescent (G(0)) state until they encounter specific antigens. In T cells, quiescence is programmed by transcription factors of the forkhead box O (FOXO) and Krüppel-like factor (KLF) families. However, the transcription factors that regulate B cell quiescence are not known. KLF4 is a candidate tumor suppressor gene in B lymphocytes, and thus a likely candidate for regulating B cell homeostasis. Here, we show that RNA and protein expression of murine KLF4 decreases following B cell activation. Forced expression of KLF4 in proliferating B cell blasts causes a G(1) cell cycle arrest. This effect requires the DNA binding and transactivation domains of KLF4 and correlates with changes in the expression of known KLF target genes. We present evidence that Klf4 is a target gene for FOXO transcription factors, which also suppress B cell proliferation. To determine the effect of KLF4 loss-of-function, we generated mice with B cell-specific deletion of the Klf4 gene. These mice exhibited normal B cell development and function with no evidence of a lowered activation threshold. Collectively, our findings indicate that KLF4 has growth-suppressive properties in B cells but might be redundant with other members of the KLF family in maintaining B cell quiescence.

Download full-text


Available from: Vincent W Yang, Jan 03, 2014
1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The transcription factor Krüppel-like factor 4 (KLF4) can activate or repress gene expression in a cell-context dependent manner. We have previously shown that KLF4 inhibits the proliferation of naïve CD8(+) T cells in vitro downstream of the transcription factor ELF4. In this work, we describe a novel role of KLF4 in the differentiation of CD8(+) T cells upon infection. Loss of KLF4 had minimal effect on thymic T cell development and distribution of mature T cells in the spleen, blood, and lymph nodes. KLF4-deficient naïve CD8(+) T cells also displayed normal homeostatic proliferation upon adoptive transfer into lymphopenic hosts. However, activation of KLF4-deficient naïve CD8(+) T cells by in vitro TCR crosslink and co-stimulation resulted in increased proliferation. Furthermore, naïve KLF4-deficient OT-I CD8(+) T cells generated increased numbers of functional memory CD8(+) T cells compared to wild type OT-I CD8(+) T cells co-injected in the same recipient in both primary and recall responses to Listeria monocytogenes-OVA. Collectively, our data demonstrate that KLF4 regulates differentiation of functional memory CD8(+) T cells while sparing development and homeostasis of naïve CD8(+) T cells.
    Immunology letters 09/2013; 156(1-2). DOI:10.1016/j.imlet.2013.09.008 · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Human memory T cells (T(M) cells) that produce IL-17 or IL-22 are currently defined as Th17 or Th22 cells, respectively. These T cell lineages are almost exclusively CCR6(+) and are important mediators of chronic inflammation and autoimmunity. However, little is known about the mechanisms controlling IL-17/IL-22 expression in memory Th17/Th22 subsets. We show that common γ chain (γc)-using cytokines, namely IL-2, IL-7, and IL-15, potently induce Th17-signature cytokine expression (Il17a, Il17f, Il22, and Il26) in CCR6(+), but not CCR6(-), T(M) cells, even in CCR6(+) cells lacking IL-17 expression ex vivo. Inhibition of phosphoinositide 3-kinase (PI-3K) or Akt signaling selectively prevents Th17 cytokine induction by γc-cytokines, as does ectopic expression of the transcription factors FOXO1 or KLF2, which are repressed by PI-3K signaling. These results indicate that Th17 cytokines are tuned by PI-3K signaling in CCR6(+) T(M) cells, which may contribute to chronic or autoimmune inflammation. Furthermore, these findings suggest that ex vivo analysis of IL-17 expression may greatly underestimate the frequency and pathogenic potential of the human Th17 compartment.
    Journal of Experimental Medicine 08/2011; 208(9):1875-87. DOI:10.1084/jem.20102516 · 13.91 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The potential for clinical application of pluripotent embryonic stem cells is immense but hampered by moral and ethical complications. Recent advances in the reprogramming of somatic cells by defined factors to a state that resemble embryonic stem cells have created tremendous excitement in the field. Four factors, Sox2, Oct4, Klf4 and c-Myc, when exogenously introduced into somatic cells, can lead to the formation of induced pluripotent stem (iPS) cells that have the capacity for self-renewal and differentiation into tissues of all three germ layers. In this review, we focus on the role of Krüppel-like factors (KLFs) in regulating somatic cell reprogramming. KLFs are zinc finger-containing transcription factors with diverse biological functions. We first provide an overview of the KLF family of regulatory proteins, paying special attention to the established biological and biochemical functions of KLF4 and KLF5. We then review the role of KLFs in somatic cell reprogramming and delineate the putative mechanism by which KLFs participates the establishment and self-renewal of iPS cells. Further research is likely to provide additional insight into the mechanisms of somatic cell reprogramming and refinement of the technique with which to generate clinically relevant iPS cells.
    Histology and histopathology 11/2009; 24(10):1343-55. · 2.24 Impact Factor