Signal Transduction Pathways in Development and Immunity: NFκB/Rel Pathways

The nuclear factor kappa B (NFB)/Rel signal transduction pathway is conserved from simple multicellular eukaryotes, such as sponges and insects, to humans and controls a variety of processes involved primarily in immunity and development. The NFB family of transcription factors includes several structurally related proteins that form dimers, which regulate the expression of numerous genes by binding to specific deoxyribonucleic acid (DNA) sites near these genes. In mammals, the NFB pathway is important in the control of innate and adaptive immunity, immune cell development, cell proliferation and cell survival. In insects, the NFB pathway controls the establishment of dorsal–ventral polarity in the early embryo and an antimicrobial response. Activation of NFB transcription factors occurs via a series of biochemical steps and involves translocation of NFB from the cytoplasm to the nucleus where it can activate gene expression. Misregulation of the NFB pathway is also implicated in several human disease states, including many types of cancer and inflammatory diseases.

Key concepts:

  • NFB and Rel proteins are part of a family of transcription factors whose activity is controlled primarily by subcellular localization.
  • Many extracellular signals can activate a multicomponent signal transduction pathway that leads to nuclear localization of NFB/Rel proteins where they control the transcription of many important effector genes.
  • NFB/Rel transcription factors control a number of evolutionarily conserved developmental and immune processes.
  • In Drosophila, NFB/Rel signalling controls the immune response of flies to fungal and bacterial infections.
  • In vertebrates, NFB/Rel signalling controls the innate immune response, cell survival and the development of several specific cell types, such as liver cells, immune cells and skin cells.
  • Misregulation of NFB/Rel activity occurs in a number of human diseases, including several chronic inflammatory diseases and cancers.

Keywords: NF-kappaB; Rel; Dorsal; transcription factor; immune response

Figure 1. Generalized structures of the two classes of NFB proteins. The Rel homology (RH) domain contains sequences important for DNA binding, inhibitor (IB) binding, dimerization and nuclear localization (N). The C-terminal halves contain inhibitory ankyrin repeats (the ‘NFB’ proteins, top) or transactivation sequences (the ‘Rel’ proteins bottom). The top class of NFB proteins can undergo proteolysis at the indicated region to remove the ankyrin repeat domain and generate an active DNA-binding protein. See text for more details.
Figure 2. Comparison of the NFB signalling pathways in Drosophila and mammals. Shown at the right is the general scheme for activation of the NFB signalling pathway. Shown at the left and centre are the corresponding components of the various NFB pathways in Drosophila and mammals. See text for more details.
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 Further Reading
    Aggarwal K and Silverman N (2008) Positive and negative regulation of the Drosophila immune response. BMB Reports 41: 267–277.
    Chen LF and Greene WC (2004) Shaping the nuclear action of NF-B. Nature Reviews Molecular and Cellular Biology 5: 392–401.
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    Gerondakis S, Grumont R, Gugasyan R et al. (2006) Unravelling the complexities of the NF-B signalling pathway using mouse knockout and transgenic models. Oncogene 25: 6781–6799.
    book Ghosh S (ed.) (2007) Handbook or Transcription Factor NF-kappaB. Boca Raton, Florida: CRC Press.
    other Gilmore TD (ed.) (2006) NF-B: from basic research to human disease. Oncogene 25(Special issue): 6679–6899.
    ePath Gilmore Laboratory Website. http://www.nf-kb.org. Maintained by the Gilmore Laboratory.
    Hayden MS and Ghosh S (2008) Shared principles in NF-B signalling. Cell 132: 344–362.
    Hayden MS, West AP and Ghosh S (2006) NF-B and the immune response. Oncogene 25: 6758–6780.
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Gilmore, Thomas D, and Tony Ip, Y(Sep 2009) Signal Transduction Pathways in Development and Immunity: NFκB/Rel Pathways. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002332.pub3]