Seminar "Single live-cell imaging of the non-canonical NF-kB pathway"
Speaker: Jun-ichiro Inoue
Division of Cellular and Molecular Biology, Department of Cancer Biology
Institute of Medical Science, University of Tokyo
Title: Single live-cell imaging of the non-canonical NF-kB pathway
The nuclear factor kB (NF-kB) represents a family of transcription factors, including RelA, RelB, c-Rel, NF-kB1 p50, NF-kB2 p52, which can be activated by two distinct pathways. The canonical NF-kB pathway is activated by a large number of stimuli, including pro-inflammatory cytokines, bacterial and viral products. These stimuli induce the degradation of IkBa and the nuclear accumulation of mainly RelA/p50 dimers, which regulate the expression of inflammatory cytokines and anti-apoptotic genes. On the other hand, the non-canonical NF-kB pathway, which targets activation of the RelB/p52 dimers, regulates expression of genes that are involved in lymphoid organogenesis and lymphocyte development. While the dynamic regulation of the canonical pathway has been well studied, that of the non-canonical pathway remains to be elucidated. Therefore, a precise understanding of the relationship between target gene expression and RelB activation at the single-cell level is required. Therefore, we generated knock-in mice expressing a fusion protein between RelB and fluorescent protein (RelB-Venus) from the Relb locus. To monitor the localization of RelB-Venus in MEF cells after stimulation by agonistic antibody against lymphotoxin b–receptor (LTbR), we performed time-lapse experiments. Surprisingly, we found that RelB-Venus show oscillations between the nucleus and the cytoplasm upon stimulation. Significance and molecular mechanism of the oscillation will be discussed.
Tadashi Yamamoto, Cell Signal Unit