Avian I kappa B alpha is transcriptionally induced by c-Rel and v-Rel with different kinetics

Abstract

The Rel/NF-B family of transcription factors participates in the regulation of genes involved in defense responses, inflammation, healing and regeneration processes, and embryogenesis. The control of the transcriptional activation potential of the Rel/NF-B proteins is mediated, in part, by their association with inhibitory proteins of the IB family. This association results in the cytoplasmic retention of these factors until the cell receives a proper stimulatory signal. The IB␣ gene is a target for regulation by the Rel/NF-B proteins and is in fact upregulated in response to Rel/NF-B activation. A naturally occurring oncogenic variant of the Rel/NF-B family, v-rel, transforms avian lymphocytes, bone marrow cells, monocytes, and fibroblasts. Avian IB␣ expression is upregulated in cells transformed by v-Rel. Avian IB␣ is also upregulated in fibroblasts overexpressing c-Rel and oncogenic variants of c-Rel. c-Rel, a carboxy-terminally truncated variant of c-Rel, and v-Rel are all able to directly transactivate the expression of the avian IB␣ gene. However, c-Rel was the most potent activator of this gene, and the induction of IB␣ expression showed faster kinetics in cells overexpressing c-Rel than in those overexpressing v-Rel. The regulation of IB␣ induction by the Rel proteins was shown to be dependent on a 362-bp region of the IB␣ promoter that contains two potential NF-B binding sites and one AP-1-like binding site. Results of electrophoretic mobility shift assays using these NF-B binding sites indicate that major changes in the profile of DNA binding complexes in fibroblasts overexpressing v-Rel correlated temporally with the kinetic changes in v-Rel's ability to activate the expression of the IB␣ gene.

Mutations of tumor necrosis factor α-responsive serine residues within the C-terminal transactivation domain of human transcription factor REL enhance its in vitro transforming ability

“…Similar to our results, a recent study showed that a truncated REL protein missing 112 C-terminal aa transactivated the IL-2 promoter more strongly than wild-type REL, but transactivated the IkBa promoter weaker than wild-type REL (Iwai et al, 2005). Moreover, v-Rel exhibits differential activation of certain target genes as compared to chicken c-Rel, and this difference is likely to contribute to v-Rel's ability to transform cells more efficiently than c-Rel (Schatzle et al, 1995;Kralova et al, 1998Kralova et al, , 2002Hrdlickova´et al, 2001). In particular, Kralova et al (2002) found that chicken c-Rel activates the IAP1 promoter more efficiently than v-Rel in transient transfection assays; however, v-Rel induces IAP1 mRNA and protein more efficiently than c-Rel in stably transformed long-term chicken cell cultures.…”

“…Cells were transfected with expression plasmids for either full-length REL, RELD424-490, or REL-S471N and different reporter gene plasmids. REL's transactivation ability was assessed on three reporter gene cassettes: a 3x-kB reporter containing a minimal c-fos promoter downstream of 3 kB sites derived from the MHC-I promoter (Mitchell and Sugden, 1995); a reporter containing 1.2 kb of the chicken ikba gene promoter, including 5 kB sites (Schatzle et al, 1995); and a reporter containing 3.3 kb of the human manganese superoside dismutase (SOD2) gene promoter (2 kB sites) and 0.4 kb of the SOD2 intronic enhancer (1 kB site) (Abid et al, 2004). REL-S471N activated approximately two-fold higher than wild-type REL from the 3x-kB promoter (Figure 3c).…”

Alcohol exposure regulates heat shock transcription factor binding and heat shock proteins 70 and 90 in monocytes and macrophages: implication for TNF-α regulation

“…Nuclear and cytoplasmic extracts from cells with or without stimulation at 37°C were performed by the method of Schatzle et al [23]. Briefly, at the end of the stimulation period, cells were scraped and washed in ice-cold PBS.…”

Inhibition of NF-??B Binding Correlates With Increased Nuclear Glucocorticoid Receptor Levels in Acute Alcohol-Treated Human Monocytes

“…Nuclear and cytoplasmic extracts from cells with or without stimulation at 37°C were performed by the method of Schatzle et al (1995). The 1-hr stimulation was selected because our previous findings had shown that acute alcohol treatment maximally inhibits NF-B at 1 hr (Mandrekar et al, 1999).…”