| Research Abstract |
1. Molecular Mechanism of Rel/NFkappaB activation
Activation of Rel/NFkappaB is achieved by the signal-induced rapid phosphorylation and degradation of inhibitory protein IkappaBalpha. To explore the molecular mechanism of signal-induced depletion of IkappaBalpha, we have delineated the domain in IkappaBalpha that is required for the regulation. In contrast to the previous reports, the PEST-like sequences dispensable for TNFalpha-induced degradation whereas the six ankyrin repeats are required. However, neither ankyrin repeats nor carboxyl-terminal region including the PEST-like sequences are required for TNFalpha-induced phosphorylation.
2. Signal transduction pathway emanating from membrane receptors to Rel/IkappaBalpha complex
We have found that signals emanating from CD40 link to Rel/NFkappaB activation. To identify molecules which transduce CD40 signalings, we have utilized the yeast two-hybrid system to clone cDNAs encoding proteins that bind the cytoplasmic tail of CD40, cDNAs encoding a putative signal transducer protein, designated TRAF5 and TRAF6, have been molecularly cloned. Overexpression of TRAF5 or TRAF6 activates transcription factor NFkappaB.Thus, we are looking for the down stream transducer of these proteins. Furthermore we have demonstrated that cupric ion blocks NFkappaB activation through inhibiting the signal-induced phosphorylation of IkappaBalpha Target molecule of cupric ion remain to be identified.
3. Identification of novel kappaB proteins
To identify novel IkappaB cDNAs, an expression cDNA library has been screened using p65 subunit of NFkappaB as a probe. This study is still in the progress.
4. Chromosomal assignment of rel, NFkappaB and IkappaB genes in Rat
We have indentified that NFKB-1 (p50, IkappaBgamma) in on the Rat chromosome #2. Assignment of rel and IkappaBalpha is still in the Progress.
|
