| Autor: |
L, Butcher Heather, A, Kennette Wendy, Olga, Collins, K, Zalups Rudolfs, James, Koropatnick |
| Zdroj: |
The Journal of Pharmacology and Experimental Therapeutics; August 2004, Vol. 310 Issue: 2 p589-98, 10p |
| Abstrakt: |
The zinc-binding protein metallothionein (MT) is associated with resistance to apoptosis. We examined whether MT regulates the zinc-dependent antiapoptotic transcription factor nuclear factor KappaB (NF-KappaB), which is up-regulated under many conditions that lead to elevated MT expression. NF-KappaB protein levels and NF-KappaB-dependent reporter gene activity were examined in clonal MT(+) (MT-WT) and MT(-) (MT-KO) fibroblastic cell lines. The amount of cellular NF-KappaB p65 protein in MT-KO was less than 20% of the amount in MT-WT cells, in accord with increased sensitivity of MT-KO cells to apoptosis. NF-KappaB p65 mRNA levels, and NF-KappaB p50 subunit and IKappaBalpha protein levels, were unchanged. NF-KappaB activity assessed by expression of a transfected NF-KappaB reporter construct was less than half that observed in MT-KO cells. Decreased nuclear localization of NF-KappaB p65 in MT-KO clones was not responsible for differences in activity. In fact, MT-KO cells had higher nuclear levels of NF-KappaB p65 than did MT-WT cells, despite a lower cellular NF-KappaB level and function, suggesting that metallothionein mediated the specific activity of NF-KappaB. Reconstitution of MT by stable incorporation of an MT-1 expression vector in MT-KO cells resulted in increased NF-KappaB p65 (but not IKappaBalpha or NF-KappaB p50), increased NF-KappaB-dependent reporter activity, and increased resistance to apoptosis. These data support the hypothesis that metallothionein positively regulates the cellular level and activity of NF-KappaB. |
| Databáze: |
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