In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 66, No. 6 ( 2006-03-15), p. 3024-3033
Abstract:
Insulin-like growth factor binding protein-3 (IGFBP-3), the product of a tumor suppressor target gene, can modulate cell proliferation and apoptosis by IGF-I-dependent and IGF-I-independent mechanisms. IGFBP-3 controls the bioavailability of IGFs in the extracellular environment and is known to be subject to degradation by various extracellular proteases. Although nuclear localization and functions of IGFBP-3 have been described in the past, we show as the novel features of this study that the abundance of nuclear IGFBP-3 is directly regulated by ubiquitin/proteasome–dependent proteolysis. We show that IGFBP-3 degradation depends on an active ubiquitin-E1 ligase, specific 26S proteasome inhibitors can efficiently stabilize nuclear IGFBP-3, and the metabolic half-life of nuclear IGFBP-3 is strongly reduced relative to cytoplasmic IGFBP-3. Nuclear IGFBP-3 is highly polyubiquitinated at multiple lysine residues in its conserved COOH-terminal domain and stabilized through mutation of two COOH-terminal lysine residues. Moreover, we show that IGFBP-3, if ectopically expressed in the nucleus, can induce apoptotic cell death. These results suggest that ubiquitin/proteasome–mediated proteolysis of IGFBP-3 may contribute to down-regulation of apoptosis. (Cancer Res 2006; 66(6): 3024-33)
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/0008-5472.CAN-05-2013
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2006
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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