TY - JOUR
T1 - Identification of STAT-1 as a molecular target of IGFBP-3 in the process of chondrogenesis
AU - Spagnoli, Anna
AU - Torello, Monica
AU - Nagalla, Srivinasa R.
AU - Horton, William A.
AU - Pattee, Patrick
AU - Hwa, Vivian
AU - Chiarelli, Francesco
AU - Roberts, Charles T.
AU - Rosenfeld, Ron G.
PY - 2002/5/24
Y1 - 2002/5/24
N2 - The chondrogenesis process requires the ordered proliferation and differentiation of chondrocytes. Insulin-like growth factor-binding protein (IGFBP)-3, well characterized as the carrier of insulin-like growth factor (IGF), has been reported to have intrinsic bioactivity that is independent of IGF binding. The mechanisms involved in this IGF-independent action are still unclear. Using the RCJ3.1C5.18 chondrogenic cells, which in culture progresses from undifferentiated to terminally differentiated chondrocytes, we have shown previously that IGFBP-3 has an IGF-independent, antiproliferative effect in undifferentiated and early differentiated but not in terminally differentiated chondrocytes. In the present study, cDNA microarray analysis was used to screen for genes: 1) that were regulated by IGFBP-3 in early but not in terminally differentiated chondrocytes; 2) that were regulated specifically by IGFBP-3, but not by IGF-I; and 3) whose regulation was abolished by coincubation of IG-FBP-3 with IGF-I. Signal transducer and activator of transcription (STAT)-I was the gene that, fulfilling the screening criteria, exhibited the greatest up-regulation by IGFBP-3 (>40-fold). STAT-1 gene up-regulation was confirmed by Northern analysis of cells treated with IGFBP-3 or transfected with an IGFBP-3 expression vector. Remarkably, similar results were obtained when cells were transfected with an IGFBP-3 mutant unable to bind IGFs, definitively demonstrating the IGF-independent action of IGFBP-3. Consistent with the up-regulation of STAT-1 mRNA, IGFBP-3 also increased STAT-1 protein expression. Furthermore, both IGFBP-3 and the IGFBP-3 mutant induced STAT-1 phosphorylation and its nuclear localization. An antisense STAT-1 oligonucleotide abolished the IGF-independent cell apoptosis induced by IGFBP-3. We have demonstrated that STAT-1 is a major intracellular signaling and transcriptional target of the IGF-independent apoptotic effect of IGFBP-3 in chondrogenesis.
AB - The chondrogenesis process requires the ordered proliferation and differentiation of chondrocytes. Insulin-like growth factor-binding protein (IGFBP)-3, well characterized as the carrier of insulin-like growth factor (IGF), has been reported to have intrinsic bioactivity that is independent of IGF binding. The mechanisms involved in this IGF-independent action are still unclear. Using the RCJ3.1C5.18 chondrogenic cells, which in culture progresses from undifferentiated to terminally differentiated chondrocytes, we have shown previously that IGFBP-3 has an IGF-independent, antiproliferative effect in undifferentiated and early differentiated but not in terminally differentiated chondrocytes. In the present study, cDNA microarray analysis was used to screen for genes: 1) that were regulated by IGFBP-3 in early but not in terminally differentiated chondrocytes; 2) that were regulated specifically by IGFBP-3, but not by IGF-I; and 3) whose regulation was abolished by coincubation of IG-FBP-3 with IGF-I. Signal transducer and activator of transcription (STAT)-I was the gene that, fulfilling the screening criteria, exhibited the greatest up-regulation by IGFBP-3 (>40-fold). STAT-1 gene up-regulation was confirmed by Northern analysis of cells treated with IGFBP-3 or transfected with an IGFBP-3 expression vector. Remarkably, similar results were obtained when cells were transfected with an IGFBP-3 mutant unable to bind IGFs, definitively demonstrating the IGF-independent action of IGFBP-3. Consistent with the up-regulation of STAT-1 mRNA, IGFBP-3 also increased STAT-1 protein expression. Furthermore, both IGFBP-3 and the IGFBP-3 mutant induced STAT-1 phosphorylation and its nuclear localization. An antisense STAT-1 oligonucleotide abolished the IGF-independent cell apoptosis induced by IGFBP-3. We have demonstrated that STAT-1 is a major intracellular signaling and transcriptional target of the IGF-independent apoptotic effect of IGFBP-3 in chondrogenesis.
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U2 - 10.1074/jbc.M200218200
DO - 10.1074/jbc.M200218200
M3 - Article
C2 - 11886859
AN - SCOPUS:0037166313
SN - 0021-9258
VL - 277
SP - 18860
EP - 18867
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 21
ER -