An interaction between insulin-like growth factor-binding protein 2 (IGFBP2) and integrin alpha5 is essential for IGFBP2-induced cell mobility.

Abstract

In the study we report here, we tested the hypothesis that insulin-like growth factor-binding protein 2 (IGFBP2) promotes cell mobility through its interaction with integrin alpha5. Our previous microarray studies showed that IGFBP2 activates the expression of integrin alpha5. In addition, IGFBP2 has an Arg-Gly-Asp (RGD) domain, which is a known integrin binding motif. We first confirmed our microarray results by showing that the expression of integrin alpha5 is indeed up-regulated at the protein level in IGFBP2-overexpressing SNB19 glioma cells. Using co-immunoprecipitation, we confirmed that IGFBP2 does interact with integrin alpha5. To confirm that IGFBP2 interacts directly with integrin alpha5 through the RGD domain, we created an RGD --> RGE mutant (D306E) IGFBP2 and stably overexpressed the mutant IGFBP2 in the same cell line. Co-immunoprecipitation then showed that D306E-IGFBP2 had no detectable binding with integrin alpha5. We further observed that IGFBP2-overexpressing cells have extensive cell surface lamellipodia, whereas D306E-IGFBP2-overexpressing cells show abundant cell surface focal adhesions. Consistent with this, phenotype analysis then showed that IGFBP2-overexpressing cells have elevated migration rates compared with vector control; in contrast, the migration rates of the D306E-IGFBP2-overexpressing cells were not elevated and were comparable with that of vector control. Decreased expression of integrin alpha5 by small interference RNA in IGFBP2-overexpressing cells also reduced cell mobility. Therefore, we have concluded that one mechanism by which IGFBP2 activates IGFBP2-induced cell mobility is through its interaction with integrin alpha5 and this interaction is specifically mediated through the RGD domain on IGFBP2.

• Authors: George K Wang, Limei Hu, Gregory N Fuller, Wei Zhang
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 281 Issue 20 Pg. 14085-91 (May 19 2006) ISSN: 0021-9258 [Print] United States
• PMID: 16569642 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Insulin-Like Growth Factor Binding Protein 2
• Integrin alpha5
• Oligopeptides
• RNA, Small Interfering
• arginyl-glycyl-aspartic acid

Topics

• Base Sequence
• Cell Line, Tumor
• Cell Movement
• Genetic Vectors
• Humans
• Insulin-Like Growth Factor Binding Protein 2 (metabolism)
• Integrin alpha5 (metabolism)
• Molecular Sequence Data
• Oligonucleotide Array Sequence Analysis
• Oligopeptides (chemistry)
• Protein Binding
• RNA, Small Interfering (metabolism)
• Up-Regulation