TY - JOUR
T1 - Identification of osteopontin as a novel ligand for the integrin α8β1 and potential roles for this integrin-ligand interaction in kidney morphogenesis
AU - Denda, Sumiko
AU - Reichardt, Louis F.
AU - Müller, Ulrich
PY - 1998/6
Y1 - 1998/6
N2 - Epithelio-mesenchymal interactions during kidney organogenesis are disrupted in integrin α8β1-deficient mice. However, the known ligands for integrin α8β1-fibronectin, vitronectin, and tenascin-C-are not appropriately localized to mediate all α8β1 functions in the kidney. Using a method of general utility for determining the distribution of unknown integrin ligands in situ and biochemical characterization of these ligands, we identified osteopontin (OPN) as a ligand for α8β31. We have coexpressed the extracellular domains of the mouse α8 and β1 integrin subunits as a soluble heterodimer with one subunit fused to alkaline phosphatase (AP) and have used the α8β1-AP chimera as a histochemical reagent on sections of mouse embryos. Ligand localization with α8β1-AP in developing bone and kidney was observed to be overlapping with the distribution of OPN. In 'far Western' blots of mouse embryonic protein extracts, bands were detected with sizes corresponding to fibronectin, vitronectin, and unknown proteins, one of which was identical to the size of OPN. In a solid-phase binding assay we demonstrated that purified OPN binds specifically to α8β1-AP. Cell adhesion assays using K562 cells expressing α8β1 were used to confirm this result. Together with a recent report that anti-OPN antibodies disrupt kidney morphogenesis, our results suggest that interactions between OPN and integrin α8β1 may help regulate kidney development and other morphogenetic processes.
AB - Epithelio-mesenchymal interactions during kidney organogenesis are disrupted in integrin α8β1-deficient mice. However, the known ligands for integrin α8β1-fibronectin, vitronectin, and tenascin-C-are not appropriately localized to mediate all α8β1 functions in the kidney. Using a method of general utility for determining the distribution of unknown integrin ligands in situ and biochemical characterization of these ligands, we identified osteopontin (OPN) as a ligand for α8β31. We have coexpressed the extracellular domains of the mouse α8 and β1 integrin subunits as a soluble heterodimer with one subunit fused to alkaline phosphatase (AP) and have used the α8β1-AP chimera as a histochemical reagent on sections of mouse embryos. Ligand localization with α8β1-AP in developing bone and kidney was observed to be overlapping with the distribution of OPN. In 'far Western' blots of mouse embryonic protein extracts, bands were detected with sizes corresponding to fibronectin, vitronectin, and unknown proteins, one of which was identical to the size of OPN. In a solid-phase binding assay we demonstrated that purified OPN binds specifically to α8β1-AP. Cell adhesion assays using K562 cells expressing α8β1 were used to confirm this result. Together with a recent report that anti-OPN antibodies disrupt kidney morphogenesis, our results suggest that interactions between OPN and integrin α8β1 may help regulate kidney development and other morphogenetic processes.
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U2 - 10.1091/mbc.9.6.1425
DO - 10.1091/mbc.9.6.1425
M3 - Article
C2 - 9614184
AN - SCOPUS:0031813775
SN - 1059-1524
VL - 9
SP - 1425
EP - 1435
JO - Molecular biology of the cell
JF - Molecular biology of the cell
IS - 6
ER -