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- Title
Regulation of α4 Integrin Avidity in Human B Cells: Requirement for Dephosphorylation Events for High Avidity VCAM-1 Binding.
- Authors
Hedman, H.; Lundgren, E.
- Abstract
The authors compared the phosphorylation-dependent signal transduction pathways involved in the regulation of adhesiveness of integrin LFA-1 with that of α4 integrins binding to VCAM-1. The authors developed an <em>in vitro</em> method to monitor changes in adhesiveness using a VCAM-1 fusion protein coupled to magnetic beads. For LFA-1, a similar method has previously been established using an ICAM-1 fusion protein. Binding of cells was monitored and found to be strictly integrin α4 and VCAM-1 dependent. The serine/threonine phosphatase inhibitors okadaic acid and calyculin A were equally potent in inhibiting binding to VCAM-1 as to ICAM-1, and inhibition of protein phosphatase-1 (PP1) is proposed to be the important denominator. Similarly, the phorbol ester PDBu, potentially stimulating protein phosphatase-1 and staurosporine, an inhibitor of serine/threonine kinases, enhanced adhesion to VCAM-1 as has previously been shown for ICAM-1. A major difference was that a significant portion of the binding to VCAM-1 was not susceptible to inhibition by drugs while binding to ICAM-1 could be completely inhibited. We propose that the adhesiveness of the α4 integrins for VCAM-1 and of LFA-1 for ICAM-1 is regulated by similar or identical protein kinases and phosphatases.
- Subjects
PHOSPHORYLATION; GENETIC transduction; INTEGRINS; PROTEINS; PHOSPHOPROTEIN phosphatases; PROTEIN kinases
- Publication
Scandinavian Journal of Immunology, 1996, Vol 44, Issue 3, p239
- ISSN
0300-9475
- Publication type
Article
- DOI
10.1046/j.1365-3083.1996.d01-305.x