The critical cytoplasmic regions of the αL/β2 integrin in Rap1-induced adhesion and migration

Yumi Tohyama, Koko Katagiri, Ruggero Pardi, Chafen Lu, Timothy A. Springer, Tatsuo Kinashi

Research output: Contribution to journalArticlepeer-review


Rap1 is a potent inside-out signal that increases LFA-1 adhesive activity. In this study, we have defined the cytoplasmic region of the αL and β2 integrin that are required for Rap1-stimulated adhesion and subsequent migration on ICAM-1. Human LFA-1 bearing truncated and point-mutated αL and β2 cytoplasmic regions were reconstituted in mouse IL-3-dependent proB cells, BAF/3. Truncation of the αL, but not β2 subunit cytoplasmic region, abolished Rap1V12-dependent adhesion to ICAM-1. The alanine substitution of two lysine residues (K1097/K1099) in the αL subunit was found to be critical in adhesion induced by Rap1V12, but not PMA. This mutation suppressed Rap1V12-induced LFA-1 conformation changes and ligand-binding affinity. The K1097/K1099 mutation also impaired binding to ICAM-1 induced by TCR cross-linking or SDF-1. In contrast, the alanine substitution for tyrosine in the β2 subunit endocytosis motif inhibited internalization of LFA-1, and severely impaired detachment at the cell rear, which resulted in long-elongated cell shapes. This result demonstrates that internalization of LFA-1 is a critical step in the deadhesion process. Our study revealed novel requirements of amino acid residues of the LFA-1 cytoplasmic region in the response to the inside-out signaling and the subsequent deadhesion process.

Original languageEnglish
Pages (from-to)2570-2582
Number of pages13
JournalMolecular Biology of the Cell
Issue number6
Publication statusPublished - Jun 1 2003

ASJC Scopus subject areas

  • Cell Biology
  • Genetics
  • Molecular Biology


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