Membrane-proximal α/β stalk interactions differentially regulate integrin activation

Tetsuji Kamata, Makoto Handa, Yukiko Sato, Yasuo Ikeda, Sadakazu Aiso

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The affinity of integrin-ligand interaction is regulated extracellularly by divalent cations and intracellularly by inside-out signaling. We report here that the extracellular, membrane-proximal α/β stalk interactions not only regulate cation-induced integrin activation but also play critical roles in propagating inside-out signaling. Two closely related integrins, αIIbβ3 and αVβ3, share high structural homology and bind to similar ligands in an RGD-dependent manner. Despite these structural and functional similarities, they exhibit distinct responses to Mn2+. Although αVβ3 showed robust ligand binding in the presence of Mn 2+, αIIbβ3 showed a limited increase but failed to achieve full activation. Swapping α stalk regions between αIIb and αV revealed that the α stalk, but not the ligand-binding head region, was responsible for the difference. A series of αIIb/αV domain-swapping chimeras were constructed to identify the responsible domain. Surprisingly, the minimum component required to render αIIbβ3 susceptible to Mn 2+ activation was the αV calf-2 domain, which does not contain any divalent cation-binding sites. The calf-2 domain makes interface with β epidermal growth factor 4 and β tail domain in three-dimensional structure. The effect of calf-2 domain swapping was partially reproduced by mutating the specific amino acid residues in the calf-2/epidermal growth factor 4-β tail domain interface. When this interface was constrained by an artificially introduced disulfide bridge, the Mn2+-induced αVβ3-fibrinogen interaction was significantly impaired. Notably, a similar disulfide bridge completely abrogated fibrinogen binding to αIIbβ3 when αIIbβ3 was activated by cytoplasmic tail truncation to mimic inside-out signaling. Thus, disruption/formation of the membrane-proximal α/β stalk interface may act as an on/off switch that triggers integrin-mediated bidirectional signaling.

Original languageEnglish
Pages (from-to)24775-24783
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number26
DOIs
Publication statusPublished - 2005 Jul 1

Fingerprint

Integrins
Chemical activation
Ligands
Membranes
Divalent Cations
Epidermal Growth Factor
Disulfides
Fibrinogen
Cations
Binding Sites
Head
Switches
Amino Acids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Membrane-proximal α/β stalk interactions differentially regulate integrin activation. / Kamata, Tetsuji; Handa, Makoto; Sato, Yukiko; Ikeda, Yasuo; Aiso, Sadakazu.

In: Journal of Biological Chemistry, Vol. 280, No. 26, 01.07.2005, p. 24775-24783.

Research output: Contribution to journalArticle

Kamata, Tetsuji ; Handa, Makoto ; Sato, Yukiko ; Ikeda, Yasuo ; Aiso, Sadakazu. / Membrane-proximal α/β stalk interactions differentially regulate integrin activation. In: Journal of Biological Chemistry. 2005 ; Vol. 280, No. 26. pp. 24775-24783.
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