Galectin-8 modulates neutrophil function via interaction with integrin alphaM.
The members of the galectin family are associated with diverse cellular events, including immune response. We investigated the effects of galectin-8 on neutrophil function. Human galectin-8 induced firm and reversible adhesion of peripheral blood neutrophils but not eosinophils to a plastic surface in a lactose-sensitive manner. Other human galectins, galectins-1, -3, and -9, showed low or negligible effects on neutrophil adhesion. Confocal microscopy revealed actin bundle formation in the presence of galectin-8. Cytochalasins inhibited both actin assembly and cell adhesion induced by galectin-8. Affinity purification of galectin-interacting proteins from solubilized neutrophil membrane revealed that N-terminal carbohydrate recognition domain (CRD) of galectin-8 bound promatrix metalloproteinase-9 (proMMP-9), and C-terminal CRD bound integrin alphaM/CD11b and proMMP-9. A mutant galectin-8 lacking the carbohydrate-binding activity of N-terminal CRD (galectin-8R69H) retained adhesion-inducing activity, but inactivation of C-terminal CRD (galectin-8R233H) abolished the activity. MMP-3-mediated processing of proMMP-9 was accelerated by galectin-8, and this effect was inhibited by lactose. Galectins-1 and -3 did not affect the processing. Superoxide production, an essential event in bactericidal function of neutrophils, was stimulated by galectin-8 to an extent comparable to that induced by fMLP. Galectin-8R69H but not galectin-8R233H could stimulate superoxide production. Taken together, these results suggest that galectin-8 is a novel factor that modulates the neutrophil function related to transendothelial migration and microbial killing.
Nishi
Nozomu
N
Department of Endocrinology, Kagawa Medical University, Kagawa 761-0793, Japan. mnishi@kms.ac.jp
Shoji
Hiroki
H
Seki
Masako
M
Itoh
Aiko
A
Miyanaka
Hiroshi
H
Yuube
Kouichi
K
Hirashima
Mitsuomi
M
Nakamura
Takanori
T
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D039481:CD11b Antigen / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology; D017364:Collagenases / Q000378:metabolism; D003572:Cytochalasins / Q000494:pharmacology; D004792:Enzyme Precursors / Q000378:metabolism; D037161:Galectins / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D007785:Lactose / Q000494:pharmacology; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9; D018613:Microscopy, Confocal; D009504:Neutrophils / Q000502:physiology*; D011485:Protein Binding; D011994:Recombinant Proteins
D000199:Actins; D039481:CD11b Antigen; D003572:Cytochalasins; D004792:Enzyme Precursors; D037161:Galectins; C091991:LGALS8 protein, human; D011994:Recombinant Proteins; D017364:Collagenases; C120487:pro-matrix metalloproteinase 9; D019278:Matrix Metalloproteinase 3; D020780:Matrix Metalloproteinase 9; D007785:Lactose