BETA 2 integrin signaling in leukocytes.
Members of the beta 2 integrin family are the dominating integrins expressed on leukocytes, and they play a major role in leukocyte cell-cell and cell-matrix adhesions during inflammation and other immune responses. Beta 2 integrins are signaling receptors, but they are also targets of and are functionally affected by intracellular signals. Accordingly, researchers usually discuss two types of signaling by beta 2 integrins (and integrins in general): transmission of signals into the cell following binding of ligands or counter-receptors to the integrins (outside-in signaling), and regulation of the avidity and conformation of integrins by signals generated by other receptors within the cell (inside-out signaling). In this review, our aim is to summarize what is known about the capacity of beta 2 integrins to generate outside-in signaling in leukocytes, in particular polymorphonuclear neutrophils. Results in the literature clearly demonstrate that one of the earliest events in beta 2 integrin signaling is activation of non-receptor tyrosine kinases, which in turn triggers downstream activation of various signaling pathways that affect different functional responses of the cell. We also discuss molecules of potential importance in beta 2 integrin signaling.
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Division of Experimental Pathology, Department of Laboratory Medicine, Lund University, Malmö University Hospital, Entrance 78, SE-20 502 Malmö, Sweden.
D018821:CD18 Antigens / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007962:Leukocytes / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D018631:ras Proteins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D018821:CD18 Antigens; D007328:Insulin; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D018631:ras Proteins; D020742:rhoA GTP-Binding Protein