Inside the crawling T cell: leukocyte function-associated antigen-1 cross-linking is associated with microtubule-directed translocation of protein kinase C isoenzymes beta(I) and delta.
T cells activated via integrin receptors can polarize and start crawling locomotion with repeated cycles of cytoskeletal reassembly processes, many of which depend on phosphorylation. We demonstrate that protein kinase C (PKC) activation represents an essential event in induction of active T cell motility. We find that in crawling T cells triggered via cross-linking of integrin LFA-1 two PKC isoenzymes, beta(I) and delta, are targeted to the cytoskeleton with specific localization corresponding to the microtubule-organizing center (MTOC) and microtubules, as detected by immunocytochemistry and immunoblotting. Clustering of LFA-1 associated with its signaling function also occurs at the membrane sites adjacent to the MTOC. We further show that cells of a PKC-beta-deficient clone derived from parental PKC-beta-expressing T cell line can neither crawl nor develop a polarized microtubule array upon integrin cross-linking. However, their adhesion and formation of actin-based pseudopodia remain unaffected. Our data demonstrate the critical importance of the microtubule cytoskeleton in T cell locomotion and suggest a novel microtubule-directed intracellular signaling pathway mediated by integrins and involving two distinctive PKC isoforms.
Volkov
Y
Y
Department of Clinical Medicine, University of Dublin, Trinity College, Ireland. yvolkov@tcd.ie
Long
A
A
Kelleher
D
D
D001692:Biological Transport / Q000187:drug effects; D002448:Cell Adhesion; D002465:Cell Movement; D018385:Centrosome / Q000201:enzymology / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005353:Fibronectins; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology*; D008870:Microtubules / Q000201:enzymology / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta; D011554:Pseudopodia / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014404:Tubulin / Q000032:analysis; D014746:Vimentin / Q000032:analysis
D004791:Enzyme Inhibitors; D005353:Fibronectins; D007527:Isoenzymes; D016169:Lymphocyte Function-Associated Antigen-1; D014404:Tubulin; D014746:Vimentin; C497258:PRKCD protein, human; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate