The spreading of B lymphocytes induced by CD44 cross-linking requires actin, tubulin, and vimentin rearrangements.
CD44 is a polymorphic family of adhesion molecules widely distributed on cells and tissues. CD44 is up-regulated on activated lymphocytes, and it can function as a receptor, mediating rolling and migration. Although it has been demonstrated that anti-CD44 antibodies bound to tissue-culture plates induce multidirectional emission of retractile dendrites ("spreading") in activated murine B lymphocytes, the involvement of cytoskeleton elements in this phenomenon is largely unknown. In this work, it is shown that the generation of dendrites induced by CD44 cross-linking in activated B cells depends on actin, microtubules, and vimentin reorganization. Immunofluorescence analysis showed that dendrite formation began with actin polymerization, and its extension was favored by microtubules and intermediate filaments of vimentin oriented to the polymerized actin. Pretreatment of activated B lymphocytes with cytochalasin E inhibited the dendrites formation; moreover, when cells were treated with this drug at different time points during the dendrite formation process, the stability of the dendrites was affected. In contrast, although the treatment with colchicine and nocodazole (tubulin polymerization inhibitors) inhibited the dendrites formation, it did not inhibit the initial phase of actin polymerization. According to these results, B cell spreading and dendrite formation induced by anti-CD44 antibodies require coordinated rearrangements of actin, microtubules, and vimentin, being the actin cytoskeleton, the most important element that confers stability and drives the morphological changes during B cell spreading, conceivably preparing B lymphocytes for locomotion.
Sumoza-Toledo
Adriana
A
Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados, IPN, Mexico.
Santos-Argumedo
Leopoldo
L
D000199:Actins / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology*; D048429:Cell Size; D022081:Cell Surface Extensions; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005260:Female; D018960:Hyaluronan Receptors / Q000276:immunology / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D014404:Tubulin / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D000906:Antibodies; D003598:Cytoskeletal Proteins; D018960:Hyaluronan Receptors; D014404:Tubulin; D014746:Vimentin