Extension, retraction and contraction in the formation of a dendritic cell dendrite: distinct roles for Rho GTPases

• Published in: European journal of immunology 2002-07, Vol.32 (7), p.2074-2083
• Main Authors: Swetman, Claire A., Leverrier, Yann, Garg, Ritu, Gan, Chih H. V., Ridley, Anne J., Katz, David R., Chain, Benjamin M.
• Format: Article
• Language: English
• Subjects: cdc42 GTP-Binding Protein - metabolism; cdc42 GTP-Binding Protein - pharmacology; Cell Adhesion; Cell Movement - drug effects; Cell Movement - physiology; Cells, Cultured; Cytoskeleton; Dendrites - drug effects; Dendrites - physiology; Dendritic cell; Dendritic Cells - cytology; Dendritic Cells - drug effects; Dendritic Cells - physiology; Fibronectins - metabolism; Humans; Intracellular Signaling Peptides and Proteins; Protein-Serine-Threonine Kinases - metabolism; rac1 GTP-Binding Protein - metabolism; rac1 GTP-Binding Protein - pharmacology; Rho GTPase; rho-Associated Kinases; rhoA GTP-Binding Protein - metabolism; rhoA GTP-Binding Protein - pharmacology
• ISSN: 0014-2980; 1521-4141
• DOI: 10.1002/1521-4141(200207)32:7<2074::AID-IMMU2074>3.0.CO;2-S

The morphology of antigen‐presenting dendritic cells (DC) is characterized by the possession of numerous long arborizing processes known as dendrites. The formation of these processes by DC, both in the periphery and in lymphoid organs, is believed to contribute to the remarkable efficiency with which they take up, process and present antigen to T cells. However, the process of dendrite formation and the signaling pathways that lead to the formation of these dendrites remain obscure. In this study we describe an in vitro model in which human immature DC form long processessimilar to those formed in vivo. The formation of these processes involves initial attachment of a cell protrusion to the extracellular matrix substrate, and subsequent movement of the cell body away from the adhesion site, leaving behind a long slender dendrite. Dendrite formation, but not their maintenance, was found to be dependent on the activity of Rho GTPases. More specifically, Cdc42 and Rac1 were both required for the migration step of process formation, promoting cell spreading and extension. In contrast, Rho, and its downstream effector p160ROCK, regulated the release of adhesions to the substratum, and associated cellular contraction. Consequently, inhibition of Rho/p160ROCK leads to the formation of longer dendrites. DC therefore coordinate adhesion and protrusion to perform a specialized process of cellular morphogenesis, which differentiates these cells from all other cells of the immune system and may contribute to their distinctive function.