Spike formation by fibroblasts adhering to fibrillar collagen I gel.
The fibrillar collagen I gel induced the formation of numerous dendritic cell-like protrusions (cell spikes) from the cell body, whereas monomeric collagen I induced typical cell spreading with filopodia and lamellipodia in skin fibroblasts. Peripheral, not central stress fibers appeared upon adhesion to fibrillar collagen gel, whereas both types of fibers were evident upon adhesion to monomeric collagen. Microtubules and vimentin filaments were elongated inside stress fibers along the terminal tip of cell spikes. Spike formation was totally inhibited by nocodazole and severely delayed by cytochalasin D. This suggests that cell spike formation is dependent on microtubules rather than on F-actin. We then investigated the intracellular signaling responsible for cytoskeleton organization to identify the key factor that induces cell spike morphology. During cell spike formation, FAK and CAS were activated. More CAS was activated in cells on fibrillar collagen gel than on the monomeric form, whereas FAK was activated to the same level on either. At 90 min of culture, Rac1 was activated in cells on monomeric collagen I, whereas Cdc42, Rac1 and RhoA were activated in cells on fibrillar collagen gel. These results suggest that microtubule organization via CAS and small GTPases is important for the cell spike formation that is involved in collagen gel contraction and in wound retraction in skin.
Department of Molecular Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan. k-kusu@rinshoken.or.jp
Kaori
K
Sato
Shunji
S
Hattori
Shinkichi
S
Irie
Seiichi
S
Kawashima
D000199:Actins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D029563:Cellular Apoptosis Susceptibility Protein / Q000378:metabolism; D024042:Collagen Type I / Q000737:chemistry*; D015638:Cytochalasin D / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D012867:Skin / Q000166:cytology / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000199:Actins; D029563:Cellular Apoptosis Susceptibility Protein; D024042:Collagen Type I; D019012:Integrin beta1; D015638:Cytochalasin D; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D015739:Nocodazole