title: Macrophage podosomes assemble at the leading lamella by growth and fragmentation.
abstract: Podosomes are actin- and fimbrin-containing adhesions at the leading edge of macrophages. In cells transfected with beta-actin-ECFP and L-fimbrin-EYFP, quantitative four-dimensional microscopy of podosome assembly shows that new adhesions arise at the cell periphery by one of two mechanisms; de novo podosome assembly, or fission of a precursor podosome into daughter podosomes. The large podosome cluster precursor also appears to be an adhesion structure; it contains actin, fimbrin, integrin, and is in close apposition to the substratum. Microtubule inhibitors paclitaxel and demecolcine inhibit the turnover and polarized formation of podosomes, but not the turnover rate of actin in these structures. Because daughter podosomes and podosome cluster precursors are preferentially located at the leading edge, they may play a critical role in continually generating new sites of cell adhesion.
authors.affiliation: BioImaging Center, Cambridge, MA 02142, USA. jgevans@wi.mit.edu
authors.forename: James G
authors.initials: JG
authors.lastname: Evans
authors.forename: Ivan
authors.initials: I
authors.lastname: Correia
authors.forename: Olga
authors.initials: O
authors.lastname: Krasavina
authors.forename: Nicki
authors.initials: N
authors.lastname: Watson
authors.forename: Paul
authors.initials: P
authors.lastname: Matsudaira
mesh_terms: D000199:Actins / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D016764:Cell Polarity; D048429:Cell Size; D005337:Fibrin / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D011554:Pseudopodia / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000199:Actins; D005337:Fibrin