Src-mediated phosphorylation of mammalian Abp1 (DBNL) regulates podosome rosette formation in transformed fibroblasts.
Podosomes are dynamic actin-based structures that mediate adhesion to the extracellular matrix and localize matrix degradation to facilitate cell motility and invasion. Drebrin-like protein (DBNL), which is homologous to yeast mAbp1 and is therefore known as mammalian actin-binding protein 1 (mAbp1), has been implicated in receptor-mediated endocytosis, vesicle recycling and dorsal ruffle formation. However, it is not known whether mAbp1 regulates podosome formation or cell invasion. In this study, we found that mAbp1 localizes to podosomes and is necessary for the formation of podosome rosettes in Src-transformed fibroblasts. Despite their structural similarity, mAbp1 and cortactin play distinct roles in podosome regulation. Cortactin was necessary for the formation of podosome dots, whereas mAbp1 was necessary for the formation of organized podosome rosettes in Src-transformed cells. We identified specific Src phosphorylation sites, Tyr337 and Tyr347 of mAbp1, which mediate the formation of podosome rosettes and degradation of the ECM. In contrast to dorsal ruffles, the interaction of mAbp1 with WASP-interacting protein (WIP) was not necessary for the formation of podosome rosettes. Finally, we showed that depletion of mAbp1 increased invasive cell migration, suggesting that mAbp1 differentially regulates matrix degradation and cell invasion. Collectively, our findings identify a role for mAbp1 in podosome rosette formation and cell invasion downstream of Src.
Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706,  USA.
Lindsy R
LR
Boateng
Christa L
CL
Cortesio
Anna
A
Huttenlocher
D016475:3T3 Cells; D008841:Actin Cytoskeleton; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002461:Cell Line, Transformed; D002465:Cell Movement; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology; D021982:Cell-Matrix Junctions / Q000502:physiology* / Q000648:ultrastructure*; D051356:Cortactin / Q000378:metabolism; D003598:Cytoskeletal Proteins; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology; D008562:Membrane Glycoproteins; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D019038:Platelet Glycoprotein GPIb-IX Complex; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering; D018909:src Homology Domains; D019061:src-Family Kinases / Q000378:metabolism*
D002352:Carrier Proteins; D051356:Cortactin; D003598:Cytoskeletal Proteins; C485512:Dbnl protein, mouse; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; D034741:RNA, Small Interfering; C491671:Waspip protein, mouse; C094990:adhesion receptor; D019061:src-Family Kinases