| First Author | Araki N | Year | 2000 |
| Journal | J Cell Sci | Volume | 113 ( Pt 18) |
| Pages | 3329-40 | PubMed ID | 10954430 |
| Mgi Jnum | J:113905 | Mgi Id | MGI:3687817 |
| Doi | 10.1242/jcs.113.18.3329 | Citation | Araki N, et al. (2000) Actinin-4 is preferentially involved in circular ruffling and macropinocytosis in mouse macrophages: analysis by fluorescence ratio imaging. J Cell Sci 113(Pt 18):3329-40 |
| abstractText | We have applied fluorescence ratio imaging to the analysis of an actin-binding protein concentration relative to F-actin in macrophages, in order to explore the role of a novel (alpha)-actinin isoform, actinin-4, relative to that of the classical isoform, actinin-1. Conventional immunofluorescence images showed that both isoforms were enriched in F-actin-rich regions such as cell surface ruffles. However, ratio images further demonstrated that actinin-4 concentrations relative to F-actin were higher in peripheral inward curved ruffles and dorsal circular ruffles, presumed precursor forms of macropinosomes, than in straight linear ruffles, while actinin-1 concentrations were uniform among the different types of ruffles. Macropinosome pulse-labeling and chase experiments indicated that actinin-4 was also closely associated with newly formed macropinosomes and gradually dissociated with their maturation. Consistent with ratio imaging data, macrophages scrape-loaded with anti-actinin-4 showed a more reduced rate of macropinocytosis than those loaded with anti-actinin-1. Altogether, these results indicate that actinin-4 and actinin-1 contribute differently to F-actin dynamics, that actinin-4 is more preferentially involved in early stages of macropinocytosis than actinin-1. A similar redistribution of actinin-4 was also observed during phagocytosis, suggesting that actinin-4 may play the same role in the two mechanistically analogous types of endocytosis, i.e. macropinocytosis and phagocytosis. |
