Arp2 depletion inhibits sheet-like protrusions but not linear protrusions of fibroblasts and lymphocytes.
The Arp2/3 complex-mediated assembly and protrusion of a branched actin network at the leading edge occurs during cell migration, although some studies suggest it is not essential. In order to test the role of Arp2/3 complex in leading edge protrusion, Swiss 3T3 fibroblasts and Jurkat T cells were depleted of Arp2 and evaluated for defects in cell morphology and spreading efficiency. Arp2-depleted fibroblasts exhibit severe defects in formation of sheet-like protrusions at early time points of cell spreading, with sheet-like protrusions limited to regions along the length of linear protrusions. However, Arp2-depleted cells are able to spread fully after extended times. Similarly, Arp2-depleted Jurkat T lymphocytes exhibit defects in spreading on anti-CD3. Interphase Jurkats in suspension are covered with large ruffle structures, whereas mitotic Jurkats are covered by finger-like linear protrusions. Arp2-depleted Jurkats exhibit defects in ruffle assembly but not in assembly of mitotic linear protrusions. Similarly, Arp2-depletion has no effect on the highly dynamic linear protrusion of another suspended lymphocyte line. We conclude that Arp2/3 complex plays a significant role in assembly of sheet-like protrusions, especially during early stages of cell spreading, but is not required for assembly of a variety of linear actin-based protrusions.
Nicholson-Dykstra
Susan M
SM
Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.
Higgs
Henry N
HN
D016475:3T3 Cells; D051377:Actin-Related Protein 2 / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion; D002465:Cell Movement; D022081:Cell Surface Extensions / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism*; D008223:Lymphoma; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D008938:Mitosis; D011554:Pseudopodia; D014162:Transfection
D051377:Actin-Related Protein 2