title: Directional Transport of a Bead Bound to Lamellipodial Surface Is Driven by Actin Polymerization.
abstract: The force driving the retrograde flow of actin cytoskeleton is important in the cellular activities involving cell movement (e.g., growth cone motility in axon guidance, wound healing, or cancer metastasis). However, relative importance of the forces generated by actin polymerization and myosin II in this process remains elusive. We have investigated the retrograde movement of the poly-d-lysine-coated bead attached with the optical trap to the edge of lamellipodium of Swiss 3T3 fibroblasts. The velocity of the attached bead drastically decreased by submicromolar concentration of cytochalasin D, latrunculin A, or jasplakinolide, indicating the involvement of actin turnover. On the other hand, the velocity decreased only slightly in the presence of 50μM (-)-blebbistatin and Y-27632. Comparative fluorescence microscopy of the distribution of actin filaments and that of myosin II revealed that the inhibition of actin turnover by cytochalasin D, latrunculin A, or jasplakinolide greatly diminished the actin filament network. On the other hand, inhibition of myosin II activity by (-)-blebbistatin or Y-27632 little affected the actin network but diminished stress fibers. Based on these results, we conclude that the actin polymerization/depolymerization plays the major role in the retrograde movement, while the myosin II activity is involved in the maintenance of the dynamic turnover of actin in lamellipodium.
authors.affiliation: Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nobezawa
authors.affiliation: Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Sho-Ichi
authors.initials: SI
authors.lastname: Ikeda
authors.affiliation: Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Eitaro
authors.initials: E
authors.lastname: Wada
authors.affiliation: Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagano
authors.affiliation: Department of Physics, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Hidetake
authors.identifier: 0000-0003-3520-4137
authors.initials: H
authors.lastname: Miyata
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D042541:Intracellular Space / Q000378:metabolism; D007734:Kymography; D051379:Mice; D008863:Microspheres; D024462:Myosin Type II / Q000378:metabolism; D058105:Polymerization / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D053778:Thiazolidines; D015638:Cytochalasin D; D024462:Myosin Type II; C037067:latrunculin A