The dynamic properties of intermediate filaments during organelle transport.
Intermediate filament (IF) dynamics during organelle transport and their role in organelle movement were studied using Xenopus laevis melanophores. In these cells, pigment granules (melanosomes) move along microtubules and microfilaments, toward and away from the cell periphery in response to alpha-melanocyte stimulating hormone (alpha-MSH) and melatonin, respectively. In this study we show that melanophores possess a complex network of vimentin IFs which interact with melanosomes. IFs form an intricate, honeycomb-like network that form cages surrounding individual and small clusters of melanosomes, both when they are aggregated and dispersed. Purified melanosome preparations contain a substantial amount of vimentin, suggesting that melanosomes bind to IFs. Analyses of individual melanosome movements in cells with disrupted IF networks show increased movement of granules in both anterograde and retrograde directions, further supporting the notion of a melanosome-IF interaction. Live imaging reveals that IFs, in turn, become highly flexible as melanosomes disperse in response to alpha-MSH. During the height of dispersion there is a marked increase in the rate of fluorescence recovery after photobleaching of GFP-vimentin IFs and an increase in vimentin solubility. These results reveal a dynamic interaction between membrane bound pigment granules and IFs and suggest a role for IFs as modulators of granule movement.
Chang
Lynne
L
Department of Microbiology and Molecular Genetics, Harvard Medical School, Harvard University, Boston, MA, USA.
Barlan
Kari
K
Chou
Ying-Hao
YH
Grin
Boris
B
Lakonishok
Margot
M
Serpinskaya
Anna S
AS
Shumaker
Dale K
DK
Herrmann
Harald
H
Gelfand
Vladimir I
VI
Goldman
Robert D
RD
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007382:Intermediate Filaments / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008547:Melanophores / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D020460:Melanosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008550:Melatonin / Q000494:pharmacology; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008954:Models, Biological; D012995:Solubility / Q000187:drug effects; D014746:Vimentin / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism*; D000521:alpha-MSH / Q000494:pharmacology
D014746:Vimentin; D049452:Green Fluorescent Proteins; D000521:alpha-MSH; D008550:Melatonin