The cytoskeleton in fish melanophore melanosome positioning.
Melanophore melanosomes organelles can be regulated to move and locate correspondingly to many other different organelle types. Comparing lessons from analysis of a specific melanosome distribution can, therefore, contribute to the understanding of distribution of other organelles, and vice versa. From such data, it is now generally accepted that microtubules provide directed long-distance movement, while cell peripheral movements include microfilaments. In fish melanophores, both actin and dynein exhibit counter-forces to the kinesin-like protein in maintaining the evenly dispersed state, while actin and kinesin exhibit counter-forces to dynein in many other systems. Lessons from elevating cAMP levels indicate the presence of a peripheral feedback regulatory system involved in maintaining the evenly dispersed state. Studies from dynein inhibition suggest that the kinesin-like protein involved in fish melanosome dispersal is regulated in contrast to many other systems. One would further expect melanosome transport to be regulated also on actin/myosin, in order to prevent actin-dependent capture of melanosomes during the microtubule-dependent aggregation and dispersion. General findings will be discussed in comparison with positioning and movement of other organelle types in cells. Finally, recent data on melanosome-dependent organising of microtubules show that dynein is involved in nucleating microtubules extending from melanosome aggregates in melanophore fragments.
Sköld
Helén Nilsson
HN
Department of Zoophysiology, Göteborg University, Sweden. helen.skold@kmf.gu.se
Aspengren
Sara
S
Wallin
Margareta
M
D000818:Animals; D001692:Biological Transport; D003599:Cytoskeleton / Q000502:physiology*; D005399:Fishes / Q000033:anatomy & histology* / Q000502:physiology; D008547:Melanophores / Q000502:physiology* / Q000648:ultrastructure; D020460:Melanosomes / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron