A role for spectrin in dynactin-dependent melanosome transport in Xenopus laevis melanophores.
The bi-directional movement of pigment granules in frog melanophores involves the microtubule-based motors cytoplasmic dynein, which is responsible for aggregation, and kinesin II and myosin V, which are required for dispersion of pigment. It was recently shown that dynactin acts as a link between dynein and kinesin II and melanosomes, but it is not fully understood how this is regulated and if more proteins are involved. Here, we suggest that spectrin, which is known to be associated with Golgi vesicles as well as synaptic vesicles in a number of cells, is of importance for melanosome movements in Xenopus laevis melanophores. Large amounts of spectrin were found on melanosomes isolated from both aggregated and dispersed melanophores. Spectrin and two components of the oligomeric dynactin complex, p150(glued) and Arp1/centractin, co-localized with melanosomes during aggregation and dispersion, and the proteins were found to interact as determined by co-immunoprecipitation. Spectrin has been suggested as an important link between cargoes and motor proteins in other cell types, and our new data indicate that spectrin has a role in the specialized melanosome transport processes in frog melanophores, in addition to a more general vesicle transport.
Aspengren
Sara
S
Department of Zoology, Zoophysiology, Göteborg University, Göteborg, Sweden. sara.aspengren@zool.gu.se
Wallin
Margareta
M
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D000072159:Dynactin Complex; D047468:Immunoprecipitation / Q000379:methods; D008547:Melanophores / Q000166:cytology / Q000502:physiology*; D020460:Melanosomes / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000502:physiology*; D013049:Spectrin / Q000502:physiology*; D014018:Tissue Distribution; D014982:Xenopus laevis
D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D013049:Spectrin