A. Gil et al., The F-actin cytoskeleton modulates slow secretory components rather than readily releasable vesicle pools in bovine chromaffin cells, NEUROSCIENC, 98(3), 2000, pp. 605-614
Adrenal chromaffin cells were used to test the role of the peripheral cytos
keleton of F-actin in controlling different vesicle pools. Phorbol 12-myris
tate 13-acetate and calyculin A, two substances affecting phosphorylation-d
ephosphorylation cycles, produced different degrees of F-actin reorganizati
on, inducing the partial and the almost total disassembly of this structure
, respectively, as visualized using rhodamine-phalloidin staining. Conseque
ntly, electron microscopy studies revealed the higher efficiency of calycul
in-A over phorbol 12-myristate 13-acetate in promoting vesicle access to th
e plasmalemma boundary. Surprisingly, only the phorbol ester enhanced fast
kinetics and the population of rapidly releasable vesicle pools as studied
by single-cell amperometry, whereas both agents, as well as the F-actin sev
ering compound, Latrunculin A, promoted an increase in the population of ve
sicles recruited in response to prolonged or repetitive stimulations.
Taken together, our data support the notion that the F-actin peripheral bar
rier controls primary granule recruitment from reserve vesicle pools, where
as the phorbol ester effect on the rapidly releasable pools might be relate
d to the alteration of late secretory stage through protein kinase C-depend
ent phosphorylation of an unidentified target. (C) 2000 IBRO. Published by
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