Recombinant scinderin enhances exocytosis, an effect blocked by two scinderin-derived actin-binding peptides and PIP2.
The cortical F-actin cytoskeleton represents a negative control for secretion, and it must be locally disassembled to allow chromaffin vesicle exocytosis. Recombinant scinderin (a Ca(2+)-dependent F-actin-severing protein) potentiated Ca(2+)-evoked F-actin disassembly and exocytosis in permeabilized chromaffin cells, an effect blocked by peptides Sc-ABP1 and Sc-ABP2 (with sequences corresponding to two actin-binding sites of scinderin), exogenous gamma-actin, or phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 effect was blocked by peptide Sc-PIP2BP (with sequence corresponding to a PIP2-binding site of scinderin). Truncated scinderin254-715 (lacking actin-severing domains) did not potentiate exocytosis. Sc-ABP1, Sc-ABP2, and gamma-actin also inhibited exocytosis in the absence of recombinant scinderin, suggesting an inhibition of endogenous scinderin. Results suggest that scinderin-evoked cortical F-actin disassembly is required for secretion and that scinderin is an important component of the exocytotic machinery.
Zhang
L
L
Department of Pharmacology, Faculty of Medicine, University of Ottawa, Ontario, Canada.
Marcu
M G
MG
Nau-Staudt
K
K
Trifaró
J M
JM
D000199:Actins / Q000187:drug effects / Q000378:metabolism / Q000494:pharmacology; D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured / Q000166:cytology / Q000502:physiology; D002838:Chromaffin System / Q000166:cytology; D005089:Exocytosis / Q000187:drug effects*; D018260:Gelsolin; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology
D000199:Actins; D018260:Gelsolin; D008840:Microfilament Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D011994:Recombinant Proteins; C065395:scinderin; D002118:Calcium