The annexin II-p11 complex is involved in regulated exocytosis in bovine pulmonary artery endothelial cells.
Annexin II is a member of a multigene family of Ca2+-regulated, membrane-binding proteins implicated through biochemical and perforated cell experiments in Ca2+-triggered secretion. Within most cells annexin II resides in a tight heterotetrameric complex with a cellular protein ligand, p11, and complex formation is mediated via the N-terminal 14 residues of annexin II including the N-terminal acetyl group. To analyze at the single cell level whether the annexin II-p11 complex is involved in regulated secretion, we used membrane capacitance measurements to follow exocytotic fusion events in bovine aortic endothelial cells manipulated with respect to their annexin II-p11 complex formation. Upon guanosine 5'-O-(thiotriphosphate) (GTPgammaS) stimulation, the endothelial cells show a significant increase in membrane capacitance which is generally preceded by a transient rise in intracellular Ca2+ and thus indicative of the occurrence of Ca2+-regulated secretion. The GTPgammaS-induced capacitance increase is markedly reduced in cells loaded with a synthetic peptide, Ac1-14, which corresponds in sequence to the N-terminal 14 residues of annexin II in their correctly acetylated form and which is capable of disrupting preformed annexin II-p11 complexes. The effect of the peptide is highly specific as the nonacetylated variant, N1-14, which is incapable of disrupting annexin II-p11, does not interfere with the GTPgammaS-induced increase in membrane capacitance. These data show that intact annexin II-p11 complexes are indispensable for regulated exocytosis to occur in an efficient manner in endothelial cells.
Insitute for Medical Biochemistry, University of Münster, von-Esmarch-Str. 56, D-48149 Münster, Federal Republic of Germany.
J
J
König
J
J
Prenen
B
B
Nilius
V
V
Gerke
D000818:Animals; D017306:Annexin A2 / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004553:Electric Conductivity; D004594:Electrophysiology; D004730:Endothelium, Vascular / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism; D008168:Lung / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000502:physiology*; D009418:S100 Proteins; D014841:von Willebrand Factor / Q000378:metabolism; D000099248:S100 Calcium Binding Protein A10
D017306:Annexin A2; D002118:Calcium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D008081:Liposomes; D010446:Peptide Fragments; D010455:Peptides; D009418:S100 Proteins; D014841:von Willebrand Factor; D000099248:S100 Calcium Binding Protein A10