Light-induced exocytosis in cell development and differentiation.
Calcium-dependent exocytosis of fluorescently labeled single secretory vesicles in PC12 cells and primary embryonic telencephalon cells can be triggered by illumination with visible light and imaged by TIRF or epifluorescence microscopy. Opsin 3 was identified by quantitative PCR expression analysis as the putative light receptor molecule for light-induced exocytosis. In primary chicken telencephalon cells, light-induced exocytosis is restricted to a specific period during embryonic development, and involves fusion of rather large vesicles. Strictly calcium-dependent exocytosis starts after a delay of a few seconds of illumination and lasts for up to 2 min. We analyzed the frequency, time course and spatial distribution of exocytotic events. Exocytosis in PC12 cells and telencephalon cells occurs at the periphery or the interface between dividing cells, and the duration of single secretion events varies considerably. Our observation strongly supports the idea that light induced exocytosis is most likely a mechanism for building plasma membrane during differentiation, development and proliferation rather than for calcium-dependent neurotransmitter release.
Henkel
Andreas W
AW
Department of Psychiatry, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen, Germany. andreas.henkel@psych.imed.uni-erlangen.de
Upmann
Irene
I
Bartl
Christina R
CR
Bönsch
Dominikus
D
Reichardt
Cornelia
C
Maler
Juan Manuel
JM
Nürnberger
Michael
M
Umstätter
Richard
R
Reulbach
Udo
U
Kornhuber
Johannes
J
Wiltfang
Jens
J
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology / Q000528:radiation effects; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002645:Chickens; D005089:Exocytosis / Q000502:physiology*; D008027:Light; D008561:Membrane Fusion; D008856:Microscopy, Fluorescence; D016716:PC12 Cells; D010782:Photolysis; D051381:Rats; D015398:Signal Transduction
D002118:Calcium