Protein kinase C modulates synaptic vesicle acidification in a ribbon type nerve terminal in the retina

被引:14
作者
Abreu, Bento J.
Guirnares, Maila
Uliana, Livia C.
Vigh, Jozsef
von Gersdorff, Henrique [3 ]
Prado, Marco A. [2 ]
Guatimosim, Cristina [1 ]
机构
[1] Univ Fed Minas Gerais, ICB, Dept Morphol, Inst Biol Sci, BR-31270901 Belo Horizonte, MG, Brazil
[2] Univ Fed Minas Gerais, Inst Biol Sci, Dept Pharmacol, BR-31270901 Belo Horizonte, MG, Brazil
[3] Oregon Hlth & Sci Univ, Vollum Inst, Portland, OR 97239 USA
关键词
Retina; Bipolar cell; PKC; Acidification; Confocal microscopy; Synaptic vesicle;
D O I
10.1016/j.neuint.2008.07.004
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The driving force for neurotransmitter accumulation into synaptic vesicles is provided by the generation of a transmembrane electrochemical gradient (Delta mu H+) that has two components: a chemical gradient (Delta pH, inside acidic) and an electrical potential across the vesicular membrane (All, inside positive). This gradient is generated in situ by the electrogenic vacuolar H+-ATPase, which is responsible for the acidification and positive membrane potential of the vesicle lumen. Here, we investigate the modulation of vesicle acidification by using the acidic-organelle probe LysoTracker and the pH-sensitive probe LysoSensor at goldfish Mb-type bipolar cell terminals. Since phosphorylation can modulate secretory granule acidification in neuroendocrine cells, we investigated if drugs that affect protein kinases modulate LysoTracker staining of bipolar cell terminals. We find that protein kinase C (PKC) activation induces an increase in LysoTracker-fluorescence. By contrast, protein kinase A (PKA) or calcium/calmodulin kinase II (CaMKII) activation or inhibition did not change LysoTracker-fluorescence. Using a pH-dependent fluorescent dye (LysoSensor) we show that the PKC activation with PMA induces an increase in LysoSensor-fluorescence, whereas the inactive analog 4alpha-PMA was unable to cause the same effect. This increase induced by PMA was blocked by PKC inhibitors, calphostin C and staurosporine. These results suggest that phosphorylation by PKC may increase synaptic vesicle acidification in retinal bipolar cells and therefore has the potential to modulate glutamate concentrations inside synaptic vesicles. (C) 2008 Elsevier Ltd. All rights reserved.
引用
收藏
页码:155 / 164
页数:10
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