Microinjection of cyclic ADP-ribose triggers a regenerative wave of Ca2+ release and exocytosis of cortical alveoli in medaka eggs
| Autor: | Andrew L. Miller, R. A. Fluck, Antony Galione, Vivek Abraham |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Cell type Oryzias chemistry.chemical_element Biology Calcium Cyclic ADP-ribose Exocytosis chemistry.chemical_compound Aequorin Internal medicine medicine Animals Microinjection Adenosine Diphosphate Ribose Cyclic ADP-Ribose Ryanodine Activator (genetics) Ryanodine receptor Temperature Ryanodine Receptor Calcium Release Channel Cell Biology Regenerative process Endocrinology chemistry Luminescent Measurements embryonic structures Oocytes Biophysics Developmental Biology |
| Zdroj: | Europe PubMed Central Hong Kong University of Science and Technology |
| ISSN: | 1469-8730 0967-1994 |
| DOI: | 10.1017/s0967199499000684 |
| Popis: | Medaka (Oryzias latipes) eggs microinjected with the Ca2+-mobilising messenger cyclic adenosine diphosphate ribose (cADPR) underwent a wave of exocytosis of cortical alveoli and were thus activated. The number of eggs activated was sharply dependent on the concentration of cADPR in the pipette, the threshold concentration was approximately 60 nM. After injection, a pronounced latency preceded the onset of cortical alveoli exocytosis; this latency was independent of the concentration of cADPR but decreased markedly with increasing temperature. Heat-treated cADPR, which yields the inert non-cyclised product ADP-ribose, was ineffective in activating eggs. When cADPR was injected into aequorin-loaded eggs, a wave of luminescence arose at the site of cADPR injection and then swept out across the egg with a mean velocity of approximately 13 μm/s; the velocity was independent of the concentration of injected cADPR. In such a large cell (diameter of around 1 mm), this is considerably faster than that possible by simple diffusion of cADPR, which unambiguously demonstrates that cADPR must activate a regenerative process. cADPR has been demonstrated to modulate Ca2+-induced Ca2+ release (CICR) via ryanodine receptors (RyRs) in many cell types, and consistent with this was the finding that microinjection of the pharmacological RyR modulator, ryanodine, also activated medaka eggs. These results suggest that a cADPR-sensitive Ca2+ release mechanism is present in the medaka egg, that cADPR is the most potent activator of medaka eggs described to date, and that it activates eggs by triggering a wave of CICR from internal stores that in turn stimulates a wave of exocytosis. |
| Databáze: | OpenAIRE |
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