Aggregation of marine sponge cells induced by Ca pulses, Ca ionophores, and phorbol esters proceeds in the absence of external Ca.
Cells of the sponge Microciona prolifera dissociated in Ca,Mg-free sea water reaggregate upon addition of Ca, an observation classically attributed to the requirement for Ca of a species-specific aggregation factor. We now report that, unexpectedly, extracellular Ca is not required during aggregation; brief Ca pulses (1-3 sec) terminated by excess EDTA suffice to prepare the cells for aggregation by Ca ionophores (e.g. A23187). We also show that phorbol myristate acetate (PMA) promotes aggregation of pulse-prepared cells. Since PMA and A23187 act synergistically in Microciona, the "twin signal" hypothesis, signalling by Ca and protein kinase C in parallel, is validated in this primitive animal.
Dunham
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Weissmann
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D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D015815:Cell Adhesion Molecules; D002449:Cell Aggregation / Q000187:drug effects; D007476:Ionophores / Q000494:pharmacology*; D010703:Phorbol Esters / Q000494:pharmacology*; D011161:Porifera / Q000166:cytology*; D011506:Proteins / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D015815:Cell Adhesion Molecules; D007476:Ionophores; D010703:Phorbol Esters; D011506:Proteins; C013065:cell aggregation factors; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium