Efficient Induction of Sporulation of Dictyostelium Prespore Cells by 8‐Bromocyclic AMP under Both Submerged‐ and Shaken‐Culture Conditions and Involvement of Protein Kinase(s) in Its Action

Abstract

It is important to establish an experimental system in which sporulation of Dictyostelium can be induced at high cell densities to obtain sufficient amounts of materials for analysis of the molecular events leading to sporulation. 8‐Bromo cAMP (Br‐cAMP) was found to be effective for inducing sporulation by prespore cells of Dictyostelium discoideum NC4 at high cell densities under both submerged‐ and shaken‐culture conditions. Ultrastructural studies revealed that the morphological changes associated with this sporulation proceeded normally in vitro. The effect of Br‐cAMP was inhibited by two protein kinase inhibitors, K252a and staurosporine. Protein‐phosphorylation experiments showed that Br‐cAMP induced increased phosphorylations of a 96 kDa spore coat protein (SP96) and a protein with a mobility corresponding to a molecular weight of 50 kDa (p50‐4). The protein kinase inhibitor K252a blocked the phosphorylations of both proteins. These proteins may be targets of particular protein kinase(s) that is activated by Br‐cAMP. These findings indicate that the present experimental system should be useful for elucidating the molecular events involved in normal sporulation and the mechanism by which Br‐cAMP induces sporulation in vitro. Copyright © 1992, Wiley Blackwell. All rights reserved