Regulation of Src homology 2-containing tyrosine phosphatase 1 during activation of human neutrophils. Role of protein kinase C

Cotylenin A, a plant-growth regulator, induces the differentiation in murine and human myeloid leukemia cells

Protein factors playing a significant part in differentiation and development have been recently elucidated. However, low molecular factors which also seem to be essential remain still unknown, although only retinoic acid has become such a candidate. Cotylenins had been isolated as the plant-growth regulators, and have been found to affect a number of physiological processes of higher plants. Here we report that at the concentrations above 12.5 microg/ml (20 microM) cotylenin A induced the functional and morphological differentiation in murine (M1) and human myeloid leukemia (HL-60) cells. Although cotylenin A has some similarity to PMA both in carbotricyclic diterpene structure and in biological activity (i.e. differentiation-induction of HL-60 cells into macrophages), the activation of PKC and the elevation of Ca2+-levels by cotylenin A were not observed. Quite recently it has been reported that fusicoccin (closely related to cotylenin A)-targets are 14-3-3 proteins, which are at the crosspoint of a huge array of signalling and regulatory pathways. These results suggest that cotylenin A might become a useful tool for the elucidation of molecular mechanisms of differentiation and development.