[Inhibition of the adenylyl cyclase signaling system by colchicine and vinblastine in ciliate Dileptus anser].

Cytoskeleton plays a key role in functioning of hormonal signaling systems in vertebrate animals. The data on the influence of cytoskeleton components, in particular the microtubules, on functional activity of chemosignaling systems of unicellular organisms are absent at the present time. The aim of this work was the study of influence of microtubule-disrupting agents, colchicine and vinblastine, on the adenylyl cyclase (AC) system of free-living ciliate Dileptus anser. The treatment of D. anser with colchicine and vinblastine (10(-5)-10(-6) M) weakly influenced basal activity of AC, but caused essential decrease or complete blocking of AC stimulation by non-hormonal (GppNHp, sodium fluoride) and hormonal (aldrenaline, serotonin, glucagon) agents. As a result of this treatment, a decrease of the basal level of GTP-binding of heterotrimeric G-proteins and inhibition of G-protein stumulation by the hormones were found. In the case of adrenaline it was that colchicine and vinblastine disturb the AC stimulation by the hormone, mediated with the G(s)-protein, but weakly influence its inhibitory AC effect, realized via the G(i)-protein. Thus, it was established for the first time that microtubules in unicellular organisms such as the ciliate D. anser are involved in regulation of functional activity of AC system, and their action is realized at the level of the G-proteins similar to the G(s)-proteins of the vertebrates.