Cyclic AMP regulation of annexins I, II, V synthesis and localization in cultured porcine thyroid cells

Abstract Porcine thyrooid cells cultured in the presence of TSH (0.1 mU/ml) or forskolin (10 −5 M) for 4 days display an increased annexin I, II, V biosynthesis when compared with unstimulated cells. Annexin I mostly accumulates in the cytosolic fraction and annexins II and V in the particulate fraction. TSH and forskolin affect in the same manner annexin biosynthesis and localization. In the TSH and forskolin treated cells PGE 2 production is very low in comparison with the very high PLA 2 activity observed in the dedifferentiated control cells. A strong inhibition of the PGE 2 production is observed in control cells incubated with a purified annexin V preparation. These results suggest the existence, in porcine thyroid cells, of a cross-talk between the adenylyl cyclase system and the phospholipase A 2 mediated pathways. Annexins' biosynthesis and localization are under the control of the adenylyl cyclase system and participate in this cross-talk.