Retroinhibition of the Calcium-Phosphatidylinositol Cascade by Diacylglycerol in Thyroid

Abstract

A few years ago, cell control was still often described by 2 or 3 simple regulatory pathways (involving cyclic AMP, calcium and cyclic GMP), the relative importance of which was much contested by their various proponents. We predicted that interconnections between these pathways and between various steps of each pathway would be progressively demonstrated, so that at some time, any possible regulatory link between the steps of the different pathways would eventually been shown to exist in at least one system (1). Thus the concept of a specific regulatory network for each type of cell would at some time prevail over simplistic theories. The present symposium clearly supports these ideas. In this communication, we wish to report evidence in favor of the operation in the dog thyroid follicular cell of a negative feedback of one of the intracellular signals generated by the phosphatidy1inositol cascade on the first step of this cascade.