Biochemistry of Direct Cell-Cell Interactions. Signaling Factors Regulating Orchestration of Cell Populations.

Biochemical mechanisms for the orchestration of cell populations are discussed in view of direct cell-cell interactions and composition of the intercellular medium. In our works of the last 20 years, we used circahoralian (ultradian) rhythm of protein synthesis as a marker of cell interactions. Experiments in cell cultures are described; some influences on the organism native medium were performed. Information is presented on the signaling membrane factors that trigger a cascade of processes in the cytoplasm and lead to the orchestration of cell activity in vitro and in vivo. Among these factors are blood serum neurotransmitters, gangliosides, and some hormones. Studying protein synthesis kinetics allowed us to understand the importance of maintaining the constant levels of signaling factors in mammalian blood. The literature on protein phosphorylation as a key process of cell organization is reviewed. The persistence of the organizing signal for several days is described as a type of cell "memory". It seems promising to extend the area for application of direct cell-cell interactions (respiration of cells, proliferation, etc.) to study possibilities of epigenetic regulation. It is important to continue the studies on the mechanisms of biochemical action of the known drugs as signaling factors.