Cell signaling under external stimulation is a critical mechanism that governs many biological processes such as cell proliferation, cell migration, and cell apoptosis, etc. For multicellular organisms, the ability to synchronize heterogeneous individual cellular responses through intercellular communication is crucial to maintain normal functionality. However, even though the biological pathways and molecular basis of signaling and intercellular communication has been well-studied,little is known about the underlying mechanisms that cells utilize to achieve highly cooperative and synchronized responses.
Since molecule exchange between neighboring cells through intercellular communication inherently leads to the information exchange, we utilized a statistical test called Granger causality test to uncover the information flow between neighboring cells communicated through gap junctions. We first applied the test to calcium signaling data obtained from a two-dimensional neuron monolayer network stimulated by periodic ATP stimulation. By varying the period and ATP concentration of the stimulation, we observed that the constructed multicellular information network was dominated by the temporal signal of the stimulation, and the network evolution maintained stationary and detailed balance. The result suggests that the multicellular network is regulated internally by intercellular communication and externally by temporal signal of the stimulation.
Next, we focused on analyzing the calcium signaling caused by shear stress stimulation in human umbilical vein endothelial cells (HUVEC). Our results indicate that cells can gradually adapt and learn their microenvironment, further stabilizing their inner state within the multicellular network architecture. This process supports the information flow from local to global scale toward synchronization.
Last but not least, we tuned the intercellular communication by micropatterning technique that can control the shape of cell monolayer. By introducing geometrical barriers that cell cannot across, we can quantitatively control intercellular communication within the neuron network. The experimental results indicate the existence of an interplay of intercellular communication and temporal signal in contributing to synchronization. Strong intercellular communication hinders synchronization under long-period stimulation but promotes synchronization under short-period stimulation. Overall, our study provides new aspects on how external stimulation can regulate intercellular synchronization by investigating the synchronization among single-cell level signaling.