Communication: the key word! Computers communicate through the Internet, dolphins through sound, human beings through their sensory organs, plants through specific molecules – they even have a social life! The study of these communication systems has given birth to a new biomedical specialization: “Signaling”.
Cellular signaling is a complex communication system which governs cells’ fundamental processes and coordinates their activity. The capacity cells have to perceive their microenvironment and to respond to it correctly is the basis of homeostasis. This is why malfunctioning of the processing of cellular information might be responsible for illnesses such as cancer, auto-immune diseases or diabetes. Cells receive information from their neighbors through a class of proteins called receptors.
A cell is first and foremost a protein production plant. These components which are essential to life are manufactured according to blueprints deposited as DNA in the cell nucleus. In order to accomplish this mission at the right time, the cell constantly receives and emits chemical messages communicating its position in space, the state of its “production equipment” or the quality of its environment. It also informs its neighbors when initiating cell division. All of these signals are transported, by hormones traveling in the blood.., Secreted by several endocrine glands, these hormones selectively activate some of the hundreds of receptors anchored on the membrane surface. The cell is therefore a production workshop as well as a colossal communications center. These different means of communication are facilitated by diffusible substances, which is why cells are equipped with specific receptors.
Typically, when a signal protein becomes embedded into its membrane receptor, it changes the geometrical configuration of the site and the message is transmitted inside the cell. Within the cytoplasm, other molecules take over and send the information through several successive steps all the way to the nucleus. A transmission error can have dramatic consequences. It can shutdown the production of essential proteins or lead to the assembly of poor quality parts.