Intercellular communication

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Intercellular communication is communication between different cells. This can be via direct cell contact, or through the use of electrical or chemical messengers.

Intercellular communication is accomplished by extracellular signalling and takes place in multicellular organisms. Within endocrinology, which is the study of intercellular signalling in animals, intercellular signalling is subdivided into the following types:

Endocrine signals are produced by endocrine cells and travel through the blood to reach all parts of the body.
Paracrine signals target only cells in the vicinity of the emitting cell. Neurotransmitters represent an example.
Autocrine signals affect only cells that are of the same cell type as the emitting cell. An example for autocrine signals is found in immune cells.
Juxtacrine signals are transmitted along cell membranes via protein or lipid components integral to the membrane and are capable of affecting either the emitting cell or cells immediately adjacent.

Communication by direct contact is usually via the interaction of the glycocalices of the cells, which consist mainly of oligosaccharides in the cell membranes. Intercellular communication is essential for the arrangement of cells in tissues.

Gap junctions are small channels formed between neighboring cells. They allow two-way intercellular communication between healthy cells by allowing the exchange of small molecules and ions (the second messengers) that affect cell communication and signaling. Six connexin proteins localized at the cell membrane are arranged in a similar manner to a camera diaphragm to form a connexon. Connexons from one cell dock with connexons from an adjacent cell to form a gap junction channel. Functional gap junction intercellular communication (GJIC) and cell signaling maintain homeostatic balance and enable healthy cells and tissue to respond to external stimuli. Conversely, disrupted GJIC is associated with almost all cancers, vascular and kidney diseases, and up to 70% of all neurodegenerative diseases.

Nerve cells, neurons, for example send signals to each other during a synapse. At the axon terminal of the neuron, ions are released into the synaptic cleft. These ions (second messengers) fit into protein receptors in the post-synaptic neuron, and the synapse passes on through the second nerve cell.

Intercellular communication

See also