To sustain life and good health, it is essential that cells and tissues can
communicate with each other. Organelles within cells, cells within tissues, tissues
within our body, and all of the bodies in a society must sense their internal and external
environments and respond appropriately to changes. Hormones, neurotransmitters and
cytokines can act as primary messengers. Secondary messengers include is Ca2+, IP3
and diacyl glycerol (produced by the hydrolysis of phosphoinositides), arachidonic acid
(produced by the hydrolysis of phospholipids that have arachidonoyl on carbon number
2 of the glycerol backbone), ceramide, eicosanoids, lysophosphatidic acid, NO (nitric
oxide), cAMP and cGMP. The IP3 receptor, or IP3R is a membrane-bound complex of
glycoproteins. It is a Ca2+ channel that is activated by IP3, which is a secondary intracellular
messenger. Inter- and intracellular communication can be thought of as a
network that contains many items (nodes) that have anywhere from one to thousands of
connections. The most widely connected nodes are called hubs. Probably the major
genetic hub in human and many other mammalian cells is the gene TP53 which codes
for the protein p53. About 50% of all human cancers have one or more mutations in
p53 that alter DNA transcription.
Keywords: Arachidonic acid, Calcium, Ca2+, Ceramide, cAMP, cGMP, Diacyl
glycerol, Eicosanoids, GPCR, IP3, Lysophosphatidic acid, Nitric oxide.
