Paracrine Information
Paracrine signaling is a form of cell signaling in which the target cell is near ("para" = near) the signal-releasing cell.
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Local action
Some signaling molecules degrade very quickly, limiting the scope of their effectiveness to the immediate surroundings. Others affect only nearby cells because they are taken up quickly, leaving few to travel further, or because their movement is hindered by the extracellular-matrix.[citation needed]
Examples
Growth factor and clotting factors are paracrine signaling agents. The local action of growth factor signaling plays an especially important role in the development of tissues. Also, retinoic acid, the active form of vitamin A, functions in a paracrine fashion to regulate gene expression during embryonic development in higher animals.[1] In insects, Allatostatin controls growth though paracrine action on the corpora allata.
In mature organisms, paracrine signaling is involved in responses to allergens, tissue repair, the formation of scar tissue, and blood clotting.[citation needed]
Autocrine and endocrine actions
Testosterone secreted from the testes acts as an endocrine agent to stimulate peripheral events, such as muscle growth, and as a paracrine agent to stimulate spermatogenesis in the adjacent seminiferous tubules.[citation needed]
See also
References
- ^ Duester, G (September 2008). "Retinoic acid synthesis and signaling during early organogenesis". Cell 134 (6): 921–31. doi:10.1016/j.cell.2008.09.002. PMC 2632951. PMID 18805086.
External links
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Categories: Signal transduction |
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