Editing Paracrine signaling (section)

{{short description|Form of localized cell signaling}}

In [[cellular biology]], '''paracrine signaling''' is a form of [[cell signaling]], a type of [[cellular communication (biology)|cellular communication]] in which a [[Cell (biology)|cell]] produces a signal to induce changes in nearby cells, altering the behaviour of those cells. Signaling molecules known as '''paracrine factors''' [[diffuse]] over a relatively short distance (local action), as opposed to cell signaling by [[endocrine system|endocrine factors]], [[hormone]]s which travel considerably longer distances via the [[circulatory system]]; [[juxtacrine signaling|juxtacrine interactions]]; and [[autocrine signaling]]. Cells that produce paracrine factors secrete them into the immediate [[extracellular]] environment. Factors then travel to nearby cells in which the gradient of factor received determines the outcome. However, the exact distance that paracrine factors can travel is not certain.

[[File:signal transduction pathways.png|thumb|500px|right|Overview of signal transduction pathways.]]

Although paracrine signaling elicits a diverse array of responses in the induced cells, most paracrine factors utilize a relatively streamlined set of [[Receptor (biochemistry)|receptor]]s and pathways. In fact, different [[organ (biology)|organ]]s in the body - even between different species - are known to utilize a similar sets of paracrine factors in differential development.<ref>{{cite web|title=Paracrine Factors|url=https://www.ncbi.nlm.nih.gov/books/NBK10071/|access-date=27 July 2018}}</ref> The highly conserved receptors and pathways can be organized into four major families based on similar structures:  [[fibroblast growth factor]] (FGF) family, [[Hedgehog signaling pathway|Hedgehog]] family, [[Wnt signaling pathway|Wnt]] family, and [[Transforming growth factor beta|TGF-β superfamily]]. Binding of a paracrine factor to its respective receptor initiates [[signal transduction]] cascades, eliciting different responses.