Editing Retrograde signaling (section)

{{Short description|In biology, a signal traveling backwards to its source}}
'''Retrograde signaling''' in biology is the process where a signal travels backwards from a target source to its original source. For example, the [[Cell nucleus|nucleus]] of a cell is the original source for creating signaling proteins. During retrograde signaling, instead of signals leaving the nucleus, they are sent to the nucleus.<ref>{{Cite journal|last=Leister|first=Dario|date=2012|title=Retrograde signaling in plants: from simple to complex scenarios|journal=Frontiers in Plant Science|volume=3|pages=135|doi=10.3389/fpls.2012.00135|pmid=22723802|pmc=3377957|issn=1664-462X|doi-access=free}}</ref> In [[cell biology]], this type of signaling typically occurs between the [[Mitochondrion|mitochondria]] or [[chloroplast]] and the nucleus. Signaling molecules from the mitochondria or chloroplast act on the nucleus to affect nuclear gene expression. In this regard, the chloroplast or mitochondria act as a sensor for internal external stimuli which activate a signaling pathway.<ref name="Nott_2006" />
[[File:Synapse Illustration2 tweaked.svg|thumb|The postsynaptic [[dendrite]] (green) and presynaptic neuron (yellow) found in '''retrograde neurotransmission.''']]
In [[neuroscience]], retrograde signaling (or '''retrograde neurotransmission''') refers more specifically to the process by which a retrograde messenger, such as [[anandamide]] or [[nitric oxide]], is released by a postsynaptic [[dendrite]] or [[perikaryon|cell body]], and travels "backwards" across a [[chemical synapse]] to bind to the [[axon terminal]] of a presynaptic [[neuron]].<ref name="Regehr 2009">{{cite journal | vauthors = Regehr WG, Carey MR, Best AR | title = Activity-dependent regulation of synapses by retrograde messengers | journal = Neuron | volume = 63 | issue = 2 | pages = 154–70 | date = July 2009 | pmid = 19640475 | pmc = 3251517 | doi = 10.1016/j.neuron.2009.06.021 }}</ref>