Retrograde signaling

Retrograde signaling in biology is the process where a signal travels backwards from a target source back to its original source. Neurons use extended axons that are away from the cell body and dendrites, by using retrograde signaling endosomes, communication can occur. This occurrence happens from the distal part of the axon, the signals then travel to the cell body. Typically, the nucleus of a cell is the original source that creates signaling proteins. However, during retrograde signaling, instead of signals leaving the nucleus, they are sent to the nucleus. Particularly, in cell biology, this type of signaling typically occurs between the 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 and external stimuli which activate a signaling pathway.

In neuroscience, retrograde signaling (or retrograde neurotransmission) refers more specifically to the process by which a retrograde messenger, such as an anandamide or nitric oxide, is released by a postsynaptic dendrite or cell body, and travels "backwards" across a chemical synapse to bind to the axon terminal of a presynaptic neuron.