The June issue of Nature Neuroscience is out, with two articles that caught my eye. The first, “Syndapin I is the phosphorylation-regulated dynamin I partner in synaptic vesicle endocytosis” is covered over by the Neurophilosopher, so I’ll simply encourage you to read about the article there.
The second, “Oncomodulin is a macrophage-derived signal for axon regeneration in retinal ganglion cells,” uncovers a mechanism for axon regeneration in the retina, associated with inflammation. While the optic nerve, like most neural pathways of the central nervous system, cannot regenerate following injury, retinal ganglion cells (RGCs) have been found to regenerate long axons beyond the site of optic nerve injuries in a manner associated with macrophage activation.
Yin et al. were able to identify the calcium (Ca2+)-binding protein oncomodulin as a potent macrophage-derived growth factor for RGCs and other neurons. As they write:
Oncomodulin binds to rat RGCs with high affinity in a cyclic AMP (cAMP)-dependent manner and stimulates more extensive outgrowth than other known trophic agents. Depletion of oncomodulin from macrophage-conditioned media (MCM) eliminates the axon-promoting activity of MCM. The effects of oncomodulin involve downstream signaling via Ca2+/calmodulin kinase and gene transcription. In vivo, oncomodulin released from microspheres promotes regeneration in the mature rat optic nerve. Oncomodulin also stimulates outgrowth from peripheral sensory neurons.
- Syndapin I is the phosphorylation-regulated dynamin I partner in synaptic vesicle endocytosis. Anggono V, Smillie KJ, Graham ME, Valova VA, Cousin MA, Robinson PJ. Nat Neurosci. 2006 Apr 30; 9: 752-760. Pubmed
- Oncomodulin is a macrophage-derived signal for axon regeneration in retinal ganglion cells. Yin Y, Henzl MT, Lorber B, Nakazawa T, Thomas TT, Jiang F, Langer R, Benowitz LI. Nat Neurosci. 2006 May 14; 9: 843-852. Pubmed