Local synthesis of axonal and presynaptic RNA in squid model systems.
The presence of active systems of protein synthesis in axons and nerve endings raises the question of the cellular origin of the corresponding RNAs. Our present experiments demonstrate that, besides a possible derivation from neuronal cell bodies, axoplasmic RNAs originate in periaxonal glial cells and presynaptic RNAs derive from nearby cells, presumably glial cells. Indeed, in perfused squid giant axons, delivery of newly synthesized RNA to the axon perfusate is strongly stimulated by axonal depolarization or agonists of glial glutamate and acetylcholine receptors. Likewise, incubation of squid optic lobe slices with [3H]uridine leads to a marked accumulation of [3H]RNA in the large synaptosomes derived from the nerve terminals of retinal photoreceptor neurons. As the cell bodies of these neurons lie outside the optic lobe, the data demonstrate that presynaptic RNA is locally synthesized, presumably by perisynaptic glial cells. Overall, our results support the view that axons and presynaptic regions are endowed with local systems of gene expression which may prove essential for the maintenance and plasticity of these extrasomatic neuronal domains.
Eyman
Maria
M
Department of Biological Sciences, University of Naples Federico II, Naples, Italy.
Cefaliello
Carolina
C
Ferrara
Eugenia
E
De Stefano
Rosanna
R
Lavina
Zeno Scotto
ZS
Crispino
Marianna
M
Squillace
Angela
A
van Minnen
Jan
J
Kaplan
Barry B
BB
Giuditta
Antonio
A
D000818:Animals; D001345:Autoradiography / Q000379:methods; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D049832:Decapodiformes / Q000166:cytology* / Q000502:physiology; D066298:In Vitro Techniques; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009899:Optic Lobe, Nonmammalian / Q000378:metabolism / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D014176:Protein Biosynthesis / Q000502:physiology; D012313:RNA / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism; D013997:Time Factors
D009419:Nerve Tissue Proteins; D012313:RNA