Intraneuronal trafficking and distribution of amphiphysin and synaptojanin in the rat peripheral nervous system and the spinal cord.
Amphiphysin and synaptojanin are two nerve terminal proteins with a putative role in synaptic vesicle endocytosis and recycling. We have investigated the intraneuronal dynamics and distribution of these two proteins, using nerve crush techniques in combination with immunofluorescence, cytofluorimetric scanning (CFS), confocal laser scanning microscopy and immuno-electron microscopy (EM). Accumulations of amphiphysin and synaptojanin immunoreactivities at the crush site were detected as short as 1 h after the lesion, indicating that a pool of these two partially cytosolic proteins moves along the axon by fast axoplasmic transport. The amount of proximal accumulation increased linearly between 1 and 8 h. CFS analysis demonstrated that only 30% of fast anterogradely transported amphiphysin and synaptojanin was returned by fast retrograde transport, in contrast to the 70% value observed for synaptophysin, a transmembrane protein. This indicates that the majority of amphiphysin and synaptojanin is degraded/metabolized in the nerve terminals. Immuno-EM showed that both amphiphysin and synaptojanin are primarily associated with heterogeneous membrane profiles in the crushed sciatic nerve and the immunoperoxidase reaction product is concentrated in the nerve terminal cytomatrix of the spinal cord. Both proteins were differentially distributed in subsets of nerve terminals, indicating heterogeneous expression in neurons.
Li
J Y
JY
Department of Anatomy and Cell Biology, Centre for Neuroscience Research, Göteborg University, Sweden.
De Camilli
P
P
Dahlström
A
A
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D017933:Peripheral Nervous System / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*
D009419:Nerve Tissue Proteins; C075637:amphiphysin; C097702:synaptojanin; D010744:Phosphoric Monoester Hydrolases