Synaptophysin is required for synaptobrevin retrieval during synaptic vesicle endocytosis

SL Gordon, RE Leube, MA Cousin - Journal of Neuroscience, 2011 - Soc Neuroscience
SL Gordon, RE Leube, MA Cousin
Journal of Neuroscience, 2011Soc Neuroscience
The integral synaptic vesicle (SV) protein synaptophysin forms∼ 10% of total SV protein
content, but has no known function in SV physiology. Synaptobrevin (sybII) is another
abundant integral SV protein with an essential role in SV exocytosis. Synaptophysin and
sybII form a complex in nerve terminals, suggesting this interaction may have a key role in
presynaptic function. To determine how synaptophysin controls sybII traffic in nerve
terminals, we used a combination of optical imaging techniques in cultures derived from …
The integral synaptic vesicle (SV) protein synaptophysin forms ∼10% of total SV protein content, but has no known function in SV physiology. Synaptobrevin (sybII) is another abundant integral SV protein with an essential role in SV exocytosis. Synaptophysin and sybII form a complex in nerve terminals, suggesting this interaction may have a key role in presynaptic function. To determine how synaptophysin controls sybII traffic in nerve terminals, we used a combination of optical imaging techniques in cultures derived from synaptophysin knock-out mice. We show that synaptophysin is specifically required for the retrieval of the pH-sensitive fluorescent reporter sybII-pHluorin from the plasma membrane during endocytosis. The retrieval of other SV protein cargo reporters still occurred; however, their recapture proceeded with slower kinetics. This slowing of SV retrieval kinetics in the absence of synaptophysin did not impact on global SV turnover. These results identify a specific and selective requirement for synaptophysin in the retrieval of sybII during SV endocytosis and suggest that their interaction may act as an adjustable regulator of SV retrieval efficiency.
Soc Neuroscience