Nerve growth occurs by activity of cytoskeletal elements, coordinated with addition of new membrane material to the growing axon. Although the dynamics of the neuronal cytoskeleton has been a subject of intensive investigation in the last years, very little is known about the phenomenon of membrane addition to the growing axon. Recent studies have given us reason to believe that at the initial stages of axonal growth, new membrane is added not at the growth cone, as it is generally accepted, but along the axon and/or at the soma, resulting in the generation of the forward flow of the plasma membrane components. We are using digital video microscopy to characterize the cellular processes involved in membrane addition to the growing neuron and to examine the relationship between topology of membrane insertion and the status of neuronal cytoskeleton. In addition we are interested in the relationship between the constitutive secretion pathway in non-neuronal cells and the synaptic vesicle pathway in neurons. This study relies heavily on the recently developed electrophysiological technique of real-time detection of single exocytotic events in non-neuronal cells. Our current focus is on the identifying the functional roles of specific synaptic vesicle proteins in the assembly of the neurotransmitter secretion machinery.
Publications:
1. Chang S., V.I. Rodionov, G. Borisy, S.V. Popov. 1998. Transport and turnover of microtubules in frog neurons depend on the pattern of axonal growth. J. Neurosci, 18: 821-829.
2. Chang S., R. Girod, T. Morimoto, M. O'Donoghue, S.V. Popov. 1998. Constitutive secretion of exogenous neurotransmitter from non-neuronal cells: implications for neuronal secretion. Biophys J. 75: 1354-1364.
3. Zakharenko S., S.V. Popov. 1998. Dynamics of axonal microtubules regulate the topology of new membrane insertion into the growing neurites. J. Cell Biol 143: 1077-1086.
4. Zakharenko S., S. Chang, M. O'Donoghue, S.V. Popov. 1999. Neurotransmitter secretion along growing nerve processes: comparison with synaptic vesicle exocytosis. J. Cell Biol., 144:507-518.
5. Antonov I., S. Chang, S. Zakharenko, S.V. Popov. 1999. Distribution of exocytotic events in growing axons. Neuroscience, 90:975-984
6. Chang S., S.V. Popov. 1999. Long-range signaling within growing neurites mediated by neurotrophin-3. Proc. Natl. Acad. Sci. USA, 96:4101-4106.
7. Chang S., T.M. Svitkina, G.G. Borisy, S.V. Popov. 1999. Speckle microscopic evaluation of microtubule transport in growing nerve processes. Nature Cell Biology, in press.
Send mail to SPopov@uic.edu
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