Zhengshan Dai

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The dynamics of synaptic vesicles (SVs) during the development of presynaptic specializations in cultured Xenopus spinal cord neurons was studied with the fluorescent vesicular probe FM1-43. In naive neurons that have not contacted synaptic targets, packets of SVs are distributed along the entire neurite and are quite mobile. The interaction with the(More)
A new method was devised to visualize actin polymerization induced by postsynaptic differentiation signals in cultured muscle cells. This entails masking myofibrillar filamentous (F)-actin with jasplakinolide, a cell-permeant F-actin-binding toxin, before synaptogenic stimulation, and then probing new actin assembly with fluorescent phalloidin. With this(More)
During the development of the neuromuscular junction (NMJ), motoneurons grow to the muscle cell and the nerve-muscle contact triggers the development of both presynaptic specialization, consisting of clusters of synaptic vesicles (SVs), and postsynaptic specialization, consisting of clusters of synaptic vesicles (SVs), and postsynaptic specialization,(More)
A postsynaptic membrane-associated protein of M(r) 43,000 (43-kD protein) is involved in clustering of the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction. Previous studies have shown that recombinant mouse 43-kD protein forms membrane-associated clusters when expressed in Xenopus oocytes. Coexpression with the AChR results in(More)
The heparan sulfate proteoglycan (HSPGs) is a components of the extracellular matrix of skeletal muscle that is concentrated at the neuromuscular junction (NMJ). Recent studies have suggested that HSPG, together with its bound peptide growth factors, plays important roles in autocrine or paracrine types of regulation of cell growth and differentiation.(More)
Innervation of the skeletal muscle involves local signaling, leading to acetylcholine receptor (AChR) clustering, and global signaling, manifested by the dispersal of preexisting AChR clusters (hot spots). Receptor tyrosine kinase (RTK) activation has been shown to mediate AChR clustering. In this study, the role of tyrosine phosphatase (PTPase) in the(More)
Recent studies have shown that the survival of mammalian motoneurons in vitro is promoted by neurotrophins (NTs) and cAMP. There is also evidence that neurotrophins enhance transmitter release. We thus investigated whether these agents also promote synaptogenesis. Cultured Xenopus spinal cord neurons were treated with a mixture of BDNF, glia-derived(More)
Nerve-muscle cocultures were used to study the relationship between neuronal Ca2+ level and the earliest nerve-muscle interaction. Xenopus spinal cord neurons were loaded with Ca2+ indicators and monitored by digital video microscopy as a myoball was manipulated into contact with it. Transmitter release was measured from the myoball by whole-cell recording.(More)
The signal transduction process involved in the development of the nerve terminal is an intriguing question in developmental neurobiology. During the formation of the neuromuscular junction, presynaptic development is induced by growth cone's contact with the target muscle cell. Fluorescence microscopy with specific markers has made it possible to follow(More)
Acetylcholine receptors (AChRs) in Xenopus muscle cells undergo changes in channel kinetics during development in culture and these changes are somehow related to innervation. Recently we showed that basic fibroblast growth factor (bFGF), when locally applied, can mimic the effect of nerve in inducing a postsynaptic-type development. In this study, we(More)