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)
The in vivo actions of insulin-like growth factor-I (IGF-I) on cerebellum development have been investigated in transgenic (Tg) mice (IGF-II/I Tg mice) in whom an IGF-II promoter-driven IGF-I transgene is highly expressed in cerebellum. Compared to normal littermates, the brains of IGF-II/I Tg mice exhibited overgrowth beginning from the second week of(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)
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)
During the development of the neuromuscular junction, acetylcholine receptors (AChRs) become clustered in the postsynaptic membrane in response to innervation. In vitro, several non-neuronal stimuli can also induce the formation of AChR clusters. DC electric field (E field) is one of them. When cultured Xenopus muscle cells are exposed to an E field of 5-10(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)
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)
Recent studies have suggested a role for molecules residing at the muscle surface in signaling presynaptic development at the neuromuscular junction (NMJ). Since heparan sulfate-proteoglycan is a major component of the extracellular matrix of skeletal muscle, factors that are bound to this proteoglycan, such as basic fibroblast growth factor (bFGF), are in(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)
Three hemizygous transgenic (Tg) mouse lines were generated with a fusion gene composed of the mouse metallothionein promoter (mMT-I) and a full-length human insulin-like growth factor binding protein-1 (hIGFBP-1) complementary DNA that was truncated in its 3'-untranslated region. Despite high serum hIGFBP-1 levels (120-2570 micrograms/liter) before puberty(More)