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141.
The mechanism of fibroblast growth factor receptor (FGFR) activation by the neural cell adhesion molecule (NCAM) is not well
understood. A motif in the second NCAM fibronectin type III (FN3) module, termed FGL, has by means of nuclear magnetic resonance
(NMR) and surface plasmon resonance (SPR) analyses been demonstrated to be involved in NCAM–FGFR interactions. An FGFR activation
motif (FRM) in the first NCAM FN3 module also has been suggested to take part in NCAM interactions with FGFR. Here, we show
for the first time that a peptide motif in the second NCAM FN3 module, different from the previously described FGL motif (NLIKQDDGGSPIRHY;
termed BCL) binds and activates FGFR and induces FGFR-dependent neurite outgrowth in cultures of cerebellar granule neurons.
Our results provide evidence that the BCL motif is one of the multiple FGFR binding sites in NCAM.
Special issue article in honor of Dr. Anna Maria Giuffrida-Stella. 相似文献
142.
The multiple peripheral projections of a single leech mechanosensory neuron form individual arbors that do not overlap at all with each other, a phenomenon that has been termed “self-avoidance” (Yau, 1976; Kramer and Stent, 1985). This is in marked contrast to the peripheral arbors of adjacent segmental homologues, which partially overlap with each other at their boundaries in target areas of the body wall (Nicholls and Baylor, 1968; Gan and Macagno, 1995). How a neurite differentiates between sibling neurites of the same cell and those of a homologue is not known, but possible mechanisms include the recognition of surface markers of neuronal identity or the detection of cell-specific patterns of activity. In order to test whether this self-recognition requires a neurite to be in direct communication with its soma, we used a laser microbeam to sever a branch of a dye-filled pressure-sensitive (P) neuron in an intact leech embryo. Time-lapse observations of the P cell arbor in the living, unanesthetized, animal for up to 24 h following the surgery showed that the detached branch continued to show dynamic growth behavior throughout the period of observation. However, the detached branch ceased being avoided by the rest of the cell within a few hours, other, attached branches of the neuron overgrowing its territory and directly overlapping with it. Our experiments provide direct evidence for the existence of strong growth-inhibiting interactions between sibling processes, and indicate that self-avoidance by the growing neurites of a cell requires physical continuity between these neurites. © 1998 John Wiley & Sons, Inc. J Neurobiol 35: 53–64, 1998 相似文献
143.
Balla J Kalousek P Reinöhl V Friml J Procházka S 《The Plant journal : for cell and molecular biology》2011,65(4):571-577
Shoot branching is one of the major determinants of plant architecture. Polar auxin transport in stems is necessary for the control of bud outgrowth by a dominant apex. Here, we show that following decapitation in pea (Pisum sativum L.), the axillary buds establish directional auxin export by subcellular polarization of PIN auxin transporters. Apical auxin application on the decapitated stem prevents this PIN polarization and canalization of laterally applied auxin. These results support a model in which the apical and lateral auxin sources compete for primary channels of auxin transport in the stem to control the outgrowth of axillary buds. 相似文献
144.
145.
Park YH Kantor L Guptaroy B Zhang M Wang KK Gnegy ME 《Journal of neurochemistry》2003,87(6):1546-1557
Repeated intermittent treatment with amphetamine (AMPH) induces both neurite outgrowth and enhanced AMPH-stimulated dopamine (DA) release in PC12 cells. We investigated the role of protein kinases in the induction of these AMPH-mediated events by using inhibitors of protein kinase C (PKC), mitogen activated protein kinase (MAP kinase) or protein kinase A (PKA). PKC inhibitors chelerythrine (100 nm and 300 nm), Ro31-8220 (300 nm) and the MAP kinase kinase inhibitor, PD98059 (30 micro m) inhibited the ability of AMPH to elicit both neurite outgrowth and the enhanced AMPH-stimulated DA release. The direct-acting PKC activator, 12-O-tetradecanoyl phorbol 13-acetate (TPA, 250 nm) mimicked the ability of AMPH to elicit neurite outgrowth and enhanced DA release. On the contrary, a selective PKA inhibitor, 100 micro m Rp-8-Br-cAMPS, blocked only the development of AMPH-stimulated DA release but not the neurite outgrowth. Treatment of the cells with acute AMPH elicited an increase in the activity of PKC and MAP kinase but not PKA. These results demonstrated that AMPH-induced increases in MAP kinase and PKC are important for induction of both the enhancement in transporter-mediated DA release and neurite outgrowth but PKA was only required for the enhancement in AMPH-stimulated DA release. Therefore the mechanisms by which AMPH induces neurite outgrowth and the enhancement in AMPH-stimulated DA release can be differentiated. 相似文献
146.
Fried K Sime W Lillesaar C Virtanen I Tryggvasson K Patarroyo M 《Experimental cell research》2005,307(2):329-341
The tooth pulp innervation originates from the trigeminal ganglion (TG) and represents an illustrative example of tissue targeting by sensory nerves. Pulpal fibroblasts strongly promote neurite outgrowth from TG neurons in vitro. In the present study, we have investigated the possible participation of laminins (LNs), potent neuritogenic extracellular matrix components. Immunohistochemistry of human tooth pulp demonstrated expression of LN alpha1, alpha2, alpha4, alpha5, beta1 and gamma1, and laminin-binding integrin alpha3, alpha6, beta1 and beta4 chains in nerves. Though faintly stained for laminins in situ, pulpal fibroblasts reacted, once cultured and permeabilized, with antibodies to LN alpha2, alpha4, beta1 and gamma1 chains by flow cytometry. The cells also expressed the corresponding mRNAs and were able to assemble and secrete LN-2 (alpha2beta1gamma1, Lm-211) and LN-8 (alpha4beta1gamma1, Lm-411). LN-8 displayed a chondroitin sulphate (CS) modification in its alpha4 chain. In functional assays, mouse LN-1 (alpha1beta1gamma1, Lm-111) and recombinant human (rh) LN-8, but not native or rhLN-2, strongly promoted neurite outgrowth from TG neurons, mimicking the effect of cultured pulp fibroblast. Altogether, the results indicate that LN-2 and LN-8 are synthesized by tooth pulp fibroblasts and differentially promote neurite outgrowth from TG neurons. LN-8 may contribute to sensory innervation of teeth and other tissues during development and/or regeneration. 相似文献
147.
The relative expression of the immunoglobulin superfamily members Thy-1 and L1 and the neural cell adhesion molecule (N-CAM) in PC12 cells grown in the presence of nerve growth factor (NGF), cholera toxin, or both has been quantified. Whereas NGF treatment induced increases in the cell surface expression of all three glycoproteins, treatment with cholera toxin resulted in the specific induction of L1. During the first few days of culture, cholera toxin acted synergistically with NGF to promote increases in neuritic outgrowth and the synthesis and cell surface accumulation of the 140- and 180-kilodalton subunits of N-CAM. In contrast, over the same period of culture, cholera toxin inhibited the NGF induction of Thy-1 and L1. Over longer periods of culture (3-5 days), cholera toxin inhibited the NGF induction of N-CAM and neurite outgrowth. A similar pattern of synergistic and inhibitory responses was observed when differentiation was induced by fibroblast growth factor (FGF) rather than NGF or when cholera toxin was replaced with forskolin. These data suggest that intracellular cyclic AMP can differentially modulate cell surface glycoprotein expression induced by either NGF or FGF. Of the three cell surface glycoproteins we have studied, temporal changes in N-CAM expression correlate best with the morphological differentiation status of PC12 cells. 相似文献
148.
The aim of this study was to investigate the influence of pulsed electromagnetic fields with various flux densities and frequencies
on neurite outgrowth in PC12 rat pheochromocytoma cells. We have studied the percentage of neurite-bearing cells, average
length of neurites and directivity of neurite outgrowth in PC12 cells cultured for 96 hours in the presence of nerve growth
factor (NGF). PC12 cells were exposed to 50 Hz pulsed electromagnetic fields with a flux density of 1.37 mT, 0.19 mT and 0.016
mT respectively. The field was generated through a Helmholtz coil pair housed in one incubator and the control samples were
placed in another identical incubator. It was found that exposure to both a relatively high flux density (1.37 mT) and a medium
flux density (0.19 mT) inhibited the percentage of neurite-bearing cells and promoted neurite length significantly. Exposure
to high flux density (1.37 mT) also resulted in nearly 20% enhancement of neurite directivity along the field direction. However,
exposure to low flux density field (0.016 mT) had no detectable effect on neurite outgrowth. We also studied the effect of
frequency at the constant flux density of 1.37 mT. In the range from 1 ∼ 100 Hz, only 50 and 70 Hz pulse frequencies had significant
effects on neurite outgrowth. Our study has shown that neurite outgrowth in PC12 cells is sensitive to flux density and frequency
of pulsed electromagnetic field. 相似文献
149.
Stimulation of mice dorsal root ganglion neurons (DRGNs) activity by human pancreatic cancer (PanCa) cell line Mia PaCa-2 and its potential molecule mechanism has been investaged. DRGNs were cultured alone or along with the MIA PaCa-2. The effects of MIA PaCa-2 to DRGNs were determined by neurofilament (NF) immunocytochemical and Nissl staining. ELISA was used to detect the concentration of insulin-like growth factor-1 (IGF-1) in the culture supernatant. Cyton size, neurite outgrowth and neuronal activity in the experimental group were greater than in the control groups. However, the concentration of IGF-1 in the supernatants was not significantly different from those in the blank and non-cultured medium groups. In the presence of MIA PaCa-2 cell line, cyton size, neurite outgrowth and neuronal activity were enhanced, which may provide more routes for the invasion of cancer cells along nerves. 相似文献
150.
低频脉冲电场对PC12细胞突起生长和NGF受体分布的影响 总被引:4,自引:0,他引:4
以PC12细胞为实验材料,研究低频脉冲电场(f=50Hz,τ=20ms,Epp=1V/m)对神经细胞突起生长及膜受体聚簇的影响。结果显示,该电场能促进NGF受体的聚簇。电场处理15min使PC12细胞表面的NGF受体发生明显的聚簇,30min组次之,5min组聚簇效果较弱。这表明细胞膜受体可能是电磁场与细胞相互作用的位点之一。运用细胞突起图形处理软件,追踪测定经电场处理后PC12细胞的突起数量和长度,发现该电场能显著促进细胞突起的生长,但对突起数量没有明显的影响。 相似文献