Intracellular fibroblast growth factor produces effects different from those of extracellular application on development of avian cochleovestibular ganglion cells in vitro

Abstract

In an avian coculture system, the neuronal precursors of the cochleovestibular ganglion typically migrated from the otocyst and differentiated in response to soluble fibroblast growth factor (FGF-2), which had free access to FGF receptors on the cell surface. Free FGF-2 switched cells from a proliferation mode to migration, accompanied by increases in process outgrowth, fasciculation, and polysialic acid expression. Microsphere-bound FGF-2 had some of the same effects, but in addition it increased proliferation and decreased fasciculation and polysialic acid. As shown by immunohistochemistry, FGF-2 that was bound to latex microspheres depleted the FGF surface receptor protein, which localized with the microspheres in the cytoplasm and nucleus. For microsphere-bound FGF-2, the surface receptor-mediated responses to FGF-2 appear to be limited and the door opened to another venue of intracellular events or an intracrine mechanism.

Survival, synaptogenesis, and regeneration of adult mouse spiral ganglion neurons in vitro

“…The upregulated FGFR-3-IIIc accumulated in the nucleus instead of the cell membrane, confirming the observation of nuclear localization of FGFR-3 in breast epithelial cells reported by Johnston et al (1995). This unusual location is supported by a recent report on embryonic avian cochleovestibular ganglion neurons, demonstrating that the membrane receptor of FGF-2 could be absent in the cell membrane when undergoing a rapid large-scale receptor internalization (Bilak et al, 2003). The nuclear location of FGFR-3-IIIc suggests FGF-2 could carry out its functions via a nuclear route instead of the typical membrane tyrosine receptor kinase cascade pathway.…”

Differentiation of an auditory neuronal cell line suitable for cell transplantation

“…Lack of FGF2 has little effect on auditory system development, which reflects overlapping functions with other FGFs, notably FGF1 (Carnicero et al ., 2004). FGF1 and FGF2 have different effects depending on whether they are available freely in solution or bound to a surface (Aletsee et al ., 2003; Bilak et al ., 2003). These differences may correspond, respectively, to earlier signals that regulate neurite outgrowth and to later signals that mediate innervation of target cells.…”

“…This behaviour thus seems to require a combination of signals from at least two different cell types, which may be possible to identify by coculture with more precisely dissected fragments of tissue. Interestingly, the effects of soluble FGF2 in the chick induced fasciculation as well as cell migration and neuritogenesis (Bilak et al ., 2003). N33 showed signs of fasciculation when cultured alone with FGF2 (Fig.…”

Neuroblast sensory quiescence depends of vascular cytoneme contacts and sensory neuronal differentiation requires initiation of blood flow

“…1a). Some of the autocrine signals regulating the balance between sensory neuroblast proliferation and differentiation have been described [22][23][24][25][26][27] . Since cranial blood vessels lie in close proximity to forming cranial ganglia it seems likely that vascular signals also influence their development 28 .…”