Restricted expression of the neuronal intermediate filament protein plasticin during zebrafish development

Abstract

In the adult goldfish visual pathway, expression of the neuronal intermediate filament (nIF) protein plasticin is restricted to differentiating retinal ganglion cells (RGCs) at the margin of the retina. Following optic nerve injury, plasticin expression is elevated transiently in all RGCs coincident with the early stages of axon regeneration. These results suggest that plasticin may be expressed throughout the nervous system during the early stages of axonogenesis. To test this hypothesis, we analyzed plasticin expression during zebrafish (Danio rerio) neuronal development. By using immunocytochemistry and in situ hybridization, we found that plasticin is expressed in restricted subsets of early zebrafish neurons. Expression coincides with axon outgrowth in projection neurons that pioneer distinct axon tracts in the embryo. Plasticin is expressed first in trigeminal, Rohon-Beard, and posterior lateral line ganglia neurons, which are among the earliest neurons to initiate axonogenesis in zebrafish. Plasticin is expressed also in reticulospinal neurons and in caudal primary motoneurons. Together, these neurons establish the first behavioral responses in the embryo. Plasticin expression also coincides with initial RGC axonogenesis and progressively decreases after RGC axons reach the tectum. At later developmental stages, plasticin is expressed in a subset of the cranial nerves. The majority of plasticin-positive neurons are within or project axons to the peripheral nervous system. Our results suggest that plasticin subserves the changing requirements for plasticity and stability during axonal outgrowth in neurons that project long axons.

Gefiltin in zebrafish embryos: sequential gene expression of two neurofilament proteins in retinal ganglion cells

“…Table 2 summarizes our current results on gefiltin expression and compares them with our previously published results on the expression pattern of plasticin [6]. Table 2 summarizes our current results on gefiltin expression and compares them with our previously published results on the expression pattern of plasticin [6].…”

“…Plasticin expression is primarily restricted to the PNS and is found in sensory neurons including Rohon-Beard neurons along the dorsal rim of the spinal cord and in the ganglia of two peripheral axonal tracts, the trigeminal ganglion cells and posterior lateral line ganglia [6]. Comparison with the previously determined developmental expression of the type III neuronal IF protein, plasticin, demonstrated marked differences in the expression patterns of the two IF proteins.…”

“…Upon leaving the eye, these first RGC axons can be highly branched [56]. The prevalent expression of plasticin during this growth phase may provide the structural flexibility that is essential for axonal branching [6,25,26]. Likewise, in mammals, peripherin is thought to support the initial outgrowth of some axons by allowing them to remain flexible and retractable [46].…”

Developmental pattern of the neuronal intermediate filament inaa in the zebrafish retina

“…The expression of gefiltin, or inab (a homolog of mammalian α‐internexin), and plasticin (a homolog of mammalian peripherin) have been characterized well in zebrafish embryos. The inab mRNA was first detected at 18 hours postfertilization (hpf) and was predominantly expressed in the CNS (Canger et al, ; Leake et al, ). Moreover, inab may play a role in retinal growth and optic nerve regeneration (Asch et al, ; Leake et al, ).…”

Nucleolar protein 4-like has a complex expression pattern in zebrafish embryos

“…3 B,C). Sixteen hpf embryos show strong expression in pronephric mesoderm (Gerlach and Wingert, 2013), the spinal cord (Lewis et al, 2003), trigeminal ganglia (Canger et al, 1998) and hind brain (Moens and Prince, 2002). Its expression in diencephalon and telencephalon also becomes visible (Fig.…”