Zebrafish semaphorin Z1b inhibits growing motor axons in vivo

Roos, Marc; Schachner, Melitta; Bernhardt, Robert R.

doi:10.1016/s0925-4773(99)00153-7

Cited by 50 publications

(46 citation statements)

References 70 publications

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“…However, shortened axons were also observed to a lesser extent (Sato-Maeda et al, 2006). Conversely, overexpression of sema3A1 or sema3A2 mainly induces reduced growth of motor axons (Roos et al, 1999;Halloran et al, 2000). In mammals, plexinA3 also mediates semaphorininduced pruning of axonal branches (Bagri et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Sema3A1 may therefore be more important during ventral growth when axons have ex- ited the spinal cord (Sato-Maeda et al, 2006). In contrast, sema3A2 mRNA is expressed continuously along the dorsoventral axis of the somite, including the level of nerve exit from the spinal cord but only in the caudal part of the somite (Roos et al, 1999). Thus, sema3A2 could restrict additional spinal exit points of motor nerves in the caudal part of the somite.…”

Section: Discussionmentioning

confidence: 99%

“…Overexpression of either ligand reduces growth of primary motor axons (Roos et al, 1999;Halloran et al, 2000). Antisense morpholino oligonucleotide knock-down of sema3A1 leads mainly to aberrant branching of the CaP axon (Sato-Maeda et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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PlexinA3 Restricts Spinal Exit Points and Branching of Trunk Motor Nerves in Embryonic Zebrafish

Feldner

Reimer²,

Schweitzer³

et al. 2007

J. Neurosci.

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The pioneering primary motor axons in the zebrafish trunk are guided by multiple cues along their pathways. Plexins are receptor components for semaphorins that influence motor axon growth and path finding. We cloned plexinA3 in zebrafish and localized plexinA3 mRNA in primary motor neurons during axon outgrowth. Antisense morpholino knock-down led to substantial errors in motor axon growth. Errors comprised aberrant branching of primary motor nerves as well as additional exit points of axons from the spinal cord. Excessively branched and supernumerary nerves were found in both ventral and dorsal pathways of motor axons. The trunk environment and several other types of axons, including trigeminal axons, were not detectably affected by plexinA3 knock-down. RNA overexpression rescued all morpholino effects. Synergistic effects of combined morpholino injections indicate interactions of plexinA3 with semaphorin3A homologs. Thus, plexinA3 is a crucial receptor for axon guidance cues in primary motor neurons.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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PlexinA3 Restricts Spinal Exit Points and Branching of Trunk Motor Nerves in Embryonic Zebrafish

Feldner

Reimer²,

Schweitzer³

et al. 2007

J. Neurosci.

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“…In fact, tenascin-R immunoreactivity is stronger in the accessory pretectal nucleus than in the magnocellular superficial/posterior pretectal nucleus, which correlates with the absence of invading fibers in the accessory pretectal nucleus after chondroitinase treatment (data not shown). In addition, two axon-repellent semaphorins, sema Z1a (Shoji et al, 1998) and sema Z1b (Roos et al, 1999), are strongly expressed in the large neurons at the medial border of the magnocellular superficial/posterior pretectal nucleus (D. Gimnopoulos, T. Becker, C. G. Becker, and M. Schachner, unpublished observations).…”

Section: Discussionmentioning

confidence: 99%

Repellent Guidance of Regenerating Optic Axons by Chondroitin Sulfate Glycosaminoglycans in Zebrafish

Becker

2002

J. Neurosci.

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We analyzed the role of chondroitin sulfate (CS) glycosaminoglycans, putative inhibitors of axonal regeneration in mammals, in the regenerating visual pathway of adult zebrafish. In the adult, CS immunoreactivity was not detectable before or after an optic nerve crush in the optic nerve and tract but was constitutively present in developing and adult nonretinorecipient pretectal brain nuclei, where CSs may form a boundary preventing regenerating optic fibers from growing into these inappropriate locations. Enzymatic removal of CSs by chondroitinase ABC after optic nerve crush significantly increased the number of animals showing erroneous growth of optic axons into the nonretinorecipient magnocellular superficial/ posterior pretectal nucleus (83% vs 42% in controls). In vitro, a substrate border of CSs, but not heparan sulfates, strongly repelled regenerating retinal axons from adult zebrafish. We conclude that CSs contribute to repellent axon guidance during regeneration of the optic projection in zebrafish.

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“…Plexin A family members function in a complex with neuropilins as receptors for semaphorins, in particular for Sema3 family members (reviewed in Negishi et al, 2005). In the zebrafish, a number of Sema3 family members have been identified, including Sema3Aa , Sema3Ab (Roos et al, 1999), Sema3C (Yu and Moens, 2005), Sema3D (Halloran et al, 1999), Sema3Fa, Sema3Fb, Sema3Ga, Sema3Gb (Yu andMoens, 2005) and Sema3H (Stevens and Halloran, 2005). Of these, Sema3Aa has been reported to be expressed in the posterior region of each somite, and knockdown of sema3Aa and nrp1a expressed in motoneurons affects axon guidance in the 3255 RESEARCH REPORT Plexin A3 in motor axon guidance periphery (Feldner et al, 2005;Sato-Maeda et al, 2006).…”

Section: Research Reportmentioning

confidence: 99%

Analysis of zebrafishsidetrackedmutants reveals a novel role for Plexin A3 in intraspinal motor axon guidance

Palaisa

Granato

2007

Development

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One of the earliest guidance decisions for spinal cord motoneurons occurs when pools of motoneurons orient their growth cones towards a common, segmental exit point. In contrast to later events, remarkably little is known about the molecular mechanisms underlying intraspinal motor axon guidance. In zebrafish sidetracked (set) mutants, motor axons exit from the spinal cord at ectopic positions. By single-cell labeling and time-lapse analysis we show that motoneurons with cell bodies adjacent to the segmental exit point properly exit from the spinal cord, whereas those farther away display pathfinding errors. Misguided growth cones either orient away from the endogenous exit point, extend towards the endogenous exit point but bypass it or exit at non-segmental, ectopic locations. Furthermore, we show that sidetracked acts cell autonomously in motoneurons. Positional cloning reveals that sidetracked encodes Plexin A3, a semaphorin guidance receptor for repulsive guidance. Finally, we show that sidetracked (plexin A3) plays an additional role in motor axonal morphogenesis. Together, our data genetically identify the first guidance receptor required for intraspinal migration of pioneering motor axons and implicate the well-described semaphorin/plexin signaling pathway in this poorly understood process. We propose that axonal repulsion via Plexin A3 is a major driving force for intraspinal motor growth cone guidance.

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Zebrafish semaphorin Z1b inhibits growing motor axons in vivo

Cited by 50 publications

References 70 publications

PlexinA3 Restricts Spinal Exit Points and Branching of Trunk Motor Nerves in Embryonic Zebrafish

PlexinA3 Restricts Spinal Exit Points and Branching of Trunk Motor Nerves in Embryonic Zebrafish

Repellent Guidance of Regenerating Optic Axons by Chondroitin Sulfate Glycosaminoglycans in Zebrafish

Analysis of zebrafishsidetrackedmutants reveals a novel role for Plexin A3 in intraspinal motor axon guidance

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