scholarly journals Nestin in immature embryonic neurons regulates axon growth cone morphology and Semaphorin3a sensitivity

2017 ◽  
Author(s):  
C.J. Bott ◽  
C. G. Johnson ◽  
C.C. Yap ◽  
N.D. Dwyer ◽  
K.A. Litwa ◽  
...  
Keyword(s):  
Growth Cone ◽  
Intermediate Filament ◽  
Cortical Neurons ◽  
Axon Growth ◽  
Neural Progenitors ◽  
Nestin Expression ◽  
Guidance Cue ◽  
Cytoskeletal Dynamics ◽  
Newborn Neurons

AbstractCorrect wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed highly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons which transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors but persists at lower levels in some newborn neurons for 2-3 days. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase. Cdk5 activity is induced by the repulsive guidance cue Sema3a leading to growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 and thereby the Sema3a response. Thus, the transient expression of nestin could allow for temporal modulation of a neuron's response to Sema3a particularly during early axon guidance decisions.

scholarly journals Nestin in immature embryonic neurons affects axon growth cone morphology and Semaphorin3a sensitivity

2019 ◽  
Vol 30 (10) ◽  
pp. 1214-1229 ◽  
Author(s):  
C. J. Bott ◽  
C. G. Johnson ◽  
C. C. Yap ◽  
N. D. Dwyer ◽  
K. A. Litwa ◽  
...  
Keyword(s):  
Growth Cone ◽  
Intermediate Filament ◽  
Cortical Neurons ◽  
Axon Growth ◽  
Neural Progenitors ◽  
Spatial Modulation ◽  
Nestin Expression ◽  
Guidance Cue ◽  
Newborn Neurons

Correct wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed strongly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons that transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors, but persists for 2–3 d at lower levels in newborn neurons. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase by binding the cdk5 activator p35. Cdk5 activity is induced by the repulsive guidance cue Semaphorin3a (Sema3a), leading to axonal growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 downstream of the Sema3a response. Thus, the transient expression of nestin could allow temporal and/or spatial modulation of a neuron’s response to Sema3a, particularly during early axon guidance.

scholarly journals CRYP-2/cPTPRO is a neurite inhibitory repulsive guidance cue for retinal neurons in vitro

2001 ◽  
Vol 154 (4) ◽  
pp. 867-878 ◽  
Author(s):  
Laurie Stepanek ◽  
Qi Lun Sun ◽  
Jun Wang ◽  
Cong Wang ◽  
John L. Bixby
Keyword(s):  
Growth Cone ◽  
Protein Tyrosine Phosphatases ◽  
Axon Growth ◽  
Extracellular Domain ◽  
Receptor Protein ◽  
Projection Neurons ◽  
Retinal Neurons ◽  
Type Iii ◽  
Guidance Cue

Receptor protein tyrosine phosphatases (RPTPs) are implicated as regulators of axon growth and guidance. Genetic deletions in the fly have shown that type III RPTPs are important in axon pathfinding, but nothing is known about their function on a cellular level. Previous experiments in our lab have identified a type III RPTP, CRYP-2/cPTPRO, specifically expressed during the period of axon outgrowth in the chick brain; cPTPRO is expressed in the axons and growth cones of retinal and tectal projection neurons. We constructed a fusion protein containing the extracellular domain of cPTPRO fused to the Fc portion of mouse immunoglobulin G-1, and used it to perform in vitro functional assays. We found that the extracellular domain of cPTPRO is an antiadhesive, neurite inhibitory molecule for retinal neurons. In addition, cPTPRO had potent growth cone collapsing activity in vitro, and locally applied gradients of cPTPRO repelled growing retinal axons. This chemorepulsive effect could be regulated by the level of cGMP in the growth cone. Immunohistochemical examination of the retina indicated that cPTPRO has at least one heterophilic binding partner in the retina. Taken together, our results indicate that cPTPRO may act as a guidance cue for retinal ganglion cells during vertebrate development.

Inhibition of motor axon growth by T-cadherin substrata

Development ◽  
1996 ◽  
Vol 122 (10) ◽  
pp. 3163-3171 ◽  
Author(s):  
B.J. Fredette ◽  
J. Miller ◽  
B. Ranscht
Keyword(s):  
Motor Neurons ◽  
Axon Growth ◽  
Neurite Growth ◽  
Motor Axon ◽  
Spinal Motor Neurons ◽  
Guidance Cue ◽  
Spinal Motor ◽  
Neuron Populations ◽  
Muscle Innervation

As spinal motor neurons project to their hindlimb targets, their growth cones avoid particular regions along their pathway. T-cadherin is discretely distributed in the avoided caudal sclerotome and on extrasynaptic muscle surfaces (B. J. Fredette and B. Ranscht (1994) J. Neurosci. 14, 7331–7346), and therefore, the ability of T-cadherin to inhibit neurite growth was tested in vitro. T-cadherin inhibited neurite extension from select neuron populations both as a substratum, and as a soluble recombinant protein. Anti-T-cadherin antibodies neutralized the inhibition. Spinal motor neurons were inhibited only during the stages of axon growth across the sclerotome and muscle innervation. Inhibitory responses corresponded to neuronal T-cadherin expression, suggesting a homophilic binding mechanism. These results suggest that T-cadherin is a negative guidance cue for motor axon projections.

scholarly journals Tubulin is phosphorylated at tyrosine by pp60c-src in nerve growth cone membranes.

1990 ◽  
Vol 111 (5) ◽  
pp. 1959-1970 ◽  
Author(s):  
W T Matten ◽  
M Aubry ◽  
J West ◽  
P F Maness
Keyword(s):  
Growth Cone ◽  
Cortical Neurons ◽  
Specific Protein ◽  
Beta Tubulin ◽  
Nerve Growth ◽  
Alpha Tubulin ◽  
Nerve Growth Cone ◽  
Phosphopeptide Mapping

We show here that tubulin is the major in vivo substrate of the tyrosine-specific protein kinase pp60c-src in nerve growth cone membranes. Phosphotyrosine antibodies were used to demonstrate phosphotyrosyl residues in a subpopulation of alpha- and beta-tubulin that was highly enriched in a subcellular fraction of growth cone membranes from fetal rat brain. The presence of phosphotyrosine-modified isoforms of alpha- and beta-tubulin in vivo was confirmed by 32p labeling of rat cortical neurons in culture. Tubulin in growth cone membranes was phosphorylated at tyrosine in endogenous membrane phosphorylation reactions (0.068 mol phosphotyrosine/mol alpha-tubulin and 0.045 mol phosphotyrosine/mol beta-tubulin), and phosphorylation was specifically inhibited by antibodies directed against pp60c-src, which is localized in the growth cone membranes. pp60c-src was capable of directly phosphorylating tubulin as shown in immune complex kinase assays with purified brain tubulin. Phosphopeptide mapping revealed a limited number of sites of tyrosine phosphorylation in alpha- and beta-tubulin, with similar phosphopeptides observed in vivo and in vitro. These results reveal a novel posttranslational modification of tubulin that could regulate microtubule dynamics at the growth cone.

scholarly journals Nestin selectively facilitates the phosphorylation of the Lissencephaly-linked protein doublecortin (DCX) by cdk5/p35 to regulate growth cone morphology and Sema3a sensitivity in developing neurons

2019 ◽  
Author(s):  
Christopher J. Bott ◽  
Lloyd P. McMahon ◽  
Jason M. Keil ◽  
Chan Choo Yap ◽  
Kenneth Y. Kwan ◽  
...  
Keyword(s):  
Growth Cone ◽  
Intermediate Filament ◽  
Functional Role ◽  
Neural Progenitors ◽  
Intermediate Filament Protein ◽  
Substrate Selectivity ◽  
Cone Morphology ◽  
Cytoskeletal Networks ◽  
Developing Neurons ◽  
Filament Protein

AbstractNestin, an intermediate filament protein widely used as a marker of neural progenitors, was recently found to be expressed transiently in developing cortical neurons in culture and in developing mouse cortex. In young cortical cultures, nestin regulates axonal growth cone morphology. In addition, nestin, which is known to bind the neuronal cdk5/p35 kinase, affects responses to axon guidance cues upstream of cdk5, specifically, to Sema3a. Changes in growth cone morphology require rearrangements of cytoskeletal networks, and changes in microtubules and actin filaments are well studied. In contrast, the roles of intermediate filament proteins in this process are poorly understood, even in cultured neurons. Here, we investigate the molecular mechanism by which nestin affects growth cone morphology and Sema3a sensitivity. We find that nestin selectively facilitates the phosphorylation of the lissencephaly-linked protein doublecortin (DCX) by cdk5/p35, but the phosphorylation of other cdk5 substrates is not affected by nestin. We uncover that this substrate selectivity is based on the ability of nestin to interact with DCX, but not with other cdk5 substrates. Nestin thus creates a selective scaffold for DCX with activated cdk5/p35. Lastly, we use cortical cultures derived from DCX knockout mice to show that the effects of nestin on growth cone morphology and on Sema3a sensitivity are DCX-dependent, thus suggesting a functional role for the DCX-nestin complex in neurons. We propose that nestin changes growth cone behavior by regulating the intracellular kinase signaling environment in developing neurons. The sex of animal subjects is unknown.Significance StatementNestin, an intermediate filament protein highly expressed in neural progenitors, was recently identified in developing neurons where it regulates growth cone morphology and responsiveness to the guidance cue Sema3a. Changes in growth cone morphology require rearrangements of cytoskeletal networks, but the roles of intermediate filaments in this process are poorly understood. We now report that nestin selectively facilitates phosphorylation of the lissencephaly-linked doublecortin (DCX) by cdk5/p35, but the phosphorylation of other cdk5 substrates is not affected. This substrate selectivity is based on preferential scaffolding of DCX, cdk5, and p35 by nestin. Additionally, we demonstrate a functional role for the DCX-nestin complex in neurons. We propose that nestin changes growth cone behavior by regulating intracellular kinase signaling in developing neurons.

Control of retinal ganglion cell axon growth: a new role for Sonic hedgehog

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 3927-3936 ◽  
Author(s):  
Françoise Trousse ◽  
Elisa Martí ◽  
Peter Gruss ◽  
Miguel Torres ◽  
Paola Bovolenta
Keyword(s):  
Ganglion Cell ◽  
Retinal Ganglion Cell ◽  
Sonic Hedgehog ◽  
Growth Cone ◽  
Ectopic Expression ◽  
Axon Growth ◽  
Negative Regulator ◽  
Retinal Ganglion ◽  
Ventral Midline

Retinal ganglion cell (RGC) axons grow towards the diencephalic ventral midline during embryogenesis guided by cues whose nature is largely unknown. We provide in vitro and in vivo evidence for a novel role of Sonic hedgehog (SHH) as a negative regulator of growth cone movement. SHH suppresses both the number and the length of neurites emerging from the chick retina but not from neural tube or dorsal root ganglia explants, without interfering with their rate of proliferation and differentiation. Similarly, retroviral-mediated ectopic expression of Shh along the chick visual pathway greatly interferes the growth of RGC axons. Upon SHH addition to grown neurites, the intracellular level of cAMP decreases, suggesting that the dampening of growth cone extension mediated by SHH may involve interaction with its receptor Patched which is expressed by RGC. Based on these findings, we propose that Shh expression at the chiasm border defines a constrained pathway within the ventral midline which serves to guide the progression of RGC axons.

scholarly journals Perinatal Exposure to Triclosan Results in Abnormal Brain Development and Behavior in Mice

2020 ◽  
Vol 21 (11) ◽  
pp. 4009 ◽  
Author(s):  
Dinh Nam Tran ◽  
Eui-Man Jung ◽  
Yeong-Min Yoo ◽  
Jae-Hwan Lee ◽  
Eui-Bae Jeung
Keyword(s):  
Brain Development ◽  
Spatial Learning ◽  
Cortical Neurons ◽  
Average Length ◽  
Axon Growth ◽  
Abnormal Behavior ◽  
Spatial Learning And Memory ◽  
Perinatal Exposure ◽  
Novelty Preference

Triclosan (TCS) is one of the most common endocrine-disrupting chemicals (EDCs) present in household and personal wash products. Recently, concerns have been raised about the association between abnormal behavior in children and exposure to EDC during gestation. We hypothesized that exposure to TCS during gestation could affect brain development. Cortical neurons of mice were exposed in vitro to TCS. In addition, we examined in vivo whether maternal TCS administration can affect neurobehavioral development in the offspring generation. We determined that TCS can impair dendrite and axon growth by reducing average length and numbers of axons and dendrites. Additionally, TCS inhibited the proliferation of and promoted apoptosis in neuronal progenitor cells. Detailed behavioral analyses showed impaired acquisition of spatial learning and reference memory in offspring derived from dams exposed to TCS. The TCS-treated groups also showed cognition dysfunction and impairments in sociability and social novelty preference. Furthermore, TCS-treated groups exhibited increased anxiety-like behavior, but there was no significant change in depression-like behaviors. In addition, TCS-treated groups exhibited deficits in nesting behavior. Taken together, our results indicate that perinatal exposure to TCS induces neurodevelopment disorder, resulting in abnormal social behaviors, cognitive impairment, and deficits in spatial learning and memory in offspring.

scholarly journals Selective rab11 transport and the intrinsic regenerative ability of CNS axons

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Hiroaki Koseki ◽  
Matteo Donegá ◽  
Brian YH Lam ◽  
Veselina Petrova ◽  
Susan van Erp ◽  
...  
Keyword(s):  
Growth Cone ◽  
Axon Growth ◽  
Retrograde Transport ◽  
Progressive Decline ◽  
Regenerative Ability

Neurons lose intrinsic axon regenerative ability with maturation, but the mechanism remains unclear. Using an in-vitro laser axotomy model, we show a progressive decline in the ability of cut CNS axons to form a new growth cone and then elongate. Failure of regeneration was associated with increased retraction after axotomy. Transportation into axons becomes selective with maturation; we hypothesized that selective exclusion of molecules needed for growth may contribute to regeneration decline. With neuronal maturity rab11 vesicles (which carry many molecules involved in axon growth) became selectively targeted to the somatodendritic compartment and excluded from axons by predominant retrograde transport However, on overexpression rab11 was mistrafficked into proximal axons, and these axons showed less retraction and enhanced regeneration after axotomy. These results suggest that the decline of intrinsic axon regenerative ability is associated with selective exclusion of key molecules, and that manipulation of transport can enhance regeneration.

scholarly journals CRMP4 and CRMP2 Interact to Coordinate Cytoskeleton Dynamics, Regulating Growth Cone Development and Axon Elongation

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Minghui Tan ◽  
Caihui Cha ◽  
Yongheng Ye ◽  
Jifeng Zhang ◽  
Sumei Li ◽  
...  
Keyword(s):  
Growth Cone ◽  
Promoting Effect ◽  
Interaction Domain ◽  
Axonal Elongation ◽  
Axon Elongation ◽  
Cellular Processes ◽  
Cytoskeletal Dynamics ◽  
Cone Development ◽  
Cytoskeleton Dynamics

Cytoskeleton dynamics are critical phenomena that underpin many fundamental cellular processes. Collapsin response mediator proteins (CRMPs) are highly expressed in the developing nervous system, mediating growth cone guidance, neuronal polarity, and axonal elongation. However, whether and how CRMPs associate with microtubules and actin coordinated cytoskeletal dynamics remain unknown. In this study, we demonstrated that CRMP2 and CRMP4 interacted with tubulin and actinin vitroand colocalized with the cytoskeleton in the transition-zone in developing growth cones. CRMP2 and CRMP4 also interacted with one another coordinately to promote growth cone development and axonal elongation. Genetic silencing of CRMP2 enhanced, whereas overexpression of CRMP2 suppressed, the inhibitory effects of CRMP4 knockdown on axonal development. In addition, knockdown of CRMP2 or overexpression of truncated CRMP2 reversed the promoting effect of CRMP4. With the overexpression of truncated CRMP2 or CRMP4 lacking the cytoskeleton interaction domain, the promoting effect of CRMP was suppressed. These data suggest a model in which CRMP2 and CRMP4 form complexes to bridge microtubules and actin and thus work cooperatively to regulate growth cone development and axonal elongation.

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