Immature corticospinal neurons respond to axotomy with changes in tubulin gene expression

doi:10.1016/0361-9230(93)90280-O

Brain Research Bulletin

Volume 30, Issues 3–4, 1993, Pages 469-475

https://doi.org/10.1016/0361-9230(93)90280-O Get rights and content

Abstract

We have examined the expression of two different tubulin mRNAs in hamster corticospinal neurons that were axotomized at three different developmental stages: postnatal day 8 (P8), P20, and adult. In situ hybridization of histological sections of the sensorimotor cortex was done with ³⁵S-labeled cDNA probes specific to α1-tubulin and βIII-tubulin mRNAs at 2–14 days following unilateral transection of the corticospinal tract in the caudal medulla. Both film and emulsion autoradiography were used to detect changes in tubulin mRNA levels. Qualitative assessment indicated substantial decreases in both α1-tubulin and βIII-tubulin mRNA levels in layer V neurons of the sensorimotor cortex following axotomy. The changes were apparent as early as 2 days postinjury for P20 and adult operates, but not for P8 operates. However, by 14 days postinjury, decreases in α1-tubulin and βIII-tubulin gene expression were apparent in animals operated at all three developmental stages. These findings indicate that both immature and adult corticospinal neurons respond to axonal injury in a manner that is distinctly different from the peripheral neuron response.

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Cited by (17)

Molecular Control of Axon Growth: Insights from Comparative Gene Profiling and High-Throughput Screening
2012, International Review of Neurobiology
Citation Excerpt :
Thus in the search for gene products that might explain the reduced regenerative capacity in mature neurons, candidates range from specific effector molecules in the growth cone to broadly acting transcription factors and signaling pathways. In the growth cone and axon, developmentally regulated genes include structural elements such as tubulin isoforms and intermediate filaments, as well as adhesion receptors (e.g., L1, PSA–NCAM, various integrins, and N-cadherin) (Condic, Snow, & Letourneau, 1999; Cousin, Leloup, Penicaud, & Price, 1997; Jiang & Oblinger, 1992; Joosten & Gribnau, 1989; Kost & Oblinger, 1993; Lariviere & Julien, 2004; Poulain & Sobel, 2010; Redies & Takeichi, 1993). Microtubule-binding proteins, which affect axon growth by regulating microtubule polymerization and bundling, are also developmentally regulated, as are upstream kinases and phosphatases that control their activity (Eto, Kawauchi, Osawa, Tabata, & Nakajima, 2010; Jeanneteau, Deinhardt, Miyoshi, Bennett, & Chao, 2010; Poulain & Sobel, 2010).
Axon regeneration in the mammalian adult central nervous system (CNS) is limited by an intrinsically low capacity for axon growth in many CNS neurons. In contrast, embryonic, peripheral, and many nonmammalian neurons are capable of successful regeneration. Numerous studies have compared mammalian CNS neurons to their counterparts in regenerating systems in an effort to identify candidate genes that control regenerative ability. This review summarizes work using this comparative strategy and examines our current understanding of gene function in axon growth, highlighting the emergence of genome-wide expression profiling and high-throughput screening strategies to identify novel regulators of axon growth.
βII-tubulin and GAP 43 mRNA expression in chronically injured neurons of the red nucleus after a second spinal cord injury
2003, Experimental Neurology
Regeneration by chronically injured supraspinal neurons is enhanced by treatment of a spinal cord lesion site with a variety of neurotrophic and growth factors. The removal of scar tissue, with subsequent reinjury of the spinal cord, is necessary for injured axons to access tissue transplants placed into the lesion to support axon regrowth. The present study examined chronically injured and reinjured rubrospinal tract (RST) neurons to determine if changes in gene expression could explain the failure of these neurons to regenerate without exogenous trophic factor support. Adult female rats were subjected to a right full hemisection lesion via aspiration of the cervical level 3 spinal cord. Using radioactive cDNA probes and in situ hybridization, RST neurons in the contralateral red nucleus were examined for changes in mRNA levels of βII-tubulin and GAP 43 in an acute injury period (6 h–3 days), a chronic injury period (28 days after spinal cord injury (SCI)) and following a second lesion of the chronic injury site (6 h–7 days). Based upon the analysis of gene expression in single cells, GAP-43 mRNA levels were increased as early as 1 day following the initial SCI, but were no different than uninjured control levels at 28 days postoperative (dpo). The response to relesion was more rapid and higher than that detected after the initial injury with a significant increase in GAP 43 mRNA at 6 h that was maintained for at least 7 days. βII-tubulin mRNA levels remained unchanged until 3 days after an acute injury followed by a decrease in expression to 30% below uninjured control values at 28 dpo. The expression of βII-tubulin mRNA was significantly higher within 6 h after a second injury, where it remained stable for 5 days before a second increase occurred at 7 days after reinjury of the spinal cord. Thus, neurons in a chronic injury state retain the ability to respond to a traumatic injury and, in fact, neurons subjected to a second injury exhibit a significantly heightened expression of regeneration-associated genes.
Multiple forms of tubulin: Different gene products and covalent modifications
1997, International Review of Cytology
Tubulin, the subunit protein of microtubules, is an α/β heterodimer. In many organisms, both α and β exist in numerous isotypic forms encoded by different genes. In addition, both α and β undergo a variety of posttranslational covalent modifications, including acetylation, phosphorylation, detyrosylation, polyglutamylation, and polyglycylation. In this review the distribution and possible functional significance of the various forms of tubulin are discussed. In analyzing the differences among tubulin isotypes encoded by different genes, some appear to have no functional significance, some increase the overall adaptability of the organism to environmental challenges, and some appear to perform specific functions including formation of particular organelles and interactions with specific proteins. Purified isotypes also display different properties in vitro. Although the significance of all the covalent modifications of tubulin is not fully understood, some of them may influence the stability of modified microtubules in vivo as well as interactions with certain proteins and may help to determine the functional role of microtubules in the cell. The review also discusses isotypes of γ-tubulin and puts various forms of tubulin in an evolutionary context.
Coordinate regulation of tubulin and microtubule associated protein genes during development of hamster brain
1994, Developmental Brain Research
The present study documents the patterns of mRNA expression for 5 different tubulin genes and 4 of the structural microtubule-associated protein (MAP) genes during normal development of hamster forebrain. Northern blotting in conjunction with densitometric analysis was used to study changes in the levels of the mRNAs for α_I-tubulin, classes β_I-, β_II-, β_III- and β_IV-tubulin, as well as the mRNAs for tau, MAP1A, MAP1B and MAP2, using total RNA isolated from hamster forebrain at various embryonic (E) and postnatal (P) stages. Densitometric analyses of the autoradiograms from the Northern blots revealed that each of the tubulin genes exhibited distinct developmental patterns of expression, several of which appeared to be temporally correlated with the expression of specific MAP mRNAs. The β_I-, β_II- and β_III-tubulin mRNAs increased rapidly between late embryonic stages to birth, reached peak levels early in the first postnatal week, and declined thereafter. α_I-Tubulin mRNA was easily detected during embryonic stages, rose to peak levels at P7–P9 and then gradually declined. A similar pattern was seen for tau mRNA. After the first postnatal week, the size of the tau mRNA also shifted to a slightly larger size, presumably due to differential splicing. β_IV-Tubulin mRNA levels did not become significant until very late in postnatal development (3–4 weeks). MAP2 mRNA expression was unusual in that peak levels were reached at two different stages of development - an initial peak occurred in the first postnatal week, followed by a decline, and then a second rise occurred during the third and fourth postnatal weeks. The expression of the β_IV-tubulin mRNA coincided temporally with the second peak in MAP2 mRNA expression. MAP1B mRNA abruptly reached high levels at birth, remained abundant during the first two postnatal weeks, and then decreased. In contrast, MAP1A mRNA levels were low in the initial postnatal interval and increased only at very late developmental stages. The findings of a temporal correspondence in expression of high levels of tau and MAP1B with β_I-, β_II-, β_III- and αI-tubulin mRNAs suggest that this profile of gene expression is one that endows greater plasticity to the neuronal cytoskeleton. Conversely, the transition to increased expression of β_IV-tubulin, MAP1A, and a larger tau mRNA species defines a portion of the molecular pattern that underpins the increased stability of neuronal form during maturation.
Chapter 22 Response of rubrospinal and corticospinal neurons to injury and neurotrophins
1994, Progress in Brain Research
This chapter focuses on problems, such as (1) the neuronal death or severe atrophy occurring in many axotomized central nervous system (CNS) and (2) the failure of CNS neurons to express growth or regeneration-associated genes, in rubrospinal and corticospinal neurons, and shows that both regeneration-associated gene expression and neuronal atrophy or death are dependent on the distance between the injury and the cell body. The chapter tests the hypothesis that peripheral nervous system (PNS) neurons and CNS neurons respond differently to axotomy by comparing facial versus rubrospinal motoneurons after axotomy. It shows that rubrospinal neurons respond to axotomy with regeneration-associated gene expression after cervical lesions but not after thoracic lesions. The chapter demonstrates that the severe atrophy which occurs 2 weeks after injury at the cervical level of the spinal cord can be prevented in full by brain-derived neurotrophic factor (BDNF). To further analyze the near/far lesion effect, the chapter reports that in corticospinal neurons the critical distance to induce GAP-43 is as short as 200 μm; lesions more than 300 μm from the cell body fail to induce GAP-43 expression.
Evaluation of the Neurogenic Potential in the Rat Inferior Colliculus from Early Postnatal Days Until Adulthood
2021, Molecular Neurobiology

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ArticleImmature corticospinal neurons respond to axotomy with changes in tubulin gene expression

Abstract

Dev. Brain Res.

Neuroscience

Anatomical plasticity and sparing of function after spinal cord damage in neonatal cats

Science

Extension of the critical period for developmental plasticity of the corticospinal pathway

J. Comp. Neurol.

Neurofilament and tubulin gene expression recapitulates the developmental program during axonal regeneration: Induction of a specific β-tubulin isotype

Neurofilament gene expression: A major determinant of axon caliber

Regrowth of severed axons in the neonatal nervous system: Establishment of normal connections

Science

A light and electron microscopic study of regrowing pyramidal tract fibers

J. Comp. Neurol.

Changes in glial fibrillary acidic protein mRNA expression after corticospinal axotomy in the adult hamster

J. Neurosci. Res.

Five mouse tubulin isotypes and their regulated expression during development

J. Cell Biol.

Development and plasticity of the brain: An introduction

Cell death of corticospinal neurons is induced by axotomy before but not after innervation of spinal targets

J. Comp. Neurol.

Central nervous system development and injury: Characterization of cytoskeletal gene expression in neurons and glia

Corticospinal neurons exhibit a novel pattern of cytoskeletal gene expression after injury

J. Neurosci. Res.

Isotypes of α-tubulin are differentially regulated during neuronal maturation

J. Cell Biol.

Article
Immature corticospinal neurons respond to axotomy with changes in tubulin gene expression