Increase in α-tubulin modifications in the neuronal processes of hippocampal neurons in both kainic acid-induced epileptic seizure and Alzheimer’s disease

Abstract

Neurodegeneration includes acute changes and slow-developing alterations, both of which partly involve common cellular machinery. During neurodegeneration, neuronal processes are impaired along with dysregulated post-translational modifications (PTMs) of cytoskeletal proteins. In neuronal processes, tubulin undergoes unique PTMs including a branched form of modification called glutamylation and loss of the C-terminal tyrosine residue and the penultimate glutamic acid residue forming Δ2-tubulin. Here, we investigated the state of two PTMs, glutamylation and Δ2 form, in both acute and slow-developing neurodegenerations, using a newly generated monoclonal antibody, DTE41, which had 2-fold higher affinity to glutamylated Δ2-tubulin, than to unmodified Δ2-tubulin. DTE41 recognised glutamylated Δ2-tubulin preferentially in immunostaining than in enzyme-linked immunosorbent assay and immunoblotting. In normal mouse brain, DTE41 stained molecular layer of the cerebellum as well as synapse-rich regions in pyramidal neurons of the cerebral cortex. In kainic acid-induced epileptic seizure, DTE41-labelled signals were increased in the hippocampal CA3 region, especially in the stratum lucidum. In the hippocampi of post-mortem patients with Alzheimer’s disease, intensities of DTE41 staining were increased in mossy fibres in the CA3 region as well as in apical dendrites of the pyramidal neurons. Our findings indicate that glutamylation on Δ2-tubulin is increased in both acute and slow-developing neurodegeneration.

Loss of tubulin deglutamylase CCP 1 causes infantile‐onset neurodegeneration

“…Since some tubulin PTMs are particularly enriched in neurons (Janke & Kneussel, 2010), these modifications represent promising candidate mechanisms for neurodegenerative disorders. This hypothesis is supported by studies in mice linking tubulin acetylation (Dompierre et al, 2007;Outeiro et al, 2007) and polyglutamylation (Rogowski et al, 2010) to neurodegeneration, as well as observations of altered tubulin PTMs in diseased human brains (Zhang et al, 2015;Vu et al, 2017).…”

“…humans, ultimately contributing to common, usually sporadic late-onset neurodegeneration. Indeed, first indications for such links have recently emerged when altered tubulin PTMs were detected in brain tissue of probands with Alzheimer's disease (Zhang et al, 2015;Vu et al, 2017). Finally, the discovery of CCP1 deficiency as a cause of human neurodegeneration also entails a promising perspective that these disorders could become therapeutically accessible.…”

Excessive tubulin polyglutamylation causes neurodegeneration and perturbs neuronal transport

“…Such alterations may lead to an increased propensity for degeneration, which could be initiated either in conjunction with other factors or by accumulation of defects over longer periods of time. First indications for such links have recently emerged: For instance, subtle alterations of tubulin PTMs have been detected in brain tissue of Alzheimer's disease patients (Zhang et al, 2015;Vu et al, 2017), and another deglutamylase, CCP2 (encoded by the AGBL2 gene), was linked to Alzheimer's disease by genome-wide association (Lambert et al, 2013) and proteome (Seyfried et al, 2017) studies. Although CCP2 is a deglutamylase with yet unknown functions, and knockout mice show no obvious defects in the nervous system (Tort et al, 2014), CCP2 dysfunction might lead to small alterations in polyglutamylation, resulting in accumulation of neuronal defects over the much longer lifespan of humans, and thus to late-onset neurodegeneration.…”

Proteomic Analyses of Exothermic Processes in Rat Brain Homogenate

“…A solution of protein standards was used to calibrate the mass scale. The mass spectrometer was externally calibrated with a mixture of angiotensin I, glu-fibrinopeptide B, ACTH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), and ACTH.…”

“…For many years, the linkage between the structure and function of tau proteins has been intensively studied primarily through molecular biology and biochemical approaches. Microtubules were found to be composed of tubulin dimers which are subject to posttranslational modifications that affect the stability and function of microtubules [4][5][6][7]. In addition to the well-known function in microtubules, tau proteins play an important role in preserving the genomic integrity in stressful situations.…”