Regulatory mechanisms for the axonal localization of tau protein in neurons

Tau is a microtubule (MT)-associated protein that is thought to be localized to the axon. However, its precise localization in developing neurons and mechanisms for the axonal localization have not been fully addressed. In this study, we found that the axonal localization of tau in cultured rat hippocampal neurons mainly occur during early neuronal development. Interestingly, transient expression of human tau in very immature neurons, but not in mature neurons, mimicked the developmental localization of endogenous tau to the axon. We therefore were able to establish an experimental model, in which exogenously expressed tau can be properly localized to the axon. Using this model, we obtained a surprising finding that the axonal localization of tau did not require stable MT binding. Tau lacking the MT-binding domain (MTBD) exhibited high diffusivity but localized properly to the axon. In contrast, a dephosphorylation-mimetic mutant of the proline-rich region 2 showed reinforced MT binding and mislocalization. Our results suggest that tight binding to MTs prevents tau from entering the axon and results in mislocalization in the soma and dendrites when expressed in mature neurons. This study therefore provides a novel mechanism independent of MTBD for the axonal localization of tau.

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Regulatory mechanisms for the axonal localization of tau in neurons

10.1101/456608 ◽

2018 ◽

Author(s):

Minori Iwata ◽

Shoji Watanabe ◽

Ayaka Yamane ◽

Tomohiro Miyasaka ◽

Hiroaki Misonou

Keyword(s):

Hippocampal Neurons ◽

Neuronal Development ◽

Experimental System ◽

Binding Domain ◽

Rich Region ◽

Phosphorylation State ◽

Microtubule Binding Domain ◽

Mature Neuron ◽

Early Expression ◽

Proline Rich Region

AbstractTau is a microtubule (MT)-associated protein, which precisely localizes to the axon of a mature neuron. Although it has been widely used as an axonal marker, the mechanisms for its axonal localization have been elusive. This might be largely due to the lack of an experimental system, as exogenously expressed tau, such as GFP-tau, mis-localizes to the soma and dendrites. In this study, we found that the expression of endogenous tau and its axonal localization in cultured rat hippocampal neurons mainly occur during early neuronal development and are coupled. By mimicking this early expression, we demonstrate that exogenously expressed human tau can be properly localized to the axon, thereby providing the first experimental model to study the mechanisms of tau localization. Using this model, we obtained surprising findings that the axonal localization of tau did not require the MT-binding domain nor correlate with the MT-binding ability. Instead, we identified a transport mechanism mediated by the proline-rich region 2 (PRR2), which contains a number of important phosphorylation sites. Mimicking phosphorylation and dephosphorylation in PRR2 disrupts the axonal localization, suggesting that it is regulated by the phosphorylation state of PRR2. These results shed new lights on the mechanism for the axonal localization of tau and indicate a link between the hyperphosphorylation and mis-localization of tau observed in tauopathies.Significance statementIn this paper, we present a first experimental system, in which expressed tau is properly localized to the axon, and which can therefore be used to study the mechanisms of tau localization and mis-localization. Using this system, we provide evidence that the microtubule binding domain of tau nor stable binding of tau to microtubules is not necessary for its axonal localization. Instead, we identified the proline-rich region and its phosphorylation-state dictate the localization of tau in neurons. These results provide a novel foundation to consider how axonal tau mis-localize to the soma and dendrites during early pathogenesis of Alzheimer’s disease.

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Structural characterization by nuclear magnetic resonance of the impact of phosphorylation in the proline-rich region of the disordered Tau protein

Proteins Structure Function and Bioinformatics ◽

10.1002/prot.23210 ◽

2011 ◽

Vol 80 (2) ◽

pp. 454-462 ◽

Cited By ~ 54

Author(s):

Nathalie Sibille ◽

Isabelle Huvent ◽

Caroline Fauquant ◽

Dries Verdegem ◽

Laziza Amniai ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Structural Characterization ◽

Tau Protein ◽

Rich Region ◽

The Impact ◽

Proline Rich Region ◽

Nuclear Magnetic

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Microtubule-associated protein-2 located in growth regions of rat hippocampal neurons is highly phosphorylated at its proline-rich region

Neuroscience ◽

10.1016/s0306-4522(00)00434-6 ◽

2000 ◽

Vol 101 (4) ◽

pp. 885-893 ◽

Cited By ~ 10

Author(s):

C Sánchez Martin ◽

D Ledesma ◽

C.G Dotti ◽

J Avila

Keyword(s):

Hippocampal Neurons ◽

Rich Region ◽

Proline Rich Region

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Phosphorylation-mimicking glutamate clusters in the proline-rich region are sufficient to simulate the functional deficiencies of hyperphosphorylated tau protein

Biochemical Journal ◽

10.1042/0264-6021:3570759 ◽

2001 ◽

Vol 357 (3) ◽

pp. 759 ◽

Cited By ~ 35

Author(s):

Jochen EIDENMÜLLER ◽

Thomas FATH ◽

Thorsten MAAS ◽

Madeline POOL ◽

Estelle SONTAG ◽

...

Keyword(s):

Tau Protein ◽

Hyperphosphorylated Tau ◽

Rich Region ◽

Hyperphosphorylated Tau Protein ◽

Proline Rich Region

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Spastin Interacts with CRMP2 to Regulate Neurite Outgrowth by Controlling Microtubule Dynamics through Phosphorylation Modifications

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527319666201026165855 ◽

2020 ◽

Vol 19 ◽

Author(s):

Sumei Li ◽

Jifeng Zhang ◽

Jiaqi Zhang ◽

Jiong Li ◽

Longfei Cheng ◽

...

Keyword(s):

Neurite Outgrowth ◽

Hippocampal Neurons ◽

Neuronal Development ◽

Phosphorylation Site ◽

Microtubule Dynamics ◽

Microtubule Assembly ◽

C Terminus ◽

Mediator Protein ◽

Branch Formation

Aims: Our work aims to revealing the underlying microtubule mechanism of neurites outgrowth during neuronal development, and also proposes a feasible intervention pathway for reconstructing neural network connections after nerve injury. Background: Microtubule polymerization and severing are the basis for the neurite outgrowth and branch formation. Collapsin response mediator protein 2 (CRMP2) regulates axonal growth and branching as a binding partner of the tubulin heterodimer to promote microtubule assembly. And spastin participates in the growth and regeneration of neurites by severing microtubules into small segments. However, how CRMP2 and spastin cooperate to regulate neurite outgrowth by controlling the microtubule dynamics needs to be elucidated. Objective: To explore whether neurite outgrowth was mediated by coordination of CRMP2 and spastin. Method: Hippocampal neurons were cultured in vitro in 24-well culture plates for 4 days before being used to perform the transfection. Calcium phosphate was used to transfect the CRMP2 and spastin constructs and their control into the neurons. An interaction between CRMP2 and spastin was examined by using pull down, CoIP and immunofluorescence colocalization assays. And immunostaining was also performed to determine the morphology of neurites. Result: We first demonstrated that CRMP2 interacted with spastin to promote the neurite outgrowth and branch formation. Furthermore, our results identified that phosphorylation modification failed to alter the binding affinities of CRMP2 for spastin, but inhibited their binding to microtubules. CRMP2 interacted with the MTBD domain of spastin via its C-terminus, and blocking the binding sites of them inhibited the outgrowth and branch formation of neurites. In addition, we confirmed one phosphorylation site S210 at spastin in hippocampal neurons and phosphorylation spastin at site S210 promoted the neurite outgrowth but not branch formation by remodeling microtubules. Conclusion: Taken together, our data demonstrated that the interaction of CRMP2 and spastin is required for neurite outgrowth and branch formation and their interaction is not regulated by their phosphorylation.

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Cystatin M/E (Cystatin 6): A Janus-Faced Cysteine Protease Inhibitor with Both Tumor-Suppressing and Tumor-Promoting Functions

Cancers ◽

10.3390/cancers13081877 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1877

Author(s):

Gilles Lalmanach ◽

Mariana Kasabova-Arjomand ◽

Fabien Lecaille ◽

Ahlame Saidi

Keyword(s):

Prognostic Significance ◽

Tight Binding ◽

Cysteine Protease Inhibitor ◽

Tumor Promoter ◽

Regulatory Mechanisms ◽

Placental Development ◽

Cysteine Cathepsins ◽

Cystatin M

Alongside its contribution in maintaining skin homeostasis and its probable involvement in fetal and placental development, cystatin M/E (also known as cystatin 6) was first described as a tumor suppressor of breast cancer. This review aims to provide an update on cystatin M/E with particular attention paid to its role during tumorigenesis. Cystatin M/E, which is related to type 2 cystatins, displays the unique property of being a dual tight-binding inhibitor of both legumain (also known as asparagine endopeptidase) and cysteine cathepsins L, V and B, while its expression level is epigenetically regulated via the methylation of the CST6 promoter region. The tumor-suppressing role of cystatin M/E was further reported in melanoma, cervical, brain, prostate, gastric and renal cancers, and cystatin M/E was proposed as a biomarker of prognostic significance. Contrariwise, cystatin M/E could have an antagonistic function, acting as a tumor promoter (e.g., oral, pancreatic cancer, thyroid and hepatocellular carcinoma). Taking into account these apparently divergent functions, there is an urgent need to decipher the molecular and cellular regulatory mechanisms of the expression and activity of cystatin M/E associated with the safeguarding homeostasis of the proteolytic balance as well as its imbalance in cancer.

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Vaccine-induced, but not natural immunity, against the Streptococcal inhibitor of complement protects against invasive disease

npj Vaccines ◽

10.1038/s41541-021-00326-3 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Lionel K. K. Tan ◽

Mark Reglinski ◽

Daryl Teo ◽

Nada Reza ◽

Lucy E. M. Lamb ◽

...

Keyword(s):

Ex Vivo ◽

Natural Infection ◽

Invasive Disease ◽

Full Length ◽

Natural Immunity ◽

Rich Region ◽

Antibody Recognition ◽

Naturally Occurring ◽

Protective Antibodies ◽

Proline Rich Region

AbstractHighly pathogenic emm1 Streptococcus pyogenes strains secrete the multidomain Streptococcal inhibitor of complement (SIC) that binds and inactivates components of the innate immune response. We aimed to determine if naturally occurring or vaccine-induced antibodies to SIC are protective against invasive S. pyogenes infection. Immunisation with full-length SIC protected mice against systemic bacterial dissemination following intranasal or intramuscular infection with emm1 S. pyogenes. Vaccine-induced rabbit anti-SIC antibodies, but not naturally occurring human anti-SIC antibodies, enhanced bacterial clearance in an ex vivo whole-blood assay. SIC vaccination of both mice and rabbits resulted in antibody recognition of all domains of SIC, whereas naturally occurring human anti-SIC antibodies recognised the proline-rich region of SIC only. We, therefore, propose a model whereby natural infection with S. pyogenes generates non-protective antibodies against the proline-rich region of SIC, while vaccination with full-length SIC permits the development of protective antibodies against all SIC domains.

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A Proline-Rich Region in the Zeste Protein Essential for Transvection and white Repression by Zeste1

Genetics ◽

10.1093/genetics/148.4.1865 ◽

1998 ◽

Vol 148 (4) ◽

pp. 1865-1874

Author(s):

Christina Rosen ◽

Dale Dorsett ◽

Joseph Jack

Keyword(s):

Dna Binding ◽

Protein Interactions ◽

Homologous Chromosome ◽

Protein Complexes ◽

Dna Binding Protein ◽

Polycomb Group ◽

The Self ◽

Rich Region ◽

Interaction Domain ◽

Proline Rich Region

Abstract The DNA-binding protein encoded by the zeste gene of Drosophila activates transcription and mediates interchromosomal interactions such as transvection. The mutant protein encoded by the zeste1 (z1) allele retains the ability to support transvection, but represses white. Similar to transvection, repression requires Zeste-Zeste protein interactions and a second copy of white, either on the homologous chromosome or adjacent on the same chromosome. We characterized two pseudorevertants of z1 (z1-35 and z1-42) and another zeste mutation (z78c) that represses white. The z1 lesion alters a lysine residue located between the N-terminal DNA-binding domain and the C-terminal hydrophobic repeats involved in Zeste self-interactions. The z78c mutation alters a histidine near the site of the z1 lesion. Both z1 pseudorevertants retain the z1 lesion and alter different prolines in a proline-rich region located between the z1 lesion and the self-interaction domain. The pseudorevertants retain the ability to self-interact, but fail to repress white or support transvection at Ultrabithorax. To account for these observations and evidence indicating that Zeste affects gene expression through Polycomb group (Pc-G) protein complexes that epigenetically maintain chromatin states, we suggest that the regions affected by the z1, z78c, and pseudorevertant lesions mediate interactions between Zeste and the maintenance complexes.

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DIP-2 suppresses ectopic neurite sprouting and axonal regeneration in mature neurons

The Journal of Cell Biology ◽

10.1083/jcb.201804207 ◽

2018 ◽

Vol 218 (1) ◽

pp. 125-133 ◽

Cited By ~ 6

Author(s):

Nathaniel Noblett ◽

Zilu Wu ◽

Zhao Hua Ding ◽

Seungmee Park ◽

Tony Roenspies ◽

...

Keyword(s):

Axonal Regeneration ◽

Neuronal Development ◽

Adult Life ◽

Progressive Increase ◽

Binding Domain ◽

Neuronal Morphology ◽

Loss Of Function ◽

Neuron Morphology ◽

Interacting Protein ◽

Mature Neurons

Neuronal morphology and circuitry established during early development must often be maintained over the entirety of animal lifespans. Compared with neuronal development, the mechanisms that maintain mature neuronal structures and architecture are little understood. The conserved disco-interacting protein 2 (DIP2) consists of a DMAP1-binding domain and two adenylate-forming domains (AFDs). We show that the Caenorhabditis elegans DIP-2 maintains morphology of mature neurons. dip-2 loss-of-function mutants display a progressive increase in ectopic neurite sprouting and branching during late larval and adult life. In adults, dip-2 also inhibits initial stages of axon regeneration cell autonomously and acts in parallel to DLK-1 MAP kinase and EFA-6 pathways. The function of DIP-2 in maintenance of neuron morphology and in axon regrowth requires its AFD domains and is independent of its DMAP1-binding domain. Our findings reveal a new conserved regulator of neuronal morphology maintenance and axon regrowth after injury.

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