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Geoffrey O Wasteneys - One of the best experts on this subject based on the ideXlab platform.
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the Microtubule Associated Protein clasp is translationally regulated in light dependent root apical meristem growth
Plant Physiology, 2020Co-Authors: Laryssa S Halat, Katherine Gyte, Geoffrey O WasteneysAbstract:The ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis (Arabidopsis thaliana) seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the Microtubule-Associated Protein CLASP sustains root apical meristem size by influencing Microtubule organization and by modulating the brassinosteroid signaling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced root apical meristem activity, as observed in the clasp-1 null mutant. We showed that CLASP Protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in Microtubule organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. Brassinosteroid receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of Protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and they advance our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant.
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the Microtubule Associated Protein clasp is translationally regulated in light dependent root apical meristem growth
bioRxiv, 2020Co-Authors: Laryssa S Halat, Katherine Gyte, Geoffrey O WasteneysAbstract:ABSTRACT The ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis thaliana seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the Microtubule-Associated Protein CLASP sustains root apical meristem (RAM) size by influencing Microtubule (MT) organization and by modulating the brassinosteroid (BR) signalling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced RAM activity that is observed in the clasp-1 null mutant. We showed that CLASP Protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in MT organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. BR receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of Protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and advances our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant. One Sentence Summary The Microtubule-Associated Protein CLASP is regulated at the translational level when root meristem growth is inhibited in dark-grown plants.
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the arabidopsis clasp gene encodes a Microtubule Associated Protein involved in cell expansion and division
The Plant Cell, 2007Co-Authors: Christian J Ambrose, Tsubasa Shoji, Amanda M Kotzer, Jamie A Pighin, Geoffrey O WasteneysAbstract:Controlling Microtubule dynamics and spatial organization is a fundamental requirement of eukaryotic cell function. Members of the ORBIT/MAST/CLASP family of Microtubule-Associated Proteins associate with the plus ends of Microtubules, where they promote the addition of tubulin subunits into attached kinetochore fibers during mitosis and stabilize Microtubules in the vicinity of the plasma membrane during interphase. To date, nothing is known about their function in plants. Here, we show that the Arabidopsis thaliana CLASP Protein is a Microtubule-Associated Protein that is involved in both cell division and cell expansion. Green fluorescent Protein–CLASP localizes along the full length of Microtubules and shows enrichment at growing plus ends. Our analysis suggests that CLASP promotes Microtubule stability. clasp-1 T-DNA insertion mutants are hypersensitive to Microtubule-destabilizing drugs and exhibit more sparsely populated, yet well ordered, root cortical Microtubule arrays. Overexpression of CLASP promotes Microtubule bundles that are resistant to depolymerization with oryzalin. Furthermore, clasp-1 mutants have aberrant Microtubule preprophase bands, mitotic spindles, and phragmoplasts, indicating a role for At CLASP in stabilizing mitotic arrays. clasp-1 plants are dwarf, have significantly reduced cell numbers in the root division zone, and have defects in directional cell expansion. We discuss possible mechanisms of CLASP function in higher plants.
Michel Goedert - One of the best experts on this subject based on the ideXlab platform.
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invited review frontotemporal dementia caused by Microtubule Associated Protein tau gene mapt mutations a chameleon for neuropathology and neuroimaging
Neuropathology and Applied Neurobiology, 2015Co-Authors: Bernardino Ghetti, Adrian L Oblak, Bradley F Boeve, Keith A Johnson, Bradford C Dickerson, Michel GoedertAbstract:Hereditary frontotemporal dementia Associated with mutations in the Microtubule-Associated Protein tau gene (MAPT) is a protean disorder. Three neuropathologic subtypes can be recognized, based on the presence of inclusions made of tau isoforms with three and four repeats, predominantly three repeats and mostly four repeats. This is relevant for establishing a correlation between structural magnetic resonance imaging and positron emission tomography using tracers specific for aggregated tau. Longitudinal studies will be essential to determine the evolution of anatomical alterations from the asymptomatic stage to the various phases of disease following the onset of symptoms.
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phosphorylation of human Microtubule Associated Protein tau by Protein kinases of the agc subfamily
FEBS Letters, 2007Co-Authors: Kanwar Virdee, Hirotaka Yoshida, Sew Y Peakchew, Michel GoedertAbstract:Intraneuronal inclusions made of hyperphosphorylated Microtubule-Associated Protein tau are a defining neuropathological characteristic of Alzheimer's disease, and of several other neurodegenerative disorders. Many phosphorylation sites in tau are S/TP sites that flank the Microtubule-binding repeats. Others are KXGS motifs in the repeats. One site upstream of the repeats lies in a consensus sequence for AGC kinases. This site (S214) is believed to play an important role in the events leading from normal, soluble to filamentous, insoluble tau. Here, we show that all AGC kinases tested phosphorylated S214. RSK1 and p70 S6 kinase also phosphorylated the neighbouring T212, a TP site that conforms weakly to the AGC kinase consensus sequence. MSK1 phosphorylated S214, as well as S262, a KXGS site in the first repeat, and S305 in the second repeat.
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evidence that phosphorylation of the Microtubule Associated Protein tau by sapk4 p38δ at thr50 promotes Microtubule assembly
Journal of Cell Science, 2005Co-Authors: Carmen Feijoo, Michel Goedert, Ross Jakes, David G Campbell, Ana CuendaAbstract:Phosphorylation regulates both normal and pathological Tau functioning. This Microtubule-Associated Protein plays a role in the organization and integrity of the neuronal cytoskeleton under normal conditions and becomes hyperphosphorylated and aggregated in a number of neurodegenerative diseases referred to as tauopathies. In this study, we identify and compare the residues in human Tau phosphorylated in vitro by all four p38 MAPK isoforms, and study the regulation of the phosphorylation of Thr50, under conditions where p38 MAPKs are active in cells. Through biochemical analysis, loss of function studies and analysis of endogenous and overexpressed Tau Proteins, we show that SAPK4/p38δ is the major kinase phosphorylating Thr50 in Tau, when cells are exposed to osmotic stress. We also show that mutation of Thr50 to glutamic acid, which mimics phosphorylation, increases the ability of Tau to promote tubulin polymerisation in vitro and in vivo. Moreover, we show that Thr50 is phosphorylated in filamentous Tau from Alzheimer9s disease brain. These findings suggest a role for Tau in the adaptative response of neurons to stress and indicate that SAPK4/p38δ and/or SAPK3/p38δ may contribute to the hyperphosphorylation of Tau in the human tauopathies.
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phosphorylation of Microtubule Associated Protein tau by stress activated Protein kinases
FEBS Letters, 1997Co-Authors: Michel Goedert, Masato Hasegawa, Ross Jakes, Sean E Lawler, Ana Cuenda, Philip CohenAbstract:The paired helical filament, which comprises the major fibrous element of the neurofibrillary lesions of Alzheimer's disease, is composed of hyperphosphorylated Microtubule-Associated Protein tau. Many of the hyperphosphorylated sites in tau are serine/threonine-prolines. Here we show that the stress-activated Protein (SAP) kinases SAPK1γ (also called JNK1), SAPK2a (also called p38, RK, CSBPs, Mpk2 and Mxi2), SAPK2b (also called p38β), SAPK3 (also called ERK6 and p38γ) and SAPK4 phosphorylate tau at many serine/threonine-prolines, as assessed by the generation of the epitopes of phosphorylation-dependent anti-tau antibodies. Based on initial rates of phosphorylation, tau was found to be a good substrate for SAPK4 and SAPK3, a reasonable substrate for SAPK2b and a relatively poor substrate for SAPK2a and SAPK1γ. Phosphorylation of tau by SAPK3 and SAPK4 resulted in a marked reduction in its ability to promote Microtubule assembly. These findings double the number of candidate Protein kinases for the hyperphosphorylation of tau in Alzheimer's disease and other neurodegenerative disorders.
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assembly of Microtubule Associated Protein tau into alzheimer like filaments induced by sulphated glycosaminoglycans
Nature, 1996Co-Authors: Michel Goedert, Masato Hasegawa, Ross Jakes, Maria Grazia Spillantini, Michael J Smith, R A CrowtherAbstract:The paired helical filament (PHF) is the major component of the neurofibrillary deposits that form a defining neuropathological characteristic of Alzheimer's disease. PHFs are composed of Microtubule-Associated Protein tau, in a hyperphosphorylated state. Hyperphosphorylation of tau results in its inability to bind to Microtubules and is believed to precede PHF assembly. However, it is unclear whether hyperphosphorylation of tau is either necessary or sufficient for PHF formation. Here we show that non-phosphorylated recombinant tau isoforms with three Microtubule-binding repeats form paired helical-like filaments under physiological conditions in vitro, when incubated with sulphated glycosaminoglycans such as heparin or heparan sulphate. Furthermore, heparin prevents tau from binding to Microtubules and promotes Microtubule disassembly. Finally, we show that heparan sulphate and hyperphosphorylated tau coexist in nerve cells of the Alzheimer's disease brain at the earliest known stages of neurofibrillary pathology. These findings, with previous studies which show that heparin stimulates tau phosphorylation by a number of Protein kinases, indicate that sulphated glycosaminoglycans may be a key factor in the formation of the neurofibrillary lesions of Alzheimer's disease.
Jesús Avila - One of the best experts on this subject based on the ideXlab platform.
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Microtubule Associated Protein 1b a neuronal marker involved in odontoblast differentiation
Journal of Endodontics, 2009Co-Authors: Jeanchristophe Maurin, Jesús Avila, Marielise Couble, M J Staquet, Florence Carrouel, Imad About, Henry Magloire, Francoise BleicherAbstract:Abstract Introduction Map-1B belongs to the family of Proteins that govern the dynamic state and organization of Microtubules within cells. MAP-1B is a Microtubule-Associated Protein highly expressed during the development of the nervous system. Its expression, regulated by the fragile X mental retardation Protein (FMRP), is essential to stabilize Microtubules during the elongation of dendrites and neurites. Other Microtubules-Associated molecules such as tau or MAP2 seem to act similarly. The aim of this work was to identify the MAP-1B expression in in vitro and in vivo human odontoblasts during development and carious processes. The expression of MAP2 and tau was also studied. Materials and Methods In cultured cells, MAP-1B expression was analyzed by real-time polymerase chain reaction, flow cytometry, and Western blot. Its distribution was visualized by in situ hybridization and immunochemistry both in vitro and in vivo . The expression of FMRP, MAP2, and tau was identified by real-time polymerase chain reaction and immunochemistry. Results MAP-1B is specifically expressed in odontoblasts from adult third molars as well as incisor germs from human embryos. In adult carious teeth, it is also expressed in newly differentiated dentin-forming cells. In vitro , MAP-1B expression is related to the differentiation state of odontoblasts. MAP-1B clearly underlines the cellular architecture of cell bodies and processes of differentiated cells. FMRP, MAP2, and tau are also detected in vivo. Conclusion On the basis of these data, MAP-1B could be considered as a new Protein involved in the terminal differentiation of odontoblasts.
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Microtubule Associated Protein 1b function during normal development regeneration and pathological conditions in the nervous system
Journal of Neurobiology, 2004Co-Authors: Francisco Wandosell, Javier Diaznido, Christian Gonzalezbillault, Eva M Jimenezmateos, Alfredo Caceres, Jesús AvilaAbstract:Microtubule-Associated Protein 1B is the first MAP to be expressed during the development of the nervous system. Several different approaches have revealed that MAP1B function is Associated with Microtubule and actin microfilament polymerization and dynamics. In recent years, the generation of molecular models to inactivate MAP1B function in invertebrates and mammals has sparked some controversy about the real role of MAP1B. Despite discrepancies between some studies, it is clear that MAP1B plays a principal role in the development of the nervous system. In this article, we summarize the evidence for MAP1B function in a wide variety of cellular processes implicated in the proper construction of the nervous system. We also discuss the role of MAP1B in pathological processes. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 48–59, 2004
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The phosphorylated isoform of Microtubule Associated Protein 1B (MAP1B) is expressed in the visual system of the tench (Tinca tinca, L) during optic nerve regeneration.
Neuroscience letters, 1998Co-Authors: Elena Vecino, Luis Ulloa, Jesús AvilaAbstract:By using Western blot analysis and immunohistochemistry we have demonstrated that Microtubule Associated Protein 1B (MAP1B)-phos is present in growing and regenerating axons of retinal ganglion cells of fish (Tinca tinca, L). We have found that the levels of MAP1B-phos substantially increase in regenerating optic nerves. Our observations suggest that MAP1B-phos plays an important role in regeneration processes in the central nervous system (CNS) of the fish. These results are compared in the present paper with that found in the regenerating peripheral nervous system (PNS) of mammals.
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Microtubule Associated Protein map1b showing a fetal phosphorylation pattern is present in sites of neurofibrillary degeneration in brains of alzheimer s disease patients
Molecular Brain Research, 1994Co-Authors: Luis Ulloa, Esteban Montejo De Garcini, Pilar Gomezramos, M A Moran, Jesús AvilaAbstract:Alzheimer's disease results in the appearance of cytoskeletal disorders yielding pathological structures such a neurofibrillary tangles or dystrophic neurites. It has been previously described that the Microtubule-Associated Protein, tau, modified by phosphorylation in serines adjacent to prolines, is a major component of these structures. Here, we show that another Microtubule Associated Protein, MAP1B, aberrantly phosphorylated by a proline-dependent Protein kinase, is a component of these previously mentioned structures. Thus, a possible common phosphorylation of axonal MAPs such as tau or MAP1B may correlate with their association with those aberrant cytoskeletal structures present in AD.
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analysis of Microtubule Associated Protein tau glycation in paired helical filaments
Journal of Biological Chemistry, 1994Co-Authors: M D Ledesma, Pedro Bonay, C Colaco, Jesús AvilaAbstract:Alzheimer's disease is typified by the characteristic histopathological lesions of neurofibrillar plaques and tangles. The latter are composed of paired helical filaments (PHFs), the major components of which are modified forms of the Microtubule-Associated Protein tau. The exact nature of these modifications remains unknown, although the presence of hyperphosphorylated tau in PHFs argues strongly that phosphorylation is one of the modifications that result in the polymerization of tau into PHFs. However, hyperphosphorylation alone is insufficient to explain the formation of PHFs. In an attempt to characterize other post-translational modifications of PHF-tau, we have analyzed its glycation. A fraction of PHF-tau seems to be glycated in vivo, whereas soluble tau from either Alzheimer's disease or non-demented human brain is not glycated at all. Purified tau from bovine brain can be efficiently glycated in vitro. Tau glycation is accompanied by a decrease in the tau binding to tubulin. These results support the view that glycation may be one of the modifications hampering the binding of tau to tubulin in Alzheimer's disease, thus facilitating tau aggregation into PHFs.
Laryssa S Halat - One of the best experts on this subject based on the ideXlab platform.
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the Microtubule Associated Protein clasp is translationally regulated in light dependent root apical meristem growth
Plant Physiology, 2020Co-Authors: Laryssa S Halat, Katherine Gyte, Geoffrey O WasteneysAbstract:The ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis (Arabidopsis thaliana) seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the Microtubule-Associated Protein CLASP sustains root apical meristem size by influencing Microtubule organization and by modulating the brassinosteroid signaling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced root apical meristem activity, as observed in the clasp-1 null mutant. We showed that CLASP Protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in Microtubule organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. Brassinosteroid receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of Protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and they advance our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant.
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the Microtubule Associated Protein clasp is translationally regulated in light dependent root apical meristem growth
bioRxiv, 2020Co-Authors: Laryssa S Halat, Katherine Gyte, Geoffrey O WasteneysAbstract:ABSTRACT The ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis thaliana seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the Microtubule-Associated Protein CLASP sustains root apical meristem (RAM) size by influencing Microtubule (MT) organization and by modulating the brassinosteroid (BR) signalling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced RAM activity that is observed in the clasp-1 null mutant. We showed that CLASP Protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in MT organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. BR receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of Protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and advances our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant. One Sentence Summary The Microtubule-Associated Protein CLASP is regulated at the translational level when root meristem growth is inhibited in dark-grown plants.
Eckhard Mandelkow - One of the best experts on this subject based on the ideXlab platform.
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Multivalent cross-linking of actin filaments and Microtubules through the Microtubule-Associated Protein Tau.
Nature communications, 2017Co-Authors: Yunior Cabrales Fontela, Harindranath Kadavath, Jacek Biernat, Dietmar Riedel, Eckhard Mandelkow, Markus ZweckstetterAbstract:Microtubule-Associated Proteins regulate Microtubule dynamics, bundle actin filaments, and cross-link actin filaments with Microtubules. In addition, aberrant interaction of the Microtubule-Associated Protein Tau with filamentous actin is connected to synaptic impairment in Alzheimer’s disease. Here we provide insight into the nature of interaction between Tau and actin filaments. We show that Tau uses several short helical segments to bind in a dynamic, multivalent process to the hydrophobic pocket between subdomains 1 and 3 of actin. Although a single Tau helix is sufficient to bind to filamentous actin, at least two, flexibly linked helices are required for actin bundling. In agreement with a structural model of Tau repeat sequences in complex with actin filaments, phosphorylation at serine 262 attenuates binding of Tau to filamentous actin. Taken together the data demonstrate that bundling of filamentous actin and cross-linking of the cellular cytoskeleton depend on the metamorphic and multivalent nature of Microtubule-Associated Proteins. The Microtubule Associated Protein Tau also interacts with filamentous actin. Here the authors combine biophysical experiments and NMR studies to characterize the structural changes that occur in Tau upon binding to filamentous actin and show that phosphorylation of serine 262 attenuates actin binding of Tau.
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rna stimulates aggregation of Microtubule Associated Protein tau into alzheimer like paired helical filaments
FEBS Letters, 1996Co-Authors: T Kampers, Jacek Biernat, Eckhard Mandelkow, Peter FriedhoffAbstract:The Microtubule-Associated Protein tau is the main component of the paired helical filaments (PHFs) of Alzheimer's disease, the most common senile dementia. To understand the origin of tau's abnormal assembly we have studied the influence of other cytosolic components. Here we report that PHF assembly is strongly enhanced by RNA. The RNA-induced assembly of PHFs is dependent on the formation of intermolecular disulfide bridges involving Cys322 in the third repeat of tau, and it includes the dimerization of tau as an early intermediate. Three-repeat constructs polymerize most efficiently, two repeat constructs are the minimum number required for assembly, and even all six full-length isoforms of tau can be induced to form PHFs by RNA.