Diverse Distribution and Function of Fibrous Microtubule-Associated Proteins in the Nervous System

1994 ◽  
pp. 67-137 ◽  
Author(s):  
Thomas A. Schoenfeld ◽  
Robert A. Obar
Keyword(s):  
Nervous System ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function

scholarly journals Map1b Is Required for Axon Guidance and Is Involved in the Development of the Central and Peripheral Nervous System

2000 ◽  
Vol 151 (6) ◽  
pp. 1169-1178 ◽  
Author(s):  
Arabella Meixner ◽  
Silke Haverkamp ◽  
Heinz Wässle ◽  
Susanne Führer ◽  
Johann Thalhammer ◽  
...  
Keyword(s):  
Nervous System ◽  
Nerve Conduction Velocity ◽  
Developmental Defect ◽  
Myelinated Fiber ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
The Brain ◽  
Deficient Mice

Microtubule-associated proteins such as MAP1B have long been suspected to play an important role in neuronal differentiation, but proof has been lacking. Previous MAP1B gene targeting studies yielded contradictory and inconclusive results and did not reveal MAP1B function. In contrast to two earlier efforts, we now describe generation of a complete MAP1B null allele. Mice heterozygous for this MAP1B deletion were not affected. Homozygous mutants were viable but displayed a striking developmental defect in the brain, the selective absence of the corpus callosum, and the concomitant formation of myelinated fiber bundles consisting of misguided cortical axons. In addition, peripheral nerves of MAP1B-deficient mice had a reduced number of large myelinated axons. The myelin sheaths of the remaining axons were of reduced thickness, resulting in a decrease of nerve conduction velocity in the adult sciatic nerve. On the other hand, the anticipated involvement of MAP1B in retinal development and γ-aminobutyric acid C receptor clustering was not substantiated. Our results demonstrate an essential role of MAP1B in development and function of the nervous system and resolve a previous controversy over its importance.

Molecular architecture and functions of the neuronal cytoskeleton

1990 ◽  
Vol 48 (3) ◽  
pp. 2-3
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Major Elements ◽  
Molecular Structures ◽  
Organelle Transport ◽  
Molecular Architecture ◽  
Neuronal Morphogenesis ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

scholarly journals The structured core of human β tubulin confers isotype-specific polymerization properties

2016 ◽  
Vol 213 (4) ◽  
pp. 425-433 ◽  
Author(s):  
Melissa C. Pamula ◽  
Shih-Chieh Ti ◽  
Tarun M. Kapoor
Keyword(s):  
Dynamic Instability ◽  
Sequence Divergence ◽  
Regulatory Proteins ◽  
Microtubule Dynamic ◽  
Microtubule Associated Proteins ◽  
Cytoskeleton Organization ◽  
Wide Range ◽  
Associated Proteins ◽  
And Function ◽  
Β Tubulin

Diversity in cytoskeleton organization and function may be achieved through variations in primary sequence of tubulin isotypes. Recently, isotype functional diversity has been linked to a “tubulin code” in which the C-terminal tail, a region of substantial sequence divergence between isotypes, specifies interactions with microtubule-associated proteins. However, it is not known whether residue changes in this region alter microtubule dynamic instability. Here, we examine recombinant tubulin with human β isotype IIB and characterize polymerization dynamics. Microtubules with βIIB have catastrophe frequencies approximately threefold lower than those with isotype βIII, a suppression similar to that achieved by regulatory proteins. Further, we generate chimeric β tubulins with native tail sequences swapped between isotypes. These chimeras have catastrophe frequencies similar to that of the corresponding full-length construct with the same core sequence. Together, our data indicate that residue changes within the conserved β tubulin core are largely responsible for the observed isotype-specific changes in dynamic instability parameters and tune tubulin’s polymerization properties across a wide range.

scholarly journals Exploring neurodegeneration at the atomic level

2018 ◽  
Vol 40 (5) ◽  
pp. 9-11
Author(s):  
Adam Tozer
Keyword(s):  
Amino Acids ◽  
Central Nervous System ◽  
Nervous System ◽  
Atomic Level ◽  
Tau Proteins ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Central Nervous System ◽  
The Brain ◽  
Cell Maintenance

Tau proteins are microtubule-associated proteins essential for the correct functioning of neurons. This small family of proteins, 352–441 amino acids in length, are abundant in the brain and exist to stabilize microtubules in neurons and glia (non-neuronal cells of the central nervous system) to ensure correct trafficking of cellular cargo and cell maintenance.

scholarly journals MAP6 is an intraluminal protein that induces neuronal microtubules to coil

2020 ◽  
Vol 6 (14) ◽  
pp. eaaz4344 ◽  
Author(s):  
Camille Cuveillier ◽  
Julie Delaroche ◽  
Maxime Seggio ◽  
Sylvie Gory-Fauré ◽  
Christophe Bosc ◽  
...  
Keyword(s):  
Nervous System ◽  
Mechanical Stress ◽  
Microtubule Associated Proteins ◽  
Left Handed ◽  
Neuronal Processes ◽  
Associated Proteins ◽  
The Face ◽  
Cold Stability

Neuronal activities depend heavily on microtubules, which shape neuronal processes and transport myriad molecules within them. Although constantly remodeled through growth and shrinkage events, neuronal microtubules must be sufficiently stable to maintain nervous system wiring. This stability is somehow maintained by various microtubule-associated proteins (MAPs), but little is known about how these proteins work. Here, we show that MAP6, previously known to confer cold stability to microtubules, promotes growth. More unexpectedly, MAP6 localizes in the lumen of microtubules, induces the microtubules to coil into a left-handed helix, and forms apertures in the lattice, likely to relieve mechanical stress. These features have not been seen in microtubules before and could play roles in maintaining axonal width or providing flexibility in the face of compressive forces during development.

scholarly journals The Light Chains of Microtubule-Associated Proteins MAP1A and MAP1B Interact with α1-Syntrophin in the Central and Peripheral Nervous System

PLoS ONE ◽  
2012 ◽  
Vol 7 (11) ◽  
pp. e49722 ◽  
Author(s):  
Heike Fuhrmann-Stroissnigg ◽  
Rainer Noiges ◽  
Luise Descovich ◽  
Irmgard Fischer ◽  
Douglas E. Albrecht ◽  
...  
Keyword(s):  
Nervous System ◽  
Peripheral Nervous System ◽  
Light Chains ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

scholarly journals Domains of Neuronal Microtubule-associated Proteins and Flexural Rigidity of Microtubules

1997 ◽  
Vol 138 (5) ◽  
pp. 1067-1075 ◽  
Author(s):  
Harald Felgner ◽  
Rainer Frank ◽  
Jacek Biernat ◽  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Flexural Rigidity ◽  
Microtubule Binding ◽  
Fourfold Increase ◽  
Microtubule Associated Proteins ◽  
Relative Contribution ◽  
Low Concentrations ◽  
Neuronal Processes ◽  
Associated Proteins ◽  
And Function

Microtubules are flexible polymers whose mechanical properties are an important factor in the determination of cell architecture and function. It has been proposed that the two most prominent neuronal microtubule-associated proteins (MAPs), tau and MAP2, whose microtubule binding regions are largely homologous, make an important contribution to the formation and maintenance of neuronal processes, putatively by increasing the rigidity of microtubules. Using optical tweezers to manipulate single microtubules, we have measured their flexural rigidity in the presence of various constructs of tau and MAP2c. The results show a three- or fourfold increase of microtubule rigidity in the presence of wild-type tau or MAP2c, respectively. Unexpectedly, even low concentrations of MAPs promote a substantial increase in microtubule rigidity. Thus at ∼20% saturation with full-length tau, a microtubule exhibits >80% of the rigidity observed at near saturating concentrations. Several different constructs of tau or MAP2 were used to determine the relative contribution of certain subdomains in the microtubule-binding region. All constructs tested increase microtubule rigidity, albeit to different extents. Thus, the repeat domains alone increase microtubule rigidity only marginally, whereas the domains flanking the repeats make a significant contribution. Overall, there is an excellent correlation between the strength of binding of a MAP construct to microtubules (as represented by its dissociation constant Kd) and the increase in microtubule rigidity. These findings demonstrate that neuronal MAPs as well as constructs derived from them increase microtubule rigidity, and that the changes in rigidity observed with different constructs correlate well with other biochemical and physiological parameters.

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