?IV tubulin is selectively expressed by oligodendrocytes in the central nervous system (original) (raw)
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Binding of microtubules to transitional elements in oligodendrocytes of the myelin mutant taiep rat
Journal of Neuroscience Research, 1997
The presence of microtubules physically bound to smooth endoplasmic reticulum profiles of oligodendrocytes constitutes the most conspicuous feature observed in the myelin mutant taiep rat. The endoplasmic reticulum membranes associated with microtubules were morphologically characterized as transitional elements that constitute the intermediate compartment according to their topographic location close to the cis-Golgi apparatus. The development of this surprising microtubular defect appears to be associated with the early events of myelination. Transitional elements associated with microtubules operate in protein transport from endoplasmic reticulum to cis-Golgi. This microtubular defect could explain the dysmyelination and neurologic alterations observed in taiep rats. Moreover, these findings allow us to propose that there is a blockage of protein traffic at the intermediate compartment of taiep oligodendrocytes, a situation that could explain the hypomyelinated axons observed in this myelin mutant. The binding of microtubules to membranous organelles promotes the stabilization of microtubules, a feature that has important implications regarding its accumulation within the cytoplasm of oligodendrocytes during the temporal evolution of this neurologic disorder. The taiep rat is a myelin mutant with a long survival and could be a useful model for understanding dysmyelinating diseases in which the intracellular transport of myelin components is affected.
The small myelin-associated glycoprotein binds to tubulin and microtubules
Molecular Brain Research, 2001
The myelin-associated glycoprotein (MAG) exists as two isoforms, differing only by their respective cytoplasmic domains, that have been suggested to function in the formation and maintenance of myelin. In the present study, a 50 kDa protein binding directly to the small MAG (S-MAG) cytoplasmic domain was detected and identified as tubulin, the core component of the microtubular cytoskeleton. In vitro, the S-MAG cytoplasmic domain slowed the polymerization rate of tubulin and co-purified with assembled microtubules. A significant sequence homology was found between the tau family tubulin-binding repeats and the carboxy-terminus of S-MAG. Our results indicate that S-MAG is the first member of the Ig superfamily that can be classified as a microtubule-associated protein, and place S-MAG in a dynamic structural complex that could participate in linking the axonal surface and the myelinating Schwann cell cytoskeleton. (P. Kursula).
Post-Translational Tubulin Modifications in Human Astrocyte Cultures
Neurochemical research, 2017
The cytoskeletal protein tubulin plays an integral role in the functional specialization of many cell types. In the central nervous system, post-translational modifications and the expression of specific tubulin isotypes in neurons have been analyzed in greater detail than in their astrocytic counterparts. In this study, we characterized post-translational specifications of tubulin in human astrocytes using the normal human astrocyte (NHA; Lonza) commercial cell line of fetal origin. Immunocytochemical techniques were implemented in conjunction with confocal microscopy to image class III β-tubulin (βIII-tubulin), acetylated tubulin, and polyglutamylated tubulin using fluorescent antibody probes. Fluorescent probe intensity differences and colocalization were quantitatively assessed with the 'EBImage' package for the statistical programming language R. Colocalization analysis revealed that, although both acetylated tubulin and polyglutamylated tubulin showed a high degree of ...
Journal of Neuroscience Research, 1991
Only a few proteins are known to be exclusively expressed in central nervous system (CNS) myelin. A novel surface membrane protein expressed only in CNS myelin and oligodendrocytes of higher vertebrates has been identified by a monoclonal antibody. This CNS myelin/oligodendrocyte-specific protein, MOSP, has a molecular weight of 48 kDa and a PI of approximately 6.7. In the presence of the monoclonal antibody, MOSP remains on the surface of cultured oligodendrocytes but becomes associated with cytoplasmic microtubules. Our results suggest that MOSP plays an important role in membranekytoskeleton interactions during the formation and maintenance of CNS myelin. MOSP also may play a critical role in the pathogenesis of diseases of CNS myelin.
Expression of the Class III β-tubulin isotype in developing neurons in culture
Journal of Neuroscience Research, 1992
The expression of the class I11 P-tubulin isotype was studied in cultured brain neurons by means of a monoclonal antibody (TuJ1). The results obtained indicate that during early axonal outgrowth most of the class I11 p-tubulin is not incorporated into microtubules, a phenomenon which is also observed under conditions which alter the rate and extent of the neurite outgrowth response. On the other hand, a dramatic increase in its incorporation into microtubules is observed after the neurons have differentiated their neurites as axons and dendrites. In addition, the appearance of colchicine-resistant microtubules containing this isotype, a phenomenon which occurs late in neurite development, is highly coincident with the appearance of stable microtubules containing high molecular weight microtubule-associated proteins (MAPs). This pattern is different from that of the accumulation and incorporation of other P-tubulin isotypes into microtubules. Taken collectively, our results indicate that differences exist in the in vivo utilization of tubulin isotypes in developing brain neurons and suggest that the class I11 P-tubulin isotype is not a primary factor involved in the regulation of microtubule assembly during early neurite outgrowth, but that it may be important for maintaining further neurite elongation and/or determining some unique binding property of MAPs to specific microtubule subsets.
Association of Newly Synthesized Tubulin with Brain Microsomal Membranes
Journal of Neurochemistry, 1980
Tubulin has been found to be synthesized on both membrane-bound and free polyribosomes prepared from brain. Cell-free studies indicate that tubulin made on rough microsomes is incorporated into the endoplasmic reticulum membrane as it is synthesized. This tubulin remains associated with the membrane after sedimentation and washing. The tubulin is not removed from the membrane after stripping ribosomes from the membranes in KCIpuromycin, followed by repeated washing by either sedimentation or flotation in 0.5 M-KCI. The membrane tubulin is partially susceptible to proteolysis by trypsin and chymotrypsin: p-tubulin is more accessible to the proteases than is a-tubulin. Nonionic detergents extract mostly 0-tubulin from the microsomal membrane. Newly synthesized tubulin which has been extracted from micro-soma1 membranes in 0.5% Nonidet P-40, coassembles and disassembles with carrier microtubule protein. The insertion of newly synthesized tubulin into endoplasmic reticulum membrane may be the first step in the incorporation of tubulin into the plasma membrane. Key words: Rough microsomes-Cell-free protein synthesis-Microtubule protein-Membrane protein. Soifer D. and Czosnek H. Association of newly synthesized tubulin with brain microsomal membranes.
Differential distribution of beta-tubulin isotypes in cerebellum
The EMBO Journal, 1988
Communicated by D.Bray We describe the structure and expression of a mammalian f-tubulin isotype (Mf6) that is weakly expressed in testis but is abundant in developing brain, with transcripts declining to lower levels in the adult brain. The expression of M,B6 was undetectable in any other mouse tissue examined. A serum specific for this isotype was prepared using a cloned fusion protein as immunogen. M36 is one of five known 3-tubulin isotypes expressed in brain, and using the anti-Mf36 serum along with sera, anti-MO32, anti-M,B3/4 and anti-Mf35, previously characterized, we have examined the pattern of expression of,-tubulin isotypes in rat cerebellum. The isotypes each have characteristic cell-type specific patterns of localization in cerebellum. M,(2, M,33/4 and M,B5 are present in both neuronal and non-neuronal cells, but in contrast M(36 was only detectable in neurons in tissue sections and in dissociated cerebellar cell culture. The majority of sequence differences among the f3-tubulin isotypes lie at the carboxy terminus, the region of,tubulin involved in MAP binding. In the case of M,(2 and M36, the patterns of expression are similar or identical to the patterns of expression of MAP3 and MAPIA respectively. These results suggest that ,B-tubulin isotypes may contribute to the determination of the specific association of MAPs with microtubules of diverse function. However, the strict subcellular segregation of other MAPs in brain may be determined by other factors.