Comparative Analysis of Rapidly Transported Axonal Proteins in Sensory Neurons of the Frog and Rat (original) (raw)
Related papers
Slab gel analysis of rapidly transported proteins in the isolated frog nervous system
Brain Research, 1977
Studies on intra-axonal transport of newly synthesized proteins in the nervous system have recently shifted from analysis of transport rate kinetics to a characterization of the proteins transported. Several recent studies have focussed on the molecular weight distribution of axonally transported protein utilizing gel electrophoresis techniques. This approach has effectively resolved 5 major proteins which are slowly transported in the nervous system 7. A more complex molecular weight distribution of rapidly transported protein has been found in a variety of neuronal systems%3,'~, 6, 8,10,t3,1~. Despite this heterogeneity, a substantially similar molecular weight distribution appears to exist among proteins rapidly transported in different neuronal systems z,3. The electrophoretic techniques employed in these studies, however, have lacked the resolving power to adequately discriminate individual rapidly transported species. We have reinvestigated the molecular weight distribution of rapidly transported proteins in functionally distinct neuronal systems using analytical slab gel electrophoresis, fluorography and optical scanning techniques. Our results support the proposal z,a that a qualitatively similar population of proteins is transported rapidly by different nerve cell types.
Brain Research, 1976
The synthesis and rapid axonal transport of [aSS]methionine-labelled proteins has been studied using the isolated frog spinal cord and peripheral nervous system. Polyacrylamide gel electrophoresis in sodium dodecylsulfate of synthesized and transported proteins revealed similar labelling patterns of proteins transported in the sensory, motor and sympathetic systems. The relative labelling pattern of transported proteins which accumulated at ligatures in peripheral nerves was different from those obtained from ganglia or nerves and roots when they were incubated in labelled methionine. When compared with methionine-labelled protein profiles of rapid axonal transport in other species and systems, a common set of rapidly transported proteins emerges. The approximate molecular weights of these common proteins include (in 1000 daltons): 18, 24-29, 34-36, 57, 65-68, 100 and 130. These proteins may represent fundamental macromolecules involved in the general maintenance of the function of nerve processes.
The Journal of Cell Biology, 1985
The distribution of the proteins migrating with the slow components a (SCa) and b (SCb) of axonal transport were studied in cross-sections of axons with electron microscope autoradiography. Radiolabeled amino acids were injected into the hypoglossal nucleus of rabbits and after 15 d, the animals were killed. Hypoglossal nerves were processed either for SDS-polyacrylamide gel electrophoresis fluorography to identify and locate the two components of slow transport, or for quantitative electron microscope autoradiography. Proteins transported in SCa were found to be uniformly distributed within the cross-section of the axon. Labeled SCb proteins were also found throughout the axonal cross-section, but the subaxolemmal region of the axon contained 2.5 times more SCb radioactivity than any comparable area in the remainder of the axon.
Electrophoretic Analysis of Axonally Transported Proteins in Toad Retinal Ganglion Cells
Journal of Neurochemistry, 1981
Abstract: As a preliminary step to studying changes in axonal transport in regenerating neurons, we have analyzed the composition and organization of polypeptides normally axonally transported in a neuronal system capable of regeneration, i.e., the retinal ganglion cells of the toad, Bufo marinus. We labeled proteins synthesized in the retina with 35S-methionine and subsequently used one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis to analyze labeled, transported proteins in tissues containing segments of the axons (the optic nerve, optic tract, and optic tecta) of the retinal ganglion cells. The transported polypeptides could be divided into five groups according to their apparent transport velocities. Many of the polypeptides of each group were electrophoretically similar to polypeptides of corresponding groups previously described in rabbit and guinea pig retinal ganglion cells, and in some cases, additional properties of the polypeptides indicated that the transported materials of the two vertebrate classes were homologous. These results serve two purposes. First they establish the retinal ganglion cells of the toad Bufo marinus as a model system in which changes in gene expression related to regeneration may be studied. Second they show that the organization and many aspects of the composition of axonal transport in retinal ganglion cells have been conserved in animals as unrelated as amphibians and mammals.
Fast Axoplasmic Transport of a Calcium-Binding Protein in Mammalian Nerve
Journal of Neurochemistry, 1978
Calcium is transported at a fast rate of 410mm/day in cat sciatic nerve on injection of 45Ca2+ into the L7 dorsal root ganglia. Nerve segments corresponding to the crest and the plateau regions of transported activity were analyzed by column chromatography on Sephadex G-100 and Biogel A 5m columns and the fast transported *%a2+ found to be bound to a protein of 15,000 dalton. Using C3H]leucine as a precursor, a labeled calcium binding protein (CaBP) was found located at the same position in elution volumes from the columns as was the protein-bound 45Ca2+. The .level of [3H]-labeled CaBP in the crest and plateau regions were compared using column chromatography and polyacrylamide gel electrophoresis techniques and approx 3 4 times more C3H]-labeled activity was found in the crest as compared to the plateau. These findings indicate that Ca'+ is fast transported in association with the CaBP. The relation of CaBP to the transport filament model of axoplasmic transport and its possible role in nerve are discussed.
Changes in axonally transported proteins during axon regeneration in toad retinal ganglion cells
Journal of Cell Biology, 1981
In an effort to understand the regulation of the transition of a mature neuron to the growth, or regenerating, state we have analyzed the composition of the axonally transported proteins in the retinal ganglion cells of the toad Bufo marinus after inducing axon regeneration by crushing the optic nerve. At increasing intervals after axotomy, we labeled the retinal ganglion cells with [35 S] methionine and subsequently analyzed the labeled transported polypeptides in the crushed optic nerve by means of one-and two-dimensional electrophoretic techniques . The most significant conclusion from these experiments is that, while the transition from the mature to the regenerating state does not require a gross qualitative alteration in the composition of axonally transported proteins, the relative labeling of a small subset of rapidly transported proteins is altered dramatically (changes of more than 20-fold) and reproducibly (more than 30 animals) by axotomy. One of these growth-associated proteins (GAPS) was soluble in an aqueous buffer, while three were associated with a crude membrane fraction . The labeling of all three of the membrane-associated GAPS increased during the first 8 d after axotomy, and they continued to be labeled for at least 4 wk . The modulation of these proteins after axotomy is consistent with the possibility that they are involved in growth-specific functions and that the altered expression of a small number of genes is a crucial regulatory event in the transition of a mature neuron to a growth state.
The Journal of …, 1987
Many of the structural and functional differences between axons are thought to reflect underlying differences in the biochemical composition and dynamic aspects of the axonal cytoskeleton and cytomatrix. In this study we investigated how the composition of the 2 slow components of axonal transport, SCa and SCb, which convey the cytoskeleton and cytomatrix, differs in axons that are structurally and functionally distinct. For this comparison we analyzed axons of retinal ganglion cells in the optic nerve (ON), axons of dorsal root ganglion (DRG) cells, and axons of ventral motor neurons (VMN) in adult rats. 35S-Methionine-labeled proteins transported with the peak of SCa and SCb were analyzed using high-resolution 2-dimensional polyacrylamide gels (PD-PAGE) and fluorography, and the amounts of major SCa and SCb proteins were quantified. The polypeptide composition of both SCa and SCb was found to be largely similar in DRG and VMN axons, but major qualitative as well as quantitative differences between these axons and ON axons were found. Notable among these were higher ratios of neurofilament protein to tubulin in SCa in DRG and VMN axons compared to ON axons, and significantly larger amounts of 2 microtubule-associated proteins relative to tubulin in SCa of ON axons than in both VMN and DRG axons. Tubulin was the major SCb protein in VMN and DRG axons, but it was not present in SCb in ON axons. Additionally, relatively larger amounts of 2 metabolic enzymes, creatine phosphokinase and nerve-specific enolase, were present in SCb in ON axons than in DRG or VMN axons. The results indicate that significant biochemical heterogeneity among different types of axons can be identified by examining the slow components of axonal transport.
Axonal Transport and Metabolism of Glycoproteins in Rat Sciatic Nerve
Journal of Neurochemistry, 1982
Abstract: The axonal transport and metabolism of glycoproteins in sciatic nerve sensory axons were examined from 2 h to 7 weeks following injection of [3H]fucose into the 5th lumbar dorsal root ganglion of adult rats. Incorporation of fucose into glycoproteins was prolonged; only half of the 3H label in the ganglion was acid-insoluble after 4 h, and maximal labeling did not occur until approximately 24 h after injection. [3H]Glycoproteins were transported distally at a rate of approximately 310 mm per day after a synthesis and/or processing lag of approximately 40 min. Gel electrophoresis demonstrated that many glycoproteins were transported, including prominent labeled species having apparent M.W. of approximately 49,000, 90,000, 118,000, and 132,000. With increasing time after injection, a peak with an apparent M.W. of 49,000 accounted for an increasing proportion of the total label in the nerve. The accumulation of this glycoprotein (possibly a subunit of Na+,K+-ATPase, an enzyme known to be present in axolemma) was due in part to its preferential deposition in the axons, while other glycoproteins passed through the axons directly to the nerve terminals. Radioactivity in another labeled glycoprotein, with an apparent M.W. of 30,000, also increased preferentially in the nerve relative to other labeled glycoproteins. This was shown to be the myelin P0 protein. This protein was not transported from the ganglion; rather, its increased prominence with time in the nerve was due both to a decrease in amounts of other labeled species and to an absolute increase in labeling of the P0 protein, possibly due to reutilization by the Schwann cells of fucose released during turnover of labeled glycoproteins delivered to the axons by axonal transport.