Biogenesis of Presynaptic Terminal Proteins (original) (raw)
Related papers
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.
Synthesis, Migration and Turnover of Protein in Retinal Ganglion Cells
Journal of Neurochemistry, 1971
The synthesis, migration and turnover of proteins in retinal ganglion cells of the adult rabbit was studied after intraocular injections of [3H]leucine. It was shown that the isotope was rapidly incorporated into proteins of the retina and some of the proteins were subsequently transported out into the axons of the retinal ganglion cells down to the tenninals. This intra-axonal transport of protein occurred at four different velocities; 150, 40, 6-12 and 2 mm/day respectively. The two most rapidly migrating phases of axonal transport were predominantly associated with light particulate fractions and had a relatively rapid tumover in the nerve terminals in the lateral geniculate body. The third phase of axonal transport which had a rate of 6-12 mm/day was possibly associated with the migration of mitochondria. The most slowly migrating proteins in the axon which moved at an average rate of 2 mm/day carried predominantly soluble proteins down to the nerve terminals. A minor part of this phase was metabolized locally in the axon with a half-life of about 14 days. When this slowly migrating phase had reached the nerve terminals in the lateral geniculate body, it was degraded with a half-life of 9 6 days. The different phases of axonal transport were of different magnitudes. As measured from the maximal amount of radioactivity present in the nerve terminals the relative amounts of radioactivity of the four phases were: 1.14, 1.5 and 8.5. THE CONCEPT of a proximo-distal transport of axonal constituents first demonstrated by WEISS and HISCOE (1948) is now well established (for reviews see LUBINSKA, . It is now commody believed that this transport in the axon occurs at a minimum of two velocities GRAFSTEIN, 1967; LIVETT, KARLSON and SJ~STRAND, 1968; and that there is a different subcellular localization of the proteins belonging to these two phases of axonal transport (MCEWEN and GRAF-STEIN, 1968; BRAY and AUSTIN, 1969; Kmwm and Oms, 1969; SJOSTRAND and K A m - SON, 1969). However, little is known about the fate of the transported protein in the axon and in the nerve terminals. The aim of the present investigation was to study the transport of proteins in the axons of the retinal ganglion cells of the rabbit and their accumulation and degradation in the nerve terminals in the lateral geniculate body after intraocular injections of labelled amino acid, The results showed that the axonal transport of protein in this system was a very complex mechanism with at least four different rates of transport operating. EXPERIMENTAL About 80 albino rabbits of both sexes weighing between 2.5 and 3.5 kg were used. The animals were injected with 50 a1 of ~-[~H]leucine (45-T, specific activity 19.7 Ci/mmol, conc. 1 mCi/d; The Radiochemical Centre, Amersham, England) inasterile aqueous solution into the vitreous body of each eye. Details of this procedure have been described elsewhere (SJ~STRANIJ and WN, 1969).
Brain Research, 1990
Cytomatrix proteins, of primary functional importance in central nervous system neuron terminals, are provided to their site of action in the terminal by axonal transport. Slow component b (SCb) of axonal transport has been proposed to be the biochemical counterpart of the moving cytoplasmic matrix, or cytomatrix, in axons. In the current study, axonally transported SCb proteins destined for neuron terminals were pulse-radiolabeled with [35S]methionine in guinea pig retinal ganglion cells. After SCb proteins reached the terminals in the superior collioili, synaptosomes were prepared to distinguish between SCb proteins in the preterminal axons and those of the presynaptic terminals, Study of the initial entry and turnover of individual SCb proteins in presynaptic terminals revealed different residence times of certain SCb proteins in comparison with their cohorts. Preliminary information about the structural relationships of the proteins comprising the presynaptic cytomatrix was obtained by examining the solubility of individual SCb proteins relative to other SCb proteins, or membranes from osmotically lysed terminals. Last, treatment of those radiolabeled synaptosomes with varying concentrations of salts was performed to determine possible effects on observed structural relationships.
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.
Brain Research, 1977
We have determined that a genetically polymorphic polypeptide (H, molecular weight _ 195,000) of the rabbit nervous system is transported down the retinal ganglion cell axons at a velocity of 0.7-1.1 mm/day. The H-polypeptide and probably at least two additional polypeptides (molecular weights approximately 145,000 and 73,000) therefore compose a group of intra-axonally transported proteins which moves more slowly than the 4 groups previously described in these neurons. The polypeptides of this fifth group are similar in molecular weight to certain polypeptides transported slowly in other mammalian neuronsL * Whether the retinal ganglion cells are homogeneous or heterogeneous with respect to their transported proteins has not been directly determined.
Axonal transport of macromolecules I. Protein migration in the central nervous system
Experimental Brain Research, 1971
The avian visual system has been used to study the transport of proteins and their precursors along the optic tract. Various labeled compounds were injected into a single eye of new hatched chicks. The radioactivity of components in the optic lobe that was contralateral to, and innervated by, the injected eye was compared to radioactivity in the ipsilateral lobe, not innervated by the treated eye. Proteins migrating from the ganglion cells of the retina to the optic tectum seemed to be relatively stable and may be rich in praline and glycine. Microtubular protein migrated at a rate similar to nonmicrotubule soluble protein, and slower than particulate protein. With the exception of y-aminobutyric acid, transport of free amino acids occurred to only a minor extent. Following monocular injection of tritiated fucose, a rapid asymmetry in the specific activities of protein from contralateral and ipsilateral lobes, was established. Thus the more rapidly migrating proteins may be attached to glycosidic residues. The carbohydrate moeity of these glycoproteins is attached in the nerve cell body, prior to their axonal transport to the optic tectum. There was no evidence for transneuronal transfer of protein as in no cai;e was a differential in specific activity observed in labeled protein from paired cerebral hemispheres.
Axoplasmic transport of a brain-specific soluble protein☆
Biochimica et Biophysica Acta (BBA) - General Subjects, 1975
The rate and extent of axoplasmic transport of the brain-specific soluble protein (14-3-2 protein) has been investigated in the avian visual system. 1-dayold chicks were injected monocularly with tritiated proline. Incorporation of the isotope into the 14-3-2 protein synthesized within the retina of the injected eye, as well as the appearance of the labeled protein in the optic lobes was determined at 6 h and 6 days. These time periods were chosen to distinguish between the rapid and slow phases of axoplasmic flow. Following preparation of high-speed supernatant fractions, dialysis, chromatography on Sephadex G-150 and immunoprecipitation with specific antiserum, identification of the labeled 14-3-2 protein was carried out by sodium dodecylsulfate-polyacrylamide gel analysis of the radioactive immunoprecipitates. 6 days after isotope administration, approx. 8% of the 14-3-2 protein synthesized in the chick retina had been transported to the contralateral optic lobe. By contrast, at 6 h no labeled 14-3-2 protein was detectable. Thus, transport of this neuronal protein appears to be a relatively slow process with little or no rapid component.