Posttranslational modification of a neurofilament protein during axoplasmic transport: implications for regional specialization of CNS axons

Nixon, RA; Brown, B. A.; Marotta, CA

doi:10.1083/jcb.94.1.150

Cited by 111 publications

(72 citation statements)

References 53 publications

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“…Although posttranslational cleavage of protein Gainer and Same, 1977;Nixon et al, 1982) and glycosylation (Ambron and Treistman, 1977) occur during the axonal transport of other proteins, our studies provided no evidence for interconversion or modification of the 2 major NCAM polypeptides detected along the optic nerve, chiasm, or tract. Furthermore, the ratio of radioactivity in the 2 higher-molecular-weight NCAM forms in the tectum did not differ between samples harvested 2 or 16 hr after injection.…”

Section: Amount Of Ncam In the Fcmentioning

confidence: 62%

Rapid axonal transport of the neural cell adhesion molecule

Garner¹,

Watanabe²,

Rutishauser³

1986

J. Neurosci.

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The neural cell adhesion molecule (NCAM) is a cell-surface glycoprotein that mediates cell-cell interactions in the nervous system during development. In the present study, we demonstrate that NCAM is axonally transported in 3-d-old chick retinal ganglion cells and that it travels within the fast component of axonal transport (FC). Proteins were radiolabeled in retinal ganglion cell bodies after intraocular injection of %-methionine. The presence of radiolabeled NCAM in the optic nerves and contralateral tecta was detected by specific immunoadsorption to a monoclonal antibody. Major radioactive polypeptide bands at relative mobilities of approximately 200,000, 150,000, and 120,000 Mr (after SDS-PAGE) were recognized by the anti-NCAM antibody. These bands comigrated in l-dimensional gels with components of purified NCAM from chick brain. The 2 largest NCAM polypeptides (at 200,000 and 150,000 Mr) were found to be transported in this system, while the 120,000 Mr form was apparently not transported. The ratio and electrophoretie profiles of the 2 transported forms of NCAM remained similar in the retina, optic nerve, chiasm, tract, and tectum, suggesting that there is no interconversion of the 2 major polypeptides. The fraction of NCAM in the %-labeled FC proteins appears to be at least an order of magnitude less than in the plasma membrane, suggesting that the turnover rate of NCAM at this age is slower than for other membrane proteins of the CNS.The neural cell adhesion molecule (NCAM), a cell-surface glycoprotein, mediates cell-cell adhesion during development of nerve tissue (for review, see Rutishauser, 1983). NCAM plays an important role during neurite fasciculation (Rutishauser et al., 1978a), in axon-muscle interaction , and in the association of nerve growth cones with glial precursors (Silver and Rutishauser, 1984).In the present study, we have examined the axonal transport characteristics of the neural cell adhesion molecule. Since there is no protein synthetic machinery within the axon, the molecule must be supplied to the neurite and its terminal by transport within 1 of the 3 major axonal transport rate-components. Each of the 3 major rate-components is thought to convey a cytoplasmic structure within the axon: the fast component (FC) (moving at approximately 250 mm/d) provides membranes and membrane proteins, while the 2 slow components (moving at 0.2 and 2 mm/d) convey cytoplasmic matrix and cytoskeleton, respectively (Lasek, 1980;Lasek et al., 1984).Received Dec. 30, 1985; revised May 8, 1986; accepted May 30, 1986. We wish to thank R. J. , 1983; Gennarini et al., 1984a, b) with a largely uniform distribution on the growth cone, axon shaft, and cell soma (Rutishauser et al., 1978b). It was therefore predicted that NCAM would be transported within the FC of axonal transport.Although the FC of axonal transport has been the subject of study for a number of years, only a few rapidly transported proteins have been well characterized: notably the Na+-K+ ATPase (Baittinger and Willard, 1981;Specht and...

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Section: Amount Of Ncam In the Fcmentioning

confidence: 62%

Rapid axonal transport of the neural cell adhesion molecule

Garner¹,

Watanabe²,

Rutishauser³

1986

J. Neurosci.

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“…Other proteins are thought to be modified during axonal transport: there is proteolysis of neurophysin, accompanying peptide processing (20); axonal glycosylation of proteins in a giant neuron of Aplysia (21); and proteolysis or regional sorting of cytoskeletal components of slowly transported proteins (22,23). Here the proportion of a, however, neither increased nor decreased significantly with time after its appearance in the optic nerve and the target areas.…”

Section: Discussionmentioning

confidence: 90%

Two different Na,K-ATPases in the optic nerve: cells of origin and axonal transport.

Specht¹,

Sweadner²

1984

Proc. Natl. Acad. Sci. U.S.A.

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Two molecular forms of Na,K-ATPase can be isolated from the central nervous system. The two forms can be distinguished by their sensitivities to cardiac glycosides and by the electrophoretic mobilities of their catalytic subunits, a and a(+). Because Na,K-ATPase is a membranebound enzyme, it would be predicted to move in the rapid phase of axonal transport, and this was used as a means to determine which form(s) is made by a defined neuron of the central nervous system. Retinal ganpglion cells were labeled in vivo by intravitreal injection of [3 Simethionine; the Na,KATPase that was axonally transported down the optic nerve was purified, and the a and a(+) forms were separated by electrophoresis and detected by fluorography. The two forms were synthesized in the retina in approximately equal amounts. The a(+) form was the predominant form transported from the retinal ganglion cells to the lateral geniculate nucleus and superior colliculus. The oligodendrocytes and other sheath cells of the excised optic nerve, in contrast, synthesized only the a form when incubated in vitro with [35S]methionine. The labeled Na,K-ATPase found at the nerve endings always included a small amount of the a form in addition to the a(+) form. The proportions of the two forms did not change with time after transport, and the presence of labeled a was not affected by infusion of cycloheximide to inhibit intracranial protein synthesis. Hence, although a(+) is the predominant form, the evidence suggests that small amounts of the a form are also made and transported by retinal ganglion cells.The ouabain-inhibited Na,K-ATPase is the enzyme responsible for active transport of Na' and K+ across the cell membrane (1), and is present in both neurons and glia. When isolated from the kidney, it is comprised of a catalytic subunit of Mr approximately 95,000 (a) and a smaller glycoprotein subunit (13) of unknown function. Preparations of Na,KATPase from the brain, however, have two biochemically distinct forms of the catalytic subunit, called a and a(+) (2). These differ in electrophoretic mobility in NaDodSO4-containing gels (2-4) and in sensitivity to cardiac glycosides (2, 5, 6). Purified axolemmal membrane from rat brain white matter contains only a(+) (2, 3), while cultured glia contain only a (2), which suggests that a(+) is characteristic of neurons and a, of nonneuronal cells. Neurons of the sympathetic nervous system contain only the a form, however, and synaptosomes from the cerebral cortex contain both forms (2). Although the presence of the a form in synaptosomes may be due to contamination with membrane of glial origin, the evidence is consistent with the hypothesis that neurons can express either form or both. A selective labeling technique is needed to determine which forms are expressed in different neurons of the central nervous system. The Na,K-ATPase of a defined population of neurons was examined by taking advantage of the axonal transport of newly synthesized radioactively labeled protein to sites distant from the cell b...

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“…It should be mentioned that FNP7 identifies selected sites on the upper and lower forms of the various NF-M bands and indicates that the apparent molecular weight of NF-M on SDS-PAGE may shift due to the content of phosphate, with a faster migration in the gels after dephosphorylation. Nixon and colleagues (Nixon et al, 1982(Nixon et al, , 1994aNixon and Logvinenko 1986) reported the presence of several NF-M species that differed along the transport in the mouse primary optic pathway. The presence of one NF-M gene (Napolitano et al, 1987) but the presence of several NF-M forms suggests that this variety is generated by posttranslational modifications such as phosphorylation or by the addition of O-linked N-acetylglucosamines (Dong et al, 1993).…”

Section: Phosphorylation Of Nf-m Adds To Cell Specificitymentioning

confidence: 97%