Abstract
The neurofilament (NF) is a member of the intermediate filament family, which is composed of different proteins but all having the same width, approximately 10 nm diameter. Among intermediate filaments, NFs have unique chemical and structural properties. They are composed of three distinctly different proteins called triplet proteins (NF-L, NF-M, and NF-H) and are constituted morphologically of two distinct domains in vivo: core filaments and cross-bridges laterally interconnecting the core filaments. Core filaments are ∼10 nm thick, and cross-bridges are much thinner, 3–5 nm thick. Cross-bridges are constructed from carboxy-terminal tail domains of NF-M and NF-H. When NFs are isolated in vitro, they are observed to be constructed of core filaments and long projections extending vertically from the core filaments. The projections, 3–5 nm in width, correspond morphologically with the tail domains of NF-M and NF-H and are much longer than cross-bridges, but with similar widths. The projections have ramified meshwork-like profiles, whereas the cross-bridges are smooth and straight; however, the projections are the structural scaffolding of cross-bridges, although the mechanism whereby projections are converted to cross-bridges is unknown. Although the tail domain of NF-H is longer and can be phosphorylated more extensively than that of NF-M, curiously NF-M appears to be more essential to form cross-bridges that are related to orienting core filaments parallel and increasing axonal calibers. However, cross-bridges are still constructed even in the presence of the NF-H tail alone without the NF-M tail, and more importantly, the cross-bridges are almost normal when having a phosphorylation-incompetent NF-M tail and an intact NF-H tail. I still have a question whether the NF-M tail or the NF-H tail is essential for cross-bridge formation but emphasize in this chapter that both tails are involved in the bridge formation and are able to compensate for each other when either protein is absent. In this reciprocity between NF-M and NF-H, phosphorylated tail domains of both proteins would be necessary. That is, normal cross-bridges are not as frequent as in either NF-M or NF-H tail-less mice when compared with wild-type mice expressing both tails, suggesting strongly that both tail domains are necessary for typical cross-bridges. When cross-bridges are not formed in the absence of both NF-M and NF-H tails, core filaments without cross-bridges are irregular in alignment, resulting in the impairment of axonal transport of membrane-bound organelles, even where microtubules are normal in appearance. Although it remains unresolved how projections are converted to cross-bridges, it seems certain that cross-bridges are an essential structure in axons, especially in long projection axons where NFs are extremely numerous. Cross-bridges are critical to enhance resistance of NFs to mechanical stress in elongated, nonrigid axoplasm and also to create a constant space between core filaments for the axonal transport of various organelles and molecules regulated by microtubules and their associated proteins.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Chen J, Kanai Y, Cowan NJ, Hirokawa N (1992) Projection domains of MAP2 and tau determine spacings between microtubules in dendrites and axons. Nature 360:674–677
Chen J, Nakata T, Zhang Z, Hirokawa N (2000) The C-terminal tail domain of neurofilament protein-H (NF-H) forms the crossbridges and regulates neurofilament bundle formation. J Cell Sci 113:3861–3869
Cleveland DW (1996) Neuronal growth and death: order and disorder in the axoplasm. Cell 84:663–666
de Waegh SM, Lee VM, Brady ST (1992) Local modulation of neurofilament phosphorylation, axonal caliber, and slow axonal transport by myelinating Schwann cells. Cell 68:451–463
Elder GA, Friedrich VL Jr, Bosco P, Kang C, Gourov A, Tu PH, Lee VM, Lazzarini RA (1998) Absence of the mid-sized neurofilament subunit decreases axonal calibers, levels of light neurofilament (NF-L), and neurofilament content. J Cell Biol 141:727–739
Elder GA, Friedrich VL Jr, Margita A, Lazzarini RA (1999) Age-related atrophy of motor axons in mice deficient in the mid-sized neurofilament subunit. J Cell Biol 146:181–192
Eyer J, Leterrier JF (1988) Influence of the phosphorylation state of neurofilament proteins on the interactions between purified filaments in vivo. Biochem J 252:655–660
Garcia ML, Lobsiger CS, Shah SB, Deerinck TJ, Crum J, Young D, Ward CM, Crawford TO, Gotow T, Uchiyama Y, Ellisman MH, Calcutt NA, Cleveland DW (2003) NF-M is an essential target for the myelin-directed “outside-in” signaling cascade that mediates radial axonal growth. J Cell Biol 163:1011–1020
Garcia ML, Rao MV, Fujimoto J, Garcia VB, Shah SB, Crum J, Gotow T, Uchiyama Y, Ellisman M, Calcutt NA, Cleveland DW (2009) Phosphorylation of highly conserved NF-M KSP repeats is not required for myelin-dependent radial axonal growth. J Neurosci 29:1277–1284
Gotow T (1995) Dynamic structure and function of neurofilaments. Ann Psychiatr 5:91–111
Gotow T (2000) Neurofilaments in health and disease. Med Electron Microsc 33:173–199
Gotow T (2008) Neurons in the klotho mutant mouse show biochemical and morphological characteristics resembling age-related disorders. Tzu Chi Med J 20:155–160
Gotow T, Hashimoto PH (1988) Deep-etch structure of astrocytes at the superficial glia limitans, with special emphasis on the internal and external organization of their plasma membranes. J Neurocytol 17:399–413
Gotow T, Leterrier JF, Ohsawa Y, Watanabe T, Isahara K, Shibata R, Ikenaka K, Uchiyama Y (1999) Abnormal expression of neurofilament proteins in dysmyelinating axons located in the central nervous system of jimpy mutant mice. Eur J Neurosci 11:3893–3903
Gotow T, Takeda M, Tanaka T, Hashimoto PH (1992) Macromolecular structure of reassembled neurofilaments as revealed by the quick-freeze deep-etch mica method: difference between NF-M and NF-H subunits in their ability to form cross-bridges. Eur J Cell Biol 58:331–345
Gotow T, Tanaka J (1994) Phosphorylation of neurofilament H subunit as related to arrangement of neurofilaments. J Neurosci Res 37:691–713
Gotow T, Tanaka T, Nakamura Y, Takeda M (1994) Dephosphorylation of the largest neurofilament subunit protein influences the structure of crossbridges in reassembled neurofilaments. J Cell Sci 107:1949–1957
Gotow T, Tanaka J, Takeda M (1995) The organization of neurofilaments accumulated in perikaryon following aluminum administration: relationship between structure and phosphorylation of neurofilaments. Neuroscience 64:553–569
Gou JP, Gotow T, Janmey PA, Leterrier JF (1998) Regulation of neurofilament interactions in vitro by natural and synthetic polypeptides sharing Lys-Ser-Pro sequences with the heavy neurofilament subunit NF-H: neurofilament crossbridging by antiparallel sidearm overlapping. Med Biol Eng Comput 36:371–387
Hirokawa N (1982) Cross-linker system between neurofilaments, microtubules, and membranous organelles in frog axons revealed by the quick-freeze, deep-etching method. J Cell Biol 94:129–142
Hirokawa N, Glicksman MA, Willard MB (1984) Organization of mammalian neurofilament polypeptides within the neuronal cytoskeleton. J Cell Biol 98:1523–1536
Hirokawa N, Noda Y (2008) Intercellular transport and kinesin superfamily proteins, KIFs: structure, function, and dynamics. Physiol Rev 88:1089–1118
Hirokawa N, Shiomura Y, Okabe S (1988) Tau proteins: the molecular structure and mode of binding on microtubules. J Cell Biol 107:1449–1459
Hisanaga S, Hirokawa N (1988) Structure of the peripheral domains of neurofilaments revealed by low angle rotary shadowing. J Mol Biol 202:297–305
Hisanaga S, Hirokawa N (1989) The effects of dephosphorylation on the structure of the projections of neurofilament. J Neurosci 9:959–966
Hisanaga S, Ikai A, Hirokawa N (1990) Molecular architecture of the neurofilament. I. Subunit arrangement of neurofilament L protein in the intermediate-sized filament. J Mol Biol 211:857–869
Jacomy H, Zhu Q, Couillard-Després S, Beaulieu JM, Julien JP (1999) Disruption of type IV intermediate filament network in mice lacking the neurofilament medium and heavy subunits. J Neurochem 73:972–984
Julien JP (1997) Neurofilaments and motor neuron disease. Trends Cell Biol 7:243–249
Lee MK, Xu Z, Wong PC, Cleveland DW (1993) Neurofilaments are obligate heteropolymers in vivo. J Cell Biol 122:1337–1350
Leterrier JF (2001) Water and the cytoskeleton. Cell Mol Biol 47:901–923
Leterrier JF, Eyer J (1987) Properties of highly viscous gels formed by neurofilaments in vitro. A possible consequence of a specific inter-filament cross-bridging. Biochem J 245:93–101
Leterrier JF, Käs J, Hartwig J, Vegners R, Janmey PA (1996) Mechanical effects of neurofilament cross-bridges. J Biol Chem 271:15687–15694
Lewis SE, Nixon RA (1988) Multiple phosphorylated variants of the high molecular mass subunit of neurofilaments in axons of retinal cell neurons: characterization and evidence for their differential association with stationary and moving neurofilaments. J Cell Biol 107:2689–2701
Matus A (1988) Neurofilament protein phosphorylation – where, when and why. Trends Neurosci 11:291–292
Nakagawa T, Chen J, Zhang Z, Kanai Y, Hirokawa N (1995) Two distinct functions of the carboxy1- terminal tail domain of NF-M upon Neurofilament assembly: cross-bridge formation and longitudinal elongation of filaments. J Cell Biol 129:411–429
Nixon RA, Sihag RK (1991) Neurofilament phosphorylation: a new look at regulation and function. Trends Neurosci 14:501–506
Rao MV, Campbell J, Yuan A, Kumar A, Gotow T, Uchiyama Y, Nixon RA (2003) The neurofilament middle molecular mass subunit carboxyl-terminal tail domains is essential for the radial growth and cytoskeletal architecture of axons but not for regulating neurofilament transport rate. J Cell Biol 163:1021–1031
Rao MV, Garcia ML, Miyazaki Y, Gotow T, Yuan A, Mattina S, Ward CM, Calcutt NA, Uchiyama Y, Nixon RA, Cleveland DW (2002) Gene replacement in mice reveals that the heavily phosphorylated tail of neurofilament heavy subunit does not affect axonal caliber or the transit of cargoes in slow axonal transport. J Cell Biol 158:681–693
Rao MV, Houseweart MK, Williamson TL, Crawford TO, Folmer J, Cleveland DW (1998) Neurofilament-dependent radial growth of motor axons and axonal organization of neurofilaments does not require the neurofilament heavy subunit (NF-H) or its phosphorylation. J Cell Biol 143:171–181
Sánchez I, Hassinger L, Sihag RK, Cleveland DW, Mohan P, Nixon RA (2000) Local control of neurofilament accumulation during radial growth of myelinating axons in vivo: selective role of site-specific phosphorylation. J Cell Biol 151:1013–1024
Shaw G (1986) Neurofilaments: abundant but mysterious neuronal structures. Bioessays 4:161–166
Shaw G (1991) Neurofilament proteins. In: Burgoyne RD (ed) The neuronal cytoskeleton. Wiley-Liss, New York, NY, 185–214
Shea TB, Chan WK-H (2008) Regulation of neurofilament dynamics by phosphorylation. Eur J Neurosci 27:1893–1901
Shiozaki M, Yoshimura K, Shibata M, Koike M, Matsuura N, Uchiyama Y, Gotow T (2008) Morphological and biochemical signs of age-related neurodegenerative changes in klotho mutant mice. Neuroscience 152:924–941
Tsukita S, Usukura J, Tsukita S, Ishikawa H (1982) The cytoskeleton in myelinated axons: a freeze-etch replica study. Neuroscience 7:2135–2147
Willard M, Simon C (1983) Modulations of neurofilament axonal transport during the development of rabbit retinal ganglion cells. Cell 35:551–559
Zhu Q, Couillard-Després S, Julien JP (1997) Delayed maturation of regenerating myelinated axons in mice lacking neurofilaments. Exp Neurol 148:299–316
Zhu Q, Lindenbaum M, Levavasseur F, Jacomy H, Julien JP (1998) Disruption of the NF-H gene increases axonal microtubule content and velocity of neurofilament transport: relief of axonopathy resulting from the toxin β,β’-iminodipropionitrile. J Cell Biol 143:183–193
Acknowledgments
The data from genetically modified mice described in this chapter were obtained from international collaboration with Drs. Mala V. Rao, Michael L. Garcia, and Don W. Cleveland. I thank Motoko Shiozaki and Naoya Hayakawa for photographic assistance.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2011 Springer Science+Business Media, LLC
About this chapter
Cite this chapter
Gotow, T. (2011). Neurofilament Cross-Bridge – A Structure Associated Specifically with the Neurofilament Among the Intermediate Filament Family. In: Nixon, R., Yuan, A. (eds) Cytoskeleton of the Nervous System. Advances in Neurobiology, vol 3. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-6787-9_10
Download citation
DOI: https://doi.org/10.1007/978-1-4419-6787-9_10
Published:
Publisher Name: Springer, New York, NY
Print ISBN: 978-1-4419-6786-2
Online ISBN: 978-1-4419-6787-9
eBook Packages: Biomedical and Life SciencesBiomedical and Life Sciences (R0)