1
|
Ridge KM, Shumaker D, Robert A, Hookway C, Gelfand VI, Janmey PA, Lowery J, Guo M, Weitz DA, Kuczmarski E, Goldman RD. Methods for Determining the Cellular Functions of Vimentin Intermediate Filaments. Methods Enzymol 2015; 568:389-426. [PMID: 26795478 DOI: 10.1016/bs.mie.2015.09.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The type III intermediate filament protein vimentin was once thought to function mainly as a static structural protein in the cytoskeleton of cells of mesenchymal origin. Now, however, vimentin is known to form a dynamic, flexible network that plays an important role in a number of signaling pathways. Here, we describe various methods that have been developed to investigate the cellular functions of the vimentin protein and intermediate filament network, including chemical disruption, photoactivation and photoconversion, biolayer interferometry, soluble bead binding assay, three-dimensional substrate experiments, collagen gel contraction, optical-tweezer active microrheology, and force spectrum microscopy. Using these techniques, the contributions of vimentin to essential cellular processes can be probed in ever further detail.
Collapse
Affiliation(s)
- Karen M Ridge
- Division of Pulmonary and Critical Care Medicine, Chicago, Illinois, USA; Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA; Veterans Administration, Chicago, Illinois, USA.
| | - Dale Shumaker
- Division of Pulmonary and Critical Care Medicine, Chicago, Illinois, USA; Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Amélie Robert
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Caroline Hookway
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Departments of Physiology and Physics & Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jason Lowery
- Division of Pulmonary and Critical Care Medicine, Chicago, Illinois, USA
| | - Ming Guo
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - David A Weitz
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA; Department of Physics, Harvard University, Cambridge, Massachusetts, USA
| | - Edward Kuczmarski
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Robert D Goldman
- Division of Pulmonary and Critical Care Medicine, Chicago, Illinois, USA; Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| |
Collapse
|
2
|
Eriksson JE, He T, Trejo-Skalli AV, Härmälä-Braskén AS, Hellman J, Chou YH, Goldman RD. Specific in vivo phosphorylation sites determine the assembly dynamics of vimentin intermediate filaments. J Cell Sci 2004. [DOI: 10.1242/jcs.00906 jcs.00906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intermediate filaments (IFs) continuously exchange between a small, depolymerized fraction of IF protein and fully polymerized IFs. To elucidate the possible role of phosphorylation in regulating this equilibrium, we disrupted the exchange of phosphate groups by specific inhibition of dephosphorylation and by specific phosphorylation and site-directed mutagenesis of two of the major in vivo phosphorylation sites determined in this study. Inhibition of type-1 (PP1) and type-2A (PP2A) protein phosphatases in BHK-21 fibroblasts with calyculin-A, induced rapid vimentin phosphorylation in concert with disassembly of the IF polymers into soluble tetrameric vimentin oligomers. This oligomeric composition corresponded to the oligopeptides released by cAMP-dependent kinase (PKA) following in vitro phosphorylation. Characterization of the 32P-labeled vimentin phosphopeptides, demonstrated Ser-4, Ser-6, Ser-7, Ser-8, Ser-9, Ser-38, Ser-41, Ser-71, Ser-72, Ser-418, Ser-429, Thr-456, and Ser-457 as significant in vivo phosphorylation sites. A number of the interphase-specific high turnover sites were shown to be in vitro phosphorylation sites for PKA and protein kinase C (PKC). The effect of presence or absence of phosphate groups on individual subunits was followed in vivo by microinjecting PKA-phosphorylated (primarily S38 and S72) and mutant vimentin (S38:A, S72:A), respectively. The PKA-phosphorylated vimentin showed a clearly decelerated filament formation in vivo, whereas obstruction of phosphorylation at these sites by site-directed mutagenesis had no significant effect on the incorporation rates of subunits into assembled polymers. Taken together, our results suggest that elevated phosphorylation regulates IF assembly in vivo by changing the equilibrium constant of subunit exchange towards a higher off-rate.
Collapse
Affiliation(s)
- John E. Eriksson
- Department of Biology, Laboratory of Animal Physiology, University of Turku, Science Building 1, FIN-20014 Turku, Finland
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, POB 123, FIN-20521 Turku, Finland
| | - Tao He
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, POB 123, FIN-20521 Turku, Finland
- Department of Biochemistry, Åbo Akademi University, FIN-20521 Turku, Finland
- Turku Graduate School of Biomedical Sciences, Kiinanmyllynkatu 13, FIN-20520, Turku, Finland
| | - Amy V. Trejo-Skalli
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL-60611-3008, USA
| | - Ann-Sofi Härmälä-Braskén
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, POB 123, FIN-20521 Turku, Finland
- Department of Biochemistry, Åbo Akademi University, FIN-20521 Turku, Finland
| | - Jukka Hellman
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, POB 123, FIN-20521 Turku, Finland
| | - Ying-Hao Chou
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL-60611-3008, USA
| | - Robert D. Goldman
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL-60611-3008, USA
| |
Collapse
|
3
|
Eriksson JE, He T, Trejo-Skalli AV, Härmälä-Braskén AS, Hellman J, Chou YH, Goldman RD. Specific in vivo phosphorylation sites determine the assembly dynamics of vimentin intermediate filaments. J Cell Sci 2004; 117:919-32. [PMID: 14762106 DOI: 10.1242/jcs.00906] [Citation(s) in RCA: 244] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Intermediate filaments (IFs) continuously exchange between a small, depolymerized fraction of IF protein and fully polymerized IFs. To elucidate the possible role of phosphorylation in regulating this equilibrium, we disrupted the exchange of phosphate groups by specific inhibition of dephosphorylation and by specific phosphorylation and site-directed mutagenesis of two of the major in vivo phosphorylation sites determined in this study. Inhibition of type-1 (PP1) and type-2A (PP2A) protein phosphatases in BHK-21 fibroblasts with calyculin-A, induced rapid vimentin phosphorylation in concert with disassembly of the IF polymers into soluble tetrameric vimentin oligomers. This oligomeric composition corresponded to the oligopeptides released by cAMP-dependent kinase (PKA) following in vitro phosphorylation. Characterization of the (32)P-labeled vimentin phosphopeptides, demonstrated Ser-4, Ser-6, Ser-7, Ser-8, Ser-9, Ser-38, Ser-41, Ser-71, Ser-72, Ser-418, Ser-429, Thr-456, and Ser-457 as significant in vivo phosphorylation sites. A number of the interphase-specific high turnover sites were shown to be in vitro phosphorylation sites for PKA and protein kinase C (PKC). The effect of presence or absence of phosphate groups on individual subunits was followed in vivo by microinjecting PKA-phosphorylated (primarily S38 and S72) and mutant vimentin (S38:A, S72:A), respectively. The PKA-phosphorylated vimentin showed a clearly decelerated filament formation in vivo, whereas obstruction of phosphorylation at these sites by site-directed mutagenesis had no significant effect on the incorporation rates of subunits into assembled polymers. Taken together, our results suggest that elevated phosphorylation regulates IF assembly in vivo by changing the equilibrium constant of subunit exchange towards a higher off-rate.
Collapse
Affiliation(s)
- John E Eriksson
- Department of Biology, Laboratory of Animal Physiology, University of Turku, Science Building 1, FIN-20014 Turku, Finland.
| | | | | | | | | | | | | |
Collapse
|
4
|
Clement S, Trejo-Skalli AV, Gu L, Velasco PT, Lorand L, Goldman RD. A transglutaminase-related antigen associates with keratin filaments in some mouse epidermal cells. J Invest Dermatol 1997; 109:778-82. [PMID: 9406820 DOI: 10.1111/1523-1747.ep12340949] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A mouse monoclonal IgG, G82, directed against guinea pig liver transglutaminase recognizes a transglutaminase-related antigen that is associated with the keratin intermediate filament network in some primary mouse keratinocytes. The association can be seen at the resolution of individual keratin tonofibrils following fixation and staining for double-label indirect immunofluorescence. Western blots indicate that G82 reacts with two proteins of 95 kDa and 280 kDa, respectively, in extracts of these cells. The 95-kDa band is also recognized by a polyclonal antibody against purified guinea pig liver transglutaminase, and the 280-kDa protein seems to correspond to a similar protein that was shown to be recognized by G92.1.2 in the intermediate filament fraction of primary mouse fibroblasts. The transglutaminase-related antigen was shown by confocal microscopy to co-localize only with nonbasal cell specific keratin intermediate filaments.
Collapse
Affiliation(s)
- S Clement
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
| | | | | | | | | | | |
Collapse
|
5
|
Paramio JM, Casanova ML, Alonso A, Jorcano JL. Keratin intermediate filament dynamics in cell heterokaryons reveals diverse behaviour of different keratins. J Cell Sci 1997; 110 ( Pt 9):1099-111. [PMID: 9175706 DOI: 10.1242/jcs.110.9.1099] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To study the dynamics of keratin intermediate filaments, we fused two different types of epithelial cells (PtK2 and BMGE+H) and studied how the keratins from the parental cells recombine and copolymerize to form the heterokaryon cytoskeleton. The behaviour of the keratins during this process was followed by immunofluorescence using specific antibodies. After fusion, the parental cytoskeletons undergo a depolymerization process most apparent in the region adjacent to the fusion area. The depolymerized subunits spread throughout the heterokaryon and copolymerize into a new hybrid cytoskeleton. The complete process is very rapid, occurring in 3–4 hours, thus demonstrating the highly dynamic nature of the keratin cytoskeleton. Although newly synthesised subunits contribute to the formation of the hybrid cytoskeleton, the process takes place with similar kinetics in the absence of protein synthesis, showing the dynamic nature of the keratins from pre-existing cytoskeletons. During this process, specific keratins behave differently. Keratins K8, K18, K5 and K10 are mobilised from the parental cytoskeletons and reassemble rapidly into the hybrid cytoskeleton (3–6 hours), whereas K14 requires a substantially longer period (9–24 hours). Thus, different keratins, even when they form part of the same heterodimeric/tetrameric complexes, as is the case for K5 and K14, exhibit different dynamics. This suggests that individual polypeptides or homopolymeric complexes rather than exclusively heterodimeric/ tetrameric subunits, as is currently thought, can also take part in keratin intermediate filament assembly and dynamics. Biochemical analysis performed in the absence of protein synthesis revealed greater amounts of K5 than of K14 in the soluble pool of BMGE+H cells. Crosslinking and immunoprecipitation experiments indicated an excess of monomeric K5, as well as of K5/K14 heterodimers and K5 homodimers in the soluble pool. These results are in agreement with the different dynamic behaviour of these keratins observed in immunofluorescence. On the contrary, the phosphorylation levels of K5 and K14 are similar in both the soluble pool and the polymerized fraction, suggesting that phosphorylation does not play an important role in the different dynamics displayed by these two proteins. In summary, our results demonstrate that, following fusion, the keratin intermediate filament network reshapes rather rapidly and that keratins are highly dynamic proteins, although this mobility depends on each particular polypeptide.
Collapse
Affiliation(s)
- J M Paramio
- Department of Cell and Molecular Biology, CIEMAT, Madrid, Spain.
| | | | | | | |
Collapse
|
6
|
Svitkina TM, Verkhovsky AB, Borisy GG. Plectin sidearms mediate interaction of intermediate filaments with microtubules and other components of the cytoskeleton. J Biophys Biochem Cytol 1996; 135:991-1007. [PMID: 8922382 PMCID: PMC2133373 DOI: 10.1083/jcb.135.4.991] [Citation(s) in RCA: 293] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
By immunogold labeling, we demonstrate that "millipede-like" structures seen previously in mammalian cell cytoskeletons after removal of actin by treatment with gelsolin are composed of the cores of vimentin IFs with sidearms containing plectin. These plectin sidearms connect IFs to microtubules, the actin-based cytoskeleton and possibly membrane components. Plectin binding to microtubules was significantly increased in cells from transgenic mice lacking IFs and was reversed by microinjection of exogenous vimentin. These results suggest the existence of a pool of plectin which preferentially associates with IFs but may also be competed for by microtubules. The association of IFs with microtubules did not show a preference for Glu-tubulin. Nor did it depend upon the presence of MAP4 since plectin links were retained after specific immunodepletion of MAP4. The association of IFs with stress fibers survived actin depletion by gelsolin suggesting that myosin II minifilaments or components closely associated with them may play a role as plectin targets. Our results provide direct structural evidence for the hypothesis that plectin cross-links elements of the cytoskeleton thus leading to integration of the cytoplasm.
Collapse
Affiliation(s)
- T M Svitkina
- Laboratory of Molecular Biology, University of Wisconsin, Madison 53706, USA.
| | | | | |
Collapse
|
7
|
Straube-West K, Loomis PA, Opal P, Goldman RD. Alterations in neural intermediate filament organization: functional implications and the induction of pathological changes related to motor neuron disease. J Cell Sci 1996; 109 ( Pt 9):2319-29. [PMID: 8886982 DOI: 10.1242/jcs.109.9.2319] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The properties regulating the supramolecular organization of neural intermediate filament (NIF) networks have been investigated in cultured dorsal root ganglion (DRG) neurons. The studies described take advantage of the ability of endogenous NIF to incorporate purified biotinylated neurofilament triplet (NFT) proteins, NF-L, NF-M and NF-H. When injected at concentrations of 0.8-1.0 mg/ml injection buffer, each of these proteins is incorporated without perturbing the endogenous NIF network. However, at progressively higher concentrations, NF-H induces the aggregation and accumulation of NIF in the cell body. Subsequent to the induction of these aggregates, numerous alterations in the cytoarchitecture of neurons can be detected. The latter occur in a temporal sequence which appears to begin with the fragmentation of the Golgi complex. At later times, accumulation of mitochondria within the proximal region of neurites, peripheralization of the nucleus, and a significant decrease in neurite caliber become obvious. After longer time periods, the NIF aggregates are seen to react with an antibody which reveals abnormally phosphorylated NF-H. These observations demonstrate that an imbalance in the normal stoichiometric relationships among the NFT proteins rapidly alters the supramolecular organization of the NIF network. These changes most likely reflect the normal functions of neurofilaments in cell shape and the organization and cytoplasmic distribution of membranous organelles. Interestingly, virtually all of these changes closely resemble those which have been reported in motor neuron diseases such as amyotrophic lateral sclerosis (ALS). These findings suggest that cultured neurons can be used as models for more precisely defining the relationships between the formation of NIF aggregates and the sequence of cytopathological events which typify neurodegenerative diseases.
Collapse
|
8
|
Abstract
Keratin intermediate filaments (IF) are obligate heteropolymers containing equal amounts of type I and type II keratin. We have previously shown that microinjected biotinylated type I keratin is rapidly incorporated into endogenous bundles of keratin IF (tonofilaments) of PtK2 cells. In this study we show that the earliest steps in the assembly of keratin subunits into tonofilaments involve the extremely rapid formation of discrete aggregates of microinjected keratin. These are seen as fluorescent spots containing both type I and type II keratins within 1 min post-injection as determined by double label immunofluorescence. These observations suggest that endogenous type II keratin subunits can be rapidly mobilized from their endogenous state to form complexes with the injected type I protein. Furthermore, confocal microscopy and immunogold electron microscopy suggest that the type I-type II keratin spots from in close association with the endogenous keratin IF network. When the biotinylated protein is injected at concentrations of 0.3-0.5 mg/ml, the organization of the endogenous network of tonofilaments remains undisturbed during incorporation into tonofilaments. However, microinjection of 1.5-2.0 mg/ml of biotinylated type I results in significant alterations in the organization and assembly state of the endogenous keratin IF network soon after microinjection. The results of this study are consistent with the existence of a state of equilibrium between keratin subunits and polymerized keratin IF in epithelial cells, and provide further proof that IF are dynamic elements of the cytoskeleton of mammalian cells.
Collapse
Affiliation(s)
- R K Miller
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | | | | |
Collapse
|
9
|
Abstract
When microinjected into the cytoplasm of 3T3 cells, biotinylated human lamin A rapidly enters the nucleus and gradually becomes incorporated into the nuclear lamina region as determined by immunofluorescence. The incorporation of the microinjected material takes several hours and progresses through a series of morphologically identifiable stages. Within minutes after microinjection, lamin A is found in spots distributed throughout the nucleus, except in nucleolar regions. Over a time course of up to 6 h, these spots appear to decrease in size and number as the biotinylated lamin A becomes associated with the endogenous nuclear lamina. Eventually, the typical nuclear rim staining pattern normally revealed by immunofluorescence with nuclear lamin antibodies is seen with antibiotin. This latter rim staining property is passed on to daughter cells following mitosis. These results indicate that the microinjected biotinylated nuclear lamin A retains those properties required for its integration into the lamina, as well as those necessary for the disassembly and subsequent reassembly of the nuclear lamina during cell division. The initial rapid accumulation into foci and the subsequent slower incorporation into the nuclear lamina appear to be analogous to the stages of incorporation following the microinjection of cytoskeletal intermediate filament proteins such as vimentin and keratin (Vikstrom, K., G. G. Borisy, and R. D. Goldman. 1989. Proc. Natl. Acad. Sci. USA. 86:549-553; Miller, R. K., K. Vikstrom, and R. D. Goldman. 1991. J. Cell Biol. 113:843-855). Foci are also observed in some uninjected cells using nuclear lamin antibodies, indicating that these features are a genuine component of nuclear substructure. Evidence is presented that shows the appearance of these nuclear structures is cell cycle dependent.
Collapse
Affiliation(s)
- A E Goldman
- Department of Cell, Molecular and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008
| | | | | | | | | |
Collapse
|
10
|
Abstract
We have conducted experiments to examine the dynamic exchange between subunit and polymer of vimentin intermediate filaments (IF) at steady state through the use of xrhodamine-labeled vimentin in fluorescence recovery after photobleaching (FRAP) analysis. The xrhodamine-vimentin incorporated into the endogenous vimentin IF network after microinjection into fibroblasts and could be visualized with a cooled charge-coupled device (CCD) camera and digital imaging fluorescence microscopy. Bar shaped regions were bleached in the fluorescent IF network using a beam from an argon ion laser and the cells were monitored at various times after bleaching to assess recovery of fluorescence in the bleached zones. We determined that bleached vimentin fibers can recover their fluorescence over relatively short time periods. Vimentin fibers in living cells also can exhibit significant movements, but the recovery of fluorescence was not dependent upon movement of fibers. Fluorescence recovery within individual fibers did not exhibit any marked polarity and was most consistent with a steady state exchange of vimentin subunits along the lengths of IF.
Collapse
Affiliation(s)
- K L Vikstrom
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | | | | | | |
Collapse
|
11
|
Abstract
Dynamin was initially identified in calf brain tissue as a protein of relative molecular mass 100,000 which induced nucleotide-sensitive bundling of microtubules. Purified dynamin showed only trace ATPase activity. But in combination with an activating factor removed during the purification, it exhibited microtubule-activated ATPase activity and dynamin-induced bundles showed evidence of ATP-dependent force production. Dynamin is the product of the Drosophila gene shibire, which has been implicated in synaptic vesicle recycling and, more generally, in the budding of endocytic vesicles from the plasma membrane. Dynamin also shows extensive homology with proteins that participate in vacuolar protein sorting and spindle pole-body separation in yeast, and in interferon-induced viral resistance in mammals. All members of this family contain consensus sequence elements consistent with GTP binding near their amino termini, although none has been shown to have GTPase activity. We report here that dynamin is a specific GTPase which can be stimulated to very high levels of activity by microtubules.
Collapse
Affiliation(s)
- H S Shpetner
- Cell Biology Group, Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545
| | | |
Collapse
|
12
|
Abstract
The properties of keratin-containing intermediate filament (IF) networks in vivo were studied following the microinjection of biotinylated keratin. Keratin-IFs were biotinylated, disassembled, and separated into type I and type II proteins by ion exchange chromatography. Recombination of these derivatized type I and type II keratins resulted in the formation of 10-nm diameter IF. The type I keratins were microinjected into epithelial cells and observed by immunofluorescence microscopy. Biotin-rich spots were found throughout the cytoplasm at 15-20 min after injection. Short biotinylated fibrous structures were seen at 30-45 min after injection, most of which colocalized with the endogenous bundles of IF (tono-filaments). By 1 1/2 to 2 h after microinjection, extensive biotinylated keratin IF-like networks were evident. These were highly coincident with the endogenous tonofilaments throughout the cell, including those at desmosomal junctions. These results suggest the existence of a relatively rapid subunit incorporation mechanism using numerous sites along the length of the endogenous tonofilament bundles. These observations support the idea that keratin-IFs are dynamic cytoskeletal elements.
Collapse
Affiliation(s)
- R K Miller
- Northwestern University Medical School, Department of Cell, Molecular, and Structural Biology, Chicago, Illinois 60611
| | | | | |
Collapse
|
13
|
Skalli O, Goldman RD. Recent insights into the assembly, dynamics, and function of intermediate filament networks. Cell Motil Cytoskeleton 1991; 19:67-79. [PMID: 1878980 DOI: 10.1002/cm.970190202] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- O Skalli
- Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, IL 60611
| | | |
Collapse
|