Immunological characterization of lamins in the nuclear matrix of onion cells

1993 ◽  
Vol 106 (1) ◽  
pp. 431-439 ◽  
Author(s):  
A. Minguez ◽  
S. Moreno Diaz de la Espina

We have used polyclonal and monoclonal antibodies against different lamins from vertebrates, and the IFA antibody recognizing all kinds of intermediate filament proteins, to investigate the lamins of the nuclear matrix of Allium cepa meristematic root cells. All the antibodies react in the onion nuclear matrix with bands in the range of 60–65 kDa, which are enriched in the nuclear matrix after urea extraction, and do not crossreact with other antibodies recognizing intermediate filaments in plants (AFB, anti-vimentin and MAC 322), ruling out crossreaction with contaminating intermediate filaments of cytoplasmic bundles. In 2-D blots the chicken anti-lamin serum reacts with one spot at 65 kDa and pI 6.8 and the anti B-type lamin antibodies with another one at 64 kDa and pI 5.75. Both crossreact with IFA. The lamin is localized at the nuclear periphery and the lamina by indirect immunofluorescence. Immunogold labelling of nuclear matrix sections reveals that the protein is not only associated with the lamina, but also with the internal matrix. Taken together these results reveal that higher plants, which do not possess an organized network of cytoplasmic intermediate filaments, nevertheless present a well-organized lamina containing lamins in which at least one of them is immunologically related to vertebrate lamin B. Our data confirm that lamins are very old members of the intermediate filament proteins that have been better conserved in plants during evolution than their cytoplasmic counterparts.

1992 ◽  
Vol 70 (10-11) ◽  
pp. 842-848 ◽  
Author(s):  
Micheline Paulin-Levasseur

Major constituents of the cytoskeleton and the nuclear matrix, cytoplasmic intermediate filament subunits and nuclear lamins belong to a multigene family of proteins whose function is poorly understood. It has now become a general contention that important clues to the physiological roles of these proteins may reside in their developmental and tissue-specific expression patterns, as well as their cellular organization. The present review brings into focus experimental strategies that have been developed, over the past few years, to gain insights into the cellular mechanisms regulating the molecular polymorphism and supramolecular assembly of intermediate filaments. In this context new concepts are discussed that may be pivotal for the orientation of future studies on intermediate filament proteins.Key words: intermediate filaments, nuclear lamins, cytoskeleton, nuclear matrix.


1991 ◽  
Vol 98 (3) ◽  
pp. 293-302
Author(s):  
ALISON BEVEN ◽  
YUHONG GUAN ◽  
JAN PEART ◽  
CHRISTINE COOPER ◽  
PETER SHAW

We have prepared a nuclear matrix fraction from purified nuclei of carrot (Daucus carota L.) suspension culture cells, and used this fraction to produce a library of monoclonal antibodies. We report the preliminary characterisation of two antibodies-JIM 62 and JIM 63. The antibodies recognise a polypeptide doublet band at 92xl03Mr, which has been partially purified by differential urea extraction. Other intermediate filament antibodies-ME101, which recognises an epitope conserved among many intermediate filament proteins, and AFB, a monoclonal antibody to plant intermediate filament proteins, and an autoimmune serum directed against human lamina A and C (LSI), also label these bands, suggesting they are related to the intermediate filament/lamin family. IFA, another intermediate filament antibody, labels a band at approximately 60x103Mr, which is also enriched in the urea extracts of nuclear matrices. Immunofluorescence microscopy with JIM 63, ME 101, AFB and LSI shows network-like staining, often extending around the nucleolus. In many cases the staining reveals structures that appear to be bundles of fibres. JIM 63 also shows a weak staining of the nuclear rim in carrot nuclei, which can be greatly enhanced by treatment of the specimen with cold methanol after fixation. JIM 63 cross-reacts with all the other plant species we have tested. Vibratome sections of pea roots, extracted as for nuclear matrix preparation and stained with JIM 63 show a clear, strong nuclear rim labelling. Furthermore, JIM 63 strongly labels the nuclear lamina in rat liver nuclei. We suggest that the 92x103Mr protein(s) are related to intermediate filaments and/or lamins, and are distributed both within the nucleus and at the nuclear periphery.


1991 ◽  
Vol 98 (3) ◽  
pp. 281-291
Author(s):  
P. Belgrader ◽  
A.J. Siegel ◽  
R. Berezney

Different agents have been employed to extract the histones and other soluble components from isolated HeLa S3 nuclei during nuclear matrix isolation. We report that 0.2M (NH4)2SO4 is a milder extracting agent than NaCl and LIS (lithium 3,5-diiodosalicylate), on the basis of the apparent preservation of the elaborate fibrogranular network and the residual nucleolus that resemble the in situ structures in whole cells and nuclei, minimal aggregation, and sufficient solubilization of DNA and histones. The importance of intermolecular disulfide bonds, RNA and 37 degrees C stabilization on the structural integrity of the nuclear matrix was examined in detail using sulfydryl alkylating, reducing and oxidizing agents, and RNase A. The data suggest that any disulfides formed during the isolation are not essential for maintaining the structural integrity of the in vitro matrix. However, structural integrity of the matrix is dependent upon RNA and to some degree on disulfides that presumably existed in situ. Sodium tetrathionate and 37 degrees C stabilization of isolated nuclei resulted in nuclear matrices containing an approximately twofold greater amount of protein, RNA and DNA than control preparations. The 37 degrees C incubation, unlike the sodium tetrathionate stabilization, does not appear to induce intermolecular disulfide bond formation. Neither stabilizations resulted in significant differences of the major matrix polypeptide pattern on two-dimensional (2-D) gels stained with Coomassie Blue as compared to that of unstabilized matrix. The major nuclear matrix proteins, other than the lamins, did not react to the Pruss murine monoclonal antibody (IFA) that recognizes all known intermediate filament proteins, suggesting that the internal matrix proteins are not related to the lamins in intermediate filament-like quality.


1993 ◽  
Vol 122 (6) ◽  
pp. 1323-1335 ◽  
Author(s):  
GY Ching ◽  
RK Liem

We report here on the in vivo assembly of alpha-internexin, a type IV neuronal intermediate filament protein, in transfected cultured cells, comparing its assembly properties with those of the neurofilament triplet proteins (NF-L, NF-M, and NF-H). Like the neurofilament triplet proteins, alpha-internexin coassembles with vimentin into filaments. To study the assembly characteristics of these proteins in the absence of a preexisting filament network, transient transfection experiments were performed with a non-neuronal cell line lacking cytoplasmic intermediate filaments. The results showed that only alpha-internexin was able to self-assemble into extensive filamentous networks. In contrast, the neurofilament triplet proteins were incapable of homopolymeric assembly into filamentous arrays in vivo. NF-L coassembled with either NF-M or NF-H into filamentous structures in the transfected cells, but NF-M could not form filaments with NF-H. alpha-internexin could coassemble with each of the neurofilament triplet proteins in the transfected cells to form filaments. When all but 2 and 10 amino acid residues were removed from the tail domains of NF-L and NF-M, respectively, the resulting NF-L and NF-M deletion mutants retained the ability to coassemble with alpha-internexin into filamentous networks. These mutants were also capable of forming filaments with other wild-type neurofilament triplet protein subunits. These results suggest that the tail domains of NF-L and NF-M are dispensable for normal coassembly of each of these proteins with other type IV intermediate filament proteins to form filaments.


1984 ◽  
Vol 246 (4) ◽  
pp. H566-H572 ◽  
Author(s):  
M. G. Price

Myocardial cells contain a cytoskeleton of intermediate filaments connecting the myofibrils. The present molecular analysis of the myocardial cytoskeleton was designed to identify the intermediate filament proteins and examine their assembly properties. The intermediate filament proteins desmin and vimentin were isolated from adult bovine myocardium by sequential extraction, urea solubilization, and chromatography on hydroxylapatite and DEAE columns. Desmin was obtained virtually pure in one peak and in a mixture of desmin and vimentin in the trailing fractions. Intermediate filaments of different morphologies polymerized in the desmin and the desmin-vimentin fractions. Isolated myocardial desmin occurs as three isozymes and isolated myocardial vimentin as two isozymes, which co-migrate on two-dimensional gels with corresponding isozymes from bovine skeletal and smooth muscle. Polypeptides of 200,000 and 220,000 daltons that fractionate with myocardial desmin and vimentin are also present in cytoskeletons of smooth and skeletal muscle. The results provide direct evidence that myocardial desmin can assemble to form intermediate filaments, suggesting that desmin is the major component of the cytoskeletal filaments in cardiomyocytes.


1984 ◽  
Vol 65 (1) ◽  
pp. 1-20
Author(s):  
P. Traub ◽  
C.E. Vorgias

When the intermediate filament proteins vimentin and desmin were reacted for a short period of time with the arginine-specific reagent 1,2-cyclohexanedione, the modification had a severe, inhibitory effect on the assembly of intermediate filaments and on the susceptibility of the basic, amino-terminal polypeptide of both proteins to degradation by the intermediate filament-specific, Ca2+-activated proteinase. However, it had only a slightly inhibitory effect on the binding of vimentin and desmin to ribosomal RNA from Ehrlich ascites tumour cells. Since the Ca2+-activated proteinase is very likely to be a trypsin-like enzyme, with a preference for arginyl and lysyl peptide bonds, the results indicate that the arginine residues of the amino-terminal polypeptide of vimentin and desmin are highly essential for filament assembly but largely dispensable for the binding of both proteins to nucleic acids. This was supported by the observation that two breakdown products of vimentin lacking a 5 X 10(3) Mr and an 8 X 10(3) Mr polypeptide from the amino terminus, respectively, did not assemble into intermediate filaments but were still capable of binding to rRNA. Both polypeptides also bound to single-stranded DNA-cellulose under non-denaturing conditions, but passed the affinity column in the presence of 6 M-urea. Thus, the binding of vimentin to nucleic acids appears to be based on two components: a non-specific electrostatic interaction mediated by the positively charged arginine residues of the amino-terminal polypeptide that is insensitive to denaturation by urea, and a specific interaction that is sensitive to denaturation by urea.


Planta ◽  
2004 ◽  
Vol 218 (6) ◽  
pp. 965-975 ◽  
Author(s):  
Gregory B. Clark ◽  
Stanley J. Roux ◽  
Sonal S. D. Blumenthal

2019 ◽  
Vol 30 (3) ◽  
pp. 357-369 ◽  
Author(s):  
Mansi Gujrati ◽  
Rohit Mittal ◽  
Lakhan Ekal ◽  
Ram Kumar Mishra

The architecture of the cytoskeleton and its remodeling are tightly regulated by dynamic reorganization of keratin-rich intermediate filaments. Plakin family proteins associate with the network of intermediate filaments (IFs) and affect its reorganization during migration, differentiation, and response to stress. The smallest plakin, periplakin (PPL), interacts specifically with intermediate filament proteins K8, K18, and vimentin via its C-terminal linker domain. Here, we show that periplakin is SUMOylated at a conserved lysine in its linker domain (K1646) preferentially by small ubiquitin-like modifier 1 (SUMO1). Our data indicate that PPL SUMOylation is essential for the proper reorganization of the keratin IF network. Stresses perturbing intermediate-filament and cytoskeletal architecture induce hyper-­SUMOylation of periplakin. Okadaic acid induced hyperphosphorylation-dependent collapse of the keratin IF network results in a similar hyper-SUMOylation of PPL. Strikingly, exogenous overexpression of a non-SUMOylatable periplakin mutant (K1646R) induced aberrant bundling and loose network interconnections of the keratin filaments. Time-lapse imaging of cells expressing the K1646R mutant showed the enhanced sensitivity of keratin filament collapse upon okadaic acid treatment. Our data identify an important regulatory role for periplakin SUMOylation in dynamic reorganization and stability of keratin IFs.


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