Kill1and Harald Herrmann3 1 Centre for Cell and Chromosome Biology, Division of Biosciences, Brunel University, London, UK 2 Institute for Medical Biochemistry, Vienna Biocenter, Austria
Trang 1The nuclear lamina
Both a structural framework and a platform for genome
organization
Joanna M Bridger1, Nicole Foeger2, Ian R Kill1and Harald Herrmann3
1 Centre for Cell and Chromosome Biology, Division of Biosciences, Brunel University, London, UK
2 Institute for Medical Biochemistry, Vienna Biocenter, Austria
3 Functional Architecture of the Cell, German Cancer Research Center (DKFZ), Heidelberg, Germany
Evolution of the intermediate filament
protein family
The nuclear lamina is a complex ensemble of proteins
that connects the inner nuclear membrane to
chroma-tin, and thus creates a link from the cytoplasm to the
genome The nuclear lamina has received much
atten-tion recently, because presently 220 mutaatten-tions have
been discovered within one of the constituent
polypep-tides, lamin A⁄ C, and these have been demonstrated
to be the cause of a number of severe human diseases,
termed laminopathies (for a recent review see [1])
Moreover, their down-regulation is associated with
specific cancers, such as lymphoma and leukaemia [2],
and lung cancer [3]
In contemporary metazoan cells the lamina is com-prised of fibrous polypeptides of the intermediate filament (IF) protein family, one type in lower phyla like cnidaria or nematodes and four major forms in mammals, designated A-type (lamin A and lamin C) and B-type (lamin B1 and lamin B2), in addition to an increasing number of associated proteins [4] Lamins were originally isolated from the high salt⁄ detergent-insoluble fractions of nuclear envelopes derived from rat liver and named according to their apparent molecular mass during SDS⁄ PAGE [5] Moreover, B-type lamins are acidic and A-type lamins are basic,
as revealed by isoelectric focusing in conventional two-dimensional polyacrylamide gel electrophoresis [6] Molecular cloning as well as their appearance in the
Keywords
chromosomal organization; fluorescence
in situ hybridization; intermediate filaments;
lamins; nuclear envelope
Correspondence
H Herrmann, B065 Functional Architecture
of the Cell, German Cancer Research
Center (DKFZ), Im Neuenheimer Feld 580,
D-69120 Heidelberg, Germany
Fax: +49 62214 23519
Tel: +49 62214 23512
E-mail: h.herrmann@dkfz-heidelberg.de
(Received 26 February 2006, accepted 8
January 2007)
doi:10.1111/j.1742-4658.2007.05694.x
The inner face of the nuclear envelope of metazoan cells is covered by a thin lamina consisting of a one-layered network of intermediate filaments inter-connecting with a complex set of transmembrane proteins and chromatin associating factors The constituent proteins, the lamins, have recently gained tremendous recognition, because mutations in the lamin A gene, LMNA, are the cause of a complex group of at least 10 different diseases in human, inclu-ding the Hutchinson–Gilford progeria syndrome The analysis of these dis-ease entities has made it clear that besides cytoskeletal functions, the lamina has an important role in the ‘behaviour’ of the genome and is, probably as a consequence of this function, intimately involved in cell fate decisions Fur-thermore, these functions are related to the involvement of lamins in organ-izing the position and functional state of interphase chromosomes as well as
to the occurrence of lamins and lamina-associated proteins within the nucleo-plasm However, the structural features of these lamins and the nature of the factors that assist them in genome organization present an exciting challenge
to modern biochemistry and cell biology
Abbreviations
IF, intermediate filament; LAP, lamina-associated protein; LBR, lamin B receptor.
Trang 2electron microscope indicated that they are bona fide
IF proteins, although distinct differences became clear
both from the amino acid sequences and electron
microscopic images [7–9] With the availability of
increasing sequence data for the IF multigene family,
they were grouped into the so-called sequence
homology class V, thereby distinguishing them from
the cytoplasmic class I acidic keratins, the class II basic
keratins, the class III desmin-like proteins and the class
IV neuronal IF proteins [10,11] In addition to carrying
a conventional nuclear localization signal, lamins differ
from the cytoplasmic IF proteins with respect to the
structural organization in the first half of their central
a-helical rod, which is 42 amino acids longer than that
of cytoplasmic IF proteins (for review see [12]) This
longer ‘rod’-version is also found in the cytoplasmic IF
proteins of lower invertebrates and this led, together
with data for the gene structure of various genes, to the
concept that lamins, though they were detected last,
were very probably the primordial IF proteins [13]
Hence, a speculative ancestral lamin gene stands at the
origin of the 65 IF genes that we know for human at
present [14] The fact that human harbours only three
genes for lamins – lamin A and C are derived by
splicing from one gene – in contrast to more than 50
genes for keratins, may indicate that they are conserved
with respect to the amino acid sequence for functional
reasons and so their number did not increase in a
corresponding fashion Only in the germ cells of several
vertebrates are additional spliced versions such as lamin
C2 and lamin B3 are found The fact that these special
lamins are expressed in spermatocytes and oocytes
possibly reflects the distinct organization of the nuclei
of these cells in general and chromatin in particular in
germ cells Indeed, alteration of chromosome
position-ing and reorganization of the genome is very noticeable
during porcine spermatogenesis [15], with
spermatogen-esis being perturbed in mice lacking A-type lamins [16]
A modulation of function, as required in various
differentiated cells, may therefore be accomplished
by a combination of various, differentially expressed
associated proteins within or near the inner nuclear
membrane [17] Nevertheless, complex multicellular
organisms such as Caenorhabditis elegans develop with
one B-type lamin in their various differentiated cells [1]
Fibrous proteins: Structural properties
and implications for function
Lamins contain a central, mainly a-helical rod of 350
amino acids with four subsegments able to form
coiled-coils with a like molecule in parallel orientation These
individual a-helical segments, coils 1A, 1B, 2A and 2B,
are separated from each other by short ‘linkers’ The first (L1) and the third (L2) linker are probably a-helical whereas the second, longer one (L12) is unstructured [18] Two such molecules are able to associate into an extended rod-like dimeric coiled-coil molecule of
50 nm length, and their formation has been demon-strated by glycerol spraying⁄ metal rotary shadowing EM techniques (for review see [19]) These experiments revealed also that the C-terminal domains of lamins form globular structures, which have recently been demonstra-ted by X-ray crystallography and NMR to be compact
Ig folds [20,21] Lamin dimers are stable under high pH and elevated salt conditions and this distinguishes them from cytoplasmic IF proteins such as vimentin, which form soluble, tetrameric complexes under low salt condi-tions, both at physiological and high pH At higher salt concentration, i.e., 150–250 mm, vimentin will, however, associate into higher assemblies and eventually filaments [22,23] Between the end of the a-helical rod and the Ig fold domain, a multitude of basic amino acids including
a conventional nuclear localization signal is found, which may interact with the acidic patches of the rod domain The non a-helical tail domain subsequent to the
Ig fold domain has been demonstrated to harbour chro-matin-binding activity in a short glycine-serine-threonine rich element near the carboxy-terminus [24]
Assembly, topogenesis and interaction partners
Assembly of intermediate filaments starts with the formation of coiled-coil dimers, which in the case of lamins preferentially associate head-to-tail to form extended threads of dimers [12,19] Whether this occurs during translation or post-translationally is unknown Moreover, it is completely unclear whether lamin B1 and lamin B2 associate into homodimers exclusively or if they are able – or even prefer – to form heterodimers With respect to the behaviour of lamins during mitosis, i.e., A-type lamins being found
in a soluble and B-type lamins in a membrane-bound form, it is rather safe to postulate that A- and B-type lamins segregate completely within the cell, at least at the dimeric level (Fig 1; see Fig 4 in [25]) Moreover, during embryogenesis B-type lamins suffice to facilitate proper development as demonstrated by gene targeting
of lamin A in mice [26] At what level lamin B1 and lamin B2 interact, is presently not known Due to the high sequence identity within the coiled-coil forming domain of both lamins, it may be safe to speculate that they are able to associate into mixed dimers With the onset of mitosis, the lamina is disassembled due
to specific phosphorylation reactions, and is, upon
Trang 3completion of mitosis, reorganized on the surface of
individual chromosomes together with inner nuclear
membrane proteins such as lamin B receptor (LBR),
emerin and lamina-associated protein (LAP)s ([27], for
review see [28,29]) Their function during this period of
the cell cycle is elusive It may be that this cell cycle
stage provides the cell with a possibility to reorganize
the nucleus, allowing genome organization within
nuc-lei to be drastically altered It is interesting to note that
if a quiescent state of chromosome positioning within
nuclei is enforced by serum starvation, it is not until
the next postmitotic G1 phase that the chromosomes
are found repositioned in a proliferating organization
[30]
Genome organization and the nuclear
lamina
One of the enigmatic suggested roles for lamins is
in genome organization, which could impact on
regulation of genome function, i.e., gene expression [31] Indeed, all the lamin subtypes have affinity for chromosomes, chromatin and⁄ or DNA [24,32–35] Because chromatin and the nuclear lamina exhibit an intimate spatial relationship, it has been suggested that chromosomes are anchored, at least to some extent, by the nuclear lamina [31,36] Chromosome positioning within nuclei is nonrandom and in human lympho-blasts and fibrolympho-blasts chromosomes are positioning according to their gene-density [37,38], with the most gene-poor chromosomes found at the nuclear periph-ery abutting the nuclear lamina (Fig 2) It is as yet unclear whether the nonrandom spatial positioning of the genome within nuclei is involved in controlling gene expression, but alterations in the level of tran-scription have been observed when specific loci change position within nuclei [39] On the other hand it may
be that chromosomes themselves do not move much within nuclei once they are positioned but specific gene sequences may be looped towards areas of the nucleus more amenable to transcription [31]
However, the question still remains as to whether the nuclear lamina anchors specific chromosomes within nuclei and whether this is relevant to the con-trol of gene expression We have assessed the posi-tioning of specific chromosomes within cells that do not appear to express A-type lamins and in human studies we find little difference in the positioning of four gene-poor chromosomes at the nuclear periphery
Fig 1 Solubility properties of lamins in human cultured cells.
(A) High salt ⁄ Triton X100 resistant fraction of SW13 cells (left lane)
and human dermal fibroblasts (right lane) separated on 20 cm long
10% polyacrylamaide gels [67] Lamins are indicated by dots
(A, B1, B2 and C from top to bottom), vimentin by an arrowhead.
Note the very low amount of lamins compared to the cytoplasmic
intermediate filament protein vimentin (B) Immunoblot of low
salt-soluble (lane 1), high salt-salt-soluble and high salt ⁄ Triton X100 resistant
protein fractions of SW13 cells Aliquot fractions were generated
according to a standard extraction protocol [67], separated by
elec-trophoresis on 10% polyacrylamide gels and either stained with
Coomassie Brilliant Blue (CBB) or blotted and immunostained
employing specific antibodies to lamin A (La A), lamin B1 (La B1),
lamin B2 (La B2) and LBR The right panels of the immunoblots
are longer exposures of the corresponding left panels Note that
lamin B1 is partially extracted into the low salt ⁄ Triton X100 fraction.
Fig 2 Chromosome territories A human nucleus with two individ-ual chromosome territories revealed after painting with a whole human chromosome painting probe by fluorescence in situ hybrid-ization (green) The total amount of the DNA is delineated by the fluorescent DNA stain DAPI (blue) Image from Ishita Mehta (Divi-sion of Biosciences, Brunel University, London, UK) Bar ¼ 10 lm.
Trang 4in lymphoblastoid cell lines from patients with
lam-in A mutations [40] One gene-poor chromosome
(chromosome 13), however, was found located away
from the nuclear periphery in two patient cell lines
Interestingly, the lamin A mutation in these two cell
lines was within a DNA⁄ chromatin binding domain
[35]
Further, we have found that in cells lacking A-type
lamins within the nuclear lamina, such as porcine
pri-mary ex vivo lymphocytes, there are fewer
chromo-somes located at the nuclear periphery Thus, in
porcine lymphocytes many of the chromosomes that
are normally located abutting the nuclear lamina in
other cell types containing A-type lamins, are located
away from the nuclear edge (Foster H, Griffin D and
Bridger J, unpublished data) Taken together these two
pieces of data could imply that in disease cells and
nondisease cells of the haemopoietic lineage lacking
A-type lamins, a distinct alteration in chromosome
anchorage at the nuclear periphery may occur The
role of the A-type lamin containing structures may not
be purely anchorage but there may be, in addition,
more subtle changes that are not elicited purely as
alternative chromosome location
We have determined phases and stages in a cell’s life
where chromosome positioning is completely altered
from that of a young proliferating cell, namely
quiescence [30] and senescence ([30,41]; Bridger J,
unpublished data) or in differentiating precursor cells,
i.e., in spermatogenesis [15] These drastic alterations
in chromosome positioning do coincide with changes
in lamin complement in spermatogenesis [42] and
poss-ible lamin interaction with chromatin in quiescence
[43] It is interesting to note that territories of
chromo-some 18, normally positioned at the nuclear periphery,
are repositioned to the nuclear interior in cells induced
to enter quiescence by serum starvation, but do not
relocate to the nuclear periphery until after a mitosis
following restimulation of the cells by the addition of
serum [30] Hence, chromosome 18 can probably
relocate in proliferating cells only because the
interac-tion with nuclear lamina components becomes possible
during the rebuilding of the nucleus at mitosis
In primary fibroblast cell lines derived from patients
with laminopathies, i.e., mutations in lamin A, we have
also observed major changes in chromosome
position-ing, away from the nuclear periphery, however, these
cells appear to have A-type lamins as part of the
nuc-lear lamina [41] These data assessing whole
chromo-some positioning support other studies in laminopathy
cell lines whereby chromatin is disorganized and
observed coming away from the nuclear periphery
[27,44–46] Chromatin disorganization is also seen in
C elegans worms that have their lamin expression down-regulated [47]
Despite the small amount of evidence one may hypothesize that nuclear lamin subtypes do play a role
in genome organization in the various cell cycle phases, life cycle stages, cell lineage and differentiation states
A functional interactive nuclear lamin network
Early investigations described the lamina as a 15 nm thick proteinaceous layer co-isolating with the nuclear pore complexes [48] Although electron microscopy of thin-sectioned nuclei of cells and tissues indicated the existence of a continuous layer of proteins apposed to the inner membrane of the nuclear envelope, in the vast majority of cells the nuclear lamina cannot be resolved as such a distinct structure separating the chromatin from the nuclear envelope However, in some special cell types of both invertebrate and verte-brate origin, a lamina of 30–300 nm isolating the inner nuclear membrane and chromatin can be visualized Most interestingly, in human synovial cells of patients suffering from rheumatoid arthritis, a 50–70 nm thick lamina containing lamin proteins can be observed [49] Both B-type and A-type lamins can be found not only at the nuclear periphery but also within nuclei localized as internal foci [50–52] Most attention has focused on the A-type lamin foci The function of these internal lamin sites is not really determined but they can also contain transcription factors [53] and important proteins associated with cell proliferation such as the retinoblastoma protein pRb [54] In addi-tion, these internal lamin structures contain lamina-associated protein 2a (LAP2a), a protein with distinct chromatin binding abilities [55] Thus, there are sites deep within nuclei that have putative chromatin⁄ chro-mosome binding and anchorage abilities There are even studies that display a networked filamentous structure anatomising through nuclei, namely the nuc-lear matrix, containing A-type lamins [56–58] It has been shown that even the internal lamin structures are affected in cells that contain mutation in the LMNA gene [59] Whether internal lamins are only found in particular foci or in a structured nuclear matrix is, however, still debated Nevertheless, both biochemical and microscopic data indicate that lamins are present throughout the nucleus Without knowing their ultra-structural state, one may consider that these lamin foci are anchor points for the genome and that they could
be involved in the control of genome function Such a
‘network’ comprised of lamins and chromatin could be thought of as ‘intelligent scaffolding’ (Fig 3) This
Trang 5net-work may furthermore be restructured dynamically
during different phases of the cell cycle and therefore
exhibit a different appearance in individual cells in
nonsynchronized cell cultures
Outlook
The nuclear lamins are a very interesting group of
structural proteins that appear to have many functions
Perhaps one of the most difficult to study functions is
the role within interphase genome organization and
their influence over genome function It appears from
our studies that A-type lamins influence chromosome
position within interphase nuclei How this happens and
what the consequences for genome function are remains
to be elucidated It is also plausible that the A-type
la-mins are not purely anchorage sites for the genome but
perhaps they are involved in a signalling pathway that is
perturbed in diseased cells, falsely changing the cellular
status and eliciting a reorganization of the genome
Indeed, signals received within the cytoplasm could be
translocated to the genome and translated by a linked
pathway of proteins from the cytoskeleton, across the
nuclear membrane to the nuclear lamin structures [60]
The existence of a structurally unified system consisting
of DNA, scaffold proteins and the surrounding
cytoske-leton has been proposed on the grounds of very
interest-ing data [61] Moreover, it has been hypothesized for many years that the cytoplasmic intermediate filament system is determining and supporting the position of the nucleus in the cell [62,63] Now, the recent identification
of an interaction between the outer nuclear membrane protein nesprin 3 and the intermediate filament-associ-ated protein plectin provides direct support for such a role [64] Moreover, as cytoplasmic proteins such as vimen-tin and plecvimen-tin are subject to multiple phosphorylation reactions [65,66], a link between the structural and the signalling state of the cytoskeleton with mechanisms that control gene expression is open for investigation
Acknowledgements
We wish to thank Peter Lichter for continuous interest and support JMB gratefully acknowledges support from Sygen International PLC and Brunel University
NF received a fellowship from the Schroedinger pro-gramme (FWF, Austria) HH wants to acknowledge funding from the European Union FP6 Life Science, Genomics and Biotechnology for Health area (LSHM-CT-2005018690) and the DKFZ-MOS program
References
1 Gruenbaum Y, Margalit A, Goldman RD, Shumaker
DK & Wilson KL (2005) The nuclear lamina comes of age Nat Rev Mol Cell Biol 6, 21–31
2 Agrelo R, Setien F, Espada J, Artiga MJ, Rodriguez M, Perez-Rosado A, Sanchez-Aguilera A, Fraga MF, Piris
MA & Esteller M (2005) Inactivation of the lamin A⁄ C gene by CpG island promoter hypermethylation in hematologic malignancies, and its association with poor survival in nodal diffuse large B-cell lymphoma J Clin Oncol 23, 3940–3947
3 Kaufmann SH, Mabry M, Jasti R & Shaper JH (1991) Differential expression of nuclear envelope lamins A and C in human lung cancer cell lines Cancer Res 51, 581–586
4 Schirmer EC & Gerace L (2005) The nuclear membrane proteome: extending the envelope Trends Biochem Sci
30, 551–558
5 Gerace L & Blobel G (1980) The nuclear envelope lamina is reversibly depolymerised during mitosis Cell
19, 277–287
6 Lehner CF, Kurer V, Eppenberger HM & Nigg EA (1986) The nuclear lamin protein family in higher vertebrates Identification of quantitatively minor lamin proteins by monoclonal antibodies J Biol Chem 261, 13293–13301
7 McKeon FD, Kirschner MW & Caput D (1986) Homologies in both primary and secondary structure
Fig 3 Hypothetical arrangement of lamins in the nucleus A
com-posite diagram showing the distribution of nuclear lamina and
inter-nal lamin structures in greyscale The network of filaments seen
within these structures is derived from the manipulated image of
an original figure in the seminal paper from Aebi and coworkers [9],
whereby the nuclear lamina is revealed by electron microscopy to
exist as a meshwork of filaments The genome is represented with
digital images of delineated chromosome territories that were
pain-ted with specific whole chromosome painting probes using
fluores-cence in situ hybridization.
Trang 6between nuclear envelope and intermediate filament
proteins Nature 319, 463–468
8 Fisher DZ, Chaudhary N & Blobel G (1986) cDNA
sequencing of nuclear lamins A and C reveals primary
and secondary structural homology to intermediate
fila-ment proteins Proc Natl Acad Sci USA 83, 6450–6454
9 Aebi U, Cohn J, Buhle L & Gerace L (1986) The
nuclear lamina is a meshwork of intermediate-type
fila-ments Nature 323, 560–564
10 Fuchs E & Weber K (1994) Intermediate filaments:
structure, dynamics, function, and disease Annu Rev
Biochem 63, 345–382
11 Herrmann H & Aebi U (2000) Intermediate filaments
and their associates: multi-talented structural elements
specifying cytoarchitecture and cytodynamics Curr Opin
Cell Biol 12, 79–90
12 Herrmann H & Aebi U (2004) Intermediate filaments:
molecular structure, assembly mechanism, and
integra-tion into funcintegra-tionally distinct intracellular scaffolds
Annu Rev Biochem 73, 749–789
13 Erber A, Riemer D, Hofemeister H, Bovenschulte M,
Stick R, Panopoulou G, Lehrach H & Weber K (1999)
Characterization of the Hydra lamin and its gene: a
molecular phylogeny of metazoan lamins J Mol Evol
49, 260–271
14 Herrmann H, Hesse M, Reichenzeller M, Aebi U &
Magin TM (2003) Functional complexity of
intermedi-ate filament cytoskeletons: from structure to assembly
to gene ablation Int Rev Cytol 223, 83–175
15 Foster HA, Abeydeera L, Griffin DK & Bridger JM
(2005) Non-random chromosome positioning in
mamma-lian sperm nuclei, with migration of the sex chromosomes
during late spermatogenesis J Cell Sci 118, 1811–1820
16 Alsheimer M, Liebe B, Sewell L, Stewart CL, Scherthan
H & Benavente R (2004) Disruption of spermatogenesis
in mice lacking A-type lamins J Cell Sci 117, 1173–1178
17 Worman HJ & Courvalin JC (2005) Nuclear envelope,
nuclear lamina, and inherited disease Int Rev Cytol 246,
231–279
18 Parry DAD & Steinert PM (1995) Intermediate Filament
Structure Springer-Verlag, Heidelberg
19 Stuurman N, Heins S & Aebi U (1999) Nuclear lamins:
their structure, assembly, and interactions J Struct Biol
122, 42–66
20 Dhe-Paganon S, Werner ED, Chi YI & Shoelson SE
(2002) Structure of the globular tail of nuclear lamin
J Biol Chem 277, 17381–17384
21 Krimm I, O¨stlund C, Gilquin B, Couprie J, Hossenlopp
P, Mornon JP, Bonne G, Courvalin JC, Worman HJ &
Zinn-Justin S (2002) The Ig-like structure of the
C-term-inal domain of lamin A⁄ C, mutated in muscular
dystro-phies, cardiomyopathy, and partial lipodystrophy
Structure 10, 811–823
22 Ip W, Hartzer MK, Pang YY & Robson RM (1985)
Assembly of vimentin in vitro and its implications
con-cerning the structure of intermediate filaments J Mol Biol 183, 365–375
23 Mu¨cke N, Wedig T, Burer A, Marekov LN, Steinert
PM, Langowski J, Aebi U & Herrmann H (2004) Mole-cular and biophysical characterization of assembly-star-ter units of human vimentin J Mol Biol 340, 97–114
24 Ho¨ger TH, Krohne G & Kleinschmidt JA (1991) Inter-action of Xenopus lamins A and LII with chromatin
in vitromediated by a sequence element in the carboxy-terminal domain Exp Cell Res 197, 280–289
25 Moir RD, Yoon M, Khuon S & Goldman RD (2000) Nuclear lamins A and B1: different pathways of assem-bly during nuclear envelope formation in living cells
J Cell Biol 151, 1155–1168
26 Sullivan T, Escalante-Alcalde D, Bhatt H, Anver M, Bhat N, Nagashima K, Stewart CL & Burke B (1999) Loss of A-type lamin expression compromises nuclear envelope integrity leading to muscular dystrophy J Cell Biol 174, 913–920
27 Ellenberg J & Lippincott-Schwartz J (1999) Dynamics and mobility of nuclear envelope proteins in interphase and mitotic cells revealed by green fluorescent protein chimeras Methods 19, 362–372
28 Gant TM & Wilson KL (1997) Nuclear assembly Annu Rev Cell Dev Biol 13, 669–695
29 Margalit A, Vlcek S, Gruenbaum Y & Foisner R (2005) Breaking and making of the nuclear envelope J Cell Biochem 95, 454–465
30 Bridger JM, Boyle S, Kill IR & Bickmore WA (2000) Re-modelling of nuclear architecture in quiescent and senescent human fibroblasts Curr Biol 10, 149–152
31 Foster HA & Bridger JM (2005) The nucleus and the genome: a marriage made by evolution Chromosoma
114, 212–219
32 Glass CA, Glass JR, Taniura H, Hasel KW, Blevitt JM
& Gerace L (1993) The alpha-helical rod domain of human lamins A and C contains a chromatin binding site EMBO J 12, 4413–4424
33 Goldberg M, Harel A, Brandeis M, Rechsteiner T, Richmond TJ, Weiss AM & Gruenbaum Y (1999) The tail domain of lamin Dm0 binds histones H2A and H2B Proc Natl Acad Sci USA 96, 2852–2857
34 Luderus ME, den Blaauwen JL, de Smit OJ, Compton
DA & van Driel R (1994) Binding of matrix attachment regions to lamin polymers involves single-stranded regions and the minor groove Mol Cell Biol 14, 6297– 6305
35 Stierle V, Couprie J, Ostlund C, Krimm I, Zinn-Justin
S, Hossenlopp P, Worman HJ, Courvalin JC &
Duband-Goulet I (2003) The carboxyl-terminal region common to lamins A and C contains a DNA binding domain Biochemistry 42, 4819–4828
36 Paddy MR, Belmont AS, Saumweber H, Agard DA & Sedat JW (1990) Interphase nuclear envelope lamins form a discontinuous network that interacts with only a
Trang 7fraction of the chromatin in the nuclear periphery Cell
62, 89–106
37 Croft JA, Bridger JM, Boyle S, Perry P, Teague P &
Bickmore WA (1999) Differences in the localization and
morphology of chromosomes in the human nucleus
J Cell Biol 145, 1119–1131
38 Boyle S, Gilchrist S, Bridger JM, Mahy N & Bickmore
WA (2001) The spatial relationship of human
chromo-somes within the nuclei of normal and emerin-mutant
cells Hum Mol Genet 10, 211–219
39 Misteli T (2004) Spatial positioning; a new dimension in
genome function Cell 119, 156
40 Meaburn KJ, Levy N, Toniolo D & Bridger JM (2005)
Chromosome Positioning is Largely Unaffected in
Lym-phoblastoid cell lines containing Emerin and A-type
Lamin Mutations Biochem Soc Trans 33, 1438–1440
41 Meaburn KJ (2005) The Role of Nuclear Architecture in
Genomic Instability, PhD Thesis, Brunel University,
London, UK
42 Alsheimer M & Benavente R (1996) Change of
karyo-skeleton during mammalian spermatogenesis: expression
pattern of nuclear lamin C2 and its regulation Exp Cell
Res 228, 181–188
43 Dyer JA, Kill IR, Pugh G, Quinlan RA, Lane EB &
Hutchison CR (1997) Cell cycle changes in A-type
lamin Associations detected in human dermal fibroblasts
using monoclonal antibodies Chromosome Res 5,
383–394
44 Sewry CA, Brown SC, Mercuri E, Bonne G, Feng L,
Camici G, Morris GE & Muntoni F (2001) Skeletal
muscle pathology in autosomal dominant
Emery-Dreifuss muscular dystrophy with lamin A⁄ C
mutations Neuropathol Appl Neurobiol 27, 281–290
45 Filesi I, Gullotta F, Lattanzi G, D’Apice MR, Capanni
C, Nardone AM, Columbaro M, Scarano G, Mattioli
E, Sabatelli P, et al (2005) Alterations of nuclear
envel-ope and chromatin organization in mandibuloacral
dys-plasia, a rare form of laminopathy Physiol Genomics
23, 150–158
46 Columbaro M, Capanni C, Mattioli E, Novelli G,
Par-naik VK, Squarzoni S, Maraldi NM & Lattanzi G
(2005) Rescue of heterochromatin organization in
Hutchinson-Gilford progeria by drug treatment Cell
Mol Life Sci 62, 2669–2678
47 Margalit A, Segura-Totten M, Gruenbaum Y & Wilson
KL (2005) Barrier to autointegration factor is required
to segregate and enclose chromosomes within the
nuclear envelope and assemble the nuclear lamina Proc
Natl Acad Sci USA 102, 3290–3295
48 Dwyer N & Blobel G (1976) A modified procedure for
the isolation of a pore complex-lamina fraction from rat
liver nuclei J Cell Biol 70, 581–591
49 Ho¨ger TH, Grund C, Franke WW & Krohne G (1991)
Immunolocalization of lamins in the thick nuclear lamina
of human synovial cells Eur J Cell Biol 54, 150–156
50 Bridger JM, Kill IR, O’Farrell M & Hutchison CJ (1993) Internal lamin structures within G1 nuclei of human dermal fibroblasts J Cell Sci 104, 297–306
51 Goldman AE, Moir RD, Montag-Lowy M, Stewart M
& Goldman RD (1992) Pathway of incorporation of microinjected lamin A into the nuclear envelope J Cell Biol 119, 725–735
52 Moir RD, Montaglowy M & Goldman RD (1994) Dyna-mic properties of nuclear lamins: Lamin B is associated with sites of DNA replication J Cell Biol 125, 1201–1212
53 Mattout-Drubezki A & Gruenbaum Y (2003) Dynamic interactions of nuclear lamina proteins with chromatin and transcriptional machinery Cell Mol Life Sci 260, 2053–2063
54 Markiewicz E, Dechat T, Foisner R, Quinlan RA & Hutchison CJ (2002) Lamin A⁄ C binding protein LAP2alpha is required for nuclear anchorage of retino-blastoma protein Mol Biol Cell 13, 4401–4413
55 Dechat T, Korbei B, Vaughan OA, Vlcek S, Hutchison
CJ & Foisner R (2000) Lamina-associated polypeptide 2alpha binds intranuclear A-type lamins J Cell Sci 113, 3473–3484
56 Hozak P, Sasseville AM, Raymond Y & Cook PR (1995) Lamin proteins form an internal nucleoskeleton
as well as a peripheral lamina in human cells J Cell Sci
108, 635–644
57 Barboro P, D’Arrigo C, Diaspro A, Mormino M, Alberti I, Parodi S, Patrone E & Balbi C (2002) Unra-veling the organization of the internal nuclear matrix: RNA-dependent anchoring of NuMA to a lamin scaf-fold Exp Cell Res 279, 202–218
58 Barboro P, D’Arrigo C, Mormino M, Coradeghini R, Parodi S, Patrone E & Balbi C (2003) An intranuclear frame for chromatin compartmentalization and higher-order folding J Cell Biochem 88, 113–120
59 Broers JLV, Kuijpers HJH, O¨stlund C, Worman HJ, Endert J & Ramaekers FCS (2005) Both lamin A and lamin C mutations cause lamina instability as well as loss of internal nuclear lamin organization Exp Cell Res 304, 582–592
60 Crisp M, Liu Q, Roux K, Rattner JB, Shanahan C, Burke B, Stahl PD & Hodzic D (2006) Coupling of the nucleus and cytoplasm: role of the LINC complex
J Cell Biol 172, 41–53
61 Maniotis AJ, Bojanowski K & Ingber DE (1997) Mechanical continuity and reversible chromosome disassembly within intact genomes removed from living cells J Cell Biochem 65, 114–130
62 Granger BL & Lazarides E (1982) Structural associa-tions of synemin and vimentin filaments in avian erythrocytes revealed by immunoelectron microscopy Cell 30, 263–275
63 Goldman RD, Goldman AE, Green KJ, Jones JC, Jones SM & Yang HY (1986) Intermediate filament net-works: organization and possible functions of a diverse
Trang 8group of cytoskeletal elements J Cell Sci Suppl 5, 69–
97
64 Wilhelmsen K, Litjens SH, Kuikman I, Tshimbalanga
N, Janssen H, van den Bout I, Raymond K &
Sonnen-berg A (2005) Nesprin-3, a novel outer nuclear
mem-brane protein, associates with the cytoskeletal linker
protein plectin J Cell Biol 171, 799–810
65 Herrmann H & Wiche G (1983) Specific in situ
phos-phorylation of plectin in detergent-resistant
cytoskele-tons from cultured Chinese hamster ovary cells J Biol Chem 258, 14610–14618
66 Matsuzawa K, Kosako H, Azuma I, Inagaki N & Inagaki M (1998) Possible regulation of intermediate filament proteins by Rho-binding kinases Subcell Biochem 31, 423–435
67 Herrmann H, Kreplak L & Aebi U (2004) Isolation, characterization, and in vitro assembly of intermediate filaments Methods Cell Biol 78, 3–24