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From the Institute for Biochemistry II*
and theDepartment of Dermatology,
Medical Faculty,University of Cologne, Cologne, Germany; the Department for ProteinChemistry,
Max-Planck Institute forBiochemistry, Martinsried, Germany; and the Laboratory of MarineBiology,
University Pierre and MarieCurie, Paris, France
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Abstract |
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 Top Abstract Materials and MethodsResultsDiscussionReferences |
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6ß4 integrin in tumor cells is weaker than in basal
keratinocytes of the epidermis. Moreover, although in the
epidermis 2ß1-integrin expression is restricted to the basal cell
layer, it is found in all neoplastic cells within the nodules.
Laminin 5 is present throughout the whole thickness of the basement
membrane-like zone whereas laminin 10 is restricted to the interface
adjacent to the tumor cells. Furthermore, laminin 5 is not
properly processed and most of the 3A and 
2 laminin chains remain
as 165-kd and 155-kd polypeptides, respectively. Mature laminin
5 is thought to be necessary for correct hemidesmosome and basement
membrane formation and its abnormal processing, as well as the
low expression of 6ß4 integrins, could explain the lack of
mature hemidesmosomes. Together, the results show that multiple
molecular defects, including alteration of laminin 5 and its
integrin receptors, contribute to structural aberrations of the
basement membrane and associated structures in
cylindromas.
6ß4, laminin 5, and collagen
VII.8-11
These represent important constituents of
specialized anchoring devices, the hemidesmosomes, which provide a
physical link between the epidermal and dermal
compartments.12
Laminins are a family of multifunctional molecules with a central role
in the organization and the physiology of basement
membranes.13,14
By interacting with cell surface receptors
of the integrin family, laminins are responsible for the anchorage of
cells and for the initiation of specific intracellular signals. Through
other interactions with extracellular matrix proteins, laminins are
involved in the architecture, the organization, and the stability of
basement membranes. At least three laminin isoforms are present at the
dermal-epidermal junction, the most abundant laminin 5 (3Aß32
), laminin 6 (3ß11 ), and laminin 10 (5ß11 ). Like
other laminins, their carboxy-terminal region is formed by the folding
of the chain into five globular domains, LG1 to LG5,13
that contain the binding sites for the 3ß1, 6ß1, and 6ß4
epithelial integrins.15-17
Because of variations in their
amino-terminal parts, these laminins differ in the binding to other
extracellular matrix proteins and in their integration into
architectural scaffolds. For instance, laminin 10 is thought to
polymerize whereas laminin 5 alone does not.14
Instead,
laminin 5 forms a dimer with laminin 6 or 718
and binds to
collagen VII.19,20
In addition, laminin 5 is synthesized
as a 460-kd precursor that is extracellularly converted into tissular
forms of 440- and 400-kd by enzymatic processing.21
A
first cleavage of the 3A chain occurs in front of the
carboxy-terminal domain LG422
and a second within the
amino-terminal domain IIIa,23
converting the 200-kd
precursor chain into 165- and 145-kd polypeptides, respectively.
Processing of the 155-kd 2 chain involves a cleavage within its
domain III leading to a 105-kd polypeptide by the removal of the
amino-terminal domains L4m and LE1 to LE3.23,24
Although
the structural and biological consequences of the processing are not
known, it can be intuitively hypothesized that it may impinge on the
function of laminin 5. In particular, removal of the carboxy-terminal
LG4 and LG5 domains may regulate the interaction between the 6ß4
integrin and laminin 5. Similarly, the amino-terminal processing of
laminin 5 may regulate the interactions with laminin 6 and collagen
VII.
The basal lamina outlining the cylindroma nodules is known to be altered at the ultrastructural level although it contains the same components as the basement membrane of the dermal-epidermal junction. To unravel the underlying molecular defects, we have examined in detail the laminin and integrin repertoire of cylindroma cells and tissues. Ultrastructural, biochemical, and immunological studies indicate an intrication of multiple defects. In particular, hemidesmosomes are not properly formed in cylindroma cells, laminin 5 is insufficiently processed and accumulates around the neoplastic nodules, and the integrin expression pattern of cylindroma cells resembles that of cells with high proliferation potential such as epidermal stem cells.
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Materials and Methods |
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TopAbstractMaterials and MethodsResultsDiscussionReferences |
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Skin biopsies from a patient affected with a sporadic form of cylindromatosis were obtained from surgical excisions of the affected areas at the Department of Dermatology. Some of the samples were immediately frozen in liquid nitrogen and stored at -80°C until used for embedding in tissue-freezing medium. Others were immersed in phosphate-buffered saline (PBS), pH 7.2, for cell cultures. Other samples were placed in a 3% solution of glutaraldehyde in PBS for further processing for histological examination and transmission electron microscopy. The patient signed the informed consent from the Department of Dermatology, University of Cologne, approved by the Institutional Commission of Ethics (Az. 9645/96).
Histology and Transmission Electron Microscopy
A portion of the tumor specimen was postfixed in Bouin fixative containing 75% (v:v) aqueous-saturated picric acid solution, 20% (v:v) formalin, and 5% (v:v) acetic acid for 24 hours and paraffin wax-embedded. Sections (5 µm) were prepared with an ultramicrotome (Reichert-Jung) and further processed for trichromatic Masson staining with hematoxylin, fuchsine-ponceau, molybdic orange-G, and light green successively. Another portion of the sample was washed with 0.1 mol/L Na-cacodylate/HCl, pH 7.4, postfixed (45 minutes) with 1% OsO4 in 0.15 mol/L Na-cacodylate/HCl, pH 7.4, dehydrated in graded ethanol and propylene oxide solutions, and embedded in Araldite resin. Ultrathin (60 to 80 nm) sections were prepared with an Ultracut (Reichert-Jung), contrasted with uranyl acetate and lead citrate, and observed with a Philips 201 transmission electron microscope operating at 80 kV.
Antibodies
For indirect immunofluorescence staining primary mouse monoclonal
antibodies against laminin chains included BM165 against 3, GB3
against 2 (Seralab), and 4C7 against native 5 chain (Life
Technologies). Affinity-purified rabbit antibodies were generated
against recombinant fragments of mouse laminin 5 produced in human
293-EBNA cells following established protocols.25
The
recombinant polypeptides (Figure 1)
included the amino-terminal 3AIIIa domain (position 1 to 212) and
carboxy-terminal modules LG4 and LG5 of the 3A chain, the
amino-terminal LN and LE portion of the ß3 chain (position 17 to
577), and the 2 chain modules L4m (position 185 to 461) and 2
LE4–6 (position 460 to 606). The characterization of fragments and
antibody specificity after affinity purification will be described
elsewhere.26
Integrin subunits were detected with mouse
monoclonal antibodies P1E6 against 2 , P1B5 against 3, P4C10
against ß1, and 3E1 against ß4 and rat monoclonal antibody GoH3
against 6 (all from Chemicon, Hofheim, Germany). Rabbit
polyclonal antibodies27
were used for immunofluorescence
detection of nidogen.
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3 (BM 165) or 2 (D4B5) chains (Chemicon) and with
a goat antibody against a carboxy-terminal peptide of the human ß3
(sc7651) chain (Santa Cruz, Heidelberg, Germany). Indirect Immunofluorescence Staining
The biopsied tumor tissue was placed in Tissue Tek OCT Compound (Sakura distributed by Vogel, Giessen, Germany) and snap-frozen in liquid nitrogen. Cryosections (5 µm) (cryostat CM3050; Leica Instruments, Nussloch, Germany) were blocked with 1% bovine serum albumin (Fraction V; Serva, Boehringer-Ingelheim, Germany) and incubated with primary antibodies followed by Cy3-conjugated antibodies against mouse, rabbit, or rat immunoglobulins (Jackson, distributed through Dianova, Hamburg, Germany). The histoslides were mounted in DAKO fluorescent mounting medium (DAKO, distributed by Dianova) and were observed with a laser confocal microscope (Leica).
Cell Cultures
Cylindroma cell cultures were initiated from excised tumor material. Tumors were dissected from overlying epidermis, minced, and dissociated by collagenase treatment (1 mg/ml; Sigma, Deisenhofen, Germany) in Dulbecco’s modified Eagle’s medium (DMEM) containing 10 mg/ml of bovine serum albumin (BSA) overnight at 37°C. The enzymatic digestion was stopped by diluting the suspension in DMEM and washing twice in PBS. The cell aggregates were further dissociated in 0.1% trypsin, 0.05% ethylenediaminetetraacetic acid in PBS for 15 minutes at 37°C. Trypsin was blocked by addition of fetal calf serum and the cell suspension was washed in DMEM. Normal human keratinocytes were isolated from post mortem skin as described previously.28 Briefly, after sterilization in betadine solution (10%) for 30 minutes and several washes in PBS, 0.3-mm thick split thickness skin was prepared and incubated in 0.6% trypsin, 0.05% ethylenediaminetetraacetic acid in PBS for 30 minutes at 37°C. The epidermis was separated from the underlying dermis with fine forceps and transferred to DMEM containing 10% fetal calf serum. Epidermal cells were released by gentle aspiration from keratinocyte sheets and a single cell suspension was obtained by filtration through nylon gauze. Dissociated cylindroma cells or normal keratinocytes were seeded at a density of 1 to 2.5 x 104 cells/cm2 on feeder layers of irradiated mouse 3T3 cells in culture medium consisting of DMEM and Ham’s F12 (3:1, v:v) supplemented with 5% fetal calf serum (Boehringer Mannheim, Mannheim, Germany), 5 µg/ml insulin, 1.8 x 10-4 mol/L adenine, 10-10 mol/L cholera toxin, 0.4 µg/ml hydrocortisone, 50 µg/ml ascorbic acid (all from Sigma Chemicals), and 10 ng/ml epidermal growth factor (Collaborative Research, Waltham, MA). Unlike normal human keratinocytes cylindroma cells grew first as tightly packed cell clumps eventually forming colonies. The medium was changed every 3 to 4 days until cells reached confluency. Conditioned medium was prepared by incubating confluent cylindroma cell and normal human keratinocyte cultures (second passage) with DMEM containing 50 µg/ml ascorbic acid for 48 hours. Centrifugation and sterile filtration removed cellular debris, NaN3 was added to 0.05% and supernatants were stored at -20°C.
Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis and Immunoblotting
Equal volumes of cell culture medium were mixed 1:1 (v/v) with Laemmli buffer and submitted to sodium dodecyl sulfate-polyacrylamide (4 to 10%) gel electrophoresis in the absence or presence of 5% ß-mercaptoethanol. The polypeptides were electrotransferred overnight (200 mA) to nitrocellulose membranes (Schleicher and Schuell, Dassel, Germany) in 50 mmol/L of borate buffer, pH 8.5, containing 5% methanol. For immunodetection, the nitrocellulose membranes were saturated with 5% milk powder and 0.1% Tween-20, and incubated with primary antibodies followed by peroxidase-conjugated secondary antibodies (DAKO). Bound immunoglobulins were revealed using an enhanced chemiluminescence kit (Amersham, Braunschweig, Germany). Measurement of band intensity by densitometry was performed with FastScan (Molecular Dynamics, Amersham Pharmacia Biotech) and calculations were made using ImageQuant software.
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Results |
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TopAbstractMaterials and MethodsResultsDiscussionReferences |
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Abnormalities of Hemidesmosomes and Enlargement of the Basal Lamina Surrounding Cylindromas
Observation of tissue sections by transmission electron microscopy
indicated that the extracellular material surrounding the cylindroma
nodules resembled a highly enlarged basement membrane, which agrees
with previous reports.8-10
At the ultrastructural level,
this basement membrane-like zone deviates, however, from a normal basal
lamina in several aspects. There was no clear distinction of a lamina
densa and most of the material appeared like a lamina lucida containing
numerous and abnormal inclusions of fibrillar material (Figure 2A
, white arrowheads). The most striking
hallmark of this basement membrane-like structure was its massive
enlargement when compared to the basement membrane of the
dermal-epidermal junction (Figure 2
, compare A and B). Precise
morphometric measurements indicated that the basement membrane-like
zone around cylindromas has a width ranging between 2.7 and 4.3 µm,
whereas that of the basement membrane at the dermal-epidermal junction
has an average thickness of 60 to 90 nm. Further, at a low-power
magnification hemidesmosomes were not distinctly seen in the tumor
cells abutting the basement membrane-like zone, whereas they were
clearly observed in basal keratinocytes of the epithelium (Figure 2B)
.
The plasma membrane of cylindroma cells facing the basal lamina was
rather linear (Figure 2A)
and did not present the typical invaginations
as those seen associated with the hemidesmosomes of basal keratinocytes
(Figure 2B)
. Examination at higher power magnification revealed that
hemidesmosomes with a heterogeneous morphology were present in cells
located at the periphery of the nodules but a lamina densa was not
clearly visible (Figure 3; B to E
). The
hemidesmosomes were irregularly spaced and displayed larger size
variation than those of the basal keratinocytes (Table 1)
. In addition, the number of
hemidesmosomes present along the surface of tumor cells facing the
basement membrane-like zone was approximately half that observed for
normal basal keratinocytes (Table 1)
.
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The basement membrane at the dermal-epidermal junction contains
several laminin isoforms, in particular laminins 5 and
10.15
Indirect immunofluorescence staining of tissue
sections with monoclonal antibodies BM165 against the laminin 3
(Figure 4A)
or GB3 against native 2
(not shown) revealed an intense and thick labeling circumscribing the
cylindromas, indicating that the entire thickness of the basement
membrane-zone delimiting the tumoral nests was heavily loaded with
laminin 5. By contrast, a monoclonal antibody against the laminin 5
chain stained the aspect of the basement membrane facing the tumor
cells only and not its whole thickness (Figure 4B)
. In this case, the
thin and linear staining observed was similar to that underneath the
epidermis on the same tissue section (Figure 4E)
. Immunofluorescence
detection of another basement membrane marker, nidogen, showed also a
thin and linear decoration of mainly the inner face of the basement
membrane surrounding the tumoral islands (Figure 4C)
, a staining
comparable to that of the laminin 5 chain. These observations
indicate that while in the basement membrane below the epidermis
laminin 5, laminin 10, and nidogen are strictly co-distributed, this is
not the case in the material surrounding the tumor nodules. Therein,
the three proteins are co-localized only in the region immediately
adjacent to the cells, whereas laminin 5 only is present throughout the
whole thickness of the basement membrane-like zone.
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Maturation of laminin 5 has been reported to require processing of
its 3A and 2 chains.23
To determine whether these
chains were processed in the basal lamina surrounding the cylindroma
nodules, domain-specific affinity-purified antibodies were used for
immunofluorescence staining of the tissue. Antibodies recognizing the
L4m (Figure 5A)
or the LG4-LG5 (Figure 5C)
domains present in unprocessed 2 or 3A chain, respectively,
decorated the periphery of the neoplastic lesions by a thin labeling
restricted to the interface where the tumor cell plasma membranes abut
the basal lamina, but they did not stain the dermal-epidermal junction
(Figure 5, E and G)
. This indicated that these domains are removed in
the laminin 5 deposited underneath the epidermis, but they are present
in the laminin 5 associated with the tumor cells. Antibodies against
domain LE4-6, which is retained in the processed form of the 2
chain, intensively stained the whole thickness of the basement
membrane-like zone delimiting the nodules (Figure 5B)
as well as a
thick line underneath the epidermis (Figure 5F)
. Finally an antibody
raised against domain IIIa of the 3A chain stained the whole
thickness of the zone surrounding the nodules (Figure 5D)
, while a thin
linear labeling of the dermal-epidermal junction was observed (Figure 5H)
. A similar staining was observed with an antibody specifically
recognizing the amino-terminal portion of the ß3 chain (not shown).
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3A and the 2 Chain of Laminin 5 Is Not
Processed in the Culture Medium of Cylindroma Cells
To test the ability of cylindroma cells to process laminin 5,
primary cultures of cylindroma cells and of human basal keratinocytes
were established. The presence of laminin 5 chains in the culture media
was analyzed by sodium dodecyl sulfate-polyacrylamide gel
electrophoresis followed by immunoblotting with specific antibodies.
Both type of cell culture media contained the 165- and 145-kd forms of
the laminin 3A chain (Figure 6A)
, the
140-kd ß3 chain (Figure 6C)
, and the 155- and 105-kd forms of the
2 chain (Figure 6, B and C)
. However, the amounts of fully processed
3A (145 kd) and 2 (105 kd) chains were consistently lower in the
medium of cylindroma cells than in the medium conditioned by basal
keratinocytes (Figure 6, A and B)
. Measurement of band intensity by
densitometry of the blots shown in Figure 6, A and B
, indicated that
the 145-kd form of the laminin 3A chain in the culture medium of
cylindroma cells or keratinocytes represented 17% and 39%,
respectively, of the total amount of laminin 3A chain (Figure 6D)
.
Similarly the 105-kd form of the 2 chain represented 43% and 80%
of the total amount of 2 polypeptides present in the medium of
cylindroma cells and keratinocytes, respectively (Figure 6E)
. These
results indicate that cylindroma cells have the capability to
synthesize and secrete laminin 5, but that the extent of processing of
both the 3A and 2 chains is decreased when compared to that
occurring in normal basal keratinocyte cultures.
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Integrins are involved in the deposition and organization of their
extracellular matrix ligands, including laminin 5.15
In
normal human epidermis, integrin expression is restricted to basal
epithelial cells and includes the 2ß1 and the 3ß1 at the
lateral cell plasma membranes and the 6ß4 integrin at the basal
surface of keratinocytes.29,30
The presence and the
distribution of these integrins was analyzed in cylindromas by indirect
immunofluorescence staining of tissue sections. Antibodies against the
6 and ß4 integrin subunits gave a linear staining restricted to
the periphery of all of the tumoral nodules (Figure 7, D and M)
. Comparison of integrin
immunostaining in cylindroma and at the dermal-epidermal junction
showed that for both integrin subunits the labeling was, however,
weaker for the tumoral cells (Figure 7, E and N)
than for the basal
keratinocytes of the epithelium (Figure 7, F and O)
. It indicated that
although expressed at a lower level in cylindromas than in the
epidermis, the 6 and ß4 subunits were correctly polarized at the
basal plasma membrane and likely to form a heterodimer associated with
its ligands in cylindroma cells such as in normal epidermal cells. The
integrin 3 chain was faintly stained in cylindroma cells in a manner
similar to that observed for basal keratinocytes (Figure 7; J to L
).
The antibodies against the 2 and ß1 integrin chains intensively
labeled all of the cylindroma nodules (Figure 7, A and G)
. Although the
pericellular localization of the 2 and ß1 integrin was identical
in cylindroma cells and keratinocytes, a major difference was that all
of the cells forming the neoplastic lesions were decorated by both
antibodies (Figure 7, B and H)
, whereas in the epidermis only the first
and second layers of epidermal cells were stained (Figure 7, C and I)
.
This suggests that all cylindroma cells display a basal cell phenotype
in term of 2ß1 integrin expression.
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Discussion |
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TopAbstractMaterials and MethodsResultsDiscussionReferences |
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In addition to a massive enlargement, the basement membrane-like zone
surrounding cylindromas is rather electron transparent with no clear
distinction of a lamina densa in agreement with previous reports. In
addition, we show here that, compared to the dermal-epidermal junction,
hemidesmosomes in cylindromas have a heterogeneous and abnormal
morphology and a twofold reduction in number. At the molecular level,
immunofluorescence staining shows the presence of laminin 5 in the
entire thickness of the basement membrane-like zone, whereas nidogen
and laminin 10 are restricted to the part immediately adjacent to
cylindroma cells. This indicates that the basal laminae around
cylindromas and at the dermal-epidermal junction differ in terms of
distribution of matrix molecules. Furthermore, a fraction of laminin 5
is not correctly processed into its mature forms in cylindroma tissue
and cultured cells. Immunofluorescence staining reveals that the
carboxy-terminal LG4-LG5 domains of the laminin 3A chain are
retained in the fraction of laminin 5 immediately associated with the
tumor cells. By contrast, these domains are absent from the
dermal-epidermal junction, which agrees with results showing that the
precursor form of the laminin 3A chain is processed into a 165-kd
polypeptide in tissue and in cell cultures.21,23,31
The
second processing of the 3A chain, ie, removal of the amino-terminal
domain IIIa, is also defective in cylindromas as shown by the presence
of this domain in the entire thickness of the basal lamina encircling
cylindromas. This is confirmed by immunoblotting analysis of the
laminin 3A chain showing less of the 145-kd form in the culture
medium of cylindroma cells compared to that of normal keratinocytes.
Conversion of the laminin 3A chain from a 165- to a 145-kd
polypeptide has been infrequently seen in keratinocyte
monocultures.21
This apparent discrepancy might be because
of the fact that, in this report, normal keratinocytes and cylindroma
cells were co-cultivated with fibroblasts, a culture condition that
favors processing of the laminin 3A chain (A El Khal, L Tunggal, N
Knöss, M Aumailley, manuscript in preparation) and that
reflects more closely the in vivo situation in which 50% of
laminin 5 is fully processed.21
A lack of processing is also observed for the laminin 2 chain in
cylindromas. Immunofluorescence labelings show the presence of the
amino-terminal domains of this chain, including domain L4m, in the
fraction of laminin 5 associated with cylindroma cells whereas they are
absent underneath the epidermis. By contrast, a strong staining of the
entire thickness of the basal lamina surrounding the neoplastic nests
and of the dermal-epidermal junction is observed with antibodies
against epitopes present in processed laminin 2 chain. It suggests
that the 2 chain is processed under basal keratinocytes but not in
cylindromas. This is confirmed by immunoblotting analysis showing that
more than half of the 2 chain remains as a 155-kd polypeptide in the
medium of cylindroma cells whereas a larger proportion is converted to
105-kd in the medium of keratinocytes. Together, these results
demonstrate that the processing of the laminin 3A and 2 chains is
impaired in cylindromas which results in the abnormal presence of
structural domains specific of immature laminin 5.
As emphasized by the phenotypes of patients affected with epidermolysis
bullosa junctionalis or resulting from site-directed mutagenesis in
mice, one of the most critical interactions required for the formation
and the stability of the dermal-epidermal junction is that occurring
between the 6ß4 integrin and the carboxy-terminus of laminin
5.32
In cylindroma cells, the expression of the 6ß4
integrin is slightly weaker than in basal keratinocytes (not shown),
suggesting a reduced number or a diminished clustering of the integrin.
Alternatively, the abnormal presence of domains LG4 and LG5 at the
carboxy-terminus of laminin 5 may sterically alter the interaction.
Furthermore, the amino-terminal region of laminin 5 develops
interactions with collagen VII and laminin 6 that are likely to be
important for the anchorage of laminin 5 to network-forming
extracellular matrix molecules located deeper in the basal lamina and
in the underlying dermis.19,20
The presence of the
uncleaved amino-terminus both in the 2 and the 3A chains may be a
steric hindrance to these interactions. The ectopic localization of
collagen VII within the basement membrane-like zone circumscribing the
neoplastic nodules (Bruckner-Tudermann et al10
; this
report) is in favor of that hypothesis. It is tempting to speculate
that the processing of the amino-terminal parts of the 3A and 2
chains are critical for the different interactions to occur and that
lack in the processing might impair the whole architecture of the basal
lamina and of the adhesion complexes including hemidesmosomes.
In addition to their role in the mechanical anchorage of cells to the
underlying basal lamina, integrins are involved in the formation of
basement membranes, including early embryonic and epidermal basal
lamina.33-36
The abnormalities discussed above, in
particular the presence of unprocessed laminin 5 directly at the
contact with cylindroma cells, could therefore trigger an altered
feed-back regulation loop leading to overproduction of laminin 5.
Although overproduction of laminin 5 was not observed in cell cultures,
it is obvious from the thickness and the immunofluorescence stainings
that an excess of laminin 5 has been produced in vivo by
cylindroma cells. Alternatively, the high expression of the 2ß1
integrins suggests that the differentiation stage of cylindroma cells
is different from that of normal keratinocytes. Up-regulation of ß1
integrins in suprabasal epithelial cells has been associated with
hyperproliferation37
and with cells of high proliferative
potential such as epidermal stem cells.38,39
Although the
profile of such cells in terms of extracellular matrix synthesis and
cell-matrix interactions is not known, it can be predicted that
de-localization out of their niche will result in an alteration of
their behavior. Finally, integrin function and cell-matrix interactions
primarily depend on the integrity of the cytoskeleton and of the
intracellular cell machinery. The gene mutated in cylindromatosis
encodes for a protein predicted to contain cytoskeletal-associated
protein-glycine-conserved (CAP-GLY) domains playing a role in the
organization of cellular microtubules and organelles.6
Absence of the product of the CYLD gene may be deleterious
for the intracellular architecture and machinery and consequently for
the interactions of integrins with their extracellular matrix ligands.
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Footnotes |
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Supported by the University of Cologne and grants from the Deutsche Forschungsgemeinschaft (Kr 558/10-1, Ti 95/8-1, Au 86/5-2, and Au 86/8-2) and BMFT/IDZ 10 (01 GB 950/4).
M. A. is a researcher from the Center National de la Recherche Scientifique.
Accepted for publication October 15, 2001.
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References |
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TopAbstractMaterials and MethodsResultsDiscussionReferences |
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3ß1, 6ß1 and 6ß4 integrins. J Cell Sci 2000, 113:869-876[Abstract]
3 chain. Biochem Biophys Res Commun 2000, 278:614-620[Medline]
2 chain. J Biol Chem 2000, 275:22728-227352 chain: structure, mechanism of processing and binding to heparin and proteins. J Mol Biol 2001, 314:751-763[Medline]
3ß1 in focal adhesions and 6ß4/bullous pemphigoid antigen in a new stable anchoring contact (SAC) of keratinocytes: relation to hemidesmosomes. J Cell Biol 1990, 111:3141-31543ß1 Integrin is required for normal development of the epidermal basement membrane. J Cell Biol 1997, 137:729-742This article has been cited by other articles:
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  C.-W. Franzke, C. Has, C. Schulte, L. Huilaja, K. Tasanen, M. Aumailley, and L. Bruckner-Tuderman C-terminal Truncation Impairs Glycosylation of Transmembrane Collagen XVII and Leads to Intracellular Accumulation J. Biol. Chem., October 6, 2006; 281(40): 30260 - 30268. [Abstract] [Full Text] [PDF]
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 K. Tasanen, L. Tunggal, G. Chometon, L. Bruckner-Tuderman, and M. Aumailley Keratinocytes from Patients Lacking Collagen XVII Display a Migratory Phenotype Am. J. Pathol., June 1, 2004; 164(6): 2027 - 2038. [Abstract] [Full Text] [PDF]
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A. Rattenholl, W. N. Pappano, M. Koch, D. R. Keene, K. E. Kadler, T. Sasaki, R. Timpl, R. E. Burgeson, D. S. Greenspan, and L. Bruckner-Tuderman Proteinases of the Bone Morphogenetic Protein-1 Family Convert Procollagen VII to Mature Anchoring Fibril Collagen J. Biol. Chem., July 12, 2002; 277(29): 26372 - 26378. [Abstract] [Full Text] [PDF]
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