Coordinated regulation of procollagens I and III and their post-translational enzymes by dissipation of mechanical tension in human dermal fibroblasts.

in European Journal of Cell Biology (2001), 80(7), 479-85

Mechanical tension governs fibroblast proliferation and survival and the homeostasis of the extracellular matrix to adapt its resistance to the mechanical requirements of the organs. To consolidate this ... [more ▼]

Mechanical tension governs fibroblast proliferation and survival and the homeostasis of the extracellular matrix to adapt its resistance to the mechanical requirements of the organs. To consolidate this view, we analysed the effect of tension release on the expression of molecules involved in the architecture and stabilisation of the collagen fibres, namely the procollagens type I and III, the amino- and carboxy-procollagen peptidases (N-pCP and C-pCP) and lysyl oxidase. Cells were cultured in conditions of high mechanical stress in monolayer on a collagen coat and under reduced tension by disruption of the cytoskeleton upon treatment with cytochalasin D in monolayer on a collagen coat or by integrin-mediated stress relaxation in a freely retracting collagen gel. The mRNAs were measured by quantitative RT-PCR monitored by simultaneous reverse-transcription and amplification of an original internal standard. Tension relaxation resulted in a decreased expression of the procollagens type I and III, of the two expressed forms of C-pCP, of the two forms of N-pCP and of lysyl oxidase. Type III collagen, known to control diameter of the fibres, was less down-regulated than type I collagen. Interestingly, the expression of the two alternatively spliced forms of the N-pCP was dissimilarly regulated. These data suggest that mechanical tension may modulate the stiffness of the extracellular matrix by controlling not only the level of expression of its fibrillar constituents but also that of the enzymes participating in their extracellular processing and mechanical stabilisation. [less ▲]

Down-Regulation of MT1-MMP expression by the alpha3 chain of type IV collagen inhibits bronchial tumor cell line invasion

in Laboratory Investigation : Journal of Technical Methods & Pathology (2001), 81

The basement membrane (BM) is the first barrier encountered by tumor cells when they become invasive. Moreover, some invasive tumor clusters are surrounded by a remnant or neosynthetized BM material. We ... [more ▼]

The basement membrane (BM) is the first barrier encountered by tumor cells when they become invasive. Moreover, some invasive tumor clusters are surrounded by a remnant or neosynthetized BM material. We have previously reported the presence of a particular alpha chain of type IV collagen, the alpha3(IV) chain, in bronchopulmonary carcinomas. This chain was not detected in the normal bronchial epithelium, but was found around some invasive tumor cluster BM. In the present study, we examined the effects of the alpha3(IV) chain on the invasive properties of bronchial tumor cell lines, with special emphasis on their expression of matrix metalloproteinase-2 (MMP-2) and its activator, membrane type 1-matrix metalloproteinase (MT1-MMP), which is largely involved in tumor progression. Two epithelial bronchial cell lines (16HBE14o- and BZR), showing different invasive abilities, were evaluated. Using the Boyden chamber invasion assay, we demonstrated that the alpha3(IV) chain inhibits the invasive properties of BZR cells and modifies their morphology by inducing an epithelial cell shape. In the presence of the recombinant NC1 domain of the alpha3(IV) chain, the expression of MMP-2 and tissue inhibitor of metalloproteinase-2 (TIMP-2) was not modified in either cell line. The NC1 alpha3(IV) domain did not modulate the MT1-MMP expression of noninvasive 16HBE14o- cells, whereas a 50% decrease of MT1-MMP mRNA was observed in invasive BZR cells. Accordingly, Western blot analyses showed a disappearance of the 45-kd MT1-MMP form when BZR cells were treated with the recombinant NC1 alpha3(IV) domain. These findings suggest that the alpha3 chain of type IV collagen may play a role in tumor invasion, at least by decreasing the expression and synthesis of MT1-MMP. [less ▲]

Liquid crystalline ordering of procollagen as a determinant of three-dimensional extracellular matrix architecture.

in Journal of Molecular Biology (2000), 301(1), 11-7

The precise molecular mechanisms that determine the three-dimensional architectures of tissues remain largely unknown. Within tissues rich in extracellular matrix, collagen fibrils are frequently arranged ... [more ▼]

The precise molecular mechanisms that determine the three-dimensional architectures of tissues remain largely unknown. Within tissues rich in extracellular matrix, collagen fibrils are frequently arranged in a tissue-specific manner, as in certain liquid crystals. For example, the continuous twist between fibrils in compact bone osteons resembles a cholesteric mesophase, while in tendon, the regular, planar undulation, or "crimp", is akin to a precholesteric mesophase. Such analogies suggest that liquid crystalline organisation plays a role in the determination of tissue form, but it is hard to see how insoluble fibrils could spontaneously and specifically rearrange in this way. Collagen molecules, in dilute acid solution, are known to form nematic, precholesteric and cholesteric phases, but the relevance to physiological assembly mechanisms is unclear. In vivo, fibrillar collagens are synthesised in soluble precursor form, procollagens, with terminal propeptide extensions. Here, we show, by polarized light microscopy of highly concentrated (5-30 mg/ml) viscous drops, that procollagen molecules in physiological buffer conditions can also develop long-range nematic and precholesteric liquid crystalline ordering extending over 100 microm(2) domains, while remaining in true solution. These observations suggest the novel concept that supra-fibrillar tissue architecture is determined by the ability of soluble precursor molecules to form liquid crystalline arrays, prior to fibril assembly. [less ▲]

Human Ehlers-Danlos syndrome type VII C and bovine dermatosparaxis are caused by mutations in the procollagen I N-proteinase gene.

in American Journal of Human Genetics (1999), 65(2), 308-17

Ehlers-Danlos syndrome (EDS) type VIIC is a recessively inherited connective-tissue disorder, characterized by extreme skin fragility, characteristic facies, joint laxity, droopy skin, umbilical hernia ... [more ▼]

Ehlers-Danlos syndrome (EDS) type VIIC is a recessively inherited connective-tissue disorder, characterized by extreme skin fragility, characteristic facies, joint laxity, droopy skin, umbilical hernia, and blue sclera. Like the animal model dermatosparaxis, EDS type VIIC results from the absence of activity of procollagen I N-proteinase (pNPI), the enzyme that excises the N-propeptide of type I and type II procollagens. The pNPI enzyme is a metalloproteinase containing properdin repeats and a cysteine-rich domain with similarities to the disintegrin domain of reprolysins. We used bovine cDNA to isolate human pNPI. The human enzyme exists in two forms: a long version similar to the bovine enzyme and a short version that contains the Zn++-binding catalytic site but lacks the entire C-terminal domain in which the properdin repeats are located. We have identified the mutations that cause EDS type VIIC in the six known affected human individuals and also in one strain of dermatosparactic calf. Five of the individuals with EDS type VIIC were homozygous for a C-->T transition that results in a premature termination codon, Q225X. Four of these five patients were homozygous at three downstream polymorphic sites. The sixth patient was homozygous for a different transition that results in a premature termination codon, W795X. In the dermatosparactic calf, the mutation is a 17-bp deletion that changes the reading frame of the message. These data provide direct evidence that EDS type VIIC and dermatosparaxis result from mutations in the pNPI gene. [less ▲]

Modulation of expression and assembly of vinculin during in vitro fibrillar collagen-induced angiogenesis and its reversal.

in Experimental Cell Research (1996), 224(2), 215-23

A model of collagen-induced in vitro angiogenesis was used to investigate the modulation of expression and assembly of focal adhesion plaque-associated proteins during the process of differentiation ... [more ▼]

A model of collagen-induced in vitro angiogenesis was used to investigate the modulation of expression and assembly of focal adhesion plaque-associated proteins during the process of differentiation. Human umbilical vein endothelial cells (HUVEC), first attached on an adhesive substratum (gelatin-, fibronectin-, or laminin-coated dish) or adherent collagen gel and then covered by an overlaying collagen get, organized within 3-4 days in tube-like structures (TLS). Removing the overlaying collagen gel from fully differentiated HUVEC induced a reversion of the process and HUVEC returned to a monolayer pattern. Modulations of focal adhesion-associated proteins occurring in HUVEC during the in vitro differentiation process and its reversal were investigated by Western blot analysis. A significant decrease of expression of vinculin, the integrin alpha2 subunit, talin, alpha-actinin, and actin was observed in TLS whereas the amount of FVIII-related antigen did not vary as compared to control monolayer cultures. During reversal, all the reduced proteins were markedly reexpressed. Human skin fibroblasts (HSF), submitted to the same experimental conditions, did not form TLS. Most of the focal adhesion proteins in HSF were similarly modulated by an overlaying collagen gel with the exception of vinculin, which was not modified. This particular protein was therefore more thoroughly investigated. In a nondifferentiated monolayer of HUVEC, a significant proportion of vinculin was organized into a detergent-resistant juxtamembranous structure (focal adhesion plaque) which disassembled early in TLS formation and reassembled during the reversal of the process. The reduction of vinculin during TLS formation was preceded by a downregulation of its mRNA while this mRNA was upregulated during reversal of the morphotype. These results suggest that the modulations of the cytoskeletal and focal adhesion proteins and more specifically of vinculin coupled to its subcellular redistribution are critical and early events in the cascade of mechanochemical signaling during in vitro angiogenesis induced by fibrillar collagen. [less ▲]

Specific inhibition of expression of a human collagen gene (COL1A1) with modified antisense oligonucleotides. The most effective target sites are clustered in double-stranded regions of the predicted secondary structure for the mRNA.

in Biochemistry (1994), 33(36), 11033-9

A series of antisense oligonucleotides (ASOs) were synthesized and tested to define the best target sites within an RNA transcript of collagen for effective inhibition of expression. The test system ... [more ▼]

A series of antisense oligonucleotides (ASOs) were synthesized and tested to define the best target sites within an RNA transcript of collagen for effective inhibition of expression. The test system consisted of mouse NIH 3T3 fibroblasts that were stably transfected with a human minigene for procollagen I so that the cells simultaneously synthesized full-length mouse pro alpha 1 (I) chains and internally deleted human pro alpha 1 (I) chains. The sequences of the transcripts from both genes were compared, and a series of 28 ASOs were designed to target sites in which there were at least two base differences within a 20-nucleotide sequence between the human and mouse transcripts. Six of the ASOs specifically decreased the levels of pro alpha 1 (I) chain synthesized from the human gene without a decrease in the levels of pro alpha 1 (I) chains from the mouse endogenous gene. The most effective ASOs reduced the intracellular levels of human pro alpha 1 (I) chains relative to the mouse pro alpha 1 (I) chains to 37-67% of the control values. Combined addition of two effective ASOs or a second administration of the same effective ASO did not produce any additive effect. The results did not support previous suggestions that the best target sites for ASOs were sequences around initiation codons for translation, at intron-exon boundaries, or in single-stranded loops in hairpin structures. Also, the results did not support previous suggestions that the most effective ASOs are those with the highest affinities for their target sequences. Instead, the most consistent pattern in the data was that the most effective ASOs were those targeted to sequences that were predicted to form clustered double-stranded structures in RNA transcripts. [less ▲]

Use of an antisense oligonucleotide to inhibit expression of a mutated human procollagen gene (COL1A1) in transfected mouse 3T3 cells.

in Biochemistry (1993), 32(1), 7-11

A series of antisense oligonucleotides were developed to inhibit specifically expression of a mutated exogenous gene for collagen without inhibiting expression of an endogenous gene for the same protein ... [more ▼]

A series of antisense oligonucleotides were developed to inhibit specifically expression of a mutated exogenous gene for collagen without inhibiting expression of an endogenous gene for the same protein. The test system consisted of mouse NIH 3T3 cells that were stably transfected with an internally deleted construct of the human gene for the pro alpha 1(I) chain of type I procollagen [Olsen et al. (1991) J. Biol. Chem. 266, 1117]. The target site was a region at the 3' end of exon 1 and the first few nucleotides of intron 1 of the exogenous human gene that differed in sequence by nine nucleotides from the sequence of the endogenous mouse gene. Expression of the two genes was assayed by Western blot with cross-reacting antibodies and by steady-state levels of mRNAs. None of the oligonucleotides were effective in concentrations up to 25 microM when administered without any carrier. However, when administered with 5 or 10 micrograms/mL lipofectin, one of the oligonucleotides in concentrations of 0.1-0.2 microM inhibited expression of the exogenous gene from 50% to 80% without significant inhibition of expression of the endogenous gene. Also, a missense version of the same oligonucleotide had no significant effect, and the inhibition observed with the most effective oligonucleotide was abolished by a single base change. Time course experiments indicated that, after a 4-h treatment, inhibition appeared at 8 h and persisted for at least 22 h.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

Effect of cell-cell and cell-matrix interactions on the response of fibroblasts to epidermal growth factor in vitro. Expression of collagen type I, collagenase, stromelysin and tissue inhibitor of metalloproteinases.

in Biochemical Journal (1992), 285 ( Pt 1)

Investigations of the effect of epidermal growth factor (EGF) on the expression of four genes involved in the turnover of the extracellular matrix, collagen type I, collagenase, stromelysin and tissue ... [more ▼]

Investigations of the effect of epidermal growth factor (EGF) on the expression of four genes involved in the turnover of the extracellular matrix, collagen type I, collagenase, stromelysin and tissue inhibitor of metalloproteinases (TIMP) were performed on four strains of skin fibroblasts in vitro. Addition of EGF to subconfluent cultures for increasing periods of time up to 5 days induced an inhibition of procollagen alpha 1(I) mRNA and a strong stimulation of collagenase (100-fold) and stromelysin (1000-fold) mRNAs, whereas the mRNA of TIMP was increased to a lesser extent (5-fold). After a 40 h pulse with EGF, these effects persisted for 24-48 h after withdrawal of the growth factor and slowly diminished thereafter to attain control values after several days. By culturing fibroblasts for increasing periods of time, different levels of confluence were obtained allowing for the deposition of an extracellular biomatrix. The steady-state level of collagenase and stromelysin mRNAs were profoundly depressed in confluent as against non-confluent cultures, whereas no major change for TIMP and procollagen alpha 1(I) mRNAs was observed. Upon treatment of these cultures with EGF for 48h, the steady-state level of collagenase, stromelysin and TIMP increased, whereas procollagen alpha 1(I) mRNA was slightly reduced. These modifications were, at least in part, dependent upon a regulation of the transcription rate, as suggested from run-off experiments. Similar states of confluence were obtained by seeding cells at increasing densities in short-term cultures in which cell-cell contact predominated. In such culture conditions, the collagenase and stromelysin mRNAs were enhanced in high as compared to low density cultures. The response to EGF was progressively decreased for collagenase, stromelysin and, to a lesser extent, TIMP mRNAs at most densities and a complete lack of response to EGF at the highest cell density was observed. Under all culture conditions the modulation of collagenase mRNA was paralleled by similar modifications of enzyme activity. These results emphasize the importance of the cell-cell contacts and cell-matrix interactions in the expression of the genes coding for metalloproteinases or their inhibitor and their modulation by growth factors. [less ▲]

Immunohistochemical expression of epidermal growth factor receptors in nuclei of a subpopulation of keratinocytes and sweat gland cells.

in Dermatologica (1991), 183(1), 7-9

We have raised a polyclonal antibody to the 170-kD epidermal growth factor receptor. We found an intercellular pattern of immunoreactivity in the epidermis as well as a positivity of the cytoplasm of ... [more ▼]

We have raised a polyclonal antibody to the 170-kD epidermal growth factor receptor. We found an intercellular pattern of immunoreactivity in the epidermis as well as a positivity of the cytoplasm of keratinocytes and eccrine secretory cells. In some samples, a nuclear labelling was evidenced in these type of cells. There is a close resemblance in the topographical distribution of these cells with nuclear labelling and those synthesizing DNA under phytohaemagglutinin stimulation. [less ▲]

Response to Epidermal Growth Factor of Skin Fibroblasts from Donors of Varying Age Is Modulated by the Extracellular Matrix

in Journal of Cellular Physiology (1990), 145(3), 450-7

The present study was undertaken to investigate the effect of epidermal growth factor (EGF) on the biosynthetic activity of skin fibroblasts from donors of varying age and the modulation of their response ... [more ▼]

The present study was undertaken to investigate the effect of epidermal growth factor (EGF) on the biosynthetic activity of skin fibroblasts from donors of varying age and the modulation of their response to this growth factor by culture in a three-dimensional extracellular matrix. When cultured in monolayer on plastic or at the surface of a collagen gel, EGF specifically inhibited collagen synthesis whatever the age of the donor (from 17 to 84 years, n = 11). This inhibition was paralleled by a significant decrease in the steady-state level of procollagen type I mRNAs. When embedded in a three-dimensional floating collagen lattice, EGF stimulated the non-collagen protein (NCP) synthesis in fibroblasts from younger donors (5 out of 6) while fibroblasts from the older ones were not affected. Collagen production by fibroblasts from younger donors was not inhibited as in monolayer (some being even stimulated) while that of the older donors was inhibited as observed in monolayer. The steady-state level of procollagen type I mRNA was not modified by EGF in the three-dimensional culture. No significant difference was observed in the affinity and the number of EGF receptors of the fibroblasts on plastic or embedded in a collagen lattice between young and aged donors. Our results suggest that the environment of the cells can modulate the reactivity to EGF and reveal differences related to in vivo aging. [less ▲]