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C M Lapière

Publications and source records attributed to C M Lapière.

At least 19 recordsLinked to original sources
PubMed2007

What are subcutaneous adipocytes really good for?

Our acute awareness of the cosmetic, psychosocial and sexual importance of subcutaneous adipose tissue contrasts dramatically with how poorly we have understood the biology of this massive, enigmatic, often ignored and much-abused skin compartment. Therefore, it is timely to recall the exciting, steadily growing, yet underappreciated body of evidence that subcutaneous adipocytes are so much more than just 'fat guys', hanging around passively to conspire, at most, against your desperate attempts to maintain ideal weight. Although the subcutis, quantitatively, tends to represent the dominant architectural component of human skin, conventional wisdom confines its biological key functions to those of energy storage, physical buffer, thermoregulation and thermoinsulation. However, already the distribution of human superficial adipose tissue, by itself, questions how justified the popular belief is that 'skin fat' (which actually may be more diverse than often assumed) serves primarily thermoinsulatory purposes. And although the metabolic complications of obesity are well appreciated, our understanding of how exactly subcutaneous adipocytes contribute to extracutaneous disease - and even influence important immune and brain functions! - is far from complete. The increasing insights recently won into subcutaneous adipose tissue as a cytokine depot that regulates innate immunity and cell growth exemplarily serve to illustrate the vast open research expanses that remain to be fully explored in the subcutis. The following public debate carries you from the evolutionary origins and the key functional purposes of adipose tissue, via adipose-derived stem cells and adipokines straight to the neuroendocrine, immunomodulatory and central nervous effects of signals that originate in the subcutis - perhaps, the most underestimated tissue of the human body. The editors are confident that, at the end, you shall agree: No basic scientist and no doctor with a serious interest in skin, and hardly anyone else in the life sciences, can afford to ignore the subcutaneous adipocyte - beyond its ample impact on beauty, benessence and body mass.

Adipocytes↗
PubMed2006

Establishment of stable human fibroblast cell lines constitutively expressing active Rho-GTPases.

Small GTP-binding proteins of the Rho family (RhoA, Cdc42, Rac1) regulate the organisation and the turnover of the cell's cytoskeleton and adhesion structures. A significant function of these cellular structures is to translate and counterbalance forces applied to, or generated by, cells in order to maintain homeostasis and control cell movement. We therefore hypothesised that Rho-GTPases are directly involved in cellular gravity perception and may participate in the alterations induced in microgravity. To define an adequate cellular model allowing to investigate this issue, we have established stable cell lines constitutively expressing active forms of either RhoA, Cdc42, or Rac1. The three cell lines differ by morphology and by their ability to form filopodia, lamellipodia, and bundles of actin stress fibers. Overexpression of the active form of either RhoA, Cdc42, or Rac1 is compatible with cell viability and does not affect cell population doubling time. Thus, our series of mutant cells appear well suited to gain further knowledge on the molecular mechanisms of cellular gravity perception.

Actin Cytoskeleton↗
PubMed2006

Effects of constitutively active GTPases on fibroblast behavior.

The GTP-binding proteins RhoA, Cdc42 and Rac1 regulate the organization and turnover of the cytoskeleton and cell-matrix adhesions, structures bridging cells to their support, and translating forces, external or generated within the cell. To investigate the specific requirements of Rho GTPases for biomechanical activities of clonal cell populations, we compared side-by-side stable lines of human fibroblasts expressing constitutively active (CA) RhoA, Cdc42 or Rac1. There was no marked effect of any CA GTPase on cell adhesion to different extracellular matrix proteins. Cell spreading was CA Rho GTPase specific and independent of the extracellular matrix proteins allowing adhesion. Mechanical properties were dramatically restricted by CA RhoA on bi- and in tri-dimensional surroundings, were boosted by CA Rac1 on bi-dimensional surroundings only, and were not or marginally affected by CA Cdc42. In conclusion, the action of Rho GTPases appears to depend on the task cells are performing.

Actins↗
PubMed2006

The in vitro influences of neurotensin on the motility characteristics of human U373 glioblastoma cells.

Astrocytic tumours are associated with dismal prognoses due to their pronounced ability to diffusely invade the brain parenchyma. Various neuropeptides, including gastrin, are able to modulate tumour astrocyte migration. While neurotensin has been shown to influence the proliferation of glioma cells and the migratory ability of a large set of other cell types, its role in glioma cell migration has never been investigated. Neurotensin-induced modifications to the motility features of human U373 glioblastoma cells therefore constitute the topic of the present study. We evidenced that three subtypes of neurotensin receptors (NTR1, NTR2 and NTR3) are expressed in U373 glioblastoma cells, at least as far as their mRNAs are concerned. Treating U373 tumour cells with 10 nM neurotensin markedly modified the morphological patterns of these cells and also profoundly altered the organization of their actin cytoskeletons. Pull-down assays revealed that neurotensin induced the activation in U373 cells of both Rac1 and Cdc42 but not RhoA. Scratch wound assays evidenced that neurotensin (0.1 and 10 nM) very significantly inhibited wound colonization by U373 cells cultured in the absence of serum. In addition, quantitative phase-contrast videomicroscopy analyses showed that neurotensin decreases the motility levels of U373 glioblastoma cells when these cells are cultured on plastic. In sharp contrast, neurotensin stimulates the motility of U373 cells when they are cultured on laminin, which is a pro-adhesive extracellular matrix component ubiquitously secreted by glioma cells. Our data thus strongly suggest that, in addition to gastrin, neurotensin is a neuropeptide capable of modulating tumour astrocyte migration into the brain parenchyma.

Actins↗
PubMed2001

Biochemical study of collagen in adult groin hernias.

BACKGROUND: Previous works have suggested that a defect in collagen fiber structure may play a role in inguinal hernia formation. These studies focused mainly on the rectus sheath or the skin, while only few reports dealt with the transversalis fascia. According to these findings and to our previous biomechanical and histological studies suggesting that a connective tissue pathology could play a role in the genesis of groin hernias, we performed a biochemical investigation of the collagen in the transversalis fascia and rectus sheath. MATERIALS AND METHODS: The samples were collected from 40 adult patients with uni- or bilateral hernias and from 20 control subjects without hernia (autopsies and organ donors). A constant area of tissue was taken by using a calibrator. The wet and dry weights per 100 mm(2) were determined and the total collagen concentration as well as its sequential extractibility in NaCl, acetic acid, and pepsin was measured. The ratios of alpha(1)/alpha(2) chains (I) and of type I/III collagen were assessed by polyacrylamide gel electrophoresis. RESULTS: Samples collected in the control and patient sheaths showed an increased wet weight per 100 mm(2) in the patients. The wet and dry weights per unit area were increased in the patient fascias. The collagen concentration was increased in the indirect hernias. The fascias from the direct hernias (DH) presented a significantly increased collagen extractibility after pepsin digestion (5.6%), when compared to the control fascias (2.6%). The extractibility was 3.4% in the nonherniated (NH) sides. The qualitative study (ratios alpha(1)/alpha(2) (I) and I/III collagen) showed no difference between the fascia groups. CONCLUSIONS: The significant increase of collagen extractibility with pepsin in the DH fascias and at a lesser degree in the NH fascias suggests that molecular alterations of collagen could be involved in the genesis of groin hernias. This connective tissue pathology would express preferentially its effects in the inguinal region, since we have observed no major difference between the rectus sheaths of controls and those of patients.

Adult↗
PubMed2001

Distinct pathways in the over-expression of matrix metalloproteinases in human fibroblasts by relaxation of mechanical tension.

The aim of the work was to analyze, on a comparative basis, the signaling pathways operating in the regulation of a panel of matrix metalloproteinases (MMP) expressed by human dermal fibroblasts submitted to mechanical stress relaxation by cytochalasin D (CD) and in a retracting collagen gel (RCG). The mRNA steady-state level of MMPs was measured by a quantitative RT-PCR procedure using a synthetic RNA as internal standard. In monolayer, most MMPs were barely detected, except MMP-2. Disruption of the actin stress fibers by CD induced a moderate increase of MMP-2 mRNA and a much larger stimulation of MMP-3, -9, -13 and -14 mRNAs. In RCG, a significant up-regulation of these MMPs was also observed although to a lower extent than in CD-treated monolayers. Among the investigated MMPs, the MMP-8 and -11 were not reproducibly detected. MMP-2 was processed to its active form both by CD and in RCG. The CD-induced up-regulation of gene expression was largely repressed by blocking protein synthesis by cycloheximide for all the MMPs, by inhibiting the tyrosine-kinases of the src family by herbimycin A for all MMPs, except MMP-2, and by inhibiting the TPA-inducible PKC isoforms by bisindoyl maleimide for all MMPs, except MMP-14. The up-regulation induced by stress relaxation in RCG was protein synthesis-dependent for MMP-2 and MMP-13, tyrosine kinases-dependent for MMP-3 and MMP-13, as previously described for MMP-1. Inhibiting TPA-inducible PKC did not affect any MMP in RCG except MMP-13, which was strongly induced. The processing of MMP-2 was tyrosine kinases-dependent but PKC-independent. Inhibitors of the ERK1,2 and p38 MAP kinases pathways diversely affected the MMPs expression. Inhibiting the Rho-kinase activity by Y-27632 was inactive. These results point to the potent regulation operated by the status of the cytoskeleton on the cell phenotype, and to distinct regulatory pathways involved in the control of different MMPs expression.

Animals↗
PubMed2001

Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis.

Ascorbic acid (vitamin C) is a cofactor required for the function of several hydroxylases and monooxygenases. It is not synthesized in humans and some other animal species and has to be provided by diet or pharmacologic means. Its absence is responsible for scurvy, a condition related in its initial phases to a defective synthesis of collagen by the reduced function of prolylhydroxylase and production of collagen polypeptides lacking hydroxyproline, therefore, they are unable to assemble into stable triple-helical collagen molecules. In fibroblast cultures, vitamin C also stimulates collagen production by increasing the steady-state level of mRNA of collagen types I and III through enhanced transcription and prolonged half-life of the transcripts. The aim of the experimental work has been to evaluate the effect on dermal cells of a preparation of vitamin C topically applied on one side vs placebo on the other side of the dorsal face of the upper forearm of postmenopausal women. Biopsies were collected on both sides and the level of mRNA measured by non competitive reverse transcription-polymerase chain reaction made quantitative by the simultaneous transcription and amplification of synthetic RNA used as internal standards. The mRNA of collagen type I and type III were increased to a similar extent by vitamin C and that of three post-translational enzymes, the carboxy- and amino-procollagen proteinases and lysyloxidase similarly increased. The mRNA of decorin was also stimulated, but elastin, and fibrillin 1 and 2 were not modified by the vitamin. The expression of matrix metalloproteinases 1, 2, and 9 was not significantly changed, but an increased level of tissue inhibitor of matrix metalloproteinase 1 mRNA was observed without modification of tissue inhibitor of matrix metalloproteinase 2 mRNA. The stimulating activity of topical vitamin C was most conspicuous in the women with the lowest dietary intake of the vitamin and unrelated to the level of actinic damage. The results indicate that the functional activity of the dermal cells is not maximal in postmenopausal women and can be increased.

Administration, Topical↗
PubMed2001

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

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.

Adolescent↗
PubMed2001

Apoptosis in v-myc-transfected MSU-1.1 fibroblasts is induced by cell-matrix contact and differs from that of normal dermal fibroblasts.

In order to characterize a fibroblast cell line representing normal human skin fibroblasts in three-dimensional cultures, we compared the fibroblast line MSU-1.1, derived from human foreskin and immortalized by v-myc, to primary human dermal fibroblasts (NDF). Our results demonstrate that in contrast to NDF, all MSU-1.1 fibroblasts die within 3-4 d when cultured within three-dimensional contractile collagen matrices. Also, in contrast to NDF. MSU-1.1 cells die markedly in anchored collagen gels as well. Death is due to apoptosis and is attenuated by addition of antibodies against collagen-recognizing receptors alpha1beta1 and alpha2beta1. Apoptosis of NDF in collagen lattices was repressed by an inhibitor of caspase-1, which was ineffective on apoptosis of MSU-1.1. Further, apoptosis by MSU-1.l fibroblasts was also observed in anchored, i.e., restrained collagen lattices, an environment that supports proliferation of NDF.

Animals↗
PubMed1999

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

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.

Alternative Splicing↗
PubMed1999

In vitro stimulation of human gingival epithelial cell attachment to dentin by surface conditioning.

BACKGROUND: Chemical root conditioning is widely used to improve the outcome of regenerative periodontal therapies by favoring the attachment of the regenerated periodontal structures. Although the effect of root conditioning on periodontal mesenchymal cells is well documented, very little is known about its potential effect on the re-formation of the junctional epithelium, a crucial event for the protection of the wound. The goal of the present study was to test in vitro the consequences of dentin conditioning with citric acid or minocycline on the attachment kinetics and morphology of human gingival keratinocytes (HGK). METHODS: The attachment kinetics of HGK to samples of powdered human dentin (particle size 44 to 76 microm) were examined by use of 3H-labeled cells. The morphology of attached epithelial cells was then determined by scanning electron microscopy (SEM). RESULTS: When the initial adhesion kinetics of cells on untreated dentin were tested, the percentage of attached HGK proved to be dependent on the number of plated cells and the time of incubation (from 0 to 12 hours). Conditioning the dentin by 3% citric acid or by minocycline-HCl (at 0.01, 0.1, or 2.5%) significantly increased (P <0.005) keratinocyte attachment beyond 6 hours, without notable differences between the 2 substances at any concentration. The attachment kinetics of HGK preincubated for 24 hours by 10 microg/ml minocyline-HCl on untreated dentin was found to be similar to that observed for non-preincubated cells. These results are in agreement with the SEM observations: indeed, the surface conditioning of dentin significantly modified the morphology of attached HGK, whereas the preincubation of these cells with minocyline-HCl did not. CONCLUSIONS: These results suggest that minocycline-HCl does not exert a direct effect on human gingival epithelial cells. In contrast, conditioning the dentin by citric acid or by minocycline stimulates the attachment of HGK, which could lead to a rapid periodontal healing by favoring the re-formation of a junctional epithelium.

Anti-Bacterial Agents↗
PubMed1998

Gelatinases in drug-induced toxic epidermal necrolysis.

BACKGROUND: The matrix metalloproteinases (MMPs) MMP2 and MMP9 play a significant role in epidermal detachment, inflammation and re-epithelialization. We have evaluated their activity in toxic epidermal necrolysis (TEN). DESIGN: The level and pattern of activity of MMP2 and MMP9 were investigated by measuring the degradation of 3H-labelled gelatin and by zymography in blister fluid from six TEN patients and compared the results with three other blistering conditions: bullous pemphigoid (n = 6), second-degree burn (n = 13) or suction blister (n = 3). RESULTS: A higher amount of MMP2 was found in TEN blister fluid with the constant presence of a significantly larger proportion of the activated forms of MMP2, a particular feature of TEN, than the other blistering diseases studied. CONCLUSION: This study emphasizes the potential role of MMP2 in the specific inflammatory reaction and reparation process in TEN skin.

Adult↗
PubMed1998

In vitro modulation of human gingival epithelial cell attachment and migration by minocycline-HCL.

Although the influence of tetracyclines on periodontal connective tissue cells has been the topic of many in vitro and in vivo studies, data regarding their effects on gingival epithelial cells are scarce. The present in vitro study was designed to examine the influence of minocycline, a semi-synthetic analog of tetracycline, on human gingival keratinocyte (HGK) attachment and migration. Attachment tests were performed with HGK prelabeled by tritiated amino-acids. Increasing concentrations of minocycline (10, 50, 100 micrograms/ml) in the medium produced no significant modification of cell adhesion kinetics compared to control conditions, except for 100 micrograms/ml which statistically significantly (p < 0.05) reduced the number of attached cells beyond 6 h. A 24-h cell preincubation in 10 micrograms/ml of minocycline did not alter the kinetics of HGK attachment. Scanning electron microscopic observations of attached HGK showed that the presence of 10 micrograms/ml of minocycline in the "attachment medium" induced the production of multiple filopodial extensions. Migration tests in Boyden chambers for 40 h demonstrated that HGK preincubation for 24 h in a 10 micrograms/ml minocycline-HCl solution increased significantly (p < 0.005) cell migration towards a gradient of fetal calf serum. The presence of 10 micrograms/ml of minocycline in contact with the keratinocytes in the upper compartment of the migration chambers also produced a significant (p < 0.005) result. In contrast, the presence of minocycline in the lower compartments did not produce any chemoattractive effect. Within the limits of their significance, these results suggest that, at concentrations not beyond 50 micrograms/ml, minocycline could fasten the periodontal wound coverage by epithelial cells and allow the normal reformation of a junctional epithelium.

Adolescent↗
PubMed1997

Angiogenesis by fibroblast growth factor 4 is mediated through an autocrine up-regulation of vascular endothelial growth factor expression.

The infection of normal mouse mammary EF43 cells by a retroviral vector carrying either Fgf-3 (EF43.Fgf-3) or Fgf-4 (EF43.Fgf-4) cDNA resulted in the transformation of cells displaying different tumorigenic potentials in nude mice (A. Hajitou and C-M. Calberg-Bacq, Int. J. Cancer, 63: 702-709, 1995). EF43.Fgf-4 produced rapidly developing tumors at all sites of inoculation, whereas EF43.Fgf-3 produced slowly growing tumors only in the mammary fat pad. Cells infected with the vector carrying the selection gene alone (EF43.C) were not tumorigenic. The angiogenic properties of these cells were tested in an in vitro angiogenesis model using human umbilical vein endothelial cells (HUVECs) cultured at the surface of a type I collagen gel and their capacity to form tube-like structures on invasion of the gel. Only the conditioned medium (CM) of EF43.Fgf-4 induced an angiogenic morphotype in HUVECs. In parallel, the mRNA expression of matrix metalloproteinase 1 and c-ETS-1 was increased in the HUVECs displaying a differentiated phenotype, whereas the tissue inhibitor of matrix metalloproteinase 1 mRNA level was decreased. Recombinant human fibroblast growth factor 4 (FGF-4) did not induce an angiogenic phenotype in HUVECs by itself. By Western blot analysis, a high expression of vascular endothelial growth factor (VEGF) was detected in the EF43.Fgf-4 CM. This result was confirmed by Northern blot analysis of total RNA extracted from the three cell types; the steady-state level of VEGF mRNA was low and equivalent in EF43.C and EF43.Fgf-3, whereas it was strongly increased in EF43.Fgf-4. Culturing EF43 cells carrying only the selection gene with increasing concentrations of recombinant human FGF-4 resulted in a dose-dependent stimulation of VEGF. The induction of the angiogenic morphotype and the parallel modulations of the biosynthetic phenotype in HUVECs were completely suppressed by adding a neutralizing antibody directed against VEGF to EF43.Fgf-4 CM. Furthermore, inhibition of protein kinase C by bisindoylmaleimide suppressed the angiogenic phenotype induced by the CM of EF43.Fgf-4. Our results point to an indirect angiogenic activity of FGF-4 through the autocrine induction of VEGF secretion by EF43.Fgf-4 cells, an original signaling pathway that might be significant in tumor progression and metastasis.

Animals↗
PubMed1997

cDNA cloning and expression of bovine procollagen I N-proteinase: a new member of the superfamily of zinc-metalloproteinases with binding sites for cells and other matrix components.

Procollagen N-proteinase (EC 3.4.24.14) cleaves the amino-propeptides in the processing of type I and type II procollagens to collagens. Deficiencies of the enzyme cause dermatosparaxis in cattle and sheep, and they cause type VIIC Ehlers-Danlos syndrome in humans, heritable disorders characterized by accumulation of pNcollagen and severe skin fragility. Amino acid sequences for the N-proteinase were used to obtain cDNAs from bovine skin. Three overlapping cDNAs had an ORF coding for a protein of 1205 residues. Mammalian cells stably transfected with a complete cDNA secreted an active recombinant enzyme that specifically cleaved type I procollagen. The protein contained zinc-binding sequences of the clan MB of metallopeptidases that includes procollagen C-proteinase/BMP-1. The protein also contained four repeats that are homologous to domains found in thrombospondins and in properdin and that can participate in complex intermolecular interactions such as activation of latent forms of transforming growth factor beta or the binding to sulfatides. Therefore, the enzyme may play a role in development that is independent of its role in collagen biosynthesis. This hypothesis was supported by the observation that in some tissues the levels of mRNA for the enzyme are disproportionately high relative to the apparent rate of collagen biosynthesis.

Amino Acid Sequence↗
PubMed1997

[Mechanism of the growth and rupture of abdominal aortic aneurysm].

The relationship between atherosclerosis and abdominal aortic aneurysm development is well known. Atherosclerosis cannot explain the whole mechanism. Genetic characters of mechanisms leading to abdominal aortic development is obvious from this study and others. Our study evidences an increased metalloproteases activity in aortic wall proportionally to the size of the abdominal aortic aneurysm. A decrease of aortic wall elastin is evidenced proportionally to the AAA size. Extractable collagen is significantly increased in the aortic wall of patients operated on for aortic rupture.

Age Factors↗