scholarly journals Non-muscle alpha-dystroglycan is involved in epithelial development.

1995 ◽  
Vol 130 (1) ◽  
pp. 79-91 ◽  
Author(s):  
M Durbeej ◽  
E Larsson ◽  
O Ibraghimov-Beskrovnaya ◽  
S L Roberds ◽  
K P Campbell ◽  
...  

The dystroglycan complex is a transmembrane linkage between the cytoskeleton and the basement membrane in muscle. One of the components of the complex, alpha-dystroglycan binds both laminin of muscle (laminin-2) and agrin of muscle basement membranes. Dystroglycan has been detected in nonmuscle tissues as well, but the physiological role in nonmuscle tissues has remained unknown. Here we show that dystroglycan during mouse development in nonmuscle tissues is expressed in epithelium. In situ hybridization revealed strong expression of dystroglycan mRNA in all studied epithelial sheets, but not in endothelium or mesenchyme. Conversion of mesenchyme to epithelium occurs during kidney development, and the embryonic kidney was used to study the role of alpha-dystroglycan for epithelial differentiation. During in vitro culture of the metanephric mesenchyme, the first morphological signs of epithelial differentiation can be seen on day two. Northern blots revealed a clear increase in dystroglycan mRNA on day two of in vitro development. A similar increase of expression on day two was previously shown for laminin alpha 1 chain. Immunofluorescence showed that dystroglycan is strictly located on the basal side of developing kidney epithelial cells. Monoclonal antibodies known to block binding of alpha-dystroglycan to laminin-1 perturbed development of epithelium in kidney organ culture, whereas control antibodies did not do so. We suggest that the dystroglycan complex acts as a receptor for basement membrane components during epithelial morphogenesis. It is likely that this involves binding of alpha-dystroglycan to E3 fragment of laminin-1.

2000 ◽  
Vol 113 (2) ◽  
pp. 259-268 ◽  
Author(s):  
M. Aumailley ◽  
M. Pesch ◽  
L. Tunggal ◽  
F. Gaill ◽  
R. Fassler

Basement membranes are the earliest extracellular matrices produced during embryogenesis. They result from synthesis and assembly into a defined supramolecular architecture of several components, including laminins, collagen IV, nidogen, and proteoglycans. In vitro studies have allowed us to propose an assembly model based on the polymerisation of laminin and collagen IV in two separate networks associated together by nidogen. How nucleation of polymers and insolubilisation of the different components into a basement membrane proceed in vivo is, however, unknown. A most important property of several basement membrane components is to provide signals controling the activity of adjacent cells. The transfer of information is mediated by interactions with cell surface receptors, among them integrins. Mouse genetics has demonstrated that the absence of these interactions is not compatible with development as deletion of either laminin (gamma)1 chain or integrin (beta)1 chain lead to lethality of mouse embryos at the peri-implantation stage. We have used embyoid bodies as a model system recapitulating the early steps of embryogenesis to unravel the respective roles of laminin and (beta)1 integrins in basement membrane formation. Our data show that there is formation of a basal lamina in wild-type, but not in (beta)1-integrin deficient, embryoid bodies. Surprisingly, in the absence of (beta)1 integrins, laminin 1 was not secreted in the extracellular space due to a rapid switch off of laminin (alpha)1 chain synthesis which normally drives the secretion of laminin heterotrimers. These results indicate that (beta)1 integrins are required for the initiation of basement membrane formation, presumably by applying a feed-back regulation on the expression of laminin (alpha)1 chain and other components of basement membranes.


1997 ◽  
Vol 136 (2) ◽  
pp. 433-444 ◽  
Author(s):  
Rong-Rong Wu ◽  
John R. Couchman

Basement membranes contain several proteoglycans, and those bearing heparan sulfate glycosaminoglycans such as perlecan and agrin usually predominate. Most mammalian basement membranes also contain chondroitin sulfate, and a core protein, bamacan, has been partially characterized. We have now obtained cDNA clones encoding the entire bamacan core protein of Mr = 138 kD, which reveal a five domain, head-rod-tail configuration. The head and tail are potentially globular, while the central large rod probably forms coiled-coil structures, with one large central and several very short interruptions. This molecular architecture is novel for an extracellular matrix molecule, but it resembles that of a group of intracellular proteins, including some proposed to stabilize the mitotic chromosome scaffold. We have previously proposed a similar stabilizing role for bamacan in the basement membrane matrix. The protein sequence has low overall homology, apart from very small NH2- and COOH-terminal motifs. At the junctions between the distal globular domains and the coiled-coil regions lie glycosylation sites, with up to three N-linked oligosaccharides and probably three chondroitin chains. Three other Ser-Gly dipeptides are unfavorable for substitution. Fusion protein antibodies stained basement membranes in a pattern commensurate with bamacan, and they also Western blotted bamacan core protein from rat L2 cell cultures. The antibodies could also specifically immunoprecipitate an in vitro transcription/translation product from a full-length bamacan cDNA. The unusual structure of this proteoglycan is indicative of specific functional roles in basement membrane physiology, commensurate with its distinct expression in development and changes in disease models.


1997 ◽  
Vol 272 (3) ◽  
pp. L494-L503
Author(s):  
L. Chen ◽  
V. Shick ◽  
M. L. Matter ◽  
S. M. Laurie ◽  
R. C. Ogle ◽  
...  

Cell adhesion to amino acids 2179-2198 (SN-peptide) of the laminin-1 alpha1-chain is required for lung alveolar formation in vitro (M. L. Matter and G. W. Laurie. J. Cell Biol. 124: 1083-1090, 1994). The nature of the SN-peptide receptor(s) was probed with neutralizing anti-integrin monoclonal antibodies (MAb), cells lacking integrin subunits, soluble heparin, and SN-peptide columns. Cell adhesion and spreading studies confirmed the specificity of SN-peptide and revealed adhesion to be unaffected by inclusion of anti-beta1-, anti-alpha(2-6)- or anti-alpha(V)beta5-integrin MAb. Cells lacking beta1- or alpha6-integrin subunits were fully adherent. Adhesion was heparin, but not chondroitin sulfate or heparinase, sensitive, much as is alpha-dystroglycan-laminin-1 binding. Heparin eluted approximately 155- and 180-kDa cell-surface proteins from SN-peptide columns. An additional approximately 91-kDa protein was eluted by EDTA. All were unrecognized by anti-beta1-integrin MAb. SN-peptide therefore interacts with three cell-surface proteins for which the identity remains to be determined.


1996 ◽  
Vol 270 (6) ◽  
pp. C1743-C1750 ◽  
Author(s):  
G. W. Laurie ◽  
J. D. Glass ◽  
R. A. Ogle ◽  
C. M. Stone ◽  
J. R. Sluss ◽  
...  

Regulated secretion requires the developmental coupling of neuronal or hormonal stimuli to an exocytotic response, a multistep pathway whose appearance may be linked with cellular adhesion to the newly formed exocrine cell basement membrane. We screened for adhesion-associated coupling activity using lacrimal acinar cells and have identified “BM180”, a novel basement membrane protein enriched in guanidine HCl extracts of lacrimal and parotid exocrine secretory glands. BM180 resides primarily in a previously inexamined lower molecular-mass basement membrane peak (peak 2) that contains cell adhesion activity inhibitable with the anti-BM180 monoclonal antibody 3E12. Removal of peak 2 by gel filtration or preincubation of basement membrane with 3E12 decreased regulated peroxidase secretion by one-half without affecting constitutive secretion or the amount of cellular peroxidase available for release. Adding back peak 2 restored regulated secretion in a dose-dependent and 3E12-inhibitable manner and suggested a synergistic relationship between BM180 and laminin 1. BM180 has a mobility of 180 and 60 kDa in the absence or presence of dithiothreitol, respectively, and shows no immunological identity by competitive enzyme-linked immunosorbent assay with laminin 1, collagen IV, entactin, fibronectin, BM-40, perlecan, or vitronectin. We propose that BM180 is an important resident of certain glandular basement membranes where it interacts with the cell surface, thereby possibly signaling the appearance of a transducing element in the stimulus-secretion coupling pathway.


2002 ◽  
Vol 22 (5) ◽  
pp. 1474-1487 ◽  
Author(s):  
Ulf Dahl ◽  
Anders Sjödin ◽  
Lionel Larue ◽  
Glenn L. Radice ◽  
Stefan Cajander ◽  
...  

ABSTRACT The distinct expression of R-cadherin in the induced aggregating metanephric mesenchyme suggests that it may regulate the mesenchymal-epithelial transition during kidney development. To address whether R-cadherin is required for kidney ontogeny, R-cadherin-deficient mice were generated. These mice appeared to be healthy and were fertile, demonstrating that R-cadherin is not essential for embryogenesis. The only kidney phenotype of adult mutant animals was the appearance of dilated proximal tubules, which was associated with an accumulation of large intracellular vacuoles. Morphological analysis of nephrogenesis in R-cadherin −/− mice in vivo and in vitro revealed defects in the development of both ureteric bud-derived cells and metanephric mesenchyme-derived cells. First, the morphology and organization of the proximal parts of the ureteric bud epithelium were altered. Interestingly, these morphological changes correlated with an increased rate of apoptosis and were further supported by perturbed branching and patterning of the ureteric bud epithelium during in vitro differentiation. Second, during in vitro studies of mesenchymal-epithelial conversion, significantly fewer epithelial structures developed from R-cadherin −/− kidneys than from wild-type kidneys. These data suggest that R-cadherin is functionally involved in the differentiation of both mesenchymal and epithelial components during metanephric kidney development. Finally, to investigate whether the redundant expression of other classic cadherins expressed in the kidney could explain the rather mild kidney defects in R-cadherin-deficient mice, we intercrossed R-cadherin −/− mice with cadherin-6−/− , P-cadherin −/−, and N-cadherin +/− mice. Surprisingly, however, in none of the compound knockout strains was kidney development affected to a greater extent than within the individual cadherin knockout strains.


1996 ◽  
Vol 133 (2) ◽  
pp. 417-430 ◽  
Author(s):  
A De Arcangelis ◽  
P Neuville ◽  
R Boukamel ◽  
O Lefebvre ◽  
M Kedinger ◽  
...  

The expression of the constituent alpha 1 chain of laminin-1, a major component of basement membranes, is markedly regulated during development and differentiation. We have designed an antisense RNA strategy to analyze the direct involvement of the alpha 1 chain in laminin assembly, basement membrane formation, and cell differentiation. We report that the absence of alpha 1-chain expression, resulting from the stable transfection of the human colonic cancer Caco2 cells with an eukaryotic expression vector comprising a cDNA fragment of the alpha 1 chain inserted in an antisense orientation, led to (a) an incorrect secretion of the two other constituent chains of laminin-1, the beta 1/gamma 1 chains, (b) the lack of basement membrane assembly when Caco2-deficient cells were cultured on top of fibroblasts, assessed by the absence of collagen IV and nidogen deposition, and (c) changes in the structural polarity of cells accompanied by the inhibition of an apical digestive enzyme, sucrase-isomaltase. The results demonstrate that the alpha 1 chain is required for secretion of laminin-1 and for the assembly of basement membrane network. Furthermore, expression of the laminin alpha 1-chain gene may be a regulatory element in determining cell differentiation.


Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3137-3146 ◽  
Author(s):  
Michael J. Parsons ◽  
Steven M. Pollard ◽  
Leonor Saúde ◽  
Benjamin Feldman ◽  
Pedro Coutinho ◽  
...  

Basement membranes are thought to be essential for organ formation, providing the scaffold on which individual cells organize to form complex tissues. Laminins are integral components of basement membranes. To understand the development of a simple vertebrate organ, we have used positional cloning to characterize grumpy and sleepy, two zebrafish loci known to control notochord formation, and find that they encode laminin β1 and laminin γ1, respectively. Removal of either chain results in the dramatic loss of laminin 1 staining throughout the embryo and prevents formation of the basement membrane surrounding the notochord. Notochord cells fail to differentiate and many die by apoptosis. By transplantation, we demonstrate that, for both grumpy and sleepy, notochord differentiation can be rescued by exogenous sources of the missing laminin chain, although notochordal sources are also sufficient for rescue. These results demonstrate a clear in vivo requirement for laminin β1 and laminin γ1 in the formation of a specific vertebrate organ and show that laminin or the laminin-dependent basement membrane is essential for the differentiation of chordamesoderm to notochord.


1995 ◽  
Vol 108 (12) ◽  
pp. 3795-3805 ◽  
Author(s):  
F. Schuler ◽  
L.M. Sorokin

The expression of laminin-1 (previously EHS laminin) and laminin-2 (previously merosin) isoforms by myogenic cells was examined in vitro and in vivo. No laminin alpha 2 chainspecific antibodies react with mouse tissues, 50 rat monoclonal antibodies were raised against the mouse laminin alpha 2 chain: their characterization is described here. Myoblasts and myotubes from myogenic cell lines and primary myogenic cultures express laminin beta 1 and gamma 1 chains and form a complex with a 380 kDa alpha chain identified as laminin alpha 2 by immunofluorescence, immunoprecipitation and PCR. PCR from C2C12 myoblasts and myotubes for the laminin alpha 2 chain gene (LamA2) provided cDNA sequences which were used to investigate the in vivo expression of mouse LamA2 mRNA in embryonic tissues by in situ hybridization. Comparisons were made with specific probes for the laminin alpha 1 chain gene (LamA1). LamA2 but not LamA1 mRNA was expressed in myogenic tissues of 14- and 17-day-old mouse embryos, while the laminin alpha 2 polypeptide was localized in adjacent basement membranes in the muscle fibres. In situ hybridization also revealed strong expression of the LamA2 mRNA in the dermis, indicating that laminin alpha 2 is expressed other than by myogenic cells in vivo. Immunofluorescence studies localized laminin alpha 2 in basement membranes of basal keratinocytes and the epithelial cells of hair follicles, providing new insight into basement membrane assembly during embryogenesis. In vitro cell attachment assays revealed that C2C12 and primary myoblasts adhere to laminin-1 and -2 isoforms in a similar manner except that myoblast spreading was significantly faster on laminin-2. Taken together, the data suggest that laminins 1 and 2 play distinct roles in myogenesis.


2021 ◽  
pp. ASN.2020081204
Author(s):  
Sarah N. Lipp ◽  
Kathryn R. Jacobson ◽  
David S. Hains ◽  
Andrew L. Schwarderer ◽  
Sarah Calve

BackgroundThe extracellular matrix (ECM) is a network of proteins and glycosaminoglycans that provides structural and biochemical cues to cells. In the kidney, the ECM is critical for nephrogenesis; however, the dynamics of ECM composition and how it relates to 3D structure during development is unknown.MethodsUsing embryonic day 14.5 (E14.5), E18.5, postnatal day 3 (P3), and adult kidneys, we fractionated proteins based on differential solubilities, performed liquid chromatography–tandem mass spectrometry, and identified changes in ECM protein content (matrisome). Decellularized kidneys were stained for ECM proteins and imaged in 3D using confocal microscopy.ResultsWe observed an increase in interstitial ECM that connects the stromal mesenchyme to the basement membrane (TNXB, COL6A1, COL6A2, COL6A3) between the embryo and adult, and a transient elevation of interstitial matrix proteins (COL5A2, COL12A1, COL26A1, ELN, EMID1, FBN1, LTBP4, THSD4) at perinatal time points. Basement membrane proteins critical for metanephric induction (FRAS1, FREM2) were highest in abundance in the embryo, whereas proteins necessary for integrity of the glomerular basement membrane (COL4A3, COL4A4, COL4A5, LAMB2) were more abundant in the adult. 3D visualization revealed a complex interstitial matrix that dramatically changed over development, including the perinatal formation of fibrillar structures that appear to support the medullary rays.ConclusionBy correlating 3D ECM spatiotemporal organization with global protein abundance, we revealed novel changes in the interstitial matrix during kidney development. This new information regarding the ECM in developing kidneys offers the potential to inform the design of regenerative scaffolds that can guide nephrogenesis in vitro.


1997 ◽  
Vol 273 (3) ◽  
pp. L663-L675 ◽  
Author(s):  
M. P. d'Ortho ◽  
C. Clerici ◽  
P. M. Yao ◽  
C. Delacourt ◽  
C. Delclaux ◽  
...  

Type II pneumocytes are key cells of the alveolar epithelium. They lie on the alveolar basement membrane, which influences their phenotype and functions. We hypothesized that type II pneumocytes degrade basement membrane components by producing gelatinases, members of the matrix metalloproteinase family. To investigate this hypothesis, we used primary cultures of rat type II pneumocytes and cultures of the human A549 cell line. We found by zymography that 70-kDa gelatinase was present in media conditioned by these cells. This 70-kDa gelatinase was identified as gelatinase A by a Western blot, and the presence of its mRNA was demonstrated by reverse transcription-polymerase chain reaction. A 95-kDa gelatinase could be induced under certain conditions. Production of gelatinases may take place during the turnover of basement membranes, in physiological and in pathophysiological processes. This was suggested by the increase in production of both gelatinases that we observed after in vitro exposure to LPS or interleukin-1. The presence of tissue inhibitors of matrix metalloproteinase-1 and -2 was also demonstrated, suggesting that degradation of extracellular matrix by type II pneumocytes is tightly regulated.


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