scholarly journals A role for the dystrophin-glycoprotein complex as a transmembrane linker between laminin and actin

1993 ◽  
Vol 122 (4) ◽  
pp. 809-823 ◽  
Author(s):  
JM Ervasti ◽  
KP Campbell
Keyword(s):  
Extracellular Matrix ◽  
Matrix Protein ◽  
Striated Muscle ◽  
Extracellular Matrix Protein ◽  
Dependent Manner ◽  
Heparin Binding ◽  
Glycoprotein Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Dystrophin Glycoprotein ◽  
Laminin Binding

The dystrophin-glycoprotein complex was tested for interaction with several components of the extracellular matrix as well as actin. The 156-kD dystrophin-associated glycoprotein (156-kD dystroglycan) specifically bound laminin in a calcium-dependent manner and was inhibited by NaCl (IC50 = 250 mM) but was not affected by 1,000-fold (wt/wt) excesses of lactose, IKVAV, or YIGSR peptides. Laminin binding was inhibited by heparin (IC50 = 100 micrograms/ml), suggesting that one of the heparin-binding domains of laminin is involved in binding dystroglycan while negatively charged oligosaccharide moieties on dystroglycan were found to be necessary for its laminin-binding activity. No interaction between any component of the dystrophin-glycoprotein complex and fibronectin, collagen I, collagen IV, entactin, or heparan sulfate proteoglycan was detected by 125I-protein overlay and/or extracellular matrix protein-Sepharose precipitation. In addition, laminin-Sepharose quantitatively precipitated purified dystrophin-glycoprotein complex, demonstrating that the laminin-binding site is accessible when dystroglycan is associated with the complex. Dystroglycan of nonmuscle tissues also bound laminin. However, the other proteins of the striated muscle dystrophin-glycoprotein complex appear to be absent, antigenically dissimilar or less tightly associated with dystroglycan in nonmuscle tissues. Finally, we show that the dystrophin-glycoprotein complex cosediments with F-actin but does not bind calcium or calmodulin. Our results support a role for the striated muscle dystrophin-glycoprotein complex in linking the actin-based cytoskeleton with the extracellular matrix. Furthermore, our results suggest that dystrophin and dystroglycan may play substantially different functional roles in nonmuscle tissues.

Sarcospan increases laminin binding capacity of α-dystroglycan to ameliorate DMD independent of Galgt2

2021 ◽  
Author(s):  
Hafsa Mamsa ◽  
Rachelle L Stark ◽  
Kara M Shin ◽  
Aaron M Beedle ◽  
Rachelle H Crosbie
Keyword(s):  
Extracellular Matrix ◽  
Duchenne Muscular Dystrophy ◽  
Binding Capacity ◽  
Cellular Adhesion ◽  
Muscle Pathology ◽  
Glycoprotein Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Dystrophin Glycoprotein ◽  
Partial Dependence ◽  
Laminin Binding

Abstract In Duchenne muscular dystrophy (DMD), mutations in dystrophin result in a loss of the dystrophin-glycoprotein complex at the myofiber membrane, which functions to connect the extracellular matrix with the intracellular actin cytoskeleton. The dystroglycan subcomplex interacts with dystrophin and spans the sarcolemma where its extensive carbohydrates (matriglycan and CT2 glycan) directly interact with the extracellular matrix. In the current manuscript, we show that sarcospan overexpression enhances the laminin-binding capacity of dystroglycan in DMD muscle by increasing matriglycan glycosylation of α-dystroglycan. Furthermore, we find that this modification is not affected by loss of Galgt2, a glycotransferase which catalyzes the CT2 glycan. Our findings reveal that the matriglycan carbohydrates, and not the CT2 glycan, are necessary for sarcospan-mediated amelioration of DMD. Overexpression of Galgt2 in the DMD mdx murine model prevents muscle pathology by increasing CT2 modified α-dystroglycan. Galgt2 also increases expression of utrophin, which compensates for the loss of dystrophin in DMD muscle. We found that combined loss of Galgt2 and dystrophin reduced utrophin expression; however, it did not interfere with sarcospan rescue of disease. These data reveal a partial dependence of sarcospan on Galgt2 for utrophin upregulation. In addition, sarcospan alters the cross-talk between the adhesion complexes by decreasing the association of integrin β1D with dystroglycan complexes. In conclusion, sarcospan functions to re-wire the cell to matrix connections by strengthening the cellular adhesion and signaling which, in turn, increases the resilience of the myofiber membrane.

scholarly journals Role of the extracellular matrix protein thrombospondin in the early development of the mouse embryo.

1990 ◽  
Vol 111 (6) ◽  
pp. 2713-2723 ◽  
Author(s):  
K S O'Shea ◽  
L H Liu ◽  
L H Kinnunen ◽  
V M Dixit
Keyword(s):  
Extracellular Matrix ◽  
Matrix Protein ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Types ◽  
Extracellular Matrix Protein ◽  
Heparin Binding ◽  
Cell Stage ◽  
Binding Domains ◽  
Heparin Binding Domain

The distribution of the extracellular matrix protein thrombospondin (TSP) in cleavage to egg cylinder staged mouse embryos and its role in trophoblast outgrowth from cultured blastocysts were examined. TSP was present within the cytoplasm of unfertilized eggs; in fertilized one- to four-cell embryos; by the eight-cell stage, TSP was also densely deposited at cell-cell borders. In the blastocyst, although TSP was present in all three cell types; trophectoderm, endoderm, and inner cell mass (ICM), it was enriched in the ICM and at the surface of trophectoderm cells. Hatched blastocysts grown on matrix-coated coverslips formed extensive trophoblast outgrowths on TSP, grew slightly less avidly on laminin, or on a 140-kD fragment of TSP containing its COOH terminus and putative cell binding domains. There was little outgrowth on the NH2 terminus heparin-binding domain. Addition of anti-TSP antibodies (but not GRGDS) to blastocysts growing on TSP strikingly inhibited outgrowth. Consistent with its early appearance and presence in trophoblast cells during implantation, TSP may play an important role in the early events involved in mammalian embryogenesis.

scholarly journals Increasing α7β1-integrin promotes muscle cell proliferation, adhesion, and resistance to apoptosis without changing gene expression

2008 ◽  
Vol 294 (2) ◽  
pp. C627-C640 ◽  
Author(s):  
Jianming Liu ◽  
Dean J. Burkin ◽  
Stephen J. Kaufman
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Muscular Dystrophy ◽  
Expression Profiles ◽  
C2c12 Cells ◽  
Glycoprotein Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Dystrophin Glycoprotein

The dystrophin-glycoprotein complex maintains the integrity of skeletal muscle by associating laminin in the extracellular matrix with the actin cytoskeleton. Several human muscular dystrophies arise from defects in the components of this complex. The α7β1-integrin also binds laminin and links the extracellular matrix with the cytoskeleton. Enhancement of α7-integrin levels alleviates pathology in mdx/utrn−/− mice, a model of Duchenne muscular dystrophy, and thus the integrin may functionally compensate for the absence of dystrophin. To test whether increasing α7-integrin levels affects transcription and cellular functions, we generated α7-integrin-inducible C2C12 cells and transgenic mice that overexpress the integrin in skeletal muscle. C2C12 myoblasts with elevated levels of integrin exhibited increased adhesion to laminin, faster proliferation when serum was limited, resistance to staurosporine-induced apoptosis, and normal differentiation. Transgenic expression of eightfold more integrin in skeletal muscle did not result in notable toxic effects in vivo. Moreover, high levels of α7-integrin in both myoblasts and in skeletal muscle did not disrupt global gene expression profiles. Thus increasing integrin levels can compensate for defects in the extracellular matrix and cytoskeleton linkage caused by compromises in the dystrophin-glycoprotein complex without triggering apparent overt negative side effects. These results support the use of integrin enhancement as a therapy for muscular dystrophy.

scholarly journals ApoE (Apolipoprotein E) in Brain Pericytes Regulates Endothelial Function in an Isoform-Dependent Manner by Modulating Basement Membrane Components

2020 ◽  
Vol 40 (1) ◽  
pp. 128-144 ◽  
Author(s):  
Yu Yamazaki ◽  
Mitsuru Shinohara ◽  
Akari Yamazaki ◽  
Yingxue Ren ◽  
Yan W. Asmann ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Basement Membrane ◽  
Matrix Protein ◽  
Extracellular Matrix Protein ◽  
Cell Phenotype ◽  
Dependent Manner ◽  
Barrier Formation ◽  
Brain Pericytes ◽  
Membrane Components ◽  
And Function

Objective: The ε4 allele of the APOE gene ( APOE4 ) is the strongest genetic risk factor for Alzheimer disease when compared with the common ε3 allele. Although there has been significant progress in understanding how apoE4 (apolipoprotein E4) drives amyloid pathology, its effects on amyloid-independent pathways, in particular cerebrovascular integrity and function, are less clear. Approach and Results: Here, we show that brain pericytes, the mural cells of the capillary walls, differentially modulate endothelial cell phenotype in an apoE isoform-dependent manner. Extracellular matrix protein induction, tube-like structure formation, and barrier formation were lower with endothelial cells cocultured with pericytes isolated from apoE4-targeted replacement (TR) mice compared with those from apoE3-TR mice. Importantly, aged apoE4-targeted replacement mice had decreased extracellular matrix protein expression and increased plasma protein leakages compared with apoE3-TR mice. Conclusions: ApoE4 impairs pericyte-mediated basement membrane formation, potentially contributing to the cerebrovascular effects of apoE4.

scholarly journals Purification and Partial Characterization of a Paracoccidioides brasiliensis Protein with Capacity To Bind to Extracellular Matrix Proteins

2005 ◽  
Vol 73 (4) ◽  
pp. 2486-2495 ◽  
Author(s):  
Angel González ◽  
Beatriz L. Gómez ◽  
Soraya Diez ◽  
Orville Hernández ◽  
Angela Restrepo ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Matrix Protein ◽  
Paracoccidioides Brasiliensis ◽  
Sodium Dodecyl ◽  
Extracellular Matrix Proteins ◽  
Matrix Proteins ◽  
Yeast Cells ◽  
Extracellular Matrix Protein ◽  
Dependent Manner ◽  
Fungal Propagules

ABSTRACT Microorganisms adhere to extracellular matrix proteins by means of their own surface molecules. Paracoccidioides brasiliensis conidia have been shown to be capable of interacting with extracellular matrix proteins. We aimed at determining the presence of fungal proteins that could interact with extracellular matrix protein and, if found, attempt their purification and characterization. Various extracts were prepared from P. brasiliensis mycelial and yeast cultures (total homogenates, β-mercaptoethanol, and sodium dodecyl sulfate [SDS] extracts) and analyzed by ligand affinity assays with fibronectin, fibrinogen and laminin. Two polypeptides were detected in both fungal forms. SDS extracts that interacted with all the extracellular matrix protein were tested; their molecular masses were 19 and 32 kDa. Analysis of the N-terminal amino acid sequence of the purified 32-kDa mycelial protein showed substantial homology with P. brasiliensis, Histoplasma capsulatum, and Neurospora crassa hypothetical proteins. Additionally, a monoclonal antibody (MAb) produced against this protein recognized the 32-kDa protein in the SDS extracts of both fungal forms for immunoblot. Immunofluorescence analysis revealed that this MAb reacted not only with mycelia and yeast cells, but also with conidia, indicating that this protein was shared by the three fungal propagules. By immunoelectron microscopy, this protein was detected in the cell walls and in the cytoplasm. Both the 32-kDa purified protein and MAb inhibited the adherence of conidia to the three extracellular matrix proteins in a dose-dependent manner. These findings demonstrate the presence of two polypeptides capable of interacting with extracellular matrix proteins on the surface of P. brasiliensis propagules, indicating that there may be common receptors for laminin, fibronectin, and fibrinogen. These proteins would be crucial for initial conidial adherence and perhaps also in dissemination of paracoccidioidomycosis.

scholarly journals Enhanced Expression of the α7β1 Integrin Reduces Muscular Dystrophy and Restores Viability in Dystrophic Mice

2001 ◽  
Vol 152 (6) ◽  
pp. 1207-1218 ◽  
Author(s):  
Dean J. Burkin ◽  
Gregory Q. Wallace ◽  
Kimberly J. Nicol ◽  
David J. Kaufman ◽  
Stephen J. Kaufman
Keyword(s):  
Extracellular Matrix ◽  
Muscular Dystrophy ◽  
Congenital Muscular Dystrophy ◽  
Transgenic Animals ◽  
Muscle Disease ◽  
Muscle Creatine Kinase ◽  
Glycoprotein Complex ◽  
Enhanced Expression ◽  
Dystrophin Glycoprotein Complex ◽  
Dystrophin Glycoprotein

Muscle fibers attach to laminin in the basal lamina using two distinct mechanisms: the dystrophin glycoprotein complex and the α7β1 integrin. Defects in these linkage systems result in Duchenne muscular dystrophy (DMD), α2 laminin congenital muscular dystrophy, sarcoglycan-related muscular dystrophy, and α7 integrin congenital muscular dystrophy. Therefore, the molecular continuity between the extracellular matrix and cell cytoskeleton is essential for the structural and functional integrity of skeletal muscle. To test whether the α7β1 integrin can compensate for the absence of dystrophin, we expressed the rat α7 chain in mdx/utr−/− mice that lack both dystrophin and utrophin. These mice develop a severe muscular dystrophy highly akin to that in DMD, and they also die prematurely. Using the muscle creatine kinase promoter, expression of the α7BX2 integrin chain was increased 2.0–2.3-fold in mdx/utr−/− mice. Concomitant with the increase in the α7 chain, its heterodimeric partner, β1D, was also increased in the transgenic animals. Transgenic expression of the α7BX2 chain in the mdx/utr−/− mice extended their longevity by threefold, reduced kyphosis and the development of muscle disease, and maintained mobility and the structure of the neuromuscular junction. Thus, bolstering α7β1 integrin–mediated association of muscle cells with the extracellular matrix alleviates many of the symptoms of disease observed in mdx/utr−/− mice and compensates for the absence of the dystrophin- and utrophin-mediated linkage systems. This suggests that enhanced expression of the α7β1 integrin may provide a novel approach to treat DMD and other muscle diseases that arise due to defects in the dystrophin glycoprotein complex. A video that contrasts kyphosis, gait, joint contractures, and mobility in mdx/utr−/− and α7BX2-mdx/utr−/−mice can be accessed at http://www.jcb.org/cgi/content/full/152/6/1207.

scholarly journals Extracellular matrix fibronectin mediates an endothelial cell response to shear stress via the heparin-binding, matricryptic RWRPK sequence of FNIII1H

2016 ◽  
Vol 311 (4) ◽  
pp. H1063-H1071 ◽  
Author(s):  
William Okech ◽  
Keren M. Abberton ◽  
Julia M. Kuebel ◽  
Denise C. Hocking ◽  
Ingrid H. Sarelius
Keyword(s):  
Extracellular Matrix ◽  
Shear Stress ◽  
Matrix Protein ◽  
Umbilical Vein ◽  
Stress Fiber ◽  
Stress Fibers ◽  
Extracellular Matrix Protein ◽  
Heparin Binding ◽  
Flow Conditions ◽  
Endothelial Cell Response

Endothelial cells (EC) respond to mechanical forces such as shear stress in a variety of ways, one of which is cytoskeletal realignment in the direction of flow. Our earlier studies implicated the extracellular matrix protein fibronectin in mechanosensory signaling to ECs in intact arterioles, via a signaling pathway dependent on the heparin-binding region of the first type III repeat of fibrillar fibronectin (FNIII1H). Here we test the hypothesis that FNIII1H is required for EC stress fiber realignment under flow. Human umbilical vein ECs (HUVECs) exposed to defined flow conditions were used as a well-characterized model of this stress fiber alignment response. Our results directly implicate FNIII1H in realignment of stress fibers in HUVECs and, importantly, show that the matricryptic heparin-binding RWRPK sequence located in FNIII1 is required for the response. Furthermore, we show that flow-mediated stress fiber realignment in ECs adhered via α5β1-integrin-specific ligands does not occur in the absence of FHIII1H, whereas, in contrast, αvβ3-integrin-mediated stress fiber realignment under flow does not require FNIII1H. Our findings thus indicate that there are two separate mechanosignaling pathways mediating the alignment of stress fibers after exposure of ECs to flow, one dependent on αvβ3-integrins and one dependent on FNIII1H. This study strongly supports the conclusion that the RWRPK region of FNIII1H may have broad capability as a mechanosensory signaling site.

scholarly journals Sarcoglycan Subcomplex Expression in Normal Human Smooth Muscle

2007 ◽  
Vol 55 (8) ◽  
pp. 831-843 ◽  
Author(s):  
Giuseppe Anastasi ◽  
Giuseppina Cutroneo ◽  
Antonina Sidoti ◽  
Carmen Rinaldi ◽  
Daniele Bruschetta ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Muscle Type ◽  
Common Assumption ◽  
Glycoprotein Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Normal Human ◽  
First Time ◽  
Dystrophin Glycoprotein ◽  
Lower Expression

The sarcoglycan complex (SGC) is a multimember transmembrane complex interacting with other members of the dystrophin–glycoprotein complex (DGC) to provide a mechanosignaling connection from the cytoskeleton to the extracellular matrix. The SGC consists of four proteins (α, β, γ, and δ). A fifth sarcoglycan subunit, ∊-sarcoglycan, shows a wider tissue distribution. Recently, a novel sarcoglycan, the ζ-sarcoglycan, has been identified. All reports about the structure of SGC showed a common assumption of a tetrameric arrangement of sarcoglycans. Addressing this issue, our immunofluorescence and molecular results showed, for the first time, that all sarcoglycans are always detectable in all observed samples. Therefore, one intriguing possibility is the existence of a pentameric or hexameric complex considering ζ-sarcoglycan of SGC, which could present a higher or lower expression of a single sarcoglycan in conformity with muscle type—skeletal, cardiac, or smooth—or also in conformity with the origin of smooth muscle. (J Histochem Cytochem 55:831–843, 2007)

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