The Experts below are selected from a list of 579 Experts worldwide ranked by ideXlab platform
Robert Passier - One of the best experts on this subject based on the ideXlab platform.
-
recombinant vitronectin is a functionally defined substrate that supports human embryonic stem cell self renewal via αvβ5 integrin
Stem Cells, 2008Co-Authors: Stefan R Braam, Laura Zeinstra, Sandy H M Litjens, Dorien Wardvan Oostwaard, Stieneke Van Den Brink, Linda W Van Laake, Franck Lebrin, Peter Kats, Ron Hochstenbach, Robert PassierAbstract:Defined growth conditions are essential for many applications of human embryonic stem cells (hESC). Most defined media are presently used in combination with Matrigel, a partially defined extracellular matrix (ECM) extract from mouse sarcoma. Here, we defined ECM requirements of hESC by analyzing integrin expression and ECM production and determined integrin function using blocking antibodies. hESC expressed all major ECM proteins and corresponding integrins. We then systematically replaced Matrigel with defined medium supplements and ECM proteins. Cells attached efficiently to natural human vitronectin, fibronectin, and Matrigel but poorly to laminin + Entactin and collagen IV. Integrin-blocking antibodies demonstrated that αVβ5 integrins mediated adhesion to vitronectin, α5β1 mediated adhesion to fibronectin, and α6β1 mediated adhesion to laminin + Entactin. Fibronectin in feeder cell-conditioned medium partially supported growth on all natural matrices, but in defined, nonconditioned medium only Matrigel or (natural and recombinant) vitronectin was effective. Recombinant vitronectin was the only defined functional alternative to Matrigel, supporting sustained self-renewal and pluripotency in three independent hESC lines. Disclosure of potential conflicts of interest is found at the end of this article.
-
recombinant vitronectin is a functionally defined substrate that supports human embryonic stem cell self renewal via αvβ5 integrin
Stem Cells, 2008Co-Authors: Stefan R Braam, Laura Zeinstra, Sandy H M Litjens, Dorien Wardvan Oostwaard, Franck Lebrin, Peter Kats, Ron Hochstenbach, Stieneke Van Den Brink, Linda W Van Laake, Robert PassierAbstract:Defined growth conditions are essential for many applications of human embryonic stem cells (hESC). Most defined media are presently used in combination with Matrigel, a partially defined extracellular matrix (ECM) extract from mouse sarcoma. Here, we defined ECM requirements of hESC by analyzing integrin expression and ECM production and determined integrin function using blocking antibodies. hESC expressed all major ECM proteins and corresponding integrins. We then systematically replaced Matrigel with defined medium supplements and ECM proteins. Cells attached efficiently to natural human vitronectin, fibronectin, and Matrigel but poorly to laminin + Entactin and collagen IV. Integrin-blocking antibodies demonstrated that alphaVbeta5 integrins mediated adhesion to vitronectin, alpha5beta1 mediated adhesion to fibronectin, and alpha6beta1 mediated adhesion to laminin + Entactin. Fibronectin in feeder cell-conditioned medium partially supported growth on all natural matrices, but in defined, nonconditioned medium only Matrigel or (natural and recombinant) vitronectin was effective. Recombinant vitronectin was the only defined functional alternative to Matrigel, supporting sustained self-renewal and pluripotency in three independent hESC lines.
William H Colledge - One of the best experts on this subject based on the ideXlab platform.
-
mice deficient for the secreted glycoprotein sparc osteonectin bm40 develop normally but show severe age onset cataract formation and disruption of the lens
The EMBO Journal, 1998Co-Authors: Darren Gilmour, Gholson J Lyon, Mark B L Carlton, Joshua R Sanes, Jeanette M Cunningham, Janice R Anderson, Brigid L M Hogan, Martin J Evans, William H ColledgeAbstract:SPARC (secreted protein acidic and rich in cysteine, also known as osteonectin/BM40) is a secreted Ca2+-binding glycoprotein that interacts with a range of extracellular matrix molecules, including collagen IV. It is widely expressed during embryogenesis, and in vitro studies have suggested roles in the regulation of cell adhesion and proliferation, and in the modulation of cytokine activity. In order to analyse the function of this protein in vivo, the endogenous Sparc locus was disrupted by homologous recombination in murine embryonic stem cells. SPARC-deficient mice (Sparctm1Cam) appear normal and fertile until around 6 months of age, when they develop severe eye pathology characterized by cataract formation and rupture of the lens capsule. The first sign of lens pathology occurs in the equatorial bow region where vacuoles gradually form within differentiating epithelial cells and fibre cells. The lens capsule, however, shows no qualitative changes in the major basal lamina proteins laminin, collagen IV, perlecan or Entactin. These mice are an excellent resource for further studies on how SPARC affects cell behaviour in vivo.
Stefan R Braam - One of the best experts on this subject based on the ideXlab platform.
-
recombinant vitronectin is a functionally defined substrate that supports human embryonic stem cell self renewal via αvβ5 integrin
Stem Cells, 2008Co-Authors: Stefan R Braam, Laura Zeinstra, Sandy H M Litjens, Dorien Wardvan Oostwaard, Stieneke Van Den Brink, Linda W Van Laake, Franck Lebrin, Peter Kats, Ron Hochstenbach, Robert PassierAbstract:Defined growth conditions are essential for many applications of human embryonic stem cells (hESC). Most defined media are presently used in combination with Matrigel, a partially defined extracellular matrix (ECM) extract from mouse sarcoma. Here, we defined ECM requirements of hESC by analyzing integrin expression and ECM production and determined integrin function using blocking antibodies. hESC expressed all major ECM proteins and corresponding integrins. We then systematically replaced Matrigel with defined medium supplements and ECM proteins. Cells attached efficiently to natural human vitronectin, fibronectin, and Matrigel but poorly to laminin + Entactin and collagen IV. Integrin-blocking antibodies demonstrated that αVβ5 integrins mediated adhesion to vitronectin, α5β1 mediated adhesion to fibronectin, and α6β1 mediated adhesion to laminin + Entactin. Fibronectin in feeder cell-conditioned medium partially supported growth on all natural matrices, but in defined, nonconditioned medium only Matrigel or (natural and recombinant) vitronectin was effective. Recombinant vitronectin was the only defined functional alternative to Matrigel, supporting sustained self-renewal and pluripotency in three independent hESC lines. Disclosure of potential conflicts of interest is found at the end of this article.
-
recombinant vitronectin is a functionally defined substrate that supports human embryonic stem cell self renewal via αvβ5 integrin
Stem Cells, 2008Co-Authors: Stefan R Braam, Laura Zeinstra, Sandy H M Litjens, Dorien Wardvan Oostwaard, Franck Lebrin, Peter Kats, Ron Hochstenbach, Stieneke Van Den Brink, Linda W Van Laake, Robert PassierAbstract:Defined growth conditions are essential for many applications of human embryonic stem cells (hESC). Most defined media are presently used in combination with Matrigel, a partially defined extracellular matrix (ECM) extract from mouse sarcoma. Here, we defined ECM requirements of hESC by analyzing integrin expression and ECM production and determined integrin function using blocking antibodies. hESC expressed all major ECM proteins and corresponding integrins. We then systematically replaced Matrigel with defined medium supplements and ECM proteins. Cells attached efficiently to natural human vitronectin, fibronectin, and Matrigel but poorly to laminin + Entactin and collagen IV. Integrin-blocking antibodies demonstrated that alphaVbeta5 integrins mediated adhesion to vitronectin, alpha5beta1 mediated adhesion to fibronectin, and alpha6beta1 mediated adhesion to laminin + Entactin. Fibronectin in feeder cell-conditioned medium partially supported growth on all natural matrices, but in defined, nonconditioned medium only Matrigel or (natural and recombinant) vitronectin was effective. Recombinant vitronectin was the only defined functional alternative to Matrigel, supporting sustained self-renewal and pluripotency in three independent hESC lines.
Willeke F Daamen - One of the best experts on this subject based on the ideXlab platform.
-
impaired primary mouse myotube formation on crosslinked type i collagen films is enhanced by laminin and Entactin
Acta Biomaterialia, 2016Co-Authors: Sander Grefte, Merel J W Adjobohermans, Elly M M Versteeg, Werner J.h. Koopman, Willeke F DaamenAbstract:Abstract In skeletal muscle, the stem cell niche is important for controlling the quiescent, proliferation and differentiation states of satellite cells, which are key for skeletal muscle regeneration after wounding. It has been shown that type I collagen, often used as 3D-scaffolds for regenerative medicine purposes, impairs myoblast differentiation. This is most likely due to the absence of specific extracellular matrix proteins providing attachment sites for myoblasts and/or myotubes. In this study we investigated the differentiation capacity of primary murine myoblasts on type I collagen films either untreated or modified with elastin, laminin, type IV collagen, laminin/Entactin complex, combinations thereof, and Matrigel as a positive control. Additionally, increased reactive oxygen species (ROS) and ROCK signaling might also be involved. To measure ROS levels with live-cell microscopy, fibronectin-coated glass coverslips were additionally coated with type I collagen and Matrigel onto which myoblasts were differentiated. On type I collagen-coated coverslips, myotube formation was impaired while ROS levels were increased. However, anti-oxidant treatment did not enhance myotube formation. ROCK inhibition, which generally improve cellular attachment to uncoated surfaces or type I collagen, enhanced myoblast attachment to type I collagen-coated coverslips and -films, but slightly enhanced myotube formation. Only modification of type I collagen films by Matrigel and a combination of laminin/Entactin significantly improved myotube formation. Our results indicate that type I collagen scaffolds can be modified by satellite cell niche factors of which specifically laminin and Entactin enhanced myotube formation. This offers a promising approach for regenerative medicine purposes to heal skeletal muscle wounds. Statement of significance In this manuscript we show for the first time that impaired myotube formation on type I collagen scaffolds can be completely restored by modification with laminin and Entactin, two extracellular proteins from the satellite cell niche. This offers a promising approach for regenerative medicine approaches to heal skeletal muscle wounds.
Albert E. Chung - One of the best experts on this subject based on the ideXlab platform.
-
Developmental Expression Pattern
2013Co-Authors: Nikolas Zagris, Albert E. Chung, Vassilis StavridisAbstract:Entactin and laminin gamma1-chain gene expression in the early chick embry
-
Amino Acid Sequence and Domain Structure of Entactin. Homology with Epidermal Growth Factor Precursor and Low Density Lipoprotein Receptor
2008Co-Authors: Marian E. Durkin, Shukti Chakravarti, Barbara B. Bartos, Shu-huang Liu, Robert L. Friedman, Albert E. ChungAbstract:Abstract. Entactin (nidogen), a 150-kD sulfated gly-coprotein, is a major component of basement mem-branes and forms a highly stable noncovalent complex with laminin. The complete amino acid sequence of mouse Entactin has been derived from sequencing of cDNA clones. The 5.9-kb cDNA contains a 3,735-bp open reading frame followed by a 3'-untranslated re-gion of 2.2 kb. The open reading frame encodes a 1,245-residue polypeptide with an unglycosylated Mr of 136,500, a 28-residue signal peptide, two Asn-linked glycosylation sites, and two potential Ca 2÷-binding sites. Analysis of the deduced amino acid se-B ASEMENT membranes are a type of extracellular matrix that form thin sheets separating epithelial, endothelial, muscle, fat, and nerve cells from connective tissue (51). Epithelial cells require contact with a basement mem-brane to maintain their morphology and differentiated phe-notype, and this is a result of interactions between basement membrane molecules and cell surface receptors for them (26). The major components of basement membranes are type IV collagen, laminin, Entactin, and heparan sulfate pro-teoglycan (reviewed in reference 48). Entactin is a 150-kD sulfated glycoprotein first identified as a product of a terato-carcinoma-derived parietal endoderm line (6). It is identical to nidogen, a polypeptide originally isolated as an 80-kD proteolytic fragment from the Engelbreth-Holm-Swarm tu-mor (49). Immunostaining has shown Entactin to be a ubiqui-tous component of adult, fetal, and extraembryonic base
-
domain specific interactions between Entactin and neutrophil integrins g2 domain ligation of integrin α3β1 and e domain ligation of the leukocyte response integrin signal for different responses
Journal of Biological Chemistry, 1996Co-Authors: H D Gresham, Li-jin Dong, Jyh-cheng Hsieh, Albert E. Chung, Gail L Griffin, Irene L Graham, Robert MAbstract:Extracellular matrix proteins activate neutrophils to up-regulate many physiologic functions that are necessary at sites of tissue injury. To elucidate the ligand-receptor interactions that mediate these functions, we examined neutrophil activation by the basement membrane protein, Entactin. Entactin is structurally and functionally organized into distinct domains; therefore, we utilized glutathione S-transferase -fusion proteins encompassing its four major domains, G1, G2, E, and G3, to assess interactions between Entactin and neutrophil integrin receptors. We show that the E domain, which contains the single RGD sequence of Entactin, is sufficient for ligation of the beta3-like integrin, leukocyte response integrin, and signaling for chemotaxis. Moreover, the G2 domain signals for stimulation of Fc receptor-mediated phagocytosis via ligation of alpha3beta1. This receptor-ligand interaction was revealed only after stimulation of neutrophil by immune complexes or phorbol esters. Interestingly, the E domain does not enhance phagocytosis, and the G2 domain is not chemotactic. Furthermore, cleavage of Entactin with the matrix metalloproteinase, matrilysin, liberates peptides that retain E domain-mediated chemotaxis and G2 domain-mediated enhancement of phagocytosis. These studies indicate that multiple domains of Entactin have the ability to ligate individual integrins expressed by neutrophils and to activate distinct functions.
-
Two distinct cell attachment sites in Entactin are revealed by amino acid substitutions and deletion of the RGD sequence in the cysteine-rich epidermal growth factor repeat 2.
The Journal of biological chemistry, 1995Co-Authors: Li-jin Dong, Jyh-cheng Hsieh, Albert E. ChungAbstract:Abstract The basement membrane glycoprotein, Entactin, has previously been shown to promote cell attachment and chemotaxis. We have constructed a panel of glutathione S-transferase fusion proteins that encompasses the four major structural domains of Entactin, G1, G2, E, and G3. These proteins have been synthesized in bacteria and purified by affinity chromatography. The connecting stalk of Entactin, E, which contains four cysteine-rich EGF homology repeats and the integrin receptor RGD recognition sequence, has been modified by deletion of the RGD sequence and substituting glutamic acid for aspartic acid. Attachment assays reveal that the RGD sequence is one of the major cell attachment sites in Entactin and that this sequence is recognized by the αβ3 integrin receptor. Analysis of cell attachment on mutant forms of full-length Entactin expressed in the baculovirus expression system revealed a second attachment site that was independent of the RGD sequence. This second site was localized to a peptide of 39 amino acid residues in the second globular G2 domain of Entactin. This peptide represents a cysteine-rich EGF repeat. Inhibition of cell attachment by anti-integrin receptor antibodies indicates that the second attachment site is recognized by a member of the β1 family of integrin receptors, possibly α3β1.