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- van Wieringen, Tijs, 1979-
(författare)
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Intra- and Extracellular Modulation of Integrin-directed Connective Tissue Cell Contraction
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All blood vessels in the microvasculature are embedded in loose connective tissue, which regulates the transport of fluid to and from tissues. The intersti-tial fluid pressure (IFP) is one of the forces that control this transport. A lowering of IFP in vivo results in an increased transport of fluid from the circulation into the underhydrated connective tissues, resulting in edema formation. During homeostasis, contractile connective tissue cells exert a tension on the connective tissue fibrous network by binding with β1 in-tegrins, thereby actively controlling IFP. During inflammation, the IFP is lowered but platelet-derived growth factor (PDGF)-BB induces an IFP nor-malization dependent on integrin αVβ3. We demonstrate that extracellular proteins from Streptococcus equi subspecies equi modulated cell-mediated and integrin αVβ3-directed collagen gel contraction in vitro. One of these proteins, the collagen- and fibronectin binding FNE, stimulated contraction by a process dependent on fibronectin synthesis. This study identified a pos-sible novel virulence mechanism for bacteria based on the ability of bacteria to modulate the edema response. Another protein, the collagen-binding pro-tein CNE, inhibited contraction and this led to the identification of sites in collagen monomers that potentially are involved in connecting αVβ3 to the collagen network. PDGF-BB and prostaglandin E1 (PGE1) stimulate and inhibit collagen gel contraction in vitro and normalize and lower IFP, respec-tively. We showed that these agents affected both similar and different sets of actin-binding proteins. PDGF-BB stimulated actin cytoskeleton dynamics whereas PGE1 inhibited processes dependent on cytoskeletal motor and adhesive functions, suggesting that these different activities may partly ex-plain the contrasting effects of PGE1 and PDGF-BB on contraction and IFP. Mutation of the phosphatidylinositol 3’-kinase (PI3K), but not phospholipase C (PLC)γ activation site, rendered cells unable to respond to PDGF-BB in contraction and in activation of the actin binding and severing protein cofilin. Ability to activate cofilin after PDGF-BB stimulation correlated with ability to respond to PDGF-BB in contraction, suggesting a role for cofilin in this process downstream of PDGF receptor-activated PI3K. Many proteins can modulate contraction either by affecting the extracellular matrix and cell adhesions or by altering cytoskeletal dynamics. Knowledge on how these proteins might influence IFP is likely to be of clinical importance for treat-ment of inflammatory conditions including anaphylaxis, septic shock and also carcinoma growth.
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| 2. |
- van Wieringen, Tijs, 1979-, et al.
(författare)
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Opposite effects of PDGF-BB and prostaglandin E(1) on cell-motility related processes are paralleled by modifications of distinct actin-binding proteins
- 2009
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 315:10, s. 1745-1758
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Tidskriftsartikel (refereegranskat)abstract
- Prostaglandin E(1) (PGE(1)) lowers dermal interstitial fluid pressure (IFP) in vivo and inhibits fibroblast-mediated collagen gel contraction in vitro. PDGF-BB, in contrast, stimulates contraction and normalizes IFP lowered as a result of anaphylaxis. Human diploid AG1518 fibroblasts expressed EP2, EP3 and IP prostaglandin receptors. The inhibitory effect of PGE(1) on contraction depended on cAMP. Short-term stimulation with PDGF-BB transiently induced formation of actin-containing membrane and circular ruffles and breakdown of stress fibers. PGE(1) had no effect on stress fibers nor did it modulate the effects of PDGF-BB. PGE(1) alone or in combination with PDGF-BB inhibited initial adhesion and spreading to collagen. PDGF-BB had no effect on adhesion but stimulated cell spreading. Two-dimensional gel electrophoresis and MALDI TOF analyses of SDS/Triton X-100-soluble proteins revealed changes in migration pattern of actin-binding proteins. Interestingly, PDGF-BB and PGE(1) affected both similar and different sets of actin-binding proteins. PDGF-BB and PGE(1) did not trans-modulate their respective effects on actin-binding proteins, cytoskeletal organization or initial adhesion. Our data show that PDGF-BB stimulates actin cytoskeleton dynamics, whereas PGE(1) inhibits processes dependent on cytoskeletal motor functions. We suggest that these different activities may partly explain the contrasting effects of PGE(1) and PDGF-BB on contraction and IFP.
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