| 1. |
- Karousou, Eugenia, et al.
(författare)
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The activity of hyaluronan synthase 2 is regulated by dimerization and ubiquitination
- 2010
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Ingår i: Journal of Biological Chemistry. - USA : The American Society for Biochemistry and Molecular Biology, Inc.. - 0021-9258 .- 1083-351X. ; 285:31, s. 23647-23654
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan is a component of the extracellular matrix, which affects tissue homeostasis. In this study, we investigated the regulatory mechanisms of one of the hyaluronan-synthesizing enzymes, HAS2. Ectopic expression of Flag- and 6myc-HAS2 in COS-1 cells followed by immunoprecipitation and immunoblotting revealed homodimers; after co-transfection with Flag-HAS3, also heterodimers were seen. Furthermore, the expressed HAS2 was ubiquitinated. We identified one acceptor site for ubiquitin on lysine residue 190. Mutation of this residue led to inactivation of the enzymatic activity of HAS2. Interestingly, K190R-mutated HAS2 formed dimers with wt HAS2 and quenched the activity of wt HAS2, thus demonstrating a functional role of the dimeric configuration.
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| 2. |
- Li, Lingli, et al.
(författare)
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Growth factor regulation of hyaluronan synthesis and degradation in human dermal fibroblasts : importance of hyaluronan for the mitogenic response of PDGF-BB
- 2007
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 404, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- The glycosaminoglycan hyaluronan is important in many tissue-repair processes. We have investigated the synthesis of hyaluronan in a panel of cell lines of fibroblastic and epithelial origin in response to PDGF (platelet-derived growth factor)-BB and other growth factors. Human dermal fibroblasts exhibited the highest hyaluronan-synthesizing activity in response to PDGF-BB. Analysis of HAS (hyaluronan synthase) and HYAL (hyaluronidase) mRNA expression showed that PDGF-BB treatment induced a 3-fold increase in the already high level of HAS2 mRNA, and increases in HAS1 and HYAL1 mRNA, whereas the levels of HAS3 and HYAL2 mRNA were not affected. Furthermore, PDGF-BB also increased the amount and activity of HAS2 protein, but not of HYAL1 and HYAL2 proteins. Using inhibitors for MEK 1/2 [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase 1/2] (U0126) and for PI3K (phosphoinositide 3-kinase) (LY294002), as well as the SN50 inhibitor, which prevents translocation of the active NF-kappa B (nuclear factor KB) to the nucleus, we observed a complete inhibition of both HAS2 transcriptional activity and hyaluronan synthesis, whereas inhibitors of other signalling pathways were without any significant effect. TGF-beta 1 (transforming growth factor-beta 1) did not increase the activity of hyaluronan synthesis in dermal fibroblasts, but increased the activity of HYALs. Imponantly, inhibition of hyaluronan binding to its receptor CD44 by the monoclonal antibody Hennes-1, inhibited PDGF-BB-stimulated [H-3]thymidine incorporation of dermal fibroblasts. We conclude that the ERK MAPK and PI3K signalling pathways are necessary for the regulation of hyaluronan synthesis by PDGF-BB, and that prevention of its binding to CD44 inhibits PDGF-BB-induced cell growth.
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| 3. |
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| 4. |
- Takahashi, Yoshinori, et al.
(författare)
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Hyaluronan fragments induce endothelial cell differentiation in a CD44- and CXCL1/GRO1-dependent manner.
- 2005
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Ingår i: J Biol Chem. - 0021-9258.
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan is a glycosaminoglycan of the extracellular matrix. In tumors and during chronic inflammatory diseases hyaluronan is degraded to smaller fragments which are known to stimulate endothelial cell differentiation. In this study we have compared the molecular mechanisms through which hyaluronan dodecasaccharides (HA12), and the known angiogenic factor, fibroblast growth factor 2 (FGF-2), induce capillary endothelial cell sprouting in a 3D collagen gel. The gene expression profiles of unstimulated and HA12 or FGF-2 stimulated endothelial cells were compared using a microarray analysis approach. The data revealed that both FGF-2 and HA12 promoted endothelial cell morphogenesis in a process depending on the expression of ornithine decarboxylase (Odc) and ornithine decarboxylase antizyme inhibitor (Oazi) genes. Among the genes selectively upregulated in response to HA12 was the chemokine CXCL1/GRO1 gene. The notion that the induction of CXCL1/GRO1 is of importance for HA12-induced endothelial cell sprouting was supported by the fact that morphogenesis was inhibited by antibodies specifically neutralizing the CXCL1/GRO1 protein product. HA12-stimulated endothelial cell differentiation was exerted via binding to CD44, since it was inhibited by antibodies blocking CD44 function. Our data show that hyaluronan fragments and FGF-2 affect endothelial cell morphogenesis by induction of overlapping, but also distinct sets of genes.
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