Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.12 (chondroitinase)
 2,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell adhesion to fibronectin results in formation of actin stress fibres and focal adhesions. In fibroblasts, this response requires two co-operative signals provided by interactions of the RGD sequence with alpha5beta1 integrin and the heparin-binding domain II (Hep II) domain with syndecan-4. Within Hep II, this activity was mapped to repeat III13 and to the peptide FN-C/H-V(WQPPRARITGY, repeat III14). We previously described that the synthetic heparin-binding peptide/III5 (HBP/III5) (WTPPRAQITGYRLTVGLTRR, repeat III5) binds heparin and mediates cell adhesion via chondroitin sulphate proteoglycans. We have now studied whether HBP/III5 co-operates with alpha5beta1 and drives a full cytoskeletal response in melanoma cells. SKMEL-178 cells attached and spread on the RGD-containing FNIII7-FNIII10 (FNIII7-10) fragment, but did not form stress fibres or focal adhesions. Co-immobilization of HBP/III5 with FNIII7-10 or adding soluble HBP/III5 to cells prespread on FNIII7-10, effectively induced these structures. Cell transfection with dominant-negative N19RhoA, a member of the small GTPase family, abolished the HBP/III5 effect. Both chondroitinase and heparitinase diminished focal adhesions, indicating that both types of proteoglycans bound HBP/III5 in melanoma cells. We have mapped the active sequence of HBP/III5 to YRLTVGLTRR, which is a novel sequence in fibronectin with focal-adhesion-promoting activity. The last two arginine (R) residues of this sequence are required for activity, since their replacement by alanine completely abrogated the HBP/III5 cytoskeletal effect. Moreover, this sequence is also active in the context of large fibronectin fragments. Our results establish that the Hep III region provides co-operative signals to alpha5beta1 for the progression of the cytoskeletal response and that these include activation of RhoA.
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PMID:A synthetic peptide from the heparin-binding domain III (repeats III4-5) of fibronectin promotes stress-fibre and focal-adhesion formation in melanoma cells. 1251 80

Arylsulfatase B (ASB; N-acetylgalactosamine-4-sulfatase; 4-sulfatase; ARSB) is the enzyme that removes 4-sulfate groups from N-acetylgalactosamine 4-sulfate, which combines with glucuronate to form the disaccharide unit of chondroitin-4-sulfate (C4S). In this study, we report how variation in expression of ASB affected the migration of human colonic epithelial cells. In the T84 cell line, derived from lung metastasis of malignant colonic epithelial cells, the activity of ASB, as well as steroid sulfatase, arylsulfatase A, and galactose-6-sulfatase, were significantly less than in normal, primary colonic epithelial cells and in the NCM460 cell line which was derived from normal colonocytes. In the T84 cells, matrix metalloproteinase 9 (MMP9), activated RhoA, and cell migration, as well as C4S content, were significantly more than in the NCM460 cells. Silencing and overexpression of ASB had inverse effects on MMP9, activated RhoA, and cell migration, as well as the C4S content, in the NCM460 and T84 cells. When ASB expression was silenced by siRNA in the NCM460 cells, MMP9 secretion increased to over 3 times the basal level, activated RhoA increased * 85%, and cell migration increased * 52%. Following overexpression of ASB, MMP9 declined 51%, activated RhoA declined * 51%, and cell migration decreased * 37%. These findings demonstrate marked effects of ASB expression on the migratory activity of colonic epithelial cells, activated RhoA, and MMP9, and suggest a potential vital role of ASB, due to its impact on chondroitin sulfation, on determination of the invasive phenotype of colonic epithelial cells.
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PMID:Arylsulfatase B regulates colonic epithelial cell migration by effects on MMP9 expression and RhoA activation. 1930 8

Mutations in the OCRL gene encoding the phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) 5-phosphatase OCRL cause Lowe syndrome (LS), which is characterized by intellectual disability, cataracts and selective proximal tubulopathy. OCRL localizes membrane-bound compartments and is implicated in intracellular transport. Comprehensive analysis of clathrin-mediated endocytosis in fibroblasts of patients with LS did not reveal any difference in trafficking of epidermal growth factor, low density lipoprotein or transferrin, compared with normal fibroblasts. However, LS fibroblasts displayed reduced mannose 6-phosphate receptor (MPR)-mediated re-uptake of the lysosomal enzyme arylsulfatase B. In addition, endosome-to-trans Golgi network (TGN) transport of MPRs was decreased significantly, leading to higher levels of cell surface MPRs and their enrichment in enlarged, retromer-positive endosomes in OCRL-depleted HeLa cells. In line with the higher steady-state concentration of MPRs in the endosomal compartment in equilibrium with the cell surface, anterograde transport of the lysosomal enzyme, cathepsin D was impaired. Wild-type OCRL counteracted accumulation of MPR in endosomes in an activity-dependent manner, suggesting that PI(4,5)P(2) modulates the activity state of proteins regulated by this phosphoinositide. Indeed, we detected an increased amount of the inactive, phosphorylated form of cofilin and lower levels of the active form of PAK3 upon OCRL depletion. Levels of active Rac1 and RhoA were reduced or enhanced, respectively. Overexpression of Rac1 rescued both enhanced levels of phosphorylated cofilin and MPR accumulation in enlarged endosomes. Our data suggest that PI(4,5)P(2) dephosphorylation through OCRL regulates a Rac1-cofilin signalling cascade implicated in MPR trafficking from endosomes to the TGN.
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PMID:The 5-phosphatase OCRL mediates retrograde transport of the mannose 6-phosphate receptor by regulating a Rac1-cofilin signalling module. 2290 55

Glial scars are widely seen as a (bio)mechanical barrier to central nervous system regeneration. Due to the lack of a screening platform, which could allow in-vitro testing of several variables simultaneously, up to now no comprehensive study has addressed and clarified how different lesion microenvironment properties affect astrogliosis. Using astrocytes cultured in alginate gels and meningeal fibroblast conditioned medium, we have built a simple and reproducible 3D culture system of astrogliosis mimicking many features of the glial scar. Cells in this 3D culture model behave similarly to scar astrocytes, showing changes in gene expression (e.g., GFAP) and increased extra-cellular matrix production (chondroitin 4 sulfate and collagen), inhibiting neuronal outgrowth. This behavior being influenced by the hydrogel network properties. Astrocytic reactivity was found to be dependent on RhoA activity, and targeting RhoA using shRNA-mediated lentivirus reduced astrocytic reactivity. Further, we have shown that chemical inhibition of RhoA with ibuprofen or indirectly targeting RhoA by the induction of extracellular matrix composition modification with chondroitinase ABC, can diminish astrogliosis. Besides presenting the extracellular matrix as a key modulator of astrogliosis, this simple, controlled and reproducible 3D culture system constitutes a good scar-like system and offers great potential in future neurodegenerative mechanism studies, as well as in drug screenings envisaging the development of new therapeutic approaches to minimize the effects of the glial scar in the context of central nervous system disease.
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PMID:Extracellular environment contribution to astrogliosis-lessons learned from a tissue engineered 3D model of the glial scar. 2648 32