Lysyl Oxidase Propeptide Inhibits FGF-2-induced Signaling and Proliferation of Osteoblasts

被引:39
作者
Vora, Siddharth R.
Palamakumbura, Amitha H.
Mitsi, Maria [2 ]
Guo, Ying
Pischon, Nicole
Nugent, Matthew A. [2 ]
Trackman, Philip C. [1 ,2 ]
机构
[1] Boston Univ, Dept Periodontol & Oral Biol, Goldman Sch Dent Med, Boston, MA 02118 USA
[2] Boston Univ, Sch Med, Dept Biochem, Boston, MA 02118 USA
基金
美国国家卫生研究院;
关键词
FIBROBLAST-GROWTH-FACTOR; TUMOR-SUPPRESSOR ACTIVITY; COLLAGEN GENE-EXPRESSION; CELL-GROWTH; TRANSCRIPTION FACTOR; BONE-FORMATION; CROSS-LINKS; RECEPTOR; FACTOR-2; BINDING;
D O I
10.1074/jbc.M109.033597
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Pro-lysyl oxidase is secreted as a 50-kDa proenzyme and is then cleaved to a 30-kDa mature enzyme (lysyl oxidase (LOX)) and an 18-kDa propeptide ( lysyl oxidase propeptide (LOX-PP)). The presence of LOX-PP in the cell layers of phenotypically normal osteoblast cultures led us to investigate the effects of LOX-PP on osteoblast differentiation. Data indicate that LOX-PP inhibits terminal mineralization in primary calvaria osteoblast cultures when added at early stages of differentiation, with no effects seen when present at later stages. LOX-PP was found to inhibit serum-and FGF-2-stimulated DNA synthesis and FGF-2-stimulated cell growth. Enzyme-linked immunosorbent assay and Western blot analyses show that LOX-PP inhibits FGF-2-induced ERK1/2 phosphorylation, signaling events that mediate the FGF-2-induced proliferative response. LOX-PP inhibits FGF-2-stimulated phosphorylation of FRS2 alpha and FGF-2-stimulated DNA synthesis, even after inhibition of sulfation of heparan sulfate proteoglycans. These data point to a LOX-PP target at or near the level of fibroblast growth factor receptor binding or activation. Ligand binding assays on osteoblast cell layers with I-125-FGF-2 demonstrate a concentration-dependent inhibition of FGF-2 binding to osteoblasts by LOX-PP. In vitro binding assays with recombinant fibroblast growth factor receptor protein revealed that LOX-PP inhibits FGF-2 binding in an uncompetitive manner. We propose a working model for the respective roles of LOX enzyme and LOX-PP in osteoblast phenotype development in which LOX-PP may act to inhibit the proliferative response possibly to allow cells to exit from the cell cycle and progress to the next stages of differentiation.
引用
收藏
页码:7384 / 7393
页数:10
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