Dissection of the sets of genes that control the behavior of biglycan-deficient pre-osteoblasts using oligonucleotide microarrays.
Biglycan (bgn) is a small leucine-rich proteoglycan (SLPR) that is enriched in the extracellular matrix of skeletal tissues. Bgn-deficient mice develop age-related osteopenia with a phenotype that resembles osteoporosis. In order to identify sets of genes that play a key role in the skeletal abnormality, we determined the global gene expression patterns in bgn-deficient (bgn-KO) pre-osteoblasts using oligonucleotide microarray technology. Calvarial cells were harvested from newborn mice and cultured in the presence or absence of BMP-4 for 7 days. The total RNA was purified, labeled and hybridized to Affymetrix chips (U74A), and analyzed with a software program called GeneSpring. Our data suggested that biglycan regulates the activity of osteoblastic progenitors through sets of genes associated with cell cycle, cell growth, and differentiation. The biological outcome from the altered expression of these genes could cause a defect in the quantity and quality of osteoblastic progenitors, which could contribute to the development of age-related osteopenia in bgn-KO mice. Moreover, the data from this approach also revealed that biglycan deficiency affected the genes that control inflammation, immune response, and growth of tumor cells. These are new and unexpected findings that lead to the formation of new paradigms for biglycan function. Based on these findings, we propose that the reduction of this small proteoglycan with aging may increase the risk of infection and autoimmune diseases, impair wound healing, and cause higher incidences of malignancy. This study provides a broad and deep foundation for understanding SLRP function at a more complex level.
Chen
Xiao-Dong
XD
Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA. chenxiaodong@uams.edu
Bian
Xiaopeng
X
Teslovich
Tanya M
TM
Stephan
Dietrich A
DA
Young
Marian F
MF
D000818:Animals; D000831:Animals, Newborn; D058578:Biglycan; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000502:physiology; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020869:Gene Expression Profiling; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000378:metabolism*; D011509:Proteoglycans / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D012313:RNA / Q000378:metabolism; D012886:Skull / Q000166:cytology; D013234:Stem Cells / Q000378:metabolism*
C546885:Bgn protein, mouse; D058578:Biglycan; C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D012313:RNA