Increased expression of matrix extracellular phosphoglycoprotein (MEPE) in cortical bone of the rat tibia after mechanical loading: identification by oligonucleotide microarray

• Published in: PloS one Vol. 8; no. 11; p. e79672
• Main Authors: Reijnders, Christianne M A, van Essen, Huib W, van Rens, Birgitte T T M, van Beek, Johannes H G M, Ylstra, Bauke, Blankenstein, Marinus A, Lips, Paul, Bravenboer, Nathalie
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.11.2013; Public Library of Science (PLoS)
• Subjects: Amine oxidase (flavin-containing); Animals; Biocompatibility; Biomedical materials; Bone growth; Calcium-binding protein; Control; Cortical bone; Creatine; Creatine kinase; Dehydrogenases; DNA microarrays; Down-regulation; Experiments; Extracellular Matrix Proteins - genetics; Extracellular Matrix Proteins - metabolism; Female; Fibrinogen; Gene expression; Gene Expression Regulation; Genes; Glycoproteins - genetics; Glycoproteins - metabolism; Histology; Immunohistochemistry; Insulin-like growth factors; Internal medicine; Kinases; Kinesin; Laboratory animals; Mechanical loading; Mechanical stimuli; Medical research; Mineralization; Monoamine oxidase; Muscles; Oligonucleotide Array Sequence Analysis; Oligonucleotides; Osteocytes; Osteogenesis; Phosphoglycoprotein; Phosphoproteins - genetics; Phosphoproteins - metabolism; Polymerase chain reaction; Protein arrays; Protein expression; Proteins; Rats; Rats, Wistar; Reproducibility of Results; Rodents; Signaling; Stimulation; Stimuli; Tibia; Tibia - metabolism; Tibia - physiology; Translation; Translation (Genetics); Troponin; Vertebra; Vertebrae; Vitamin deficiency; Weight-Bearing; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0079672

Skeletal integrity in humans and animals is maintained by daily mechanical loading. It has been widely accepted that osteocytes function as mechanosensors. Many biochemical signaling molecules are involved in the response of osteocytes to mechanical stimulation. The aim of this study was to identify genes involved in the translation of mechanical stimuli into bone formation. The four-point bending model was used to induce a single period of mechanical loading on the right tibia, while the contra lateral left tibia served as control. Six hours after loading, the effects of mechanical loading on gene-expression were determined with microarray analysis. Protein expression of differentially regulated genes was evaluated with immunohistochemistry. Nine genes were found to exhibit a significant differential gene expression in LOAD compared to control. MEPE, Garnl1, V2R2B, and QFG-TN1 olfactory receptor were up-regulated, and creatine kinase (muscle form), fibrinogen-B beta-polypeptide, monoamine oxidase A, troponin-C and kinesin light chain-C were down-regulated. Validation with real-time RT-PCR analysis confirmed the up-regulation of MEPE and the down-regulation of creatine kinase (muscle form) and troponin-C in the loaded tibia. Immunohistochemistry showed that the increase of MEPE protein expression was already detectable six hours after mechanical loading. In conclusion, these genes probably play a role during translation of mechanical stimuli six hours after mechanical loading. The modulation of MEPE expression may indicate a connection between bone mineralization and bone formation after mechanical stimulation.