Expression of Tenascin‐C in Bones Responding to Mechanical Load

• Published in: Journal of bone and mineral research Vol. 12; no. 1; pp. 52 - 58
• Main Authors: Webb, Chloë M. B., Zaman, Gul, Mosley, John R., Tucker, Richard P., Lanyon, Lance E., Mackie, Eleanor J.
• Format: Journal Article
• Language: English
• Published: Washington, DC John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR) 01.01.1997; American Society for Bone and Mineral Research
• Subjects: Animals; Biological and medical sciences; Blotting, Northern; Bone Resorption - pathology; Cells, Cultured; Extracellular Matrix - metabolism; Female; Fluorescent Antibody Technique, Indirect; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Immunohistochemistry; Nucleic Acid Hybridization; Osteoblasts - cytology; Osteoblasts - metabolism; Osteoblasts - physiology; Rats; Rats, Sprague-Dawley; RNA - genetics; RNA - isolation & purification; RNA - metabolism; Skeleton and joints; Space life sciences; Staining and Labeling; Tenascin - biosynthesis; Tenascin - genetics; Tenascin - physiology; Transcription, Genetic - genetics; Ulna - cytology; Ulna - metabolism; Ulna - physiology; Vertebrates: osteoarticular system, musculoskeletal system; Weight-Bearing; Tenascin; Ulna; Rat; Rodentia; Gene expression; Osteoarticular system; Biomechanics; Vertebrata; Mammalia; Mechanical stress; Extracellular matrix; Bone; Mechanical stimulus; Response stimulus relation
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.1997.12.1.52

A number of early biochemical responses of bone cells to mechanical loading have been identified, but the full sequence of events from the sensing of strain to the formation of new bone is poorly characterized. Extracellular matrix proteins can modulate cell behavior and would be ideal molecules to amplify the early response to loading. The extracellular matrix protein, tenascin‐C, supports differentiation of cultured osteoblast‐like cells. The current study was carried out to investigate whether expression patterns of tenascin‐C in loaded bones support a role for this protein as a mediator of the osteoregulatory response to loading. Tenascin‐C expression was investigated by Northern blot analysis in rat ulnae subjected to an established noninvasive loading regimen engendering physiological strain levels. RNA extracted from loaded compared with contralateral control bones 6 h after loading showed a significant increase in tenascin‐C transcript expression. The presence of tenascin‐C was investigated by immunohistochemistry in bones of animals killed 3, 5, or 15 days after the initiation of daily loading. In animals killed at 3 or 5 days, periosteal surfaces undergoing load‐induced reversal from resorption to formation showed enhanced tenascin‐C staining. In animals killed at 15 days, the bone formed in response to loading was clearly demarcated from old bone by strong tenascin‐C staining of reversal lines. Within this new bone, tenascin‐C staining was seen in the lacunae of older but not more recently embedded osteocytes. The results presented here indicate that tenascin‐C expression by bone cells is enhanced in the early osteogenic response to loading. This may indicate that tenascin‐C acts as a mediator of the mechanically adaptiveresponse.