I. Tsukamoto; M. Akagi; S. Inoue; Y. Oda; T. Teramura; T. Takehara; Y. Onodera
OSTEOARTHRITIS AND CARTILAGE 21 Suppl. S S130 - S130 2013年04月
[査読有り] Purpose: Recently, the local renin-angiotensin system (RAS) has attracted many researchers in many pathophysiological issues. Also in orthopedics, expression of the local RAS was found in fracture callus, bone tissues and arthritic synovium. In the last year, we reported that the local RAS expressed in chondrocytes of the epiphyseal plates of mice. The purpose of this study is to reveal immunohistological localization of the RAS components in the limb buds of mice where another physiological hypertrophic differetiation occurs and to analyze function of the local RAS in the processes of hypertrophic differentiation using ATDC5 cell line.
Methods: The limb buds of 15-day-viviparous mice were immunostained with antibodies to angiotensinogen, angiotensinogen converting enzyme 1 (ACE1), angiotensinII type 1 receptor (AT1R) and angiotensinII type 2 receptor (AT2R). We cultured ATDC5 cell line and evaluated expression of angiotensinogen, ACE1, AT1R and AT2R during the hypertrophic term using quantitative real-time PCR and Western blot analysis. Then, we separately stimulated AT1R and AT2R in hypertrophic term using angiotensin II, olmesartan and PD123319 and evaluated expression of type X collagen using quantitative real-time PCR and Western blot analysis.
Results: In the limb buds of mice, angiotensinogen and AT1R expressed in the resting chondrocytes, the proliferative chondrocytes and hypertrophic chondrocytes; however, ACE1 and AT2R expressed only in the hypertrophic chondrocytes. In ATDC5 cell line, angiotensinogen and AT1R expressed mainly in the proliferative term and slightly in the hypertrophic term; conversely, ACE1 and AT2R expressed mainly in the hypertrophic term and slightly in the proliferating term. In the hypertrophic term, expression of type X collagen were downregulated activating AT1R and were conversely upregulated activating AT2R.
Conclusions: The local RAS also expresses in the limb buds of mice. In the hypertrophic term of the chondrocyte differentiation, activating AT1R decelerates the hypertrophic differentiation; conversely, activating AT2R accelerates the hypertrophic differentiation. Therefore, the local RAS might regulate the chondrocyte hypertrophic differentiation.