Osteopontin OPN and Bone Morphogenetic Proteins BMP

Osteopontin is a noncollagenous adhesive protein that is found at dysmorphic calcification sites (Wada et al., 1999). This protein is synthesized by macrophages in atherosclerotic plaques and calcified aortic values representing an adaptive mechanism aimed at prevention of vascular calcification.

In bone tissue, OPN is produced by osteoclasts as well as osteoblasts, and inhibits matrix mineralization (Wada et al., 1999).

OPN is essential in the development of postmenopau-sal osteoporosis. OPN knockout mice are resistant to ovariectomy-induced bone resorption, compared to wildtype mice (Yoshitake et al., 1999). Furthermore, in the absence of OPN, PTH-induced increase in bone resorption is suppressed, via osteoclastic inhibition (Ihara et al., 2001). In calcified atheromatous tissues, OPN is upregu-lated (Dhore et al., 2001), probably as a compensatory response to the decrease in the mineralization process. OPN is also likely to play an important role in atherosclerosis (Isoda et al., 2002). Transgenic mice over-expressing the OPN gene develop both medial thickening without injury and vascular remodeling, and restenosis after angioplasty (Isoda et al., 2002).

BMPs are members of the transforming growth factor (TGF-^) super-family of proteins (Wozney et al., 1998). Among the 15 BMPs that are currently identified, BMP-2 and BMP-4 induce differentiation of osteoblast precursor cells into more mature osteoblast-like cells (Yamagushi et al., 1991). BMPs stimulate the expression of core-binding factor-alpha 1 (Cbfa-1), a key molecule in osteo-blast differentiation (Lee et al., 2000). Application of BMPs to mandibular defects in humans stimulated osteogenesis with mineralized bone trabeculae with copious osteoid seams (Ferretti et al., 2002). In human atherosclerotic lesions there is an enhanced BMP-2 and Cbfa-1 (Engelese et al., 2001). These factors are absent in normal arteries, suggesting a role for these molecules in vascular calcification (Engelese et al., 2001).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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