Objective: Osteoporotic fracture is one of the most common health risks and aggravates
the quality of life among postmenopausal women worldwide. In this study, osteoporosis-associated
protein biomarkers were identified from urine of osteoporotic female Sprague-Dawley rats developed
Method: Four months after the operation, the bone mineral density of the femur of ovariectomized
rats was significantly lowered in comparison with that of the sham operated rats. The protein profiles
of the urine samples collected from the sham, ovariectomized (OVX) and 2 month-old non-operated
(Young) rats were compared by 2-D gel and MS spectrometry.
Results: Proteins consistently expressed between Young and sham but differentially expressed in
OVX rats were selected and identified. One down-regulated 21 kDa protein, superoxide dismutase
(SOD), and 1 up-regulated 53-54 kDa protein, alph-1-antitrypsin (A1AT), were selected from urine
of the ovariectomized rats by 2-D gel analysis. Further, a total of 30 with 19 up-regulated and 11-
down-regulated proteins were selected by LC-MS analysis with more than 2-fold differences in spectral
counts. The fact that SOD and A1AT are also listed in the 30 differential proteins suggests that
our biomarker isolation procedure suitably represents osteoporosis-associated proteins in urine.
Conclusion: Supporting the facts, the differential expressions of SOD and A1AT in urine could be
validated by Western blotting. These urinary osteoporosis-associated proteins have high potentials to
become candidates for non-invasive diagnosis of osteoporosis from urine.