Lentivirus-TAZ Administration Alleviates Osteoporotic Phenotypes in the Femoral Neck of Ovariectomized Rats

Abstract

Background: Osteoporosis is characterized by impairment of bone mass, strength, and microarchitecture, leading to the susceptibility to fragility fractures, especially in femoral neck region. Transcriptional coactivator with PDZ-binding motif (TAZ) facilitates osteogenesis while suppressing adipogenesis via regulation of transcriptional activities of runt-related transcription factor 2 and peroxisome proliferator-activated receptor γ. Here, we validated the role of TAZ in vivo using an ovariectomized (OVX) rat model of osteoporosis. Methods: Serum alkaline phosphatase, triglyceride, cholesterol and urinary hydroxyproline were measured on an automatic analyzer using diagnostic reagent kits. Serum OCN and C-terminal cross-linked telopeptides of type I collagen were measured using ELISA. Bone mineral density was measured using dual-energy X-ray scanner. Mechanical parameters were detected by three-point bending assays. Bone volume per tissue volume (BV/TV), trabecular thickness (Tb. Th), trabecular number (Tb. No), and trabecular separation (Tb. Sp) were measured by MicroCT. The mRNA and protein levels were quantified by Realtime PCR and Western Blotting respectively. Results: After injections of lentivirus overexpressing TAZ into the femoral neck region, bone mineral density, ultimate force, stiffness, BV/TV, Tb. Th, and Tb. No were significantly increased, whereas Tb. Sp was dramatically decreased. In the TAZ-overexpression region in the femoral neck of OVX rats, the mRNA levels of Runx2 and osteocalcin were obviously elevated, whereas that of PPARγ and adipocyte protein 2 were downregulated. Conclusion: Lentivirus-mediated TAZ gene therapy alleviated the osteoporotic phenotypes in the femoral neck of OVX rats, providing an alternative strategy for the treatment of postmenopausal osteoporosis and prevention of osteoporotic fracture.