Abstract
Mechanical regulation of bone formation involves a complex biophysical process, yet the underlying mechanisms remain poorly understood. Polycystin-1 (PC1) is postulated to function as a mechanosensory molecule mediating mechanical signal transduction in renal epithelial cells. To investigate the involvement of PC1 in mechanical strain-induced signaling cascades controlling osteogenesis, PKD1 gene was stably silenced in osteoblastic cell line MC3T3-E1 by using lentivirus-mediated shRNA technology. Here, our findings showed that mechanical tensile strain sufficiently enhanced osteogenic gene expressions and osteoblastic proliferation. However, PC1 deficiency resulted in the loss of the ability to sense external mechanical stimuli thereby promoting osteoblastic osteogenesis and proliferation. The signal pathways implicated in this process were intracellular calcium and Akt/β-catenin pathway. The basal levels of intracellular calcium, phospho-Akt, phospho-GSK-3β and nuclear accumulation of active β-catenin were significantly attenuated in PC1 deficient osteoblasts. In addition, PC1 deficiency impaired mechanical strain-induced potentiation of intracellular calcium, and activation of Akt-dependent and Wnt/β-catenin pathways, which was able to be partially reversed by calcium ionophore A23187 treatment. Furthermore, applications of LiCl or A23187 in PC1 deficient osteoblasts could promote osteoblastic differentiation and proliferation under mechanical strain conditions. Therefore, our results demonstrated that osteoblasts require mechanosensory molecule PC1 to adapt to external mechanical tensile strain thereby inducing osteoblastic mechanoresponse, partially through the potentiation of intracellular calcium and downstream Akt/β-catenin signaling pathway.
Highlights
Mechanical loading is an important epigenetic factor for the regulation of skeletal tissue regeneration [1]
We investigated whether PC1 expression may be influenced by mechanical strain in osteoblasts
Mechanical stimuli in an optimal biological environment result in osteogenesis and proliferation [3]
Summary
Mechanical loading is an important epigenetic factor for the regulation of skeletal tissue regeneration [1]. Increased mechanical loading stimulates osteoblastic differentiation and proliferation thereby resulting in bone formation [2]. Low level or absence of mechanical loading leads to either no response or reduced bone synthesis [3,4]. Osteopenia or osteoporosis is in part caused by lack of physiological mechanical loading [5]. Understanding the physiological mechanisms of bone how to adapt to mechanical stimuli should contribute greatly to prevent bone loss [6]. Mechanical regulation of bone formation involves a complex biophysical process, including the perception of extracellular mechanical stimuli applied, their conversion into intracellular biochemical cascades and adaptive responses of bone cells [7,8]. Mechanosensors sensing extracellular mechanical stimuli is a critical step of this process. The molecular mechanism how original mechanosensory molecule perceives mechanical signals thereby transforming into biochemical signals still remains poorly understood
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call