Study on the mechanisms of Piezo1-lars2 signal path mediating the mechanical loading on endochondral ossification process of fracture healing
In China, the incidence of fracture non-unions is relatively high. Impaired endochondral ossification may lead to nonunion due to improper mechanical loading. As a mechanosensitive ion channel protein, Piezo1mediates mechanical transduction and induces calcium inward flow. Our early study showed that the osteogenic and angiogenic capacity of chondrocytes was reduced, if Piezo1 gene was knocked out on chondrocytes. Moreover, the expression of mitochondrion translation related gene LARS2 was signaling increased. Therefore, we hypothesize that the mechanical loading may cause endochondral ossification through the Piezo1- LARS2 signaling pathway. We will use conditioned gene knockout mice and Peizo1 knockdown stable cell line to support the hypothesis. Our goals include investigating the changes of Piezo1 expression during endochondral ossification of femoral fracture healing in mice under mechanical loading; investigating the response of Piezo1 channels on chondrocytes to mechanical stimulation and its role and mechanism in regulating chondrocyte osteogenesis and angiogenesis, maintaining the normal mitochondrial function in vitro; analysing the key molecular and signal network downstream of Piezo1 through the multi-omics techniques; and exploring the response mechanism of Piezo1 under vibrating stimulus. This project aims to study the molecular mechanism of Piezo1-mediated force-biological information transition and its role in endochondral ossification. We hope it provides an effective intervention target for preventing and treating fracture nonunion. Overall design: three samples from the callus tissue of  Col2CreERT; Piezo1-/- and wt mice