CHARACTERIZING AQP9: A REGULATOR OF EPIPHYSEAL PLATE CHONDROCYTE PROLIFERATION, HYPERTROPHY, AND LONG BONE GROWTH

Abstract

Aquaporin-9 (AQP9) is a membrane channel protein suspected to regulate growth in the epiphyseal plate. As long bone defects often possess limited non-surgical options, novel factors underlying bone growth must be continuously explored to advance effective treatments. I hypothesized that Aqp9 is an important epiphyseal plate chondrocyte channel regulating the process of endochondral ossification. In this study, Aqp9 -/- mouse long bones compared to wildtype mouse long bones showed a neonatal hindlimb-specific acceleration of growth followed by reduced length in the juvenile age. Analysis of Aqp9 -/- epiphyseal plates and chondrocytes showed an early disposition for proliferation and aversion from hypertrophy, suggesting that Aqp9 may function similarly to genes such as Col10a1 and Mmp13. This study provides insight into chondrocyte membrane channel proteins and their regulation of the growing epiphyseal plate, demonstrating that Aqp9 may be a novel therapeutic target for the non-invasive intervention of leg length discrepancies.