Phenotypic Analysis of Long Bones in Pannexin 3 Knockout Mice Using a Geometric Morphometric Approach

Abstract

Pannexin 3 (Panx3) is a channel‐forming glycoprotein that is expressed in skin, mammary gland and skeletal tissues. In vitro studies have shown that Panx3 is induced at the growth plate where it is thought to promote cell differentiation, a key role in bone formation. However, whether or not the ablation of Panx3 in mice causes phenotypic anomalies is unknown.The study objective is to analyze the phenotype of long bones in a new Panx3 knockout (KO) mouse to assess the role of Panx3 in bone formation.Ten KO and 10 wild‐type (WT) adult mice were scanned using high resolution in vivo micro‐CT. Each long bone studied was digitized using homologous landmarks. Data analysis using geometric morphometrics (multivariate statistical methods) allowed for a quantitative comparison of shape, size and variation of long bones between KO and WT mice.KO mice demonstrated distinct long bone shape differences that were greatest at the joint surfaces. As well, long bones in KO mice were 5% smaller. A significant portion of the shape difference (20%) can be attributed to the size component of shape. KO mice demonstrated greater shape variation that also appeared to be driven by different patterns of growth.Our findings suggest that Panx3 affects long bone shape through its effect on size. Importantly, KO mice appear to have altered and less predictable patterns of long bone growth. Thus, Panx3 may have a role in maintaining optimum bone growth.