Sorcin expression in the epiphyseal growth plates of mice

Sorcin is a small calcium-binding protein that is widely expressed in many tissues. Sorcin regulates cardiac myocyte apoptosis by modulating mitochondrial Ca²⁺ cycling and regulates fibroblast cell cycling and apoptosis via Ca²⁺ signaling through the endoplasmic reticulum (ER). During endochondral ossification, some chondrocytes undergo apoptosis after their terminal differentiation; however, Sorcin’s expression in these cells has not been characterized. Here we examined Sorcin’s gene expression in the chondrocytes derived from mouse growth plate by reverse transcription PCR (RT-PCR), and its protein localization in the chondrocytes of femoral growth plate using immunohistochemistry. Sorcin protein was detected in the chondrocytes, and was particularly abundant in the cytoplasm and nuclei of proliferative zone chondrocytes and in the nuclei of hypertrophic chondrocytes. Apoptotic analysis of the growth plate revealed that many of the hypertrophic chondrocytes undergo the DNA fragmentation. We report for the first time the localization of Sorcin in the epiphyseal growth plate in which one of the apoptotic phenomenon was detected.