[Endoplasmic reticulum stress response involved in osteogenesis and chondrogenesis]

The endoplasmic reticulum (ER) is a central cellular organelle responsible for the synthesis, folding and posttranslational modifications of proteins destined for the secretory pathway. Various pathophysiological conditions, such as ER-calcium depletion, oxidative stress, hypoglycemia, expression of mutated proteins and hypoxia, interfere with the correct folding of proteins and these misfolded or unfolded proteins accumulate in the ER lumen. These conditions, which are collectively termed ER stress, have the potential to induce cellular damage. Recently, the ER stress has been demonstrated to be associated with bone and cartilage diseases. Further, it has been known that the ER stress and its stress response also play important roles in osteogenesis and chondrogenesis.