Rat Articular Cartilages Change Their Tissue and Protein Compositions During Perinatal Period.

Articular cartilage (AC) covers the surface of bones in joints and functions as a cushion against mechanical loading. The tissue contains abundant extracellular matrix (ECM), which mainly consists of proteoglycans (PG) and collagen (COL) fibres. The property of AC is gradually changing by ageing with gravity loading. To know the property change of AC by initial gravity loading during short period after birth, we performed histological assays and proteomics assay on the AC of the femoral condyle in knee joints of perinatal rats. The water content (%) was significantly decreased in neonate AC compared with fetal AC. During the perinatal stages (E19 and P0), the localizations of glycosaminoglycan (GAG) and type I and II COLs were homogeneous. The density of chondrocytes was significantly decreased in the deeper layers comparing with the surface layer in neonate AC. In addition, we found a drastic change in the protein expression pattern on proteomic analysis. The expressions of ECM components were relatively increased in neonate AC compared with fetal AC.

Oxygen sensing and redox signaling: the role of thioredoxin in embryonic development and cardiac diseases.

It is important to regulate the oxygen concentration and scavenge oxygen radicals throughout the life of animals. In mammalian embryos, proper oxygen concentration gradually increases in utero and excessive oxygen is rather toxic during early embryonic development. Reactive oxygen species (ROS) are generated as by-products in the respiratory system and increased under inflammatory conditions. In the pathogenesis of a variety of adult human diseases such as cancer and cardiovascular disorders, ROS cause an enhancement of tissue injuries. ROS promote not only the development of atherosclerosis but also tissue injury during the reperfusion process. The thioredoxin (TRX) system is one of the most important mechanisms for regulating the redox balance. TRX is a small redox active protein distributed ubiquitously in various mammalian tissues and cells. TRX acts as not only an antioxidant but also an anti-inflammatory and an antiapoptotic protein. TRX is induced by oxidative stress and released from cells in response to oxidative stress. In various human diseases, the serum/plasma level of TRX is a well-recognized biomarker of oxidative stress. Here we discuss the roles of TRX on oxygen stress and redox regulation from different perspectives, in embryogenesis and in adult diseases focusing on cardiac disorders.