Cathepsin K Regulates Adipocyte Differentiation: Possible Involvement of Type I Collagen Degradation

Abstract

We previously found that cathepsin K (CTSK) played an important role in adipocyte differentiation. However, the underlying molecular mechanism is not clear. Through the time window study, it was observed that CTSK activities were required mainly in the early phases of adipogenic process. At the same time, the expression of typ I collagen disappeared. However, type I collagen can still be observed during the whole process when the CTSK inhibitor-E64 was added. The mRNA levels of peroxisome proliferator-activated receptor γ (PPAR-γ) and CCAAT/enhancer binding protein α (C/EBP-α) was also declining. These imply that CTSK may play a role in adipogenesis in early differentiation phases and produce an effect at least partly by degrading type I collagen, which may provides a basis for developing novel therapeutic approaches to treat obesity and the diseases associated with it.