Prostate transmembrane protein androgen induced 1 is induced by activation of osteoclasts and regulates bone resorption

What is it about?

Bone is a dynamic tissue that is disrupted by osteoclasts and formed by osteoblasts. Balancing bone resorption and bone formation is important for maintaining healthy skeletal homeostasis. However, bone loss is occurred in bone diseases such as osteoporosis and rheumatoid arthritis. Bone loss also causes loss of teeth in chronic periodontitis that is common disease. Osteoclasts are sole cells responsible for bone resorption. Osteoclasts are formed from hematopoietic cells, and are activated on bone surface to resorb bone. However the details of activation are unclear and useful molecular marker for bone resorbing osteoclasts are not available. Identification of osteoclast activation markers and understanding the mechanism of osteoclast activation will provide novel diagnostic markers and powerful strategy to prevent bone loss. All of the cells have membrane-enclosed organelles, and one of them, lysosomes contain acid and enzymes capable of breaking down biological compounds. Interestingly, osteoclasts release acid and enzymes of lysosomal contents to the outside of the cells to destroy bone tissues. This process is performed by intracellular membrane trafficking. We found Prostate transmembrane protein androgen induced-1 (Pmepa1) which is involved in membrane trafficking in cancer cells, is specifically expressed in activated osteoclasts. Our results demonstrate that Pmepa1 is a critical regulator of bone resorption, and is a novel marker for osteoclasts. Pmepa1 could be a promising therapeutic target molecule in bone disease.

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