Molecule that controls obesity helps to maintain bone health

What is it about?

Thy1 (also called CD90) is a surface cell membrane protein originally identified as a marker for mouse T cells but subsequent reports noted high expression on subsets of stem cells, fibroblasts and bone forming cells called osteoblasts. We previously discovered that Thy1 regulates fat cell (adipocyte) differentiation and that mice without Thy1 are more prone to obesity than normal wild-type mice fed a high fat diet. Interestingly, adipocytes and osteoblasts originate from progenitor cells called mesenchymal stem cells (MSCs) and altered commitment of mesenchymal stem cells to adipocytes or osteoblasts has been implicated in pathological conditions of abnormal bone remodeling. The role of Thy1 in osteoblast differentiation and bone homeostasis has been poorly studied and represents a major knowledge gap. Thus, the goal of this study was to examine the contribution of Thy1 to osteoblast formation and to determine if it is required for bone homeostasis.

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Why is it important?

We find that Thy1 is a positive regulator of osteoblast differentiation and modulates bone homeostasis in obese mice. Absence of Thy1 was associated with reduced bone quality and fewer osteoblasts. Additionally, cells without Thy1 or reduced levels of Thy1 showed decreased ability to form osteoblasts. Thus, Thy1 may serve as an important mechanistic link between bone formation and obesity.