Aging is associated with profound changes in bone mass and body composition. Emerging evidence supports the hypothesis that alterations in mesenchymal stromal cell fate are a critical etiologic factor. In addition, time-keeping at the cellular level is affected as aging progresses, particularly in the adipocyte. In this Extra View we discuss the interactive role of three molecules, PPARĪ³, nocturnin and IGF-I in regulating stem cell fate in the marrow and the potential implications of this network for understanding cellular aging.
