Role of p300, a histone acetyltransferase enzyme, in osteoblast differentiation

Bone is a dynamic and tough connective tissue that undergoes constant remodeling throughout life. Boneforming osteoblasts respond to various hormones, cytokines, and growth factors, and synthesize extracellular matrix components. Runx2 (Runt-related transcription factor 2), a bone transcription factor, is essential for ossification by stimulating the expression of osteoblast differentiation marker genes, including type I collagen, alkaline phosphatase, and osteocalcin. Coactivators, such as p300, CBP (CREB-binding protein), and PCAF (p300/CBP associated factor) tightly regulate osteoblast differentiation via Runx2. There is growing evidence indicating the role of p300, which possesses histone acetyltransferase (HAT) activity, in regulating histones and transcription factors such as Runx2 during osteoblast differentiation. In this review, we aim to delineate the role of p300 at the molecular level, emphasizing the importance of its HAT activity during osteoblast differentiation. Furthermore, this review intends to highlight the regulation of p300 at multiple levels, including posttranslational and ncRNAs, that might exert an indirect influence on bone formation.