A Specific Osteogenic Transcription Factor - Activating Transcription Factor 4(ATF4)
As we all known, skeleton remodeling exists in all process of tooth movement which is highly related with the orthodontics treatment. During the past several years, we have witnessed significant progresses in skeleton biology. The mechanisms and therapy of molecular, cellular and genetic is crucial to make a good understanding of complicated intracellular and extracellular signals involved in bone formation and homeostasis. Various transcription factors have been identified to play important roles during the skeleton remodeling, such as inducing the expression of osteogenic genes at the transcriptional level, promoting the differentiation of osteoblasts, osteoclasts and chondrocytes, and assisting these cells to accomplish their normal functions. The role of activating transcription factor 4 (ATF4) as a specific osteogenic transcription factor has come under attention since the year 2004. It has also been demonstrated there are more and more upstream and downstream factors of ATF4 in the intracellular and extracellular signal pathways regulating the expression of osteogenic genes. However, there exist other many nuclear accessory factors that interact with ATF4 to promote or prohibit its role of transactivation of the osteogenic genes, which is indispensable in the strictly regulated network to control the osteogenic cells differentiation and bone remodeling. In this review, we distill the factor functions about ATF4 into four types .Each type is illustrated with examples to demonstrate the functional complexity.