Global analysis of tissue-differential gene expression patterns and functional regulation of rapid antler growth.

Deer antlers are unique mammalian appendages that grow faster than any other known organ. During the rapid growth stage at 60 days after casting the previous antler, the maximal antler growth rate is up to or even more than 2 cm/day. Antler growth is driven by the growth center located in the antler tip. The growth center consists of several tissue layers from distal to proximal, including the skin, mesenchyme, precartilage, and cartilage. To analyze the gene expression patterns of the antler growth center in a tissue-differential manner and explore the molecular mechanism responsible for rapid antler growth, we used an RNA-Seq method to analyze gene expression patterns in different tissues of the Sika deer antler growth center during the rapid growth stage. We demonstrated considerable diversity in the expression levels of functional genes among different tissues within the antler growth center. These tissue-differentially expressed genes included transcription factors, growth factors, and extracellular matrix proteins. We identified a series of genes that contribute to chondrogenesis from mesenchymal cell condensation to chondrocyte differentiation. The genes identified in the antler growth center at the rapid growth stage provide valuable insight into the physiological mechanisms underlying rapid antler growth. [ABSTRACT FROM AUTHOR]