Expression and Modulation of Ghrelin O-Acyltransferase in Cultured Chondrocytes

Objective. To use reverse transcription-polymerase chain reaction to detect ghrelin O-acyltransferase (GOAT) transcripts in both murine and human chondrocytes, to evaluate the effect of pharmacologic in vitro treatments with lipopolysaccharide (LPS), growth hormone, ghrelin, and dexamethasone on GOAT messenger RNA (mRNA) expression, and to study the GOAT mRNA profile during chondrocyte differentiation. Methods. Murine and human GOAT and ghrelin mRNA levels were determined by the SYBR Green-based quantitative real-time polymerase chain reaction method. Results. GOAT mRNA was expressed in murine cartilage explants as well as in the cultured murine chondrogenic ATDC-5 cell line. GOAT was also expressed in human immortalized chondrocyte cell lines and in human cultured primary chondrocytes. In addition, GOAT mRNA expression in differentiating ATDC-5 cells was lower at the early stage of differentiation (days 3-7), whereas GOAT mRNA levels increased progressively at the late stages. Finally, among the drugs and hormones tested, only LPS was able to strongly decrease GOAT mRNA expression. Conclusion. These data indicate that chondrocytes are equipped with biochemical machinery for the synthesis of acylated ghrelin and suggest a novel role of the ghrelin axis in prehypertrophic and hypertrophic chondrocyte differentiation during endochondral ossification.