Ets1 regulates the transcription of a cartilage-specific S100 protein in gilthead seabream

Abstract

Summary A novel S100 calcium-binding protein has been recently identified in teleost fish. Its expression is restricted in vivo to chondrocytes of cartilaginous tissues undergoing endo/perichondral mineralization and its function has been associated in vitro with mechanisms of extracellular matrix mineralization. To get more insights into this mineralogenic role, the transcriptional regulation of S100 gene was investigated using luciferase reporter constructs. The occurrence of several silencers was revealed through the analysis of the basal activity of promoter constructs in HEK-293 cells. Among those, a silencer located in the region −883/−768 had the capacity to shut down completely the activity of S100 gene promoter. The presence of several putative binding sites for Ets1, a transcription factor regulating the expression of several cartilage-related proteins, was predicted through in silico analysis. Analysis of luciferase activity in cells expressing zebrafish Ets1a revealed that regions −636/−513 and −82/+62 contain active Ets1 binding sites and decrease luciferase activity upon mutation of specific sites confirmed the effectiveness of Ets1 binding at positions −552/−539 and −517/−501. In conclusion, this work provided novel evidence for the transcriptional regulation of fish cartilage-specific S100 protein by Ets1.