Unravelling the role of Arylsulfatase E (ARSE) in bone mineralization and development.

The balance between sulfation and desulfation of extracellular matrix glycosaminoglycans (GAGs) plays an important role in bone mineralization. In humans, a majority of bone dysplasias are caused by mutations in either Golgi sulfotransferases or lysosomal sulfatases. Another sulfatase named arylsulfatase E (ARSE) has been described in Golgi, and when mutated it is associated to X-linked Chondrodisplasia Punctata (CDPX). CDPX is characterized by aberrant bone mineralization with epiphyseal punctate calcifications. Interestingly, an identical phenotype is observed in Warfarin embryopathy (WE). Up to now, however neither ARSE function nor substrates are known. The aim of this study is to define the function of ARSE and to understand its role in WE. The subcellular fractionation and immunofluorescence experiments localized ARSE in the trans-Golgi network. Consistently, a very high ARSE sulfatase activity was detected in the Golgi fraction isolated from rat chondrocytes (RCS). . Interestingly, warfarin administration inhibited the ARSE enzymatic activity, both in the total cell lysate and in Golgi extracts. In search for the ARSE substrates we have analysed the sulfation states of extracellular matrix components by High Performance Liquid Chromatography (HPLC) from RCS wild type (WT), overexpressing (OE) and silenced (KD) for ARSE. This analysis showed differences in the levels of sulfation of specific GAGs. In conclusion, ARSE is a sulfatase localized in the trans-Golgi network that may regulate the sulfation state of specific GAGs in the cartilage during development.