Characterization of the arylsulfatase I (ARSI) gene preferentially expressed in the human retinal pigment epithelium cell line ARPE-19.
OBJECTIVE
The aim of this study was to characterize the arylsulfatase I (ARSI) gene that has been shown to be preferentially expressed in the human retinal pigment epithelium cell line ARPE-19 and to propose it as a candidate gene responsible for inherited eye diseases such as retinitis pigmentosa (RP).


METHODS
Full-length cDNA clones encoding ARSI, arylsulfatase A (ARSA), and sulfatase modifying factor 1 (SUMF1) were isolated from ARPE-19 cDNA libraries constructed using the vector-capping method. The expression vectors for their FLAG-tagged proteins were transfected into ARPE-19 cells, and the expression products were characterized by western blot analysis and arylsulfatase assay. The entire region of the ARSI gene locus was sequenced using the genomic DNA samples of 68 RP patients.


RESULTS
Transiently produced ARSI-FLAG was localized to the endoplasmic reticulum and was detected in the cellular fraction and the medium. When ARSI-FLAG and SUMF1-FLAG were coexpressed, the conditioned medium of the transfected cells showed arylsulfatase activity at a range of neutral pH. No mutation was found in the ARSI gene locus of the RP patients examined.


CONCLUSIONS
ARSI may be a secreted sulfatase and may function in the extracellular space. Although ARSI may not be a causative gene for lysosomal storage diseases, preferentially expressed in the eye, ARSI would be a candidate gene causing inherited eye diseases for future mutation screening.
Oshikawa
Mio
M
Department of Rehabilitation Engineering, Research Institute, National Rehabilitation Center for Persons with Disabilities, Saitama, Japan.
Usami
Ron
R
Kato
Seishi
S
D019943:Amino Acid Substitution; D001192:Arylsulfatases / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000201:enzymology*; D012174:Retinitis Pigmentosa / Q000201:enzymology / Q000235:genetics; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; C511170:ARSI protein, human; D001192:Arylsulfatases