Nuclear Localization of SYT, SSX and the Synovial Sarcoma-Associated SYT-SSX Fusion Proteins

• Published in: Human molecular genetics 1997-09, Vol.6 (9), p.1549-1558
• Main Authors: dos Santos, Nuno R., de Bruijn, Diederik R. H., Balemans, Matthé, Janssen, Bert, Gärtner, Fátima, Lopes, José Manuel, de Leeuw, Bertie, Geurts van Kessel, Ad
• Format: Article
• Language: English
• Subjects: Adult; Animals; Antibody Specificity; Biological and medical sciences; Blotting, Western; Cell Nucleus - immunology; Cell Nucleus - metabolism; COS Cells; Diseases of the osteoarticular system; Fluorescent Antibody Technique, Indirect; Gene Expression; Humans; Immunoblotting; Male; Medical sciences; Neoplasm Proteins - immunology; Neoplasm Proteins - metabolism; Proteins - immunology; Proteins - metabolism; Proto-Oncogene Proteins; Repressor Proteins - immunology; Repressor Proteins - metabolism; Sarcoma, Synovial - genetics; Sarcoma, Synovial - metabolism; Sarcoma, Synovial - pathology; Transfection; Tumor Cells, Cultured - pathology; Tumors of striated muscle and skeleton
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/6.9.1549

Synovial sarcoma is characterized by a prevalent chromosomal translocation, t(X;18)(p11;q11). As a result of this translocation the SYT gene on chromosome 18 fuses to either the SSX1 or the SSX2 gene on the X chromosome. In this study, we generated polyclonal antibodies against the SYT and SSX2 proteins. These antibodies specifically detected both these proteins and the SYT-SSX fusion proteins in transfected COS-1 cell extracts. Indirect immunofluorescence analysis of COS-1 cells expressing tagged or untagged SYT, SSX2, SYT-SSX1 or SYT-SSX2 indicated that all these proteins are localized in the nucleus, excluding the nucleoli. The SSX2 protein exhibited a diffuse staining pattern whereas both the SYT and SYT-SSX proteins appeared in several nuclear dots. Similar nuclear dots were also detected in primary synovial sarcoma cells growing in a short-term in vitro culture. Double immunofluorescence in conjunction with confocal laser-scanning microscopy revealed that the SYT and SYT-SSX nuclear dots do not co-localize with known nuclear structures as e.g. coiled bodies, SC35 interchromatin granules or PML bodies. The similar nuclear localization patterns of SYT and SYT-SSX suggest that the SYT-SSX fusion proteins are directed to SYT-associated nuclear domains where an abnormal function may be exerted.