ONE GENE, 2 TRANSCRIPTS - ISOLATION OF AN ALTERNATIVE TRANSCRIPT ENCODING FOR THE AUTOANTIGEN LA SS-B FROM A CDNA LIBRARY OF A PATIENT WITHPRIMARY SJOGRENS-SYNDROME/

A cDNA library was prepared from peripheral blood lymphocytes of an au toimmune patient with primary Sjogrens' syndrome. The cDNA library was screened with the patients own autoimmune serum being monospecific fo r the nuclear autoantigen La/SS-B. Thereby an alternative type of La m RNA was identified that differed from the known La mRNA due to an exch ange of the exon 1. Sequencing of the genomic region between the exons 1 and 2 showed that the alternative 5'-end is a part of the intron. I n addition, the presence of an alternative promoter site, which exists within the intron downstream of the exon 1, became evident. In conseq uence, the alternative La mRNA is the result of a promoter switching c ombined with an alternative splicing mechanism. In the intron, further transcription factor binding sites, including a NF-kappa B element, w ere identified leading to the suggestion that the expression of the ge ne encoding for the nuclear autoantigen La/SS-B alters in dependence o n disease conditions.