Abnormal DNA damage-inducible protein in cells from Sjogren's syndrome patients

Antinuclear antibodies are commonly found in patients with Sjogren's syndrome. It has been suggested that the development of antinuclear antibodies depends on the activation of the spliceosome and other transcription-related subcellular particles, some of which have recently been shown also to function in DNA-modifying processes, such as DNA repair and V(D)J recombination. These observations add weight to a previously proposed model for the aetiology of Sjogren's syndrome. This includes the abnormal processing of the T-cell receptor and immunoglobulin genes. To test this hypothesis further, the present study on DNA-modifying proteins in Sjogren's syndrome was initiated. Gel-shift experiments using protein extracted from UV-treated Sjogren cells provided evidence of high molecular weight DNA-binding protein in six out of 12 Sjogren patients studied (but not among seven healthy controls). Some Sjogren sera displayed antibodies to protein extracts from cells treated with psoralen plus UVA radiation. These results indicate an abnormal DNA damage-inducible response in Sjogren's syndrome. It may therefore be concluded that alterations in nuclear protein may play a role in the aetiology of Sjogren's syndrome.