MOLECULAR-CLONING OF A NEW INTERFERON-INDUCED PML NUCLEAR BODY-ASSOCIATED PROTEIN

Transcriptional induction of genes is an essential part of the cellula r response to interferons. We have established a cDNA library from hum an lymphoblastoid Daudi cells treated for 16 h with human alpha/beta-i nterferon (IFN) and made use of differential screening to search for a s yet unidentified IFN regulated genes, In the course of this study, w e have isolated a human cDNA that codes for a 20-kDa protein sharing s triking homology with the product of the Xenopus laevis XPMC2 gene. Th is new gene is induced by both type I and II IFNs in various cell line s and will be referred to as ISG20 for interferon-stimulated gene prod uct of 20 kDa. Confocal immunofluorescence analysis of the subcellular localization of ISG20 protein reveals that it is closely associated w ith PML and SP100 gene products within the large nuclear matrix associ ated multiprotein complexes termed the PML nuclear bodies.