Identification and characterization of genes upregulated in cells transformed by v-Jun

The transcription factor Jun (c-Jun) functions as a recipient of extracellu lar growth signals and converts them into patterns of gene expression. An o ncogenic variant of c-Jun was isolated from the acutely transforming retrov irus ASV17, Overexpression of this viral Jun (v-Jun) induces transformation of chicken embryo fibroblasts (CEF) in culture and fibrosarcomas in chicke ns. v-Jun is constitutively active form of c-Jun and transforms cells presu mably by deregulating the expression of specific target genes. In this repo rt, we describe six genes whose transcripts are upregulated in v-Jun-transf ormed CEF, Three of these genes show homology to known mammalian genes, to MAP kinase phosphatase 2 (MKP-2), to reversion-induced LIM protein (RIL) an d to cytokine-inducible SH2-containing protein (CIS), Northern blot analysi s, using CEF infected with various Jun mutants or an estrogen-regulatable J un chimera, revealed distinct induction patterns of individual targets by v -jun, The chicken RIL homolog showed an expression pattern tightly correlat ed with the activity of v-Jun, Its expression is also transformation-depend ent, suggesting a role for this gene in v-Jun transformation, The newly ide ntified v-Jun targets can serve as molecular markers in the v-Jun transform ation process.