A novel oncogene, v-ryk, encoding a truncated receptor tyrosine kinase is transduced into the RPL30 virus without loss of viral sequences

Abstract

The RPL viruses are acute oncogenic avian retroviruses isolated from chicken tumors. We carried out a genetic analysis of three of the viruses, RPL25, RPL28, and RPL3O. While RPL25 and RPL28 were shown to contain the erbB oncogene, RPL3O appeared to contain a novel protein tyrosine kinase oncogene. This gene, v-ryk, was cloned and sequenced. The v-ryk oncogene contains a 1.39-kb nonretroviral sequence that includes a tyrosine kinase domain which was inserted into the viral envelope protein gp37-coding region and fused in frame with upstream gp37 to generate a p69m,37-y fusion oncoprotein. Unlike that of other acutely transforming retroviruses, transduction of the v-ryk gene into RPL30 did not result in deletion of viral sequences. Sequence analysis suggested that v-Ryk is more homologous to receptor-type tyrosine kinases than to nonreceptor-type kinases. By reconstitution of a virus from its cDNA, the v-ryk oncogene has been shown to be fully responsible for the transforming activity of the RPL30 virus. Antibodies specific to v-Ryk immunoprecipitated the v-Ryk oncoprotein from cells transformed by the RPL30 virus. The v-Ryk protein was shown to be first synthesized as a 150-kDa precursor and then cleaved into the mature 69-kDa gp37-Ryk fusion protein, both parts of which were found to be localized to the membrane fraction. As expected from the sequence of v-Ryk, immunoprecipitates of v-Ryk from RPL3O-transformed cells were found to display a protein tyrosine kinase activity in vitro, and the levels of tyrosine-phosphorylated proteins are elevated in

Unique signal transduction of Eyk: constitutive stimulation of the JAK-STAT pathway by an oncogenic receptor-type tyrosine kinase.

“…Immunoprecipitation, SDS-PAGE, Western blot and in vitro kinase assay The protocol for immunoprecipitation has been reported previously (Jia et al, 1992). The SDS-PAGE gel electrophoresis and electroblotting of proteins to a supporting material were carried out as described (Sambrook et al, 1989).…”

“…The oncogene v-eyk (East Lansing tyrosine kinase) was first isolated from an acute avian retrovirus, RPL30 (Jia et al, 1992). It encodes a transmembrane receptor-type tyrosine kinase (TK), p69gp37-Eyk, in which the intracellular (IC) region of a putative receptor tyrosine kinase (RTK) is fused to the viral gp37 glycoprotein (Jia et al, 1992). The proto-oncogene c-evk, from which v-eyk was derived, codes for an RTK with a distinctive extracellular (EC) region, containing two immunoglobulin-like and two fibronectin III-like motifs (Jia and Hanafusa, 1994).…”

“…However, unlike the stringently regulated c-Eyk, which is inactive and not transforming in chicken cells (C.Zong and H.Hanafusa, unpublished data), v-Eyk kinase is constitutively active. It significantly increases cellular tyrosine phosphorylation and causes transformation of chicken embryo fibroblasts (CEFs) (Jia et al, 1992). Consequently, RPL30 infection in vivo induces chicken erythroblastosis, fibrosarcomas, endotheliomas, visceral lymphomatosis and hemorrhage (Fredrickson et al, 1964).…”

Expression of the receptor protein-tyrosine kinases Tyro-3, Axl, and Mer in the developing rat central nervous system

“…Axl is also known as UFO, Tyro‐7, and Ark (Janssen et al, 1991; Lai and Lemke, 1991; O'Bryan et al, 1991; Rescigno et al, 1991). Mer is also called Tyro‐12, eyk, and Nyk (Lai and Lemke, 1991; Jia et al, 1992; Jia and Hanafusa, 1994; Ling and Kung, 1995). Tyro‐3 has been designated as etk2, Dtk, brt, Rse, sky, and tif (Lai and Lemke, 1991; Biesecker et al, 1993; Dai et al, 1994; Mark et al, 1994; Ohashi et al, 1994; Crosier et al, 1996).…”

Role of oligomerization of the S13 Env-Sea oncoprotein in cell transformation

“…Thus, the Env-Sea oncoprotein appears to exist as an oligomer but in a constitutive manner. Interestingly, another env-tyrosine kinase fusion gene has been recently isolated (14). env-ryk is a fusion of the majority of the RPL30 viral envelope gene to cell-derived sequences encoding a tyrosine kinase domain, Ryk.…”