Protein product of proto-oncogene c-mil.

Abstract

Using antipeptide antibodies with specificity for the carboxyl termini of v-raf and v-mil protein products, two proteins with apparent molecular weights of approximately 71,000/73,000 and 215,000 were detected in immunoprecipitates from normal uninfected chicken cells. The 71,000/73,000-molecular-weight protein was identified as the product of the c-mil proto-oncogene by the close structural relationship of its 42,000-molecular-weight carboxyl-terminal domain to the v-mil-encoded domain of the hybrid protein p100gag-mil specified by the avian retrovirus MH2. The amino-terminal domain of the cellular protein is encoded by 5' c-mil sequences that have not been transduced into the genome of MH2. The c-mil protein (p71/73c-mil) was found to be phosphorylated in vivo, and homologous proteins were detected at variable levels in a variety of vertebrate cells, including human cells.

Cooperative cell transformation by Myc/Mil(Raf) involves induction of AP-1 and activation of genes implicated in cell motility and metastasis

“…The v-Myc protein in MH2A10 cells, the v-Mil protein in QEF transformed by retroviral construct RCAS-v-Mil, and the v-Jun protein in RCASv-Jun-transformed QEF are devoid of Gag sequences. In accordance with previous observations (Patschinsky and Bister, 1988;Hartl and Bister, 1998), the cellular proto-oncoproteins c-Myc or c-Jun were not detectable in Q8, MH2A10, or QEF/RCAS-v-Jun cells, respectively, which contain high levels of the corresponding viral oncoproteins v-Myc or v-Jun, whereas expression of c-Mil was observed at low levels in all cell types tested. Interestingly, expression levels of c-Jun and c-Fos were elevated in v-myc-transformed and particularly in v-myc/v-mil-transformed cells (Figure 1c), suggesting that cell transformation induced by MH2 may involve activation of AP-1.…”

“…Immunization and antiserum preparation were done as described (Hartl and Bister, 1998;Bader et al, 2001). Polyclonal antisera directed against recombinant Jun, Fos, or Myc proteins, or against a carboxyl terminal Mil undecapeptide, and a monoclonal antibody directed against the FLAG epitope have been described (Hartl and Bister, 1998;Patschinsky and Bister, 1988;Hartl et al, 2001).…”

Alternative splicing of RNAs transcribed from the chicken c-mil gene.

“…These two polypeptides, specifically immunoprecipitated with the anti-v-mil serum, were absent in untransfected COS-1 cells. The sizes of the polypeptides synthesized by pKCR3-6C (71 kDa) and pKCR3-1A (73 kDa) agree with the 71/73-kDa c-mil protein observed in previous in vivo studies, although the 73-kDa form was attributed to phosphorylation of the 71-kDa protein (15). Hence, on the basis of these considerations, we suggest that the p71/73c'i' detected in various cells (15) could also correspond to two distinct protein products generated by differential splicing.…”

“…c-mil, which is highly conserved among avian and mammalian species, is transcribed as an mRNA of 4.0 kilobases in chickens (3) and has been shown to encode a 71/73-kilodalton (kDa) phosphoprotein (15). The 42-kDa carboxy terminus, closely related to the product of its human counterpart rafi (2), is identical to the v-mil-encoded portion of the MH2 gag-mil hybrid protein, except for some point mutations (7), while the 30-kDa amino terminus is encoded by 5' c-mil sequences that have not been transduced into the genome of MH2 (7,15). It has been shown that the viral P100gag-mi fusion protein is associated with a serine-threonine kinase activity in vitro (14), whereas little is known about the physiological function of the c-mil gene.…”

Expression of the oncogenes mil and ras abolishes the in vivo differentiation of mammary epithelial cells

“…Deletion mutants of MH2 suggest that v-myc is the primary oncogene of this virus whilst v-mil has auxilliary oncogenic functions (44). In contrast, the murine homolog, v-raf, found in the virus 3611-MSV, efficiendy transforms established (20) as well as primary epithelial cells and established fibroblasts (21).…”