Isolation of the oncogene and epidermal growth factor-induced transin gene: complex control in rat fibroblasts.

Abstract

Various oncogenes or epidermal growth factor (EGF) induce transcription of a 1.9-kilobase RNA (transin RNA) in rat fibroblasts. The induction by EGF can be blocked by cycloheximide. Thus the response of the transin gene to EGF appears to require de novo protein synthesis. Transin RNA induction is specific to EGF, as neither insulin, platelet-derived growth factor, fibroblast growth factor, nor transforming growth factor P could elicit the same response. However, transforming growth factor 3 could block the EGF induction of transin RNA. Whereas the calcium ionophore A23187 and the tumor promoter TPA, either alone or administered together, did not increase transin RNA levels, TPA could synergise with a serum factor to effect such an increase. Dibutyryl cyclic AMP also induced transin RNA. Treatment of cells with the microfilamentdisrupting agent cytochalasin B, but not the microtubule-disrupting agent colcemid, resulted in an increase in transin RNA levels, suggesting a role for the cytoskeleton in control of transin gene expression. The transin RNA does not contain repeated sequences and appears to be encoded by a single-copy gene. The protein sequence encoded by the last four exons of the transin gene shows some homology to two regions of the heme-binding protein hemopexin.Detailed knowledge of the mechanisms of action of oncogenes, growth factors, and growth factor receptors is important as a means of furthering our understanding of the loss of growth control characteristic of the neoplastic state. The recent discoveries of structural and functional similarities between certain oncogene products and growth factors or growth factor receptors has opened avenues of research that continually reveal new links between the action of oncogenes and growth factors (9, 21). Thus the recent finding that the c-fms proto-oncogene product is related to the receptor for the mononuclear phagocyte growth factor colony stimulating factor (CSF-1) (49) joins the previous observations that the cellular homolog of the oncogene v-sis is a gene encoding platelet-derived growth factor (PDGF; 12, 59) and that the product of the retroviral oncogene v-erbB appears to be a truncated version of the cellular epidermal growth factor (EGF) receptor, lacking the EGF binding domain (13). While these findings show that some oncogenes may function by imitating growth factors or occupied growth factor receptors, little is known about how the growth factor/receptor interaction itself leads to accomplishment of the complex events involved in cell division.One of the most studied growth factor/receptor systems is the interaction between EGF and its receptor at the cell surface. This interaction activates the receptor's tyrosine kinase activity (58) and leads to a rapid increase in intracellular calcium levels and pH (22,36). Another consequence of EGF treatment of a variety of cell types is a rapid increase in levels of c-myc, c-fos, and actin mRNAs (8,15,33,37). This increase, a result either of a decreased rate of mRNA degradation (c-myc; 7) or an i...

Epidermal growth factor stimulation of stromelysin mRNA in rat fibroblasts requires induction of proto-oncogenes c-fos and c-jun and activation of protein kinase C.

“…3 and 4). This finding is consistent with our previous observations that de novo protein synthesis is required for EGF induction of stromelysin RNA (30). The antisense oligonucleotides significantly reduce but do not abolish the stromelysin response to EGF (Fig.…”

“…Both Jun homodimers and the Jun-Fos heterodimer complex have been found to possess DNA-binding properties, though the Jun-Fos heterodimer has a much greater affinity for the AP-1-binding site and is a more potent transcriptional activator than the Jun homodimers (18,34,39). Interestingly, an AP-1-binding site has been identified in the rat stromelysin promoter at the -71-base-pair position (30). These observations suggest the possibility that c-fos and/or c-jun may be "third messengers" in the EGF induction of stromelysin gene transcription.…”

Regulation of Membrane‐Type Matrix Metalloproteinase‐1 Expression by Growth Factors and Phorbol 12‐Myristate 13‐Acetate

“…PMA induces the mRNA levels of collagenase, stromelysin and 92-kDa gelatinase mainly by increasing gene transcription (Brinckerhoff et al, 1986;Matrisian et al, 1986;Angel et al, 1987;Sat0 and Seiki, 1993). To find out whether the increase of MT-MMP-I mRNA levels by PMA was caused by stabilization of the mRNA or increase of gene transcription, the stability of mRNA was studied by actinomycin D treatment.…”

Negative regulation of the rat stromelysin gene promoter by retinoic acid is mediated by an AP1 binding site.

“…Requirement of RAR and of 5'-flanking DNA sequences To determine if DNA sequences located in the 5'-flanking region of the rat stromelysin gene were involved in the RA dependent transcriptional response, DNA sequences from -1100 to + 8 of the stromelysin gene (Matrisian et al, 1986b) were linked upstream of a promoterless chloramphenicol acetyltransferase (CAT) gene to create the fusion plasmid STR-CAT. RA treatment of PyT21 cells transfected with STR -CAT ( Figure 2A) showed an average of 50% of the CAT activity detected in the absence of RA.…”