78-kilodalton glucose-regulated protein is induced in Rous sarcoma virus-transformed cells independently of glucose deprivation.
To identify mRNAs with altered expression in Rous sarcoma virus (RSV)-transformed cells, we screened a chicken embryo fibroblast (CEF) cDNA library by differential hybridization. One clone, designated R1H, showed markedly elevated mRNA expression in RSV-transformed cells. Nucleotide sequence analysis indicated that R1H mRNA encodes 78-kilodalton glucose-regulated protein (GRP78). Chicken GRP78 was found to be very highly conserved in comparison with rat GRP78 (96% identity between chicken and rat amino acid sequences). In contrast to previous observations, we found that GRP78 was induced in RSV-transformed cells in the absence of glucose deprivation. When cells were grown in glucose-supplemented medium, the level of GRP78 mRNA was approximately fivefold higher in RSV-transformed CEF than in transformation-defective virus-infected or uninfected CEF. Similar changes in GRP78 protein content were also found. Using a temperature-sensitive mutant of RSV and supplemental glucose, we found a gradual increase in the level of GRP78 mRNA beginning at 4 h after shiftdown to permissive temperature. Uridine supplementation did not block the induction seen in CEF infected with a temperature-sensitive mutant. These results indicate that GRP78 is induced by p60v-src in the absence of glucose deprivation.
Stoeckle
M Y
MY
Rockefeller University, New York, New York 10021.
Sugano
S
S
Hampe
A
A
Vashistha
A
A
Pellman
D
D
Hanafusa
H
H
D000818:Animals; D001358:Avian Sarcoma Viruses; D001483:Base Sequence; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D003001:Cloning, Molecular; D005347:Fibroblasts; D005786:Gene Expression Regulation; D005947:Glucose / Q000032:analysis; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data
D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; C018551:glucose-regulated proteins; D005947:Glucose