Alpha B crystallin accumulation is a specific response to Ha-ras and v-mos oncogene expression in mouse NIH 3T3 fibroblasts.
The conditional expression of the v-mos and Ha-ras(EJ) oncogenes in NIH 3T3 cells leads to the accumulation of a 23-kDa protein (p23) (R. Klemenz, S. Hoffmann, R. Jaggi, and A.-K. Werenskiold, Oncogene 4:799-803, 1989). We purified p23 to homogeneity and determined part of the amino acid sequence. The obtained sequence is identical with that of the eye lens protein alpha B crystallin. Northern (RNA) blot and Western immunoblot experiments were performed to demonstrate that alpha B crystallin mRNA and protein do indeed accumulate as a consequence of v-mos and Ha-ras oncogene expression. Comparison of cDNA clones obtained from the mRNA of eye lenses and of oncogene-expressing fibroblasts revealed identity between them. The major transcription initiation site of the alpha B crystallin gene in our experimental system was shown by primer extension experiments to be identical with the one used in eye epithelial cells. In addition, we identified a second minor initiation site 49 nucleotides further upstream. Serum growth factors did not stimulate alpha B crystallin expression in growth-arrested cells.
Klemenz
R
R
Division of Cancer Research, University Hospital, Zurich, Switzeland.
Fröhli
E
E
Aoyama
A
A
Hoffmann
S
S
Simpson
R J
RJ
Moritz
R L
RL
Schäfer
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003459:Crystallins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005347:Fibroblasts / Q000378:metabolism; D016258:Genes, mos; D011905:Genes, ras; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
D003459:Crystallins; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D004247:DNA