Identification of a novel serum and growth factor-inducible gene in vascular smooth muscle cells.
We have used subtraction cloning to isolate a cDNA (PS4) that identified a serum-inducible mRNA of 1.9 kilobases in rabbit vascular smooth muscle cells. DNA sequence analysis revealed one major open reading frame encoding a 9,442 M(r) protein. Comparison of the DNA as well as the putative protein sequence with various data bases revealed no homology with other sequences. In vitro translation of synthesized PS4 mRNA generated a major polypeptide of 12 kDa. Serum stimulation of quiescent smooth muscle cells in culture induced a rapid increase in the level of PS4 mRNA. Expression of this message was detected by 1 h, peaked at approximately 4 h, and became undetectable by 12 h. The induction of PS4 by serum was completely blocked by cycloheximide, indicating its expression required prior protein synthesis. Epidermal growth factor, acidic fibroblast growth factor, and transforming growth factor-beta 1 also induced a strong increase in PS4 expression. By contrast, platelet-derived growth factor-BB was only able to mildly stimulate the level of PS4 mRNA and insulin-like growth factor-I was unable to enhance PS4 expression. There was a high level of PS4 mRNA in rabbit fetal muscle, esophagus, kidney, and lung, a low level in fetal aorta and heart, and an undetectable level in fetal liver, brain, as well as, in the placenta. The expression of PS4 in the corresponding adult tissues was low or undetectable. Our analysis indicate that PS4 expression is developmentally regulated and tightly controlled by growth factors, suggesting this novel gene has a role in cell growth and differentiation.
Feng
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P
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855.
Liau
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G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003470:Culture Media; D004247:DNA / Q000235:genetics*; D005333:Fetus; D005786:Gene Expression Regulation / Q000187:drug effects; D015723:Gene Library; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009124:Muscle Proteins / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D016366:Open Reading Frames; D009928:Organ Specificity; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D003470:Culture Media; D006133:Growth Substances; D009124:Muscle Proteins; C081025:PS4 protein, Oryctolagus cuniculus; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011061:Poly A; D004247:DNA