Related Experiment Videos
Induction of four proteins in chick embryo cells by sodium arsenite
Abstract:
Four proteins of Mr = 89,000, 73,000, 35,000, and 27,000 are strongly induced in chick fibroblasts by sodium arsenite. Induction of these proteins is discoordinate as a function of arsenite concentration. Kinetically, all species appear 1 h after exposure to 50 microM arsenite, after 24 and 48 h of exposure, the 27,000 protein is still synthesized extensively, whereas normal cell proteins and the three other induced proteins are greatly reduced. The four proteins are unrelated by tryptic peptide-mapping procedures. Multiple subspecies of p89, p73, and p27 were observed in two-dimensional gels. The subspecies of p73 appear to be related as determined by partial proteolytic maps as are those of p27. Two-dimensional gel analysis of in vitro translation products from rabbit reticulocyte lysates primed with mRNA from uninduced and induced cells reveals that the amount of translatable mRNA specific for these proteins is increase by induction. This increase is attributable to new mRNA synthesis since actinomycin D prevent induction and new bands of RNA (Mr = 0.9 X 10(6) and 1.3 X 10(6)) appear in methyl mercury gels of oligo(dT) selected RNA from induced cells. These bands are assigned to p73 and p89 based on translation of electroeluted RNA from a similar preparative gel. A comparison is made between induction of these proteins and the heat shock response in Drosophilla melanogaster.
Insights
Sodium arsenite induces four specific proteins in chick fibroblasts. Their synthesis is regulated by new messenger RNA production, suggesting a stress response mechanism.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cellular stress responses involve the induction of specific proteins.
- Sodium arsenite is a known inducer of cellular stress responses.
Purpose of the Study:
- To investigate the induction of proteins in chick fibroblasts by sodium arsenite.
- To characterize the kinetics and regulation of these induced proteins.
Main Methods:
- Sodium arsenite treatment of chick fibroblasts.
- Analysis of protein synthesis using gel electrophoresis and tryptic peptide mapping.
- Messenger RNA isolation and in vitro translation.
- RNA analysis using methyl mercury gels.
Main Results:
- Four proteins (89, 73, 35, and 27 kDa) were strongly induced by sodium arsenite.
- Induction was dose-dependent and discoordinate.
- Synthesis of the 27 kDa protein persisted longer than others.
- New mRNA synthesis was responsible for the increased protein levels.
- Specific RNA bands (0.9 and 1.3 x 10^6 Da) were identified and assigned to induced proteins.
Conclusions:
- Sodium arsenite induces a specific set of proteins in chick fibroblasts.
- The induction involves de novo mRNA synthesis, indicating a regulated stress response.
- The findings provide insights into cellular adaptation mechanisms to toxic agents.