Related Experiment Videos
Functional conservation of 14-3-3 isoforms in inhibiting bad-induced apoptosis
R R Subramanian1, S C Masters, H Zhang
1Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Abstract:
14-3-3 proteins are a family of homologous eukaryotic molecules with seven distinct isoforms in mammalian cells. Isoforms of 14-3-3 proteins interact with diverse ligands and are involved in the regulation of mitogenesis, cell cycle progression, and apoptosis. However, whether different 14-3-3 isoforms are responsible for distinct functions remains elusive. Here we report that multiple isoforms of 14-3-3 proteins were capable of binding to several ligands, Bad, Raf-1, and Cbl. In a functional assay of 14-3-3 isoforms, all mammalian 14-3-3 isoforms could inhibit Bad-induced apoptosis. Thus, 14-3-3 function in regulating one of its ligands, Bad, is conserved among mammalian isoforms. We addressed whether 14-3-3 isoforms are differentially expressed in tissues, which may in part determine isoform-specific interactions. In situ hybridization revealed that 14-3-3zeta was present in most tissues tested, but sigma was preferentially expressed in epithelial cells. Thus, isoforms of 14-3-3 can interact and control the function of selected protein ligands, and differential tissue distribution of 14-3-3 isoforms may contribute to their specific interactions and subsequent downstream signaling events.
Insights
This study shows that all mammalian 14-3-3 protein isoforms inhibit Bad-induced apoptosis, indicating conserved function. Differential tissue expression of 14-3-3 isoforms may lead to specific interactions and signaling.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- 14-3-3 proteins are homologous eukaryotic molecules with seven isoforms in mammals.
- These proteins regulate critical cellular processes including mitogenesis, cell cycle progression, and apoptosis.
- The specific functions of individual 14-3-3 isoforms remain largely undetermined.
Purpose of the Study:
- To investigate whether different 14-3-3 protein isoforms exhibit distinct functions.
- To determine the binding capabilities of various 14-3-3 isoforms with ligands like Bad, Raf-1, and Cbl.
- To explore the differential expression patterns of 14-3-3 isoforms in mammalian tissues.
Main Methods:
- Ligand binding assays were performed to assess interactions between 14-3-3 isoforms and target proteins (Bad, Raf-1, Cbl).
- Functional assays evaluated the ability of different 14-3-3 isoforms to inhibit Bad-induced apoptosis.
- In situ hybridization was employed to analyze the tissue-specific expression of 14-3-3 isoforms.
Main Results:
- Multiple 14-3-3 isoforms demonstrated binding affinity for Bad, Raf-1, and Cbl.
- All tested mammalian 14-3-3 isoforms effectively inhibited Bad-induced apoptosis, suggesting conserved functionality.
- 14-3-3zeta was broadly expressed across tissues, while 14-3-3sigma showed preferential expression in epithelial cells.
Conclusions:
- The inhibitory function of 14-3-3 proteins on Bad-induced apoptosis is conserved among mammalian isoforms.
- Differential tissue distribution of 14-3-3 isoforms likely contributes to isoform-specific protein interactions.
- These isoform-specific interactions and distributions may play a role in downstream signaling events.