Related Experiment Video
Updated: Aug 7, 2026
10:52
A High-content Imaging Workflow to Study Grb2 Signaling Complexes by Expression Cloning
Published on: October 30, 2012
Grb2 regulates Stat3 activation negatively in epidermal growth factor signalling
Tong Zhang1, Jing Ma, Xinmin Cao
1Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Singapore.
The Biochemical Journal
|September 23, 2003
Summary
Growth factor receptor-binding protein 2 (Grb2) negatively regulates Signal Transduction and Activator of Transcription (STAT) activation by competing with STAT for binding to the epidermal growth factor receptor (EGFR). This Grb2-mediated inhibition impacts STAT transcriptional activity in EGF signaling.
Area of Science:
- Cellular signaling pathways
- Molecular biology
- Receptor-mediated signal transduction
Background:
- Epidermal growth factor (EGF) binding to its receptor (EGFR) triggers downstream signaling cascades.
- Key pathways activated by EGF include Ras-MAPK and STAT.
- EGFR tyrosine residues 1086 and 1068 are binding sites for both Grb2 and STAT3.
Purpose of the Study:
- To investigate the regulatory role of Grb2 in EGF-stimulated STAT activation.
- To determine if Grb2 influences STAT3 tyrosine phosphorylation and transcriptional activity.
Main Methods:
- Transient expression of Grb2.
- RNA interference to deplete Grb2.
- Analysis of tyrosine phosphorylation of STAT3.
- Assessment of STAT3 transcriptional activity.
- Site-directed mutagenesis of Grb2 (SH2 and SH3 domains).
- Investigation of Grb2 interaction with IL-6 receptor.
Main Results:
- Grb2 expression down-regulates EGF-stimulated STAT3 tyrosine phosphorylation and transcriptional activity.
- Grb2 depletion enhances EGF-induced STAT3 tyrosine phosphorylation.
- Grb2 inhibits STAT3-EGFR interaction via competitive binding to EGFR, dependent on its SH2 domain.
- Grb2 does not affect IL-6-induced STAT3 phosphorylation.
Conclusions:
- Grb2 acts as a negative regulator of STAT3 activation specifically in the context of EGF signaling.
- Grb2 inhibits STAT3 activation at the receptor level by competing for binding sites on EGFR.
- This mechanism highlights a novel regulatory crosstalk between Grb2 and STAT3 in EGF-driven cellular responses.
Related Concept Videos
01:23Negative Regulator Molecules
Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
02:38Mitogens and the Cell Cycle
Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
01:15Receptor Downregulation in MVBs
Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
01:22Amplifying Signals via Enzymatic Cascade
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
01:20The JAK-STAT Signaling Pathway
Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as SH2...
01:16TGF - β Signaling Pathway
The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...