Related Experiment Video
Updated: May 9, 2026
06:54
Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
Smad phospho-isoforms direct context-dependent TGF-β signaling
1Department of Gastroenterology and Hepatology, Kansai Medical University, 10-15 Fumizonocho, Moriguchi, Osaka 570-8506, Japan.
Cytokine & Growth Factor Reviews
|July 23, 2013
Summary
Transforming growth factor-beta (TGF-β) signaling involves distinct Smad phospho-isoforms that regulate epithelial cell homeostasis and dysfunction in cancer and fibrosis. Understanding these pathways is key to developing cancer risk interventions.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Transforming growth factor-beta (TGF-β) signaling is crucial for epithelial cell homeostasis.
- Dysregulation of TGF-β signaling contributes to human diseases like cancer and fibrosis.
- Smad proteins act as key intermediaries in TGF-β signal transduction to the nucleus.
Purpose of the Study:
- To elucidate the diverse roles of Smad phospho-isoforms in TGF-β signaling.
- To categorize Smad phospho-isoform pathways based on domain-specific phosphorylation and functional outcomes.
- To explore the implications of Smad phospho-isoforms in normal cell maturation, cancer progression, and potential therapeutic interventions.
Main Methods:
- Analysis of Smad protein phosphorylation at different sites (C-tail, linker regions).
- Classification of Smad phospho-isoform pathways into four distinct types based on phosphorylation patterns and cellular responses.
- Investigation of Smad phospho-isoform dynamics during epithelial cell differentiation and in the context of Ras-activating mutations.
Main Results:
- Four distinct Smad phospho-isoform pathways (cytostatic, mitogenic, invasive/fibrogenic, mitogenic/migratory) were identified, each with specific phosphorylation sites and functions.
- TGF-β responses vary significantly with Smad phospho-isoforms during epithelial cell maturation.
- Constitutive Ras-activating mutations promote Smad phospho-isoform pathways associated with tumor progression.
Conclusions:
- Smad phospho-isoforms represent functionally distinct signaling units within the TGF-β pathway.
- The context-dependent nature of TGF-β signaling is explained by the spatiotemporal activity of specific Smad phospho-isoforms.
- Clinical analysis of Smad phospho-isoform signaling may offer insights into cancer risk and therapeutic strategies.
Related Concept Videos
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...
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...
01:22Amplifying 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...
01:22PI3K/mTOR/AKT Signaling Pathway
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a rapamycin-insensitive companion...
01:07MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
01:19Interactions Between Signaling Pathways
Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...