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Updated: Feb 17, 2026

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Published on: October 27, 2020
Intracellular trafficking of transforming growth factor β receptors
Ihor Yakymovych1, Mariya Yakymovych1, Carl-Henrik Heldin1
1Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala 75123, Sweden.
Abstract:
Transforming growth factor β (TGFβ) family members signal via heterotetrameric complexes of type I (TβRI) and type II (TβRII) dual specificity kinase receptors. The availability of the receptors on the cell surface is controlled by several mechanisms. Newly synthesized TβRI and TβRII are delivered from the Golgi apparatus to the cell surface via separate routes. On the cell surface, TGFβ receptors are distributed between different microdomains of the plasma membrane and can be internalized via clathrin- and caveolae-mediated endocytic mechanisms. Although receptor endocytosis is not essential for TGFβ signaling, localization of the activated receptor complexes on the early endosomes promotes TGFβ-induced Smad activation. Caveolae-mediated endocytosis, which is widely regarded as a mechanism that facilitates the degradation of TGFβ receptors, has been shown to be required for TGFβ signaling via non-Smad pathways. The importance of proper control of TGFβ receptor intracellular trafficking is emphasized by clinical data, as mislocalization of receptors has been described in connection with several human diseases. Thus, control of intracellular trafficking of the TGFβ receptors together with the regulation of their expression, posttranslational modifications and down-regulation, ensure proper regulation of TGFβ signaling.
Insights
Transforming growth factor β (TGFβ) receptor trafficking controls cell surface availability and signaling. Proper intracellular transport and localization are crucial for TGFβ pathway regulation and preventing disease.
Area of Science:
- Cell biology
- Molecular signaling
- Receptor trafficking
Background:
- Transforming growth factor β (TGFβ) signaling is mediated by type I (TβRI) and type II (TβRII) kinase receptors.
- Receptor availability at the cell surface is tightly regulated through synthesis, transport, and internalization.
- Dysregulation of TGFβ receptor localization is linked to human diseases.
Purpose of the Study:
- To elucidate the mechanisms controlling TGFβ receptor intracellular trafficking.
- To understand the role of trafficking in TGFβ signaling pathways.
- To highlight the clinical relevance of receptor localization.
Main Methods:
- Investigated receptor delivery from the Golgi to the cell surface.
- Examined cell surface distribution and microdomain localization.
- Studied clathrin- and caveolae-mediated endocytosis pathways.
- Assessed the impact of endocytosis on Smad and non-Smad signaling.
- Correlated receptor mislocalization with clinical data.
Main Results:
- TβRI and TβRII utilize distinct routes for cell surface delivery.
- Receptors are compartmentalized within plasma membrane microdomains.
- Endocytosis, while not essential for all TGFβ signaling, influences Smad activation via early endosomes.
- Caveolae-mediated endocytosis is critical for non-Smad TGFβ signaling.
- Receptor mislocalization is observed in several human diseases.
Conclusions:
- Intracellular trafficking is a key regulatory point for TGFβ receptor function.
- Distinct endocytic pathways differentially impact TGFβ signaling.
- Precise control of TGFβ receptor trafficking, expression, and degradation is vital for cellular homeostasis.
- Understanding receptor trafficking offers insights into disease pathogenesis and potential therapeutic strategies.
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