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ErbB-4 and TNF-alpha converting enzyme localization to membrane microdomains
Kristina W Thiel1, Graham Carpenter
1Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, TN 37232-0146, USA.
Biochemical and Biophysical Research Communications
|October 10, 2006
Summary
ErbB-4 receptor processing involves sequential proteolytic cleavage. Ligand addition causes cleavable ErbB-4 to move to lipid rafts, suggesting microdomain assembly of the cleavage machinery.
Area of Science:
- Cell biology
- Molecular and cell biology
- Biochemistry
Background:
- ErbB-4 undergoes sequential proteolytic processing upon ligand stimulation.
- Understanding the precise localization of ErbB-4 isoforms is crucial for elucidating its signaling pathways.
Purpose of the Study:
- To investigate the localization of cleavable and non-cleavable ErbB-4 isoforms within membrane microdomains.
- To determine the role of ligand-induced signaling in ErbB-4 translocation to specific membrane compartments.
Main Methods:
- Assessing ErbB-4 localization using Triton X-100-insolubility, Brij98-insolubility, and detergent-free density gradient centrifugation.
- Analyzing the distribution of ErbB-4 isoforms and TACE (Tumor necrosis factor-alpha converting enzyme) in different membrane fractions.
- Treating T47D cells with heregulin to induce ligand-dependent signaling.
Main Results:
- ErbB-4 constitutively associated with Brij98-insoluble fractions and lipid rafts (detergent-free).
- Heregulin treatment induced translocation of the cleavable ErbB-4 isoform to detergent-free lipid rafts.
- Tumor necrosis factor-alpha converting enzyme (TACE) was found in its active form across most analyzed microdomains.
Conclusions:
- Both cleavable and non-cleavable ErbB-4 isoforms exhibit distinct localization patterns in membrane microdomains.
- Ligand stimulation triggers the relocation of cleavable ErbB-4 to lipid rafts, indicating a role for membrane microdomains in regulating ErbB-4 processing.
- Data suggest the formation of the ErbB-4 ectodomain cleavage complex within specific membrane microdomains.
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