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Updated: Jul 14, 2026

Cell Type-specific Gene Expression Profiling in the Mouse Liver
Published on: September 17, 2019
New liver cell mutants defective in the endocytic pathway
Richard J Stockert1, Barry Potvin, Sangeeta Nath
1The Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA. stockert@aecom.yu.edu
Researchers identified novel liver cell mutants (Trf2-Trf7) with defects in endocytic trafficking, showing altered receptor expression and impaired endosomal fusion. These trafficking mutants offer new insights into cellular transport mechanisms.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The endocytic pathway is crucial for cellular uptake and transport of molecules.
- Defects in endocytosis can lead to various cellular dysfunctions and diseases.
- Understanding membrane protein trafficking is essential for cellular homeostasis.
Purpose of the Study:
- To isolate and characterize liver cell mutants with defects in the endocytic pathway.
- To investigate the molecular mechanisms underlying impaired membrane protein trafficking.
- To identify novel protein interactions involved in endosomal trafficking.
Main Methods:
- Utilized a selection strategy with toxic ligands targeting membrane receptors to isolate mutants.
- Characterized mutant cell lines (Trf2-Trf7) for resistance to toxins and altered receptor expression.
- Assessed endocytic uptake and trafficking using fluorescently labeled ligands (Alexa(488)-ASOR) and receptor binding assays.
- Analyzed endosomal fusion dynamics in parental and mutant cells.
Main Results:
- Isolated stable trafficking mutants (Trf2-Trf7) exhibiting resistance to toxin conjugates.
- Mutants showed reduced binding and cell surface expression of asialoglycoprotein receptor (ASGPR) and transferrin receptor.
- Differential resistance to lectins, toxins, and UV-induced cell death observed in mutants.
- Impaired endosomal fusion was evident in mutants, with cargo remaining in small vesicles for extended periods.
Conclusions:
- Novel liver cell mutants (Trf2-Trf7) defective in endocytic trafficking were identified.
- These mutants exhibit impaired endosomal fusion, a key step in the endocytic pathway.
- The study highlights the potential for uncovering novel protein-protein or protein-lipid interactions governing membrane trafficking.
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