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Ricin intoxicates End4 mutants that have an aberrant Golgi complex
1Molecular and Cell Biology Program, University of Texas at Dallas, Richardson 75083.
The Journal of Biological Chemistry
|September 25, 1993
Summary
Ricin toxin enters cells by inactivating ribosomes. Studies show ricin toxicity is unaffected by Golgi apparatus disruption, suggesting it bypasses this organelle during cell entry.
Area of Science:
- Cell Biology
- Molecular Toxicology
Background:
- Ricin toxin inhibits protein synthesis by inactivating ribosomes.
- Ricin's A chain must reach the cytosol, involving endocytosis and membrane penetration.
- The specific cellular compartment for ricin penetration remains unidentified, with the endoplasmic reticulum proposed.
Purpose of the Study:
- To investigate the role of the Golgi apparatus in ricin intoxication.
- To determine if ricin traverses the Golgi complex to enter the cytosol.
Main Methods:
- Utilized End4 Chinese hamster ovary cell mutants with temperature-sensitive secretion defects.
- Observed Golgi stack morphology via fluorescence microscopy.
- Assessed ricin sensitivity and protein synthesis inhibition in mutant and wild-type cells at restrictive temperatures.
Main Results:
- End4 mutants showed temperature-sensitive defects in secretion and Golgi stack loss.
- Ricin sensitivity was comparable between End4 mutants and wild-type cells.
- A longer lag time for protein synthesis inhibition was noted in mutant cells.
Conclusions:
- Ricin does not appear to transit through the cis, medial, or trans Golgi stacks.
- These findings suggest ricin bypasses the Golgi apparatus on its pathway to the cytosol.