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Analysis of post-lysosomal compartments.
Yuko Hirota1, Naoko Masuyama, Toshio Kuronita
1Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, 812-8582 Fukuoka, Japan.
Biochemical and Biophysical Research Communications
|January 22, 2004
Summary
Excess accumulation of indigestible molecules in lysosomes can create new, non-acidic compartments. These post-lysosomal compartments are dependent on lysosomal acidification and microtubule organization for their formation.
Area of Science:
- Cell Biology
- Molecular Biology
- Endocytosis
Background:
- Lysosomes are key acidic organelles in the endocytic pathway responsible for degradation.
- The accumulation of non-digestible materials can disrupt normal lysosomal function.
Purpose of the Study:
- To investigate the formation of novel cellular compartments resulting from the accumulation of indigestible macromolecules in lysosomes.
- To characterize the properties and origins of these post-lysosomal compartments.
Main Methods:
- Utilized Texas red-dextran (TR-Dex) as a non-digestible macromolecule in NRK cells.
- Employed immunofluorescence staining for lysosomal enzymes (cathepsin D) and membrane proteins (LGP85).
- Assessed compartment acidity using DAMP staining and investigated formation dependency using U18666A, lysosomotropic amines, and microtubule-depolymerizing agents.
Main Results:
- Accumulation of TR-Dex led to the formation of cathepsin D-negative vesicles derived from lysosomes.
- These novel compartments were non-acidic and positive for LGP85, a lysosomal membrane protein.
- Formation was inhibited by U18666A, indicating lysosomal origin, and dependent on lysosomal acidification and microtubule organization.
Conclusions:
- Excess accumulation of non-digestible macromolecules induces the formation of acid hydrolase-poor, non-acidic post-lysosomal compartments.
- These compartments are dynamically linked to lysosomes, suggesting bidirectional membrane transport.
- Lysosomal acidification and microtubule organization are critical for the biogenesis of these compartments.