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LAPTM4B facilitates late endosomal ceramide export to control cell death pathways
Tomas Blom1,2, Shiqian Li1,2, Andrea Dichlberger1,2
1Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
Nature Chemical Biology
|August 18, 2015
Summary
Lysosome-associated protein transmembrane-4b (LAPTM4B) removes ceramide from late endosomes, impacting cell death pathways. This discovery offers new targets for sphingolipid-based cancer therapies.
Area of Science:
- Cell Biology
- Cancer Biology
- Biochemistry
Background:
- Lysosome-associated protein transmembrane-4b (LAPTM4B) is linked to poor cancer prognosis.
- The precise physiological role of LAPTM4B remains largely unknown.
Purpose of the Study:
- To elucidate the function of LAPTM4B in cellular sphingolipid metabolism.
- To investigate LAPTM4B's role in regulating ceramide levels and cell death.
Main Methods:
- Utilized novel ceramide probes to track ceramide localization and transport.
- Employed gene silencing (siRNA) and overexpression techniques for LAPTM4B.
- Assessed lysosomal membrane stability and apoptosis markers (caspase-3 activation).
Main Results:
- LAPTM4B directly interacts with ceramide, facilitating its export from late endosomes (LEs).
- LAPTM4B regulates LE ceramide levels independently of acid ceramidase.
- LAPTM4B modulation impacts lysosomal stability and sensitivity to apoptosis.
Conclusions:
- Identified a novel ceramide export pathway from LEs regulated by LAPTM4B.
- LAPTM4B controls sphingolipid-mediated cell death, suggesting its potential as a therapeutic target.
- LAPTM4B's role in ceramide compartmentalization has implications for cancer treatment strategies.
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