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Ceramide triggers an NF-kappaB-dependent survival pathway through calpain
F Demarchi1, C Bertoli, P A Greer
1L.N.C.I.B. Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie AREA Science Park, Padriciano 99, 34012 Trieste, Italy.
Cell Death and Differentiation
|June 4, 2005
Summary
C2 ceramide activates a survival pathway via NF-kappaB, dependent on calpain activity. Silencing calpain small subunit (Capn4) stabilizes NF-kappaB1 (p105) and prevents this survival signaling.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- C2 ceramide acts as a lipid second messenger.
- Nuclear factor-kappaB (NF-kappaB) is a key transcription factor involved in cell survival and death.
- Calpains are calcium-dependent cysteine proteases crucial for cellular processes.
Purpose of the Study:
- To investigate the role of calpain activity in C2 ceramide-induced NF-kappaB activation.
- To elucidate the involvement of the calpain small subunit (Capn4) in this pathway.
- To identify potential targets of calpain within the NF-kappaB signaling cascade.
Main Methods:
- Utilized C2 ceramide treatment in cell culture models.
- Employed RNA interference (RNAi) to silence Capn4 expression.
- Performed in vitro assays with calpains and NF-kappaB1 (p105) and its product p50.
- Analyzed protein stabilization and gene expression changes.
- Used Capn4-deficient mouse embryonic fibroblasts (MEFs).
Main Results:
- C2 ceramide triggers an NF-kappaB dependent survival pathway.
- Calpain activity is essential for NF-kappaB activation and prosurvival gene induction.
- Silencing Capn4 prevents NF-kappaB activation and leads to stabilization of p105 and p50.
- p105 and p50 are identified as in vitro targets of calpain.
- C2 ceramide-induced NF-kappaB activation is impaired in Capn4-/- MEFs.
Conclusions:
- A novel ceramide-calpain-NF-kappaB signaling axis with prosurvival functions has been identified.
- Capn4 is critical for calpain-mediated processing of NF-kappaB1 (p105) and subsequent activation of prosurvival genes.
- This pathway represents a potential therapeutic target for conditions involving cell death.