Characterising the inhibitory actions of ceramide upon insulin signaling in different skeletal muscle cell models: a mechanistic insight.
Level 5 - mechanism / opinion, no new human data
In vitro cell culture mechanistic study without clinical outcome data.
PubMed 25058613 · doi:10.1371/journal.pone.0101865
What was done
Researchers compared the mechanisms of ceramide-induced inhibition of PKB/Akt (a mediator of insulin signaling) across three skeletal muscle cell culture models: rat L6 myotubes, mouse C2C12 myotubes, and cultured primary human skeletal muscle cells (including palmitate-treated cells and cells from diabetic patients). They evaluated the involvement of atypical protein kinase C (aPKC) isoforms, protein phosphatase-2A (PP2A), and the abundance of plasma membrane caveolin-enriched domains (CEM).
What was found
The abstract reports qualitative pathway differences without numeric data: - Ceramide-enriched CEMs were markedly more abundant in L6 myotubes compared to C2C12 myotubes. - In L6 myotubes, ceramide inhibited PKB/Akt primarily via coordinating aPKC-directed repression. - In C2C12 myotubes, ceramide-induced PKB/Akt inhibition was predominantly mediated by a PP2A-dependent pathway. - In palmitate-treated primary human muscle cells and muscle cells derived from patients with diabetes, ceramide repressed insulin-induced PKB/Akt activation via an aPKC-dependent pathway.
Why it matters
The study demonstrates that commonly used skeletal muscle cell lines (L6 vs. C2C12) utilize distinct signaling pathways in response to ceramide, and indicates that primary human muscle cells behave more similarly to L6 myotubes via an aPKC-dependent mechanism.
Limits
This is entirely an in vitro cell culture study, meaning physiological in vivo dynamics and tissue-level crosstalk were not evaluated. The abstract provides no quantitative effect sizes, variance measures, or details regarding the sample size or number of human donor cell lines analyzed.
Cited by
- supports Ceramides directly block insulin signaling by inhibiting Akt phosphorylation.