Regulation of insulin action by ceramide: dual mechanisms linking ceramide accumulation to the inhibition of Akt/protein kinase B.
Level 5 - mechanism / opinion, no new human data
In vitro bench mechanistic study without human clinical data.
PubMed 15220355 · doi:10.1074/jbc.M406499200
What was done
Researchers utilized deletion constructs encoding two functional domains of Akt/PKB—an isolated pleckstrin homology (PH) domain and a construct lacking the PH domain—to determine the molecular mechanisms by which ceramide impairs insulin-induced Akt/PKB activation.
What was found
Ceramide inhibited insulin-stimulated Akt/PKB through two distinct mechanisms. In the isolated PH domain construct, ceramide selectively blocked Akt/PKB translocation to the plasma membrane without affecting the translocation of phosphoinositide-dependent kinase-1. In the construct lacking the PH domain, which activates without translocation, ceramide stimulated Akt/PKB dephosphorylation via protein phosphatase 2A. The abstract reports no numerical values or effect sizes.
Why it matters
The study resolves conflicting reports regarding ceramide action by demonstrating dual, independent mechanisms of Akt/PKB inhibition, providing a mechanistic basis for how ceramide accumulation drives cellular insulin resistance.
Limits
This is purely in vitro bench research using protein domain deletion constructs. The abstract does not specify the host cell type, quantitative measurements, sample sizes, or in vivo relevance in intact animal or human models.
Cited by
- supports Ceramides directly block insulin signaling by inhibiting Akt phosphorylation.