Phosphatidylinositol-3-kinase (PI3K) activity decreases in C2C12 myotubes during acute simulated ischemia at a cost to their survival.
OBJECTIVE
It is well known that acute ischemia resulting from several pathophysiological conditions, disturb cellular function and lead to cell and tissue damage. An increasing body of evidence implies that the phosphatidylinositol-3-kinase (PI3-K) signaling pathway plays a key role in a multitude of cellular processes which include the regulation of cell death. However, the role of the PI3-K pathway during simulated ischemia (SI) is not yet fully understood and conflicting data exists in this regard. Therefore, we aimed to determine the role of the PI3K signaling pathway during acute SI in C2C12 myotubes and analyze the related impact on cell death parameters occurring within this context.


METHODS
Cells are grown in Dulbecco's Modified Eagle's Medium (DMEM) with 10% fetal bovine serum (FBS), and incubated under 5% CO(2) conditions, until reaching 90% confluency. Using DMEM supplemented with 1% horse serum, cell differentiation into myotubes was induced. Mitochondrial reductive capacity was assessed with the MTT assay. Phosphorylation of proteins was analyzed by Western blotting and immunocytochemistry was used to assess cell death.


RESULTS
We present evidence that simulated ischemia attenuated PI3K activity which was also associated with decreased Akt-dependent phosphorylation at the level of FoxO1, FoxO4, TSC2 and mTOR.


CONCLUSIONS
An ischemic microenvironment leads to a reduction in PI3K activity with subsequent induction of apoptosis.
Department of Physiological Sciences, University of Stellenbosch, Stellenbosch, South Africa.
M P
MP
Thomas
J
J
Mills
A-M
AM
Engelbrecht
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D007511:Ischemia / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000201:enzymology* / Q000473:pathology*; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D015398:Signal Transduction
D058539:Phosphatidylinositol 3-Kinase