Identical amounts of cell protein per lane were resolved by electro phoresis on

We observed that the addition of exogenous PA suppressed the negative effects of TNF on both myotube size and CK activity. Taken together, these data demonstrate that both PLD1 overexpression and ex ogenous PA supply had an anti atrophic AP24534 FLT-3 阻害剤 effect, in the presence of two different atrophy inducing treatments. Modulation of PLD activity affects the expression of atrogenes Muscle atrophy is closely related to changes in the expres sion of a set of genes called atrogenes, that include the E3 ubiquitin ligases Murf1 and Atrogin 1 involved in the proteasome dependent muscle protein catabolism. Cell proteolytic systems are under the positive con trol of Foxo transcription factors, in particular Foxo3. To get insight into PLD action on muscle proteolytic ma chinery, we assessed the expression of Murf1, Atrogin 1 and Foxo3 transcripts in L6 myotubes subjected to PLD modulation.<br><br> As shown in Figure 7A, we observed a strong inhibition of the basal expression AT-406 臨床試験 of the three genes specif ically in cells overexpressing PLD1, but not in PLD2 overexpressing cells. Furthermore, the siRNA mediated depletion of PLD1 induced a marked increase in Murf1 and Foxo3 expression, whereas the down regulation of PLD2 had no significant effect. From here we deduced that PLD1 hypertrophic effects may be related to its capacity to down regulate the basal expression of genes involved in proteolysis. To confirm the role of PLD in the negative control of atrogene expression, we then treated myotubes with the PLD inhibitor FIPI. We observed that PLD inhibition markedly increased atrogene mRNA levels.<br><br> We next evaluated the effects of a PA treat ment on atrogene expression induced by dexamethasone. In agreement with its pro atrophic properties, we found dexamethasone to induce a robust expression of the atrogenes. However, these effects were significantly low ered by the addition of exogenous Akt2 阻害剤 PA. On the whole, these observations show that PLD and PA are able to down regulate atrogene expression, both in basal condi tions and in dexamethasone induced atrophy. PLD1 effects on muscle cells are mediated by mTOR PLD being an upstream regulator of the mTOR pathway, we next assessed whether the activity of mTOR is re quired for the hypertrophic effect of PLD1 over expression. To this end, we used the PP242 inhibitor, which blocks both mTORC1 and mTORC2 complexes.<br><br> In line with published work showing that mTORC1 is inhibited in muscle atrophy, we observed a marked re duction of myotube size and CK activity in myotubes treated by PP242 alone. Moreover, we found the PP242 treatment to totally abolish the hyper trophic effects induced in myotubes by PLD1 over expression, supporting the view that PLD1 acted through mTOR stimulation. We further explored the influence of PLD on mTOR signaling by evaluating the consequences of PLD modula tion on the phosphorylation of S6K1 and Akt, which are downstream effectors of, respectively, mTORC1 and mTORC2. Whereas PLD1 overexpression increased S6K1 phosphorylation, siRNA mediated PLD depletion had the opposite effect. In the same line of observations, we found the PLD inhibitors able to decrease S6K1 phosphorylation, FIPI and the PLD1 specific inhibitor being more efficient than the PLD2 specific inhibitor.