Car boxyfluorescein labeled phenylalanine chloromethyl ketone was from Immuno C

Furthermore, PLD2 was reported to form with mTOR and Raptor a functional complex that is essential for mitogen stimula tion of S6K1. Thus it appears that both PLD isoforms can be involved in mTOR オーダー AP24534 regulation, depend ing on the cellular context. Although in our exerimental setting PLD2 inhibition tended to decrease S6K1 phos phorylation, and thus mTORC1 activity, this did not sig nificantly affect myotube size, suggesting that the impact of PLD2 activity on mTOR is insufficient to regulate downstream pathways. We also observed that PLD1 overexpression induces a hypertrophy of myofibres in vivo, similar to what observed in L6 myotubes. The ability of PLD1 overexpression to up regulate cell size had been reported in non muscle HEK293 cells.<br><br> Our results further establish that PLD1 is able to induce hypertrophy of differentiated muscle cells, and suggest that it may play a role purchase AT7519 in physiological situations that impact muscle mass. In this regard, PLD has been proposed to be a link between mechanical stimu lation of muscle and mTORC1 activation resulting in hypertrophic response. This hypothesis is supported by the co localization that exists in muscle tissue between both PLD1 and PLD2 and the z band protein actinin, z band being considered a focal point for mechanical force transmission. Our finding that PLD1 overexpression prevents the se vere myotube atrophy induced by dexamethasone treat ment shows that PLD1 has also a protective effect. This observation is further confirmed by the effects of PA, the product of PLD which directly binds to mTOR.<br><br> Exogenous PA was indeed able to protect myotubes against atrophy induced by both dexamethasone and TNF, indicating that the catalytic pan Akt 阻害剤 activity of PLD is re quired for its anti atrophic effects. This was confirmed by our observation that the inhibition of PLD activity by FIPI suppresses both the hypertrophic and anti atrophic effects of PLD1. Surprisingly, we did not observe a hypertrophic effect of exogenous PA when added alone to the myotubes. Therefore, it is likely that the subcellular site of PA accumulation is critical for its trophic effects, and that, in cells submitted to PLD1 overexpression PA accumulation occurs in a compartment that is inefficiently reached by exogenous PA. PA target might become more sensitive to PA supply under atrophic conditions, and could be affected by lower concentrations of the compound, explaining why exogenous PA addition had an anti atrophic effect.<br><br> The positive trophic effects of PLD1 or PA in basal conditions and in the presence of dexamethasone were both associated with a reduced expression of genes in volved in muscle protein breakdown, Murf1, Atrogin 1 and Foxo3. We addressed the mechanism by which PLD exerts its trophic effects by using PP242, a mTOR inhibitor di rected at the catalytic site of the kinase, and that thus in hibits the activity of both mTORC1 and mTORC2 complexes. Interestingly, compared with rapamycin PP242 has been shown to more completely inhibit the phosphorylation of mTORC1 substrates and mTORC2 substrates. PP242 treat ment blocked PLD1 hypertrophic effects, showing that they rely on the activation of either mTORC1, or mTORC2, or of both complexes.