After 48 hr, cells were transiently transfected with 1 g total DNA, compris ing

In contrast, cGMP independent actions are more fre quently postulated to be involved in the pathological responses which are primarily effected by nitrosative post translational modifications ABT-888 of proteins such as S nitrosylation and tyrosine nitration. Although low nanomolar concentrations of NO donors are suffi cient to elicit cGMP dependent signals, 50 100 uM of NO donors is required for S nitrosylation mediated alterations of protein function in cultured cells. Based on these ideas, we speculate that the NO gener ated by different NOSs exerts differential modulations of BACE1. For example, the low levels of NO that result in suppression of BACE1 transcription may represent the NO released from vascular eNOS.<br><br> Although it is difficult to measure the precise concentration of the bioreactive NO in the blood circulation of a healthy vertebrate, the decreased BACE1 transcription induced at the 10 100 nM range of NO donors may be related to the protective actions caused by the release of NO from vascular eNOS. In fact, this AEB071 分子量 is collaborated by the recent finding that BACE1 expression was elevated in mice deficient in eNOS. Our data also suggest that PGC 1a, a crucial PPARg coactivator in the transcriptional controls of gluconeogen esis and energy metabolism, may be the key factor executing the effects of low NO, through the activated cGMP PKG signaling pathway. Since PGC 1a is the most critical regulator in response to metabolic stress, it is believed to play a key role in AD pathogenesis. Our find ing that PGC 1a is likely involved in BACE1 transcrip tional control provides the first molecular basis of a metabolic signal factor regulating an AD gene.<br><br> In support of this, PGC 1a expression was found to be reduced in AD brains and it was recently reported that PGC 1a facilitates BACE1 protein degradation via the UPS. Further characterization of the transcriptional network involving PGC 1a, directly or indirectly, on BACE1 pro moter, will draw a fuller picture of the metabolic factors AG-014699 価格 regulating AD genes, which likely involve the entire AMPK SIRT1 PGC 1a pathway, in which NO signaling plays an important role. On the other hand, the high levels of NO mediated BACE1 inactivation via post translational modification in cultured neurons likely reflects the NO generated by iNOS, known to elicit much higher NO production compared with that generated by the constitutive NOSs.<br><br> Inducible iNOS, shown to be involved in the pathogenesis of AD, is activated under inflammatory conditions and may upregulate BACE1 as a result of activated NF B and toxic peroxynitrite formed by NO and superoxide anions. Although we show that SNO BACE1 is associated with reduced enzy matic activity, the elevated protein expression and enzy matic activity of BACE1 in late stages of AD may reflect the dominant effect of severe oxidation by H2O2 and peroxynitrite, it has been shown previously that lipid oxidative products, such as 4 HNE, can upregulate BACE1 transcriptionally. H2O2 induced modification and S nitrosylation repre sent the two dominant oxidative events modifying criti cal Cys residues in proteins. Interestingly, we observed opposite effects from these two oxidative modifications in BACE1 expression and activity.