The transcriptional response of human macrophages to murabutide reflects a spectrum of biological effects for the synthetic immunomodulator.

The synthetic immunomodulator murabutide (MB) presents multiple biological activities with minimal toxicity in animals and in man. Although MB is known to target cells of the reticuloendothelial system and to regulate cytokine synthesis, the molecular mechanisms underlying several of its biological effects are still largely unknown. In an effort to define cellular factors implicated in the immunomodulatory and HIV-suppressive activities of MB, we have undertaken profiling the regulated expression of genes in human monocyte-derived macrophages (MDM) following a 6-h stimulation with this synthetic glycopeptide.

CYP2E1 degradation by in vitro reconstituted systems: role of the molecular chaperone hsp90.

One major mode of regulation of cytochrome P450 2E1 (CYP2E1) is at the posttranscriptional level, since many low-molecular-weight compounds stabilize the enzyme against proteolysis by the proteasome complex. In an in vitro system containing human liver microsomes, degradation of CYP2E1 in the microsomes required addition of the human liver cytosol fraction in a reaction sensitive to inhibitors of the proteasome complex. It is not clear how CYP2E1 in the microsomal membrane becomes accessible to the cytosolic proteasome.

NADPH-dependent microsomal electron transfer increases degradation of CYP2E1 by the proteasome complex: role of reactive oxygen species.

Increased levels of cytochrome P450 2E1 (CYP2E1) produced by low-molecular-weight compounds is mostly due to stabilization of the enzyme against proteolytic degradation. CYP2E1, in the absence of substrate or ligand, normally has a short half-life, but the factors which regulate CYP2E1 turnover or trigger its rapid degradation are not known. Since CYP2E1 is active in producing reactive oxygen species, experiments were carried out to evaluate whether reactive oxygen species modulated the degradation of CYP2E1.

Both cytochromes P450 2E1 and 3A are involved in the O-hydroxylation of p-nitrophenol, a catalytic activity known to be specific for P450 2E1.

4-Nitrophenol 2-hydroxylation activity was previously shown to be mainly catalyzed by P450 2E1 in animal species and humans. As this chemical compound is widely used as an in vitro probe for P450 2E1, this study was carried out to test its catalytic specificity. First, experiments were carried out on liver microsomes and hepatocyte cultures of rat treated with different inducers.

Noninvolvement of CYP2E1 in the (omega-1)-hydroxylation of fatty acids in rat kidney microsomes.

Pyrazole, acetone, and ethanol are known to induce cytochrome P450 2E1 (CYP2E1) and fatty acid (omega-1)-hydroxylation in rat liver microsomes. However, the nature of the P450 enzyme involved in this (omega-1)-hydroxylation has not been clearly established in extrahepatic tissues such as kidney. Four enzymatic activities (hydroxylations of chlorzoxazone, 4-nitrophenol, and two fatty acids) were assayed in kidney microsomal preparations of rats treated with CYP2E1 inducers.