Lactacystin is a microbial metabolite isolated from Streptomyces that is now widely used as a selective inhibitor of the 20S proteasome.{10086,2351,10073} Clasto-lactacystin β-lactone was later identified as the active metabolite of lactacystin, resulting from the elimination of cysteine and the formation of a reactive β-lactone. Both lactacystin and its β-lactone metabolite induce differentiation and inhibit cell cycle progression in several tumor cell lines.{1659} Clasto-lactacystin β-lactone irreversibly alkylates subunit X of the 20S proteasome.{10073} It is at least 10 times more active than the parent compound; this increased activity may be a function of increased cell permeability. Inhibition of proteasome peptidase activity results in the accumulation of a variety of ubiquitinated proteins which would normally undergo rapid degradation. Thus, the effects of clasto-lactacystin β-lactone are pleiotropic and depend substantially on the expression pattern of signaling proteins within the treated cell.
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Active metabolite of lactacystin, a widely used selective inhibitor of the 20S proteasome, with at least 10 times better activity; irreversibly alkylates subunit X of the 20S proteasome
Formal name: 1R-[1S-1hydroxy-2-methylpropyl]-4R-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
Synonyms: Omuralide|β-Clastolactacystin
Molecular weight: 213.2
CAS: 154226-60-5
Purity: ≥95%
Formulation: A solution in methyl acetate
The nuclear factor-κB (NF-κB) regulates the expression of numerous genes involved in immunity and inflammation, cellular stress responses, growth, and apoptosis. Resveratrol, a polyphenolic trans-stilbene, is a known inhibitor of the activation of NF-κB and exhibits activity against a wide variety of cancer cells. CAY10512 is a substituted trans-stilbene analog of resveratrol that is 100-fold more potent as measured by antioxidant activity. The IC50 value for inhibition of TNFα-induced activation of NF-κB by CAY10512 is 0.15 µM compared to 20 µM by resveratrol.{14545}
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The maintenance of embryonic stem cells in culture typically requires feeder cells and various exogenous factors found in serum. Murine embryonic stem (mES) cells can be maintained in the absence of feeder cells and serum but require the leukemia inhibitor factor (LIF) and bone morphogenic protein (BMP) to prevent differentiation and promote self-renewal. SC-1 is a small molecule activator of stem cell renewal that allows the propagation of OG2 mES cells for at least 10 passages in an undifferentiated state.{14533} The activity of SC-1 is mediated by the combined inhibition of RasGAP and ERK1 with Kd values of 98 and 212 nM, respectively.{14533} Inhibition of RasGAP increases Ras signaling via the PI3-kinase pathway which promotes self-renewal, whereas inhibition of ERK blocks differentiation.
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The tetracycline repressor (TetR) is a transcriptional regulator which normally binds tightly to its palindromic tetO operator DNA, blocking gene expression.{17508} Tet causes the repressor to dissociate from the DNA, allowing transcription to occur. A novel reverse TetR (revTetR) requires tetracycline as a co-repressor to bind tetO and block transcription.{17509,17510} Anhydrotetracycline (hydrochloride) is a powerful effector in both the tetracycline repressor (TetR) and reverse TetR (revTetR) systems, binding the Tet repressor 35-fold more strongly than Tet.{17508,17511} Moreover, anhydrotetracycline poorly binds the 30S ribosomal subunit, compared to Tet,{17512} so it does not act as a general inhibitor of translation and is a poor antibiotic. Perhaps related to this, the concentration of anhydrotetracycline that inhibits eukaryotic cell growth is more than a 1,000-fold above the dose that alters transcription through TetR.{17508}
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1,2-Dipalmitoyl-sn-glycero-3-PC (DPPC) is a zwitterionic glycerophospholipid commonly used in the formation of lipid monolayers, bilayers, and liposomes for use in a variety of applications.{14480,24261,14478,14479} It has been used in the formation of proteoliposomes for implantation of γ-glutamyl transpeptidase into human erythrocyte membranes.{14478} Incorporation of glycosphingolipid antigens into DPPC-containing liposomes increases the immunogenicity of the antigens in mice.{14479}
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