RESUMEN
Mycophenolic acid (MPA, ) and its derivatives are first-line immunosuppressants used in organ transplantation and for treating autoimmune diseases. Despite chemical synthetic achievements, the biosynthetic formation of a seven-carbon carboxylic acid pharmacophore side chain of , especially the processes involving the cleavage of the prenyl side chain between DHMP () and DMMPA (), remains unknown. In this work, we identified a membrane-bound prenyltransferase, PgMpaA, that transfers FPP to to yield FDHMP (). Compound undergoes the first cleavage step a new globin-like enzyme PgMpaB to form a cryptic intermediate . Heterologous expression of genes in demonstrates that the second cleavage step (from to ) of is a cluster-independent process . Our results, especially the discovery of the broad tolerance of substrates recognized by PgMpaB, set up a strategy for the formation of "pseudo-isopentenyl" natural products using fungal globin-like enzymes.
RESUMEN
The flavonoids with the prenylation on site 8 are a unique class of natural flavonoids. The existence of prenyl-moiety could dramatically increase the lipophilicity and the relevant bioactivities of flavonoids. This review discussed the influences of the prenylation at C-8 of ring A in flavonoids on the activities of antioxidant, anti-bone resorption, antimicrobial activity, anti-tumor activity, and tyrosinase inhibition of the backbone flavonoids.
RESUMEN
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily of cytokines, is one of the most promising candidates for cancer therapeutics. However, many osteosarcomas are resistant to TRAIL. Bisphosphonates are very effective in the treatment of bone problems associated with malignancies; the antitumor effects are due to the inhibition of protein prenylation that is essential for cell function and survival. The purpose of this study was to determine the effects of bisphosphonates on TRAIL-resistant MG 63 human osteosarcoma cells. The cells showed no response to TRAIL alone; however, pre-treatment with bisphosphonates significantly increased TRAIL-mediated apoptosis and cellular activation of caspase-3. Bisphosphonates significantly induced mRNA and protein expression of the TRAIL receptor, DR5. Bisphosphonates induced protein unprenylation in MG 63 cells; in addition, co-treatment with TRAIL also significantly increased protein unprenylation. Blocking of protein unprenylation using geranylgeraniol attenuated the cellular responses, including cell apoptosis and protein unprenylation induced by bisphosphonates and TRAIL. This is the first study to demonstrate that bisphosphonates markedly enhanced TRAIL-induced apoptosis in human osteosarcoma cells. These findings suggest that bisphosphonates may be a new and effective anticancer treatment with TRAIL proteins for TRAIL-resistant cancer cells.