EI-1511-3, -5 and EI-1625-2, novel interleukin-1 beta converting enzyme inhibitors produced by Streptomyces sp. E-1511 and E-1625. I. Taxonomy of producing strain, fermentation and isolation

The culture conditions which are able to support the differentiation of bovine intramuscular (i.m.) stromal-vascular (S-V) cells into adipocytes were investigated. Bovine i. m. S-V cells were able to undergo adipose conversion, assessed by emergence of lipid droplets and induction of glycerol-3-phosphate dehydrogenase (GPDH) activity, when treated with 0.25 microM dexamethasone and 0.5 mM 1-methyl-3-isobutylxanthine in a serum-deprived (0.1%) medium containing 850 nM insulin and 1 mM octanoate. Octanoate was essential for morphological differentiation and addition of 25 microM of cholesterol with octanoate induced higher GPDH activity. The differentiation of the cells was not observed in the medium containing 10% fetal calf serum which supported the cell proliferation of undifferentiated cells even after confluence. Similarly, both bovine brain extracts and muscle extracts inhibited the differentiation of S-V cells in the serum-deprived condition. These results suggest that the existence of lipids such as octanoate and the process of growth-arrest in preadipocytes and/or other cells are necessary for the differentiation of bovine S-V cells into adipocytes in culture.