Kunihiko Kodaira

Cloning and characterization of the gene encoding mouse osteoclast differentiation factor.

Osteoclast differentiation factor (ODF), a ligand for osteoclastogenesis inhibitory factor (OCIF)/ osteoprotegerin (OPG), is a member of the membrane-associated tumor necrosis factor (TNF) family and induces osteoclast-like cell formation in vitro. In the present study, mouse ODF genomic clones were isolated and sequenced to determine their gene structure. The mouse ODF gene is a single copy gene consisting of five exons and spans approximately 40kb of the mouse genome. The first exon encodes the intracellular and transmembrane domains. The extracellular region of ODF containing the TNF homologous domain is encoded by exons 1 through 5. The translation-termination codon and six polyadenylation signal residues are present in exon 5. A major transcription-initiation site is present 143 nucleotides upstream of the initiation-ATG codon. This genomic organization is similar to that of other members of the TNF family, especially the CD40 ligand.

Optimization of chemically defined feed media for monoclonal antibody production in Chinese hamster ovary cells.

Chinese hamster ovary (CHO) cells are the most commonly used mammalian host for large-scale commercial production of therapeutic monoclonal antibodies (mAbs). Chemically defined media are currently used for CHO cell-based mAb production. An adequate supply of nutrients, especially specific amino acids, is required for cell growth and mAb production, and chemically defined fed-batch processes that support rapid cell growth, high cell density, and high levels of mAb production is still challenging. Many studies have highlighted the benefits of various media designs, supplements, and feed addition strategies in cell cultures. In the present study, we used a strategy involving optimization of a chemically defined feed medium to improve mAb production. Amino acids that were consumed in substantial amounts during a control culture were added to the feed medium as supplements. Supplementation was controlled to minimize accumulation of waste products such as lactate and ammonia. In addition, we evaluated supplementation with tyrosine, which has poor solubility, in the form of a dipeptide or tripeptide to improve its solubility. Supplementation with serine, cysteine, and tyrosine enhanced mAb production, cell viability, and metabolic profiles. A cysteine-tyrosine-serine tripeptide showed high solubility and produced beneficial effects similar to those observed with the free amino acids and with a dipeptide in improving mAb titers and metabolic profiles.