Fifty-seven-kDa protein in royal jelly enhances proliferation of primary cultured rat hepatocytes and increases albumin production in the absence of serum.
We have previously shown that 57-kDa protein in royal jelly (RJ) was specifically degraded in proportion to both storage temperature and storage period, and we suggested that it could be useful as a marker of freshness of RJ (Kamakura, M., Fukuda, T., Fukushima, M. and Yonekura, M. (2001) Biosci. Biotechnol. Biochem. 65, 277-284.). Here, we investigated the physiological effects of 57-kDa protein on primary cultured rat hepatocytes in the absence of serum. The 57-kDa protein and RJ significantly stimulated hepatocyte DNA synthesis, whereas bovine serum albumin and RJ stored at 40 degrees C for 7 days, which lacks 57-kDa protein, did not. The mitogenic activity of 57-kDa protein was lost after treatment with trypsin. These results indicate that 57-kDa protein acts as a mitogen. The stimulatory effect of 57-kDa protein was dose-dependent and was more potent at lower than at higher cell densities. The 57-kDa protein also prolonged the cell proliferation of primary cultured rat hepatocytes, with an enhancement of albumin production compared to untreated cells. Therefore, 57-kDa protein is likely to promote liver regeneration and may have a cytoprotective action on hepatocytes.
Kamakura
M
M
POLA R&D Laboratories, POLA Corporation, 560 Kashio-cho, Totuka-ku, Yokohama, 244-0812, Japan. m-kamakura@pola.co.jp
Suenobu
N
N
Fukushima
M
M
D000418:Albumins / Q000096:biosynthesis*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000737:chemistry* / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D019476:Insect Proteins / Q000737:chemistry / Q000494:pharmacology*; D008970:Molecular Weight; D051381:Rats; D000099219:Royal Jelly
D000418:Albumins; D016895:Culture Media, Serum-Free; D004247:DNA; D005227:Fatty Acids; D019476:Insect Proteins; D000099219:Royal Jelly