A hypopharyngeal gland protein of the worker honeybee Apis mellifera L. enhances proliferation of primary-cultured rat hepatocytes and suppresses apoptosis in the absence of serum.
The worker honeybees of Apis mellifera L. age-dependently change from nurse bees which take care of their brood to forager bees which collect for nectar and convert it into honey during their lifespan of 30-40 days. A 56-kDa protein (p56kP-4) was shown to be present only in the nurse-bee hypopharyngeal gland. Here, we investigated the physiological effects of p56kP-4 on primary-cultured rat hepatocytes in the absence of serum. The p56kP-4 recombinant protein expressed in Escherichia coli significantly stimulated hepatocyte DNA synthesis and protected cells from apoptosis induced by serum deprivation. It also activated mitogen-activated protein kinase, as well as protein kinase B, which is a key regulator of cell survival. These findings suggest that p56kP-4 has a growth factor-like action on primary-cultured rat hepatocytes.
Kamakura
Masaki
M
Biotechnology Research Center, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan. kamakura@pu-toyama.ac.jp
Sakaki
Toshiyuki
T
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001516:Bees / Q000033:anatomy & histology / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D007013:Hypopharynx; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D044967:Serum / Q000378:metabolism*
D019476:Insect Proteins; D011994:Recombinant Proteins; D004247:DNA; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases