title: Royalactin induces queen differentiation in honeybees.
abstract: The honeybee (Apis mellifera) forms two female castes: the queen and the worker. This dimorphism depends not on genetic differences, but on ingestion of royal jelly, although the mechanism through which royal jelly regulates caste differentiation has long remained unknown. Here I show that a 57-kDa protein in royal jelly, previously designated as royalactin, induces the differentiation of honeybee larvae into queens. Royalactin increased body size and ovary development and shortened developmental time in honeybees. Surprisingly, it also showed similar effects in the fruitfly (Drosophila melanogaster). Mechanistic studies revealed that royalactin activated p70 S6 kinase, which was responsible for the increase of body size, increased the activity of mitogen-activated protein kinase, which was involved in the decreased developmental time, and increased the titre of juvenile hormone, an essential hormone for ovary development. Knockdown of epidermal growth factor receptor (Egfr) expression in the fat body of honeybees and fruitflies resulted in a defect of all phenotypes induced by royalactin, showing that Egfr mediates these actions. These findings indicate that a specific factor in royal jelly, royalactin, drives queen development through an Egfr-mediated signalling pathway.
authors.affiliation: Biotechnology Research Center, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan. kamakura@pu-toyama.ac.jp
authors.forename: Masaki
authors.initials: M
authors.lastname: Kamakura
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D049628:Body Size / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects; D002364:Caseins / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects; D004331:Drosophila melanogaster / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D066246:ErbB Receptors / Q000172:deficiency / Q000378:metabolism; D005216:Fat Body / Q000187:drug effects / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D005298:Fertility / Q000187:drug effects; D006023:Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D007605:Juvenile Hormones / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D008136:Longevity / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010053:Ovary / Q000187:drug effects / Q000254:growth & development; D010641:Phenotype; D055550:Protein Stability; D034622:RNA Interference; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012930:Social Dominance; D013696:Temperature; D013997:Time Factors; D000099219:Royal Jelly
chemical_list: D002364:Caseins; D066246:ErbB Receptors; D005227:Fatty Acids; D006023:Glycoproteins; D019476:Insect Proteins; D007605:Juvenile Hormones; D020928:Mitogen-Activated Protein Kinases; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D000099219:Royal Jelly; C559157:MRJP1 protein, Apis mellifera