The activity of Mblk-1, a mushroom body-selective transcription factor from the honeybee, is modulated by the ras/MAPK pathway.
We previously identified a gene, termed Mblk-1, that encodes a putative transcription factor with two DNA-binding motifs expressed preferentially in the mushroom body of the honeybee brain, and its preferred binding sequence, termed Mblk-1-binding element (MBE) (Takeuchi, H., Kage, E., Sawata, M., Kamikouchi, A., Ohashi, K., Ohara, M., Fujiyuki, T., Kunieda, T., Sekimizu, K., Natori, S., and Kubo, T. (2001) Insect Mol Biol 10, 487-494; Park, J.-M., Kunieda. T., Takeuchi, H., and Kubo, T. (2002) Biochem. Biophys. Res. Commun. 291, 23-28). In the present study, the effect of Mblk-1 on transcription of genes containing MBE in Drosophila Schneider's Line 2 cells was examined using a luciferase assay. Mblk-1 expression transactivated promoters containing MBEs approximately 2-7-fold. Deletion experiments revealed that RHF2, the second DNA-binding domain of Mblk-1, was necessary for the transcriptional activity. Furthermore, mitogen-activated protein kinase (MAPK) phosphorylated Mblk-1 at Ser-444 in vitro, and the Mblk-1-induced transactivation was stimulated by phosphorylation of Ser-444 by the Ras/MAPK pathway in the luciferase assay. These results suggest that Mblk-1 is a transcription factor that might function in the mushroom body neuronal circuits downstream of the Ras/MAPK pathway in the honeybee brain.
Park
Jung-Min
JM
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Kunieda
Takekazu
T
Kubo
Takeo
T
D000818:Animals; D001516:Bees; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D004331:Drosophila melanogaster / Q000378:metabolism; D017353:Gene Deletion; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008957:Models, Genetic; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
D014157:Transcription Factors; D008156:Luciferases; D005982:Glutathione Transferase; D018631:ras Proteins