title: Myocyte enhancer factor 2 (MEF2) is a key modulator of the expression of the prothoracicotropic hormone gene in the silkworm, Bombyx mori.
abstract: Prothoracicotropic hormone (PTTH) plays a central role in controlling molting, metamorphosis, and diapause termination in insects by stimulating the prothoracic glands to synthesize and release the molting hormone, ecdysone. Using Autographa californica nucleopolyhedrovirus (AcNPV)-mediated transient gene transfer into the central nervous sytem (CNS) of the silkworm, Bombyx mori, we identified two cis-regulatory elements that participate in the decision and the enhancement of PTTH gene expression in PTTH-producing neurosecretory cells (PTPCs). The cis-element mediating the enhancement of PTTH gene expression binds the transcription factor Bombyx myocyte enhancer factor 2 (BmMEF2). The BmMEF2 gene was expressed in various tissues including the CNS. In brain, the BmMEF2 gene was expressed at elevated levels in two types of lateral neurosecretory cells, namely PTPCs and corazonin-like immunoreactive lateral neurosecretory cells. Overexpression of BmMEF2 cDNA caused an increase in the transcription of PTTH. Therefore, BmMEF2 appears to be particularly important in the brain where it is responsible for the differentiation of lateral neurosecretory cells, including the enhancement of PTTH gene expression. This is the first report to identify a target gene of MEF2 in the invertebrate nervous system.
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Nagano, Japan. shiomi@giptc.shinshu-u.ac.jp
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Shiomi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Atsumi
authors.forename: Zenta
authors.initials: Z
authors.lastname: Kajiura
authors.forename: Masao
authors.initials: M
authors.lastname: Nakagaki
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Akira
authors.initials: A
authors.lastname: Mizoguchi
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Yaginuma
authors.forename: Okitsugu
authors.initials: O
authors.lastname: Yamashita
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D012831:Bombyx / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D017930:Genes, Reporter; D007301:Insect Hormones / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D064326:MEF2 Transcription Factors; D008969:Molecular Sequence Data; D018006:Myogenic Regulatory Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D007301:Insect Hormones; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D014157:Transcription Factors; C009089:prothoracicotropic hormone