Regulation of insect steroid hormone biosynthesis by innervating peptidergic neurons.
In insects, steroid hormones named ecdysteroids elicit molting and metamorphosis. The prothoracic gland (PG) is a predominant source of ecdysteroids, where their biosynthesis (ecdysteroidogenesis) is regulated by several neuropeptides. Here, we report that FMRFamide-related peptides (FaRPs) regulate ecdysteroidogenesis through direct innervation of the PG in the silkworm Bombyx mori. We purified a previously uncharacterized Bombyx FaRP, DPSFIRFamide, and identified the corresponding Bombyx FMRFamide gene (Bommo-FMRFamide, BRFa), which encodes three additional FaRPs. All BRFa peptides suppressed ecdysteroidogenesis in the PG by reducing cAMP production by means of the receptor for Bommo-myosuppressin, another FaRP we have previously shown to act as a prothoracicostatic factor. BRFa is predominantly expressed in neurosecretory cells of thoracic ganglia, and the neurons in the prothoracic ganglion innervate the PG to supply all four peptides to the gland surface. Electrophysiological recordings during development confirmed the increased firing activity of BRFa neurons in stages with low PG activity and decreased ecdysteroid levels in the hemolymph. To our knowledge, this study provides the first report of peptides controlling ecdysteroidogenesis by direct innervation.
Yamanaka
Naoki
N
Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan.
Zitnan
Dusan
D
Kim
Young-Joon
YJ
Adams
Michael E
ME
Hua
Yue-Jin
YJ
Suzuki
Yusuke
Y
Suzuki
Minoru
M
Suzuki
Akemi
A
Satake
Honoo
H
Mizoguchi
Akira
A
Asaoka
Kiyoshi
K
Tanaka
Yoshiaki
Y
Kataoka
Hiroshi
H
D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000378:metabolism; D019835:FMRFamide / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005724:Ganglia / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007301:Insect Hormones / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D007301:Insect Hormones; D012333:RNA, Messenger; D019835:FMRFamide