Protein kinase C modulates ecdysteroidogenesis in the prothoracic gland of the tobacco hornworm, Manduca sexta.
The prothoracic gland is the primary source of ecdysteroid hormones in the immature insect. Ecdysteroids coordinate gene expression necessary for growth, molting and metamorphosis. Prothoracicotropic hormone (PTTH), a brain neuropeptide, regulates ecdysteroid synthesis in the prothoracic gland. PTTH stimulates ecdysteroid synthesis through a signal transduction cascade that involves at least four protein kinases: protein kinase A (PKA), p70 S6 kinase, an unidentified tyrosine kinase, and the extracellular signal-regulated kinase (ERK). In this report, the participation of protein kinase C (PKC) in PTTH signalling is demonstrated and characterized. PTTH stimulates PKC activity through a PLC and Ca(2+)-dependent pathway that is not cAMP regulated. Inhibition of PKC inhibits PTTH-stimulated ecdysteroidogenesis as well as PTTH-stimulated phosphorylation of ERK and its upstream regulator, MAP/ERK kinase (MEK). These observations reveal that the acute regulation of prothoracic gland steroidogenesis is dependent on a web of interacting kinase pathways, which probably converge on factors that regulate translation.
Rybczynski
Robert
R
Department of Biology, University of North Carolina at Chapel Hill, 27599-3280, USA. rybczy@bio.unc.edu
Gilbert
Lawrence I
LI
D000818:Animals; D020013:Calcium Signaling; D026461:Ecdysteroids / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007301:Insect Hormones / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D018402:Manduca / Q000378:metabolism / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018978:Molting / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism; D054799:Phospholipase C beta; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism* / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
D026461:Ecdysteroids; D007301:Insect Hormones; D007527:Isoenzymes; D009479:Neuropeptides; D043562:Receptors, G-Protein-Coupled; C009089:prothoracicotropic hormone; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D054799:Phospholipase C beta