Dynamic regulation of prothoracic gland ecdysteroidogenesis: Manduca sexta recombinant prothoracicotropic hormone and brain extracts have identical effects

Gilbert, Lawrence I.; Rybczynski, Robert; Song, Qisheng; Mizoguchi, Akira; Morreale, Rosalba A.; Smith, Wendy A.; Matubayashi, H; Shionoya, Motoko; Nagata, Shinji; Kataoka, Hiroshi

doi:10.1016/s0965-1748(00)00083-7

Cited by 43 publications

(29 citation statements)

References 36 publications

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“…In such a model, the application of calcium ionophores to molting glands in vitro is sufficient to stimulate maximal steroidogenesis. The effect of purified brain extracts on external Ca 2+ influx, also observed in Galleria mellonella (Birkenbeil 1996), has been recently confirmed in Bombyx mori (Gu et al 1998) and Manduca sexta (Gilbert et al 2000) using recombinant PTTHs.…”

Section: Introductionmentioning

confidence: 71%

Calcium inhibits ovarian steroidogenesis in the blowfly Phormia regina

Manière

Vanhems²,

Gautron³

et al. 2002

Journal of Endocrinology

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Calcium is frequently involved in the stimulation of steroidogenesis in gonads and endocrine glands, generally in association with cAMP. However, our present observations show that it has the opposite effect in the ovary of the blowfly Phormia regina. Our in vitro experiments first showed that extracellular calcium does not play a role during the stimulation of steroidogenesis in fly ovaries; indeed steroidogenesis was activated in vitro as efficiently in a medium with or without calcium, either by pharmacological compounds mimicking cAMP signaling or by active brain extracts. When calcium was experimentally introduced into biosynthetic cells by ionophores or liberated from internal stores by thapsigargin, it did not activate, but clearly inhibited both basal and acute steroidogenesis respectively in previtellogenic and in vitellogenic ovaries. Our experiments also demonstrated that calcium decreases cAMP concentrations in the ovaries of Phormia, by stimulating its degradation, without modifying its biosynthesis. Moreover, inhibitors of calcium-calmodulin phosphodiesterases (PDEs) increased steroid biosynthesis in vitro, whereas inhibitors of calciuminsensitive PDEs did not. These data thus demonstrate that, in blowfly ovaries, calcium ions inhibit cAMPstimulated steroidogenesis by activating a calmodulinsensitive (type I) PDE.

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Section: Introductionmentioning

confidence: 71%

Calcium inhibits ovarian steroidogenesis in the blowfly Phormia regina

Manière

Vanhems²,

Gautron³

et al. 2002

Journal of Endocrinology

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“…Although one could argue that the above results are artifacts of the in vitro conditions, this is highly unlikely. Earlier studies with rPTTH indicate that the extracts used in these experiments (0.25 to 0.75 brain equivalents of PTTH) contain physiologically realistic amounts of PTTH, i.e., in the low nanogram to sub-nanogram range (Gilbert et al, 2000).…”

Section: Discussionmentioning

confidence: 94%

“…For experiments with tissues other than the prothoracic gland, the standard, wellcharacterized PTTH-containing brain extract was utilized (Gilbert et al, 2000). A starting test dose of 0.25 brain equivalent and a 1-h incubation were used but higher doses and other incubation times were also tested.…”

Section: Animal Rearing and Dissectionsmentioning

confidence: 99%

Manduca sexta prothoracicotropic hormone: evidence for a role beyond steroidogenesis

Rybczynski

Snyder

Hartmann

et al. 2009

Arch Insect Biochem Physiol

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Prothoracicotropic hormone (PTTH) is a homodimeric brain peptide hormone that positively regulates the production of ecdysteroids by the prothoracic gland of Lepidoptera and probably other insects. PTTH was first purified from heads of adult domestic silkworms, Bombyx mori. Prothoracic glands of Bombyx and Manduca sexta undergo apoptosis well before the adult stage is reached, raising the recurring question of PTTH function at these later stages. Because Bombyx has been domesticated for thousands of years, the possibility exists that the presence of PTTH in adult animals is an accidental result of domestication for silk production. In contrast, Manduca has been raised in the laboratory for only five or six decades. The present study found that Manduca brains contain PTTH at all stages examined post-prothoracic gland apoptosis, i.e., pharate adult and adult life, and that PTTH-dependent changes in protein phosphorylation and protein synthesis were observed in several reproductive and reproduction-associated organs. The data indicate that PTTH indeed plays a role in non-steroidogenic tissues and suggest possible future avenues for determining which cellular processes are being so regulated.

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“…The cellular action of PTTH is best understood for lepidopteran insects such as Manduca sexta and Bombyx mori. PTTH stimulates an influx of extracellular calcium (Birkenbeil, 1996(Birkenbeil, , 1998(Birkenbeil, , 2000Birkenbeil and Dedos, 2002) and an increase in the synthesis of cAMP Smith and Pasquarello, 1989;Gilbert et al, 2000). It is believed these events are linked through the activation of a calcium/calmodulin-sensitive adenylyl cyclase in the prothoracic glands (Smith et al, 1985;Meller et al, 1988;Gu et al, 1998).…”

Section: Introductionmentioning

confidence: 99%