Identification of a Novel Prothoracicostatic Hormone and Its Receptor in the Silkworm Bombyx mori (original) (raw)
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Febs Journal, 2006
The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and metamorphosis through binding with a heterodimer of two nuclear receptors, the ecdysone receptor (EcR) and ultraspiracle (USP). Expression of the specific isoforms EcR-A and EcR-B1 governs steroid-induced responses in the developing cells of the silkworm Bombyx mori. Here, analysis of EcR-A and EcR-B1 expression during larval-pupal development showed that both genes were up-regulated by 20E in the B. mori brain. Whole-mount in situ hybridization and immunohistochemistry revealed that EcR-A and EcR-B1 mRNAs and proteins were exclusively located in two pairs of lateral neurosecretory cells in the larval brain known as the prothoracicotropic hormone (PTTH)- producing cells (PTPCs). In the pupal brain, EcR-A and EcR-B1 expression was detected in tritocerebral cells and optic lobe cells in addition to PTPCs. As PTTH controls ecdysone secretion by the prothoracic gland, these results indicate that 20E-responsive PTPCs are the master cells of insect metamorphosis.
Journal of Insect Physiology, 1999
The ability of recombinant prothoracicotropic hormone (rPTTH) or crude brain extract (cBRAIN) of Bombyx mori to stimulate ecdysteroid secretion from prothoracic glands (PGs) was investigated throughout the fifth instar and the first day of the pupal stage. Crude brain extracts could stimulate much higher ecdysteroid secretion than rPTTH during a 2 h incubation. Recombinant PTTH did not increase the level of glandular cyclic AMP, except on days 4 and 5 of the fifth instar. Glandular cAMP levels were increased by cBRAIN from day 0 until day 5 of the fifth instar with the highest increase on day 3. On this day, rPTTH could not stimulate any increase of ecdysteroid secretion from the PGs during a 30 min incubation. On the contrary, PGs incubated with cBRAIN for 30 min showed increased secretory activity. Furthermore, on day 3 and in the absence of extracellular Ca 2 ϩ , rPTTH did not increase the glandular cAMP levels but cBRAIN did. Recombinant PTTH-stimulated ecdysteroid secretion from day 3 PGs was dependent on extracellular Ca 2 ϩ in a dose-dependent manner. However, cBRAIN could stimulate ecdysteroid secretion even in the absence of extracellular Ca 2 ϩ . Taken together, the results of these experiments suggest the presence of a previously unknown cerebral prothoracicotropic factor that can stimulate glandular cAMP levels and ecdysteroid secretion from the PGs of Bombyx mori.
Journal of Insect Physiology, 1987
The presence and fluctuation of prothoracicotropic hormone (PTTH) activity have been shown in brainless Bombyx mori pupae and in developing embryos. The embryonic PITH is only effective in eliciting adult development of brainless pupae. PTTH activity first became detectable in embryos which had developed almost to the stage of differentiation of their neuroendocrine systems. The hormone was partially purified from pharate first-instar larvae (1 day before hatching) and approx a 300-fold purification was achieved. 0.2 pg of the partial purified hormone can evoke adult development in brainless pupae. The molecular weight of the hormone was estimated to be 20,000-30,000 daltons by gel-filtration on a Sephadex G-SO. Two distinct forms of PTTH are present in developing embryos of B. mori.
A monoclonal antibody to the insect prothoracicotropic hormone
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1988
The prothoracicotropic hormone (PTTH) is an insect cerebral peptide that stimulates the prothoracic glands to produce the steroid hormone ecdysone thus initiating molting and metamorphosis. "Big" PTTH, one of several molecular forms of the neurohormone, was isolated from brains of the tobacco hornworm Manduca sexta, and fractionated by high-pressure liquid chromatography (HPLC) for use in antibody production. A murine polyclonal antiserum and a monoclonal antibody (MAb) have been generated using this highly purified preparation of big PTTH. Antisera and hybridoma supernatants were screened with an indirect, brain whole-mount immunocytological assay, and antibody specificity was confirmed by immunocytological, ELISA, and functional criteria. In brain whole-mount preparations, the MAb (A2H5) and antiserum specifically immunostained the lateral protocerebral neurosecretory cells (L-NSC III), the prothoracicotropes, which produce PTTH. This immunostaining was blocked by preads...
The Biology of the Prothoracicotropic Hormone Peptidergic Neurons in an Insect
Integrative and Comparative Biology, 1993
SYNOPSIS. The prothoracicotropic hormone and the cerebral peptidergic neurons that produce it have traditionally been thought to have the singular function of acting as a primary effector of insect postembryonic development. Recent investigations of this neuroendocrine axis in the tobacco hornworm, Manduca sexta, are leading to a new view that these peptidergic neurons and their peptide phenotypes may be multifunctional. They may act in different ways depending upon the animal's developmental stage and site of phenotype release. The possibility for this functional diversity of the prothoracicotropic hormone is possibly even greater due to multiple neuronal sites of peptide expression within the central nervous system. Similarly, the L-NSC III may have more functions due to the expression of multiple peptide phenotypes. The data, thus far, have not enabled us to identify additional physiological roles for the peptide, but they have provided insight into the experimental approaches that might be effective in resolving these functions.
Proceedings of the National Academy of Sciences, 1979
The distribution of prothoracicotropic hormone in the pupal brain of Manduca sexta has been determined by an in vitro assay for prothoracic gland activation. Prothoracicotropic activity was observed in both the brain and retrocerebral complex, but predominantly in the dorosolateral regions of the protocerebrum. Of the two groups of neurosecretory cells present in this area of the brain, only the two lateral type III neurosecretory cells exhibited significant prothoracicotropic hormone activity. Further analysis revealed that the neurohormone was localized in only one of the two type III cells, suggesting that a single neurosecretory cell in each hemisphere is the source of the hormone at the stage examined (day 0). Prothoracicotropic hormone activity was detected in both the corpora allata and the corpora cardiaca, but the corpora allata contained 2 to 9 times the activity of the corpora cardiaca, depending on developmental stage. The significantly higher level of activity in the co...