20-hydroxyecdysone reprograms amino acid metabolism to support the metamorphic development of Helicoverpa armigera.

Amino acid metabolism is regulated according to nutrient conditions; however, the mechanism is not fully understood. Using the holometabolous insect cotton bollworm (Helicoverpa armigera) as a model, we report that hemolymph metabolites are greatly changed from the feeding larvae to the wandering larvae and to pupae. Arginine, alpha-ketoglutarate (α-KG), and glutamate (Glu) are identified as marker metabolites of feeding larvae, wandering larvae, and pupae, respectively.

20-Hydroxyecdysone counteracts insulin to promote programmed cell death by modifying phosphoglycerate kinase 1.

Background: The regulation of glycolysis and autophagy during feeding and metamorphosis in holometabolous insects is a complex process that is not yet fully understood. Insulin regulates glycolysis during the larval feeding stage, allowing the insects to grow and live. However, during metamorphosis, 20-hydroxyecdysone (20E) takes over and regulates programmed cell death (PCD) in larval tissues, leading to degradation and ultimately enabling the insects to transform into adults.

Krüppel-like factor 15 integrated autophagy and gluconeogenesis to maintain glucose homeostasis under 20-hydroxyecdysone regulation.

The regulation of glycometabolism homeostasis is vital to maintain health and development of animal and humans; however, the molecular mechanisms by which organisms regulate the glucose metabolism homeostasis from a feeding state switching to a non-feeding state are not fully understood. Using the holometabolous lepidopteran insect Helicoverpa armigera, cotton bollworm, as a model, we revealed that the steroid hormone 20-hydroxyecdysone (20E) upregulated the expression of transcription factor Krüppel-like factor (identified as Klf15) to promote macroautophagy/autophagy, apoptosis and gluconeogenesis during metamorphosis. 20E via its nuclear receptor EcR upregulated Klf15 transcription in the fat body during metamorphosis.

Insulin-like Growth Factor 2 Promotes Tissue-Specific Cell Growth, Proliferation and Survival during Development of .

During development, cells constantly undergo fate choices by differentiating, proliferating, and dying as part of tissue remodeling. However, we only begin to understand the mechanisms of these different fate choices. Here, we took the lepidopteran insect , the cotton bollworm, as a model to reveal that insulin-like growth factor 2 (IGF-2-like) prevented cell death by promoting cell growth and proliferation.

Identification and Functional Analysis of G Protein-Coupled Receptors in 20-Hydroxyecdysone Signaling From the Genome.

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors in animals and humans, which transmit various signals from the extracellular environment into cells. Studies have reported that several GPCRs transmit the same signal; however, the mechanism is unclear. In the present study, we identified all 122 classical GPCRs from the genome of , a lepidopteran pest species.

The Steroid Hormone 20-Hydroxyecdysone Promotes the Cytoplasmic Localization of Yorkie to Suppress Cell Proliferation and Induce Apoptosis.

The transcriptional co-activator Yki (Yorkie), a member of the Hippo pathway, regulates cell proliferation or apoptosis, depending on its nuclear or cytoplasmic location. However, the upstream factors regulating the subcellular localization of Yki are unclear. We found that the steroid hormone 20-hydroxyecdysone (20E) induces phosphorylation of Yki, causing it to remain in the cytoplasm, where it promotes apoptosis in the midgut of the lepidopteran insect Helicoverpa armigera Yki is expressed in various tissues, with an increase in the epidermis and midgut during early metamorphic molting.

The Steroid Hormone 20-Hydroxyecdysone Enhances Gene Transcription through the cAMP Response Element-binding Protein (CREB) Signaling Pathway.

Animal steroid hormones regulate gene transcription through genomic pathways by binding to nuclear receptors. These steroid hormones also rapidly increase intracellular calcium and cyclic adenosine monophosphate (cAMP) levels and activate the protein kinase C (PKC) and protein kinase A (PKA) nongenomic pathways. However, the function and mechanism of the nongenomic pathways of the steroid hormones are unclear, and the relationship between the PKC and PKA pathways is also unclear.

The Steroid Hormone 20-Hydroxyecdysone Up-regulates Ste-20 Family Serine/Threonine Kinase Hippo to Induce Programmed Cell Death.

The steroid hormone 20-hydroxyecdysone (20E) and the serine/threonine Ste20-like kinase Hippo signal promote programmed cell death (PCD) during development, although the interaction between them remains unclear. Here, we present evidence that 20E up-regulates Hippo to induce PCD during the metamorphic development of insects. We found that Hippo is involved in 20E-induced metamorphosis via promoting the phosphorylation and cytoplasmic retention of Yorkie (Yki), causing suppressed expression of the inhibitor of apoptosis (IAP), thereby releasing its inhibitory effect on caspase.

G-protein-coupled receptor participates in 20-hydroxyecdysone signaling on the plasma membrane.

Background: Animal steroid hormones are conventionally known to initiate signaling via a genomic pathway by binding to the nuclear receptors. The mechanism by which 20E initiates signaling via a nongenomic pathway is unclear.

Results: We illustrate that 20E triggered the nongenomic pathway through a plasma membrane G-protein-coupled receptor (named ErGPCR) in the lepidopteran insect Helicoverpa armigera.

Steroid hormone 20-hydroxyecdysone regulation of the very-high-density lipoprotein (VHDL) receptor phosphorylation for VHDL uptake.

During the metamorphic stage of holometabolous insects, the biosynthetic precursors needed for the synthesis of a large number of adult proteins are acquired from the selective absorption of storage proteins. The very-high-density lipoprotein (VHDL), a non-hexameric storage protein, is consumed by the fat body from the hemolymph through VHDL receptor (VHDL-R)-mediated endocytosis. However, the mechanism of the uptake of VHDL by a VHDL-R remains unclear.

The knockdown of Ha-GRIM-19 by RNA interference induced programmed cell death.

GRIM-19 (genes associated with retinoid-IFN-induced mortality-19) is a subunit of mitochondrial respiratory complex I in mammalian systems. However, its function in vivo is not really understood. We cloned GRIM-19 and explored its function and hormonal regulation in insect, the cotton bollworm, Helicoverpa armigera.

A eukaryotic initiation factor 5C is upregulated during metamorphosis in the cotton bollworm, Helicoverpa armigera.

Background: The orthologs of eukaryotic initiation factor 5C (eIF5C) are essential to the initiation of protein translation, and their regulation during development is not well known.

Results: A cDNA encoding a polypeptide of 419 amino acids containing an N-terminal leucine zipper motif and a C-terminal eIF5C domain was cloned from metamorphic larvae of Helicoverpa armigera. It was subsequently named Ha-eIF5C.

Identification of genes differentially expressed during larval molting and metamorphosis of Helicoverpa armigera.

Background: Larval molting and metamorphosis are important physiological processes in the life cycle of the holometabolous insect. We used suppression subtractive hybridization (SSH) to identify genes differentially expressed during larval molting and metamorphosis.

Results: We performed SSH between tissues from a variety of developmental stages, including molting 5th and feeding 6th instar larvae, metamorphically committed and feeding 5th instar larvae, and feeding 5th instar and metamorphically committed larvae.

Cathepsin B-like proteinase is involved in the decomposition of the adult fat body of Helicoverpa armigera.

Cathepsin B-like proteinase (HCB, EC 3.4.22.

Expression of the Helicoverpa cathepsin B-like proteinase during embryonic development.

Cathepsin B-like proteinase from Helicoverpa armigera (HCB) was proposed as being involved in the degradation of yolk proteins during embryonic development. Recombinant HCB was expressed as a fusion protein with GST in Escherichia coli BL21 on the basis of its cDNA and purified to homogeneity. The fusion protein was cleaved with thrombin to generate a soluble protease with a mass of 37 kDa.