scholarly journals Myoglianin triggers the pre-metamorphosis stage in hemimetabolan insects

2018 ◽  
Author(s):  
Orathai Kamsoi ◽  
Xavier Belles

ABSTRACTInsect metamorphosis is triggered by a decrease in juvenile hormone (JH) in the final juvenile instar. What induces this decline is therefore a very relevant question. Working with the cockroach Blattella germanica, we found that Myoglianin (Myo), a ligand in the TGF-β signaling pathway, is highly expressed in the corpora allata (CA, the JH producing glands) and prothoracic glands (PG, which produce ecdysone) during the penultimate nymphal instar (N5). In the CA, high Myo levels during N5 repress the expression of jhamt, a JH biosynthesis gene. In the PG, decreasing JH levels trigger gland degeneration, mediated by the factors Kr-h1, FTZ-F1, E93 and IAP1. Also in the PG, a peak of myo expression in N5 stimulates the expression of ecdysone biosynthesis genes, such as nvd, thus enhancing the production of the metamorphic ecdysone pulse in N6. The myo expression peak in N5 also represses cell proliferation, which can contribute to enhance ecdysone production. The data indicate that Myo triggers the pre-metamorphic nymphal instar in B. germanica, and possibly in other hemimetabolan insects.


2015 ◽  
Vol 112 (12) ◽  
pp. 3740-3745 ◽  
Author(s):  
Jesus Lozano ◽  
Raúl Montañez ◽  
Xavier Belles

In 2009 we reported that depletion of Dicer-1, the enzyme that catalyzes the final step of miRNA biosynthesis, prevents metamorphosis inBlattella germanica. However, the precise regulatory roles of miRNAs in the process have remained elusive. In the present work, we have observed that Dicer-1 depletion results in an increase of mRNA levels of Krüppel homolog 1 (Kr-h1), a juvenile hormone-dependent transcription factor that represses metamorphosis, and that depletion of Kr-h1 expression in Dicer-1 knockdown individuals rescues metamorphosis. We have also found that the 3′UTR of Kr-h1 mRNA contains a functional binding site for miR-2 family miRNAs (for miR-2, miR-13a, and miR-13b). These data suggest that metamorphosis impairment caused by Dicer-1 and miRNA depletion is due to a deregulation of Kr-h1 expression and that this deregulation is derived from a deficiency of miR-2 miRNAs. We corroborated this by treating the last nymphal instar ofB. germanicawith an miR-2 inhibitor, which impaired metamorphosis, and by treating Dicer-1-depleted individuals with an miR-2 mimic to allow nymphal-to-adult metamorphosis to proceed. Taken together, the data indicate that miR-2 miRNAs scavenge Kr-h1 transcripts when the transition from nymph to adult should be taking place, thus crucially contributing to the correct culmination of metamorphosis.



PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e86923 ◽  
Author(s):  
Ana Durvalina Bomtorin ◽  
Aline Mackert ◽  
Gustavo Conrado Couto Rosa ◽  
Livia Maria Moda ◽  
Juliana Ramos Martins ◽  
...  


1971 ◽  
Vol 26 (2) ◽  
pp. 154-157 ◽  
Author(s):  
Ch. Hintze-Podufal

The two synthetic farnesol derivatives, farnesyl methyl ether and the dihydrochloride of ethylfarnesoate were found to be morphogenetically effective in a distinguishable manner in the last larval instar of Cerura vinula L. by topical application assays. The juvenile hormone-like activity of the two substances correlates with the amount of applied substances and a critical time interval to the prepupal processes. In spite of the deficiency of some prepupal processes, it is possible, that the pupal moult occurs after a long period of delay.The time lapse of the pupal development is suggested to be dependent upon some balance of the hormones of the prothoracic glands, ecdysone, and the juvenile hormone of the corpora allata.



2016 ◽  
Vol 113 (20) ◽  
pp. 5634-5639 ◽  
Author(s):  
Yoshiyasu Ishimaru ◽  
Sayuri Tomonari ◽  
Yuji Matsuoka ◽  
Takahito Watanabe ◽  
Katsuyuki Miyawaki ◽  
...  

Although butterflies undergo a dramatic morphological transformation from larva to adult via a pupal stage (holometamorphosis), crickets undergo a metamorphosis from nymph to adult without formation of a pupa (hemimetamorphosis). Despite these differences, both processes are regulated by common mechanisms that involve 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH regulates many aspects of insect physiology, such as development, reproduction, diapause, and metamorphosis. Consequently, strict regulation of JH levels is crucial throughout an insect’s life cycle. However, it remains unclear how JH synthesis is regulated. Here, we report that in the corpora allata of the cricket, Gryllus bimaculatus, Myoglianin (Gb’Myo), a homolog of Drosophila Myoglianin/vertebrate GDF8/11, is involved in the down-regulation of JH production by suppressing the expression of a gene encoding JH acid O-methyltransferase, Gb’jhamt. In contrast, JH production is up-regulated by Decapentaplegic (Gb’Dpp) and Glass-bottom boat/60A (Gb’Gbb) signaling that occurs as part of the transcriptional activation of Gb’jhamt. Gb’Myo defines the nature of each developmental transition by regulating JH titer and the interactions between JH and 20E. When Gb’myo expression is suppressed, the activation of Gb’jhamt expression and secretion of 20E induce molting, thereby leading to the next instar before the last nymphal instar. Conversely, high Gb’myo expression induces metamorphosis during the last nymphal instar through the cessation of JH synthesis. Gb’myo also regulates final insect size. Because Myo/GDF8/11 and Dpp/bone morphogenetic protein (BMP)2/4-Gbb/BMP5–8 are conserved in both invertebrates and vertebrates, the present findings provide common regulatory mechanisms for endocrine control of animal development.



2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Takumi Kayukawa ◽  
Kenjiro Furuta ◽  
Keisuke Nagamine ◽  
Tetsuro Shinoda ◽  
Kiyoaki Yonesu ◽  
...  

Abstract Insecticide resistance has recently become a serious problem in the agricultural field. Development of insecticides with new mechanisms of action is essential to overcome this limitation. Juvenile hormone (JH) is an insect-specific hormone that plays key roles in maintaining the larval stage of insects. Hence, JH signaling pathway is considered a suitable target in the development of novel insecticides; however, only a few JH signaling inhibitors (JHSIs) have been reported, and no practical JHSIs have been developed. Here, we established a high-throughput screening (HTS) system for exploration of novel JHSIs using a Bombyx mori cell line (BmN_JF&AR cells) and carried out a large-scale screening in this cell line using a chemical library. The four-step HTS yielded 69 compounds as candidate JHSIs. Topical application of JHSI48 to B. mori larvae caused precocious metamorphosis. In ex vivo culture of the epidermis, JHSI48 suppressed the expression of the Krüppel homolog 1 gene, which is directly activated by JH-liganded receptor. Moreover, JHSI48 caused a parallel rightward shift in the JH response curve, suggesting that JHSI48 possesses a competitive antagonist-like activity. Thus, large-scale HTS using chemical libraries may have applications in development of future insecticides targeting the JH signaling pathway.



2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Haoqi Zhao ◽  
Lan Wang ◽  
Shufang Wang ◽  
Xihua Chen ◽  
Min Liang ◽  
...  

Abstract Background Metastasis and invasion are crucial in determining the mortality of cervical carcinoma (CC) patients. The epithelial–mesenchymal transition (EMT) is now a universal explanation for the mechanisms of tumor metastasis. Α-chimeric protein (α-chimaerin, CHN1) plays an important role in the regulation of signal transduction and development. However, the molecular regulatory relationships between CHN1 and CC progression in relation to EMT have not yet been identified. Methods The expression of CHN1 in CC tissues, adjacent tissues, and lymph node metastases from CC patients was detected by immunohistochemistry. Upregulation and knockdown of CHN1 were achieved by transfection of CC cells. The effect of CHN1 on cell proliferation was determined by CCK-8 and plate clone formation assays. Changes in migration and invasion capabilities were evaluated using scratch migration and transwell invasion assays. The effect of CHN1 overexpression and interference on xenograft tumor growth was determined by tumor weight and pathological analyses. The expression of EMT-related mRNAs was measured by qRT-PCR in transfected CC cells. EMT-related proteins and Akt/GSK-3β/Snail signaling pathway-related proteins were also evaluated by western blotting. Results CHN1 was overexpressed in CC tissues and was associated with lymph node metastasis and low survival in CC patients. Overexpression of CHN1 promoted cell proliferation, migration, and invasion in CC cells. In contrast, silencing of CHN1 inhibited these phenomena. Overexpression of CHN1 promoted tumor formation in an in vivo xenograft tumor mouse model, with increased tumor volumes and weights. In addition, CHN1 induced the expression of EMT-related transcription factors, accompanied by the decreased expression of epithelial markers and increased expression of mesenchymal markers. The Akt/GSK-3β/Snail signaling pathway was activated by overexpression of CHN1 in vitro, and activation of this pathway was inhibited by the signaling pathway inhibitor LY294002. Conclusion These results suggest that CHN1 promotes the development and progression of cervical carcinoma via the Akt/GSK-3β/Snail pathway by inducing EMT.



2021 ◽  
Vol 20 ◽  
pp. 153303382199007
Author(s):  
Wenlin Liu ◽  
Jiandong Zhan ◽  
Rong Zhong ◽  
Rui Li ◽  
Xiaoli Sheng ◽  
...  

Background: Laryngeal cancer is one of the most common malignant tumors among head and neck cancers. Accumulating studies have indicated that long noncoding RNAs (lncRNAs) play an important role in laryngeal cancer occurrence and progression, however, the functional roles and relative regulatory mechanisms of lncRNA growth arrest-specific transcript 5 (GAS5) in laryngeal cancer progression remain unclear. Methods: The expression of lncRNA GAS5 in both laryngeal cancer tissues and cell lines was evaluated using quantitative reverse transcription-polymerase chain reaction (RT-qPCR) assay. The relationships between lncRNA GAS5 expression and clinical parameters were also analyzed. To determine the biological function of lncRNA GAS5, a lncRNA GAS5-specific plasmid was first transfected into laryngeal cancer cells using lentiviral technology. Cell counting kit-8 assay, flow cytometry, and Transwell assays were used to detect in vitro cell proliferation, apoptosis, cycle distribution, and metastasis abilities, respectively. Furthermore, in vivo cell growth experiments were also performed using nude mice. Additionally, western blotting was performed to identify the underlying regulatory mechanism. Results: In the current study, lncRNA GAS5 was downregulated in laryngeal cancer tissues and its low expression was closely associated with poor tumor differentiation, advanced TNM stage, lymph node metastasis, and shorter overall survival time. In addition, lncRNA GAS5 upregulation significantly inhibited laryngeal cancer cell proliferation both in vitro and in vivo. Moreover, in response to lncRNA GAS5 overexpression, more laryngeal cancer cells were arrested at the G2/M stage, accompanied by increased cell apoptosis rates and suppressed migration and invasion capacities. Mechanistically, our data showed that the overexpression of lncRNA GAS5 significantly regulated the PI3K/AKT/mTOR signaling pathway. Conclusion: LncRNA GAS5 might act as a suppressor gene during laryngeal cancer development, as it suppressed cell proliferation and metastasis by regulating the PI3K/AKT/mTOR signaling pathway; thus, lncRNA GAS5 is a promising therapeutic biomarker for the treatment of laryngeal cancer.



2021 ◽  
Author(s):  
Zhan-Long Li ◽  
Jia Mi ◽  
Lu Lu ◽  
Qing Luo ◽  
Xi Liu ◽  
...  

Pt3G inhibits DU-145 cell proliferation and induces apoptosis through the ROS/PTEN/PI3K/Akt/caspase-3 signaling pathway.



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