The horticulture and urban entomology team of Huazhong Agricultural University has made new progress in the study of the regulatory mechanism of metabolic homeostasis in orange fruit flies

On October 5, Professor Zhang Hongyu of Huazhong Agricultural University published a report entitled "miR-275/305 cluster is essential for maintaining energy me" online in the well-known journal PLoS Genetics Tabolic homeostasis by the insulin signaling pathway in Bactrocera dorsalis" confirmed for the first time that microRNA (miR-275/305 clusters) is involved in the homeostatic regulation of energy metabolism in orange fruit flies, and the research results have important scientific significance
for understanding the nutritional regulation of insect metabolism physiology.

 

As an important environmental limiting factor, dietary nutrition is essential
for the growth, development and reproduction of insects.
In most diptera insects, feathered adults must ingest a certain amount of protein to reach sexual maturity and reproduce
.
In addition, organisms need to constantly adjust the metabolic status between tissues and organs to adapt to nutritional fluctuations, and precise control of metabolic homeostasis is critical to cell differentiation and tissue integrity, and metabolic disorders can lead to serious physiological diseases such as obesity and insulin resistance
.
However, the molecular mechanisms that insects use to adjust their metabolism in response to different nutritional changes are still poorly
understood.

 

The study first clarified the effect of eating yeast on adult fruit fly metabolism (elevated triglycerides, glycogen and total sugar content).

The latest research found that diet can reshape miRNA expression profile, and further interference with miRNA biosynthesis pathway genes through RNAi found that interference with AGO1 and DCR1 can also affect the metabolic state of adult worms, indicating that dietary yeast may affect the metabolic state
of orange flies through miRNA.
A total of 19 differentially expressed miRNAs
were identified by small-RNA high-throughput sequencing.
Among them, the evolutionarily conserved miR-275/305 cluster showed positive synergistic response in response to yeast food stimuli, and was highly expressed
in adipose-enriched tissues such as adiposomes and intestines of Orange fruit fly.
Using CRISPR/Cas9 gene editing technology, knocking out miR-275 and miR-305 significantly reduced triglyceride and glycogen content, while total sugar content was significantly increased, and impaired the ability of
orange fruit flies to fly.

 

In order to further explore the mechanism of action of miR-275 and miR-305, the authors used two-omics association analysis to screen target genes in the whole gene, and then used microinjection, double luciferase detection, RNA co-immunoprecipitation and in situ hybridization to finally confirm that miR-275 and miR-305 act on the 3'UTR region binding of SLC2A1 and GLIS2, respectively, to inhibit their expression
。 Functional analysis showed that SLC2A1 and GLIS2 were involved in carbon degradation and lipid metabolism, respectively, and that the metabolic phenotype
caused by inhibition of miR-275 and miR-305 could be partially rescued by interference with the target gene through RNAi.
Further studies found that exogenous insulin injection could significantly promote the transcription of miR-275/305 clusters and inhibit the expression of SLC2A1/GLIS2, while interfering with the insulin receptor substrate IRS showed the opposite trend
.
Interfering with the TOR pathway can also affect the transcription
of the target gene.
These results suggest that the metabolic network mediated by the miR-275/305 cluster is regulated
by the insulin signaling pathway.

 

Based on the above conclusions, the authors propose a network model
of miR-275/305 clusters regulating energy metabolism homeostasis.
After ingestion of dietary yeast, the activated insulin signaling pathway promotes the transcription of miR-275/305 clusters, which binds to the target gene SLC2A1/GLIS2 and inhibits its transcription, thereby ensuring normal metabolic physiology, and the TOR pathway can independently regulate the target gene without affecting the transcription
of miRNA.
Under yeast deprivation conditions, TOR and insulin signaling pathway activity is inhibited, miRNA transcription is reduced, and miRNA-mediated inhibition is weakened, manifested by enhanced SLC2A1/GLIS2 transcription to maintain the energy supply
required for basic metabolism.

 

Junfei Xie, a doctoral student of Huazhong Agricultural University, is the first author of the paper, Professor Zhang Hongyu and Professor Li Xiaoxue are the co-corresponding authors, and graduated doctoral students Zheng Wenping, Cai Zhaohui and graduate student Chen Hao participated in some of the research work
.
This research was supported
by the National Key Research and Development Program of China (2019YFD1002100) and the National Modern Agricultural Industry Technology System (CARS-26).

 

Professor Hongyu Zhang's team has long been committed to the research of fruit fly and other horticulture and urban pest catastrophe law and green prevention and control, invasive biology and biosecurity, and has made a series of research progress, some of which have been published in Nature Communications, ISME J, PLoS Pathogens, Cells, Fro ntiers in Microbiology, and Evolutionary Published
in high-level magazines such as Applications and Insect Mol Biol.

 

English Summary:

 

Increasing evidence indicates that miRNAs play crucial regulatory roles in various physiological processes of insects, including systemic me tabolism.
However, the molecular mechanisms of how specific miRNAs regulate energy metabolic homeostasis remain largely unknown.
In the present study, we found that an evolutionarily conserved miR-275/305 cluster was essential for maintaining energy metabolic homeostasis in respo nse to dietary yeast stimulation in Bactrocera dorsalis.
Depletion of miR-275 and miR-305 by the CRISPR/Cas9 system significantly reduced triglyceride and glycogen contents, elevated total sugar levels, and impaired flight capacity.
Combined in vivo and in vitro experiments, we demonstrated that miR-275 and miR-305 can bind to the 3'UTR regions of SLC2A1 and GLIS2 to repress their ex pression, respectively.
RNAi-mediated knockdown of these two genes partially rescued me tabolic phenotypes caused by inhibiting miR-275 and miR-305.
Furthermore, we further illustrated that the miR-275/305 cluster acting as a regulator of the metabolic axis was co ntrolled by the insulin signaling pathway.
In conclusion, our work combined genetic and physiological approaches to clarify the molecular mechanism of metabolic homeostasis in respo nse to different dietary stimulations and provided a reference for deciphering the potential targets of physiologically important miRNAs in a non-model organism.

 

Original link:

 

　　https://journals.
plos.
org/plosgenetics/article?id=10.
1371/journal.
pgen.
1010418