MiR-210 regulates coelomocyte proliferation through targeting E2F3 in Apostichopus japonicus

MicroRNA miR-210 Modulates the Water Flea Daphnia magna Response to Cyanobacterial Toxicity

As a key form of post-transcriptional regulation, microRNAs (miRNAs) regulate gene expression by binding to target mRNAs, leading to mRNA decay or translational repression. Recently, the role of miRNAs in the response of aquatic organisms to environmental stressors has emerged. Daphnia, widely distributed cladocerans, play a crucial role in aquatic ecosystems. Cyanobacterial blooms often cause Daphnia populations to decrease, thereby disrupting ecosystem functionality and water quality. However, the post-transcriptional mechanisms behind Daphnia's response to toxic cyanobacteria are insufficiently understood. This study investigated the role of miR-210, a multifunctional miRNA involved in stress response and toxicity pathways, and its target genes (MLH3, CDHR5, and HYOU1) in two Daphnia magna clones exposed to toxic Microcystis aeruginosa. Results showed that M. aeruginosa inhibited somatic growth rates, led to microcystin accumulation, caused abnormal ultrastructural alterations in the digestive tract, and induced DNA damage in both clones. Notably, exposure significantly increased miR-210 expression and decreased the expression of its target genes compared with the controls. We identified miR-210s regulation on clonal-tolerance variations in D. magna to M. aeruginosa, emphasizing miRNAs' contribution to adaptive responses. Our work uncovered a novel post-transcriptional mechanism of cyanobacterial impact on zooplankton and provided essential insights for assessing cyanobacterial toxicity risks.

MiR-210, not let-7, regulates Akt gene expression against Vibrio splendidus infection in the sea cucumber Apostichopus japonicus

The immune regulatory roles of microRNAs (miRNAs) have recently attracted considerable attention. Bioinformatics prediction revealed that both let-7 and miR-210 provide potential binding sites for the Akt (rac-alpha serine/threonine-protein kinase) gene sequence in the sea cucumber Apostichopus japonicus (termed AjAkt). In this study, we first used a dual-luciferase reporter assay and functional validation techniques to verify the interactions between these two miRNAs (let-7 and miR-210) and AjAkt, and then investigated the functions of the validated miRNA/mRNA pair as part of the innate immune response against Vibrio splendidus infection. We found that AjAkt interacts with miR-210 rather than let-7, and miR-210 negatively regulates the expression of AjAkt. From 8 to 48 h after infection with V. splendidus, opposite trends were observed in the expression levels of miR-210 and AjAkt (mRNA and protein) in coelomocytes, suggesting that the miR-210/AjAkt pair is involved in immune regulation during this period after infection. Both AjAkt silencing and miR-210 overexpression enhanced the phagocytic capacity and reduced the infectivity of A. japonicus after pathogen infection, suggesting that the miR-210/AjAkt pair may regulate the innate immune response of A. japonicus by altering phagocytic capacity. The findings of this study enrich our knowledge of the role of miRNA/mRNA pairs in immune regulation in sea cucumbers and provide insights into the molecular mechanisms of the innate immune response in marine echinoderms.

miR-210 promotes immune- and suppresses oocyte meiosis-related genes in the zebrafish ovarian cells

microRNA-210 (miRNA), a well-documented miRNA, has been implicated in a myriad of biological processes, including responses to hypoxia, angiogenesis, cell proliferation, and male infertility in humans. However, a comprehensive understanding of its functions in fish requires further investigation. This study pursued to elucidate the downstream effect of dre-miR-210-5p on primary ovarian cell culture in zebrafish (Danio rerio), an animal model. A protocol was settled down by incubations with either an miR-210 mimic or a scrambled miRNA in the isolated ovaries. RNA-sequencing analysis identified ∼6000 differentially expressed target genes revealing that downregulated genes were associated with reproduction-related pathways while immune-related pathways displayed an upregulated pattern. To identify molecular markers, predicted target genes were classified into reproduction and immune cell types. These findings underscore the existence of a profound interplay between the reproductive and immune systems, with miR-210 emerging as a pivotal player in orchestrating transcriptomic alterations within fish ovaries.

Identification and functional characterization of a novel TRPA1 gene from sea cucumber Apostichopus japonicus and interaction with miR-2013 in response to salt stress

Salinity is important abiotic factor influencing sea cucumber aquaculture. This study aimed to identify and functional study of a novel transient receptor potential cation channel subfamily A member 1 (TRPA1) involved in salinity stress through interaction with miR-2013 in the sea cucumber. The full-length cDNA sequence was 1369 bp in length and encoded 138 amino acids. The TRPA1 homolog protein was a hydrophilic protein without a signal peptide and was predicted to a spatial structure of seven helices and eight random coils and two major ANK functional domains. Bioinformatic analysis and luciferase reporter assays confirmed TRPA1 as a target gene of miR-2013. Quantitative PCR revealed that miR-2013 was induced upregulation after salinity stress, while TRPA1 showed upregulated expression with maximum expression at 24 h. The expression of miR-2013 and TRPA1 was negatively regulated. Transfection experiments were conducted to validate the role of miR-2013 and TRPA1 in salinity response. The results showed that miR-2013 was upregulated and TRPA1 was downregulated after transfection with miR-2013 mimics, while miR-2013 was downregulated and TRPA1 was upregulated after transfection with miR-2013 inhibitor. Transfection with si-TRPA1 homolog resulted in upregulation of miR-2013 and downregulation of TRPA1 homolog. These findings suggest that miR-2013 can regulate the expression of TRPA1 under salt stress, and highlight the importance of miR-2013 and TRPA1 in salt stress response. miR-2013 mimics improved the survival rate, while miR-2013 inhibitor and si-TRPA1 reduced it. These findings suggest that miR-2013 and TRPA1 play important roles in sea cucumbers adaptation to salinity changes.

CircRNA254 functions as the miR-375 sponge to inhibit coelomocyte apoptosis via targeting BAG2 in V. splendidus-challenged Apostichopus japonicus

Circular RNAs (circRNAs) function as immune regulators in many biological processes in mammals, while their function and underlying mechanisms in invertebrates are largely unexplored. In this study, the competing endogenous RNA (ceRNA) mechanism of circRNA that sponges miR-375 and thus regulates AjBAG2-mediated coelomocyte apoptosis was evaluated in Apostichopus japonicus. The results showed that circRNA254 (circ254) was significantly down-regulated in the intestines and coelomocytes after Vibrio splendidus challenge or Lipopolysaccharide exposure, which matched the RNA-seq results in A. japonicus within skin ulceration syndrome. Dual-luciferase and RNA FISH assays indicated that circ254 could directly combine with miR-375, in which circ254 possesses three binding sites of miR-375. Moreover, circ254 knockdown significantly promoted the coelomocyte apoptosis levels upon pathogen infection in vivo and in vitro. Furthermore, circ254 silencing could also down-regulate AjBAG2 expression and thereby promoting the levels of coelomocyte apoptosis levels and the expression of caspase 3, which the phenomenon could be reversed by treatment with miR-375 inhibitors. Taken together, our results confirmed that circ254 functions as a ceRNA of AjBAG2 by sponging miR-375, resulting in the inhibition of coelomocyte apoptosis in A. japonicus.

MiR-493-5p inhibits the malignant development of gliomas via suppressing E2F3-mediated dysfunctions of P53 and PI3K/AKT pathways

BACKGROUND

Gliomas is a major challenge of current medical system, and thousands of people are struggling in the pain of this disease worldwide. In the last decade, the functions of miRNAs have been revealed by many studies, and the intervention on miRNA dysfunctions has been thought as a promising way to counter cancer. MiR-493-5p has been identified as a tumor inhibitor to suppress the progressions of several tumors while its role in gliomas remains unknown. Hence, the study investigated the expression levels of miR-493-5p in glioma tissues and cell lines.

METHODS

CCK-8 assay, transwell assay and flow cytometry assay were used to observe the effects of miR-493-5p on tumor cells. The downstream targets of miR-493-5p were also searched and verified with online databases and dual-luciferase reporter assay. Moreover, the activities of P53 and PI3K/AKT pathways were also explored by western blot to illustrate the regulation mechanism of miR-493-5p on glioma development.

RESULTS

The results showed that miR-493-5p was significantly downregulated in pathological tissues and glioma cell lines, and the increased miR-493-5p effectively inhibited the malignant behavior and promoted the apoptosis of glioma cells.

CONCLUSIONS

E2F3 was confirmed as a target of miR-493-5p, and the effects of miR-493-5p on the phenotype of glioma cells could be partly reversed by E2F3. Besides, it was also found that miR-493-5p could effectively suppress the expression of E2F3 and then improve the dysfunctions of the P53 and PI3K/AKT pathways.