Potential roles for microRNAs in facilitating physiological adaptation to low-temperature stress in Penaeus vannamei

Deficiency of PvDRAM2 increased the nitrite sensitivity of Pacific white shrimp (Penaeus vannamei) by inhibiting autophagy

Autophagy is an essential response mechanism to environmental stress during the evolution of organisms. DRAM2 (Damage-regulated autophagy regulator 2) is recognized as necessary for the process of p53-mediated cell apoptosis. Although the role of DRAM2 in apoptosis has been confirmed, the mechanism of its relationship with autophagy is still unclear. Here we describe PvDRAM2 features and functions. We found that nitrite stress induced autophagy accumulation and ROS production. A novel DRAM-homologous protein, DRAM2, was cloned, and its expression is significantly up-regulated under nitrite stress conditions. PvDRAM2 primarily localizes within the cytoplasmic lysosome.Loss of PvDRAM2 increased sensitivity response to nitrite stress of Pacific white shrimp. And silenced of PvDRAM2 promoted ROS production and inhibited autophagy accumulation. In addition, silenced of PvDRAM2 decreased the autophagy-related protein of p62, Beclin 1, and LC3 expression under nitrite stress of Pacific white shrimp. Collectively, these studies uncover a novel critical role for PvDRAM2 in regulating autophagy under nitrite stress. Specifically, PvDRAM2 is essential for the induction of autophagy, enabling Pacific white shrimp to adapt to environmental stress. This provides mechanistic insight into how autophagy functions as a way for Pacific white shrimp to cope with environmental challenges.

Construction and integrative analysis of miRNA-mRNA response to salinity stress in Oreochromis mossambicus cells

This study investigated the genetic response of tilapia (Oreochromis mossambicus) brain cells to hypertonic stress, focusing on miRNAs regulation. Three hundred and thirty-one known miRNAs and 163 novel miRNAs which responded to hypertonic stress were identified by high-throughput sequencing in tilapia brain cells. Differential expression analysis revealed that 16 miRNAs were significantly upregulated, while 11 miRNAs were significantly downregulated. These differentially expressed miRNAs are closely related to metabolism, immune response, and neural regulation. The target genes of these miRNAs are implicated in neurotrophic and synaptic signaling pathways, potentially affecting metabolic and apoptotic processes. GO and KEGG enrichment analyses provided insights into the biological processes and pathways affected by hypertonic stress. Furthermore, correlation analysis between mRNA and miRNA highlighted miRNA-mRNA interactions related to cell cycle and apoptosis regulation. These results indicated significant changes of miRNA expression under hypertonic stress and their crucial role in osmotic pressure regulation. This study offers a basis for further exploration of miRNA functions and molecular mechanisms in tilapia, potentially informing practices for aquaculture in challenging environments such as saline-alkaline waters.

miRNA-seq analysis of liver tissue from largemouth bass (Micropterus salmoides) in response to oxytetracycline and enzyme-treated soy protein

The specific miRNA regulation triggered by enzyme-treated soybean protein in response to well-known stressors, such as the prophylactic use of the antimicrobial oxytetracycline, remains unknown. Hence, this study aimed to evaluate the regulatory changes of hepatic miRNAs induced by oxytetracycline and enzyme-treated soybean protein in largemouth bass dietary formulations. The experiment was designed with three groups: the normal control (NC), the oxytetracycline exposure treatment group (OTC), and the pre-treatment with enzyme-treated soybean protein before oxytetracycline exposure group (ETSP). miRNA sequencing was employed to characterize the differences between these groups. In conclusion, the NC group exhibited up-regulation of 13 host miRNAs and down-regulation of 1 miRNA compared to the OTC group, whereas the ETSP group showed an increasing trend of 36 host miRNAs and a decreasing trend of 13 host miRNAs compared to the OTC group. Nine miRNAs were identified as prudential targets for enzyme-treated soy protein, protecting the largemouth bass liver from oxytetracycline. Furthermore, gene ontology analysis revealed nine key miRNAs that mediate signaling pathways with significant differences. The cellular lipid metabolic process was identified as the most important biological process, and the propanoate metabolism pathway was highlighted as significant. These results will facilitate further exploration of the mechanism by which enzyme-treated soy protein alleviates the effects of oxytetracycline on largemouth bass in water environments.

miR-2765 involved in ammonia nitrogen stress via negative regulation of autophagy in shrimp

MicroRNA (miRNA) is a highly conserved non-coding tiny endogenous RNA molecule that regulates various cellular functions by inhibiting mRNA translation or promoting the degradation of proteins. In this study, we identified a specific miRNA (designed as Pva-miR-2765) from Penaeus vannamei, which widely distributed in different tissues of shrimp, with the highest concentration found in the intestine. Through fluorescence in situ hybridization (FISH), we observed that Pva-miR-2765 is primarily located in the cytoplasm. Interestingly, we found that the expression of Pva-miR-2765 significantly decreased in hemocytes, hepatopancreas and gill under ammonia nitrogen stress. Furthermore, when Pva-miR-2765 was silenced, the autophagy level in shrimp significantly increased. Additionally, Pva-miR-2765 was found to promote pathological damage in the hepatopancreas of shrimp. Subsequently, correlation analysis revealed a negative relationship between the expression of Pva-miR-2765 and PvTBC1D7. To confirm this interaction, we conducted a dual luciferase reporter gene assay, which demonstrated that Pva-miR-2765 inhibit the expression of PvTBC1D7 by interacting with its 3'UTR. And the expression level of PvTBC1D7 in shrimp decreased significantly under ammonia nitrogen stress in Pva-miR-2765 overexpressed. Our findings suggest that Pva-miR-2765 can reduce autophagy in P. vannamei by inhibiting the regulation of PvTBC1D7, thereby participating in the oxidative stress of shrimp caused by ammonia nitrogen stress.

c-Jun N-terminal kinase activation contributes to improving low temperature tolerance via regulating apoptosis in the Pacific white shrimp Penaeus vannamei

Temperature is an essential environmental factor for the survival of aquatic animals. Low temperature stress can induce mitochondria to produce excessive ROS and free radicals, and destroy homeostasis. c-Jun N-terminal kinase (JNK) is involved in regulating various physiological processes, including inflammatory responses, cell cycle, reproduction, and apoptosis. Here, we investigated the mechanism of ROS/JNK pathway under low temperature stress both in vitro and in vivo. In this study, transcriptome analysis revealed that apoptosis, autophagy, calcium channel, and antioxidant were involved in the mediation of low temperature tolerance in Pacific white shrimp (penaeus vannamei). PvJNK was activated in response to low temperature stress. Treatments with different temperature caused oxidative stress as demonstrated by increased intensity of the ROS indicator H2DCF-DA, and induced apoptosis as confirmed by indicator FITC. Pretreatment with N-acetylcysteine, an ROS scavenger, attenuated low temperature induced apoptosis, and inhibited the expression of PvJNK. In addition, we demonstrate that mediator PvJNK translocated to nuclear through interacting with PvRheb. By using flow cytometry, inhibiting PvJNK can increase the expression of apoptosis related genes, accelerate tissue damage, and induce ROS and cell apoptosis. The ultimate inhibition of PvJNK accelerates the mortality of shrimp under low temperature stress. Overall, these findings suggest that during low temperature stress, PvJNK was activated by ROS to regulates apoptosis via interacting with PvRheb to promote PvJNK into the nucleus and to improve low temperature tolerance of shrimp.

PmKuSPI is regulated by pmo-miR-bantam and contributes to hemocyte homeostasis and viral propagation in shrimp

The Kunitz-type serine protease inhibitor (KuSPI) is a low molecular weight protein that plays a role in modulating a range of biological processes. In Penaeus monodon, the PmKuSPI gene has been found to be highly expressed in the white spot syndrome virus (WSSV)-infected shrimp and is predicted to be regulated by a conserved microRNA, pmo-miR-bantam. We reported that, despite being upregulated at the transcriptional level, the PmKuSPI protein was also upregulated after WSSV infection. Silencing the PmKuSPI gene in healthy shrimp had no effect on phenoloxidase activity or apoptosis but resulted in a delay in the mortality of WSSV-infected shrimp as well as a reduction in the total hemocyte number and WSSV copies. According to an in vitro luciferase reporter assay, the pmo-miR-bantam bound to the 3'UTR of the PmKuSPI gene as predicted. In accordance with the loss of function studies using dsRNA-mediated RNA interference, the administration of the pmo-miR-bantam mimic into WSSV-infected shrimp lowered the expression of the PmKuSPI transcript and the PmKuSPI protein, as well as the WSSV copy number. According to these results, the protease inhibitor PmKuSPI is posttranscriptionally controlled by pmo-miR-bantam and plays a role in hemocyte homeostasis, which in turn affects shrimp susceptibility to WSSV infection.