Role of miR-451 in mediating cadmium induced head kidney injury in common carp via targeting cacna1ab through autophagy pathways

Environmental endocrine disrupting chemical 4-tert-butylphenol induced calcium overload and subsequent autophagy impairment via miRNA-363/CACNA1D Axis in epithelioma papulosum cyprini cells

Environmental endocrine disrupting chemical 4-tert-butylphenol (4-tBP), a widely-utilized surfactant in various industries, poses potential risks to aquatic organisms. Our previous sequencing results suggested that 4-tBP-induced common carp liver injury might be associated with Ca2+ signaling and autophagy. However, the intricate involvement of these pathways in 4-tBP-induced cytotoxic mechanisms remained unexplored. To bridge these knowledge gaps, this study focused on epithelioma papulosum cyprini (EPC) cells, a significant cell type in fish biology. Initial observations showed that 4-tBP induced a dose-dependent perturbation in Ca2+ levels. Further investigations, with siRNA and L-type Ca2+ channel agonist (BAYK8644), identified L-type calcium channel gene CACNA1D as a critical regulator of 4-tBP-induced Ca2+ overload. Predictive analysis using miRanda platform suggested a potential interaction between miR-363 and CACNA1D, which was subsequently verified through dual-luciferase reporter gene assays. We then established miR-363 mimic/inhibitor models, along with miR-363 and CACNA1D co-suppression models in EPC cells. Through TEM observation, immunofluorescence assay, Ca2+ staining, and qRT-PCR analysis, we evaluated the role of miR-363/CACNA1D axis in modulating the effects of 4-tBP on Ca2+ signaling and autophagy. Results showed that miR-363 inhibitor exacerbated 4-tBP-induced increase in CALM2, CAMKII, Calpain2, and p62 expression and also led to decrease in ATG5, ATG7, and LC3b expression. In contrast, miR-363 mimic notably alleviated these changes. Notably, siRNA CACNA1D effectively modulating miR-363 inhibitor's effect. Our study revealed that 4-tBP induced Ca2+ overload and subsequent autophagy impairment via miR-363/CACNA1D axis. These findings illuminated a profound understanding of molecular mechanisms underlying 4-tBP-induced cytotoxicity and spotlighted a potential therapeutic target.

miR-22a targets p62/SQSTM1 to negatively affect autophagy and disease resistance of grass carp (Ctenopharyngodon idella)

MicroRNAs (miRNAs) are integral to many biological functions, including autophagy, a process recently proven to be closely linked to innate immunity. In this study, we present findings on miR-22a, a teleost homolog of mammalian miR-22, illustrating its capacity to target the autophagy adaptor p62, subsequently inducing downregulation at both mRNA and protein levels. Utilizing Western blot analyses, we demonstrated that miR-22a inhibits the autophagy flux of CIK cells, correlated with an elevated presence of LC3 II. Additionally, the overexpression of miR-22a resulted in the suppression of NF-κB signaling, leading to reduced cellar antimicrobial abilities and increased apoptosis. These findings provide novel insights into the role of miR-22a as an autophagy-related miRNA and its immune mechanisms against pathogens via p62 in teleost, enriching our understanding of the interplay between autophagy and innate immunity.

Cadmium exposure caused cardiotoxicity in common carps (Cyprinus carpio L.): miR-9-5p, oxidative stress, energetic impairment, mitochondrial division/fusion imbalance, inflammation, and autophagy

Cadmium (Cd), a toxic heavy metal pollutant, is a threat to human and eatable fish health. Common carps are widely cultivated and eaten by humans. However, there are no reports about Cd-damaged common carp hearts. Our experiment attempted to investigate the cardiotoxicity of Cd to common carps by establishing a common carp Cd exposure model. Our results showed that Cd injured hearts. Moreover, Cd treatment induced autophagy via miR-9-5p/Sirt1/mTOR/ULK1 pathway. Cd exposure caused oxidant/antioxidant imbalance and oxidative stress; and led to energetic impairment. Energetic impairment partook in oxidative stress-mediated autophagy through AMPK/mTOR/ULK1 pathway. Furthermore, Cd caused mitochondrial division/fusion imbalance and resulted in inflammatory injury via NF-κB-COX-2-PTGEs and NF-κB-COX-2-TNF-α pathways. Oxidative stress mediated mitochondrial division/fusion imbalance, further induced inflammation and autophagy via OPA1/NF-κB-COX-2-TNF-α-Beclin1 and OPA1/NF-κB-COX-2-TNF-α/P62 pathways under Cd treatment. Taken together, miR-9-5p, oxidative stress, energetic impairment, mitochondrial division/fusion imbalance, inflammation, and autophagy participated in the mechanism of Cd-cardiotoxicity to common carps. Our study revealed harmful effect of Cd on hearts, and provided new information for researches of environmental pollutant toxicity.

Co-exposure to molybdenum and cadmium triggers pyroptosis and autophagy by PI3K/AKT axis in duck spleens

Excessive amounts of molybdenum (Mo) and cadmium (Cd) are toxicant, but their combined immunotoxicity are not clearly understood. To estimate united impacts of Mo and Cd on pyroptosis and autophagy by PI3K/AKT axis in duck spleens, Mo or/and Cd subchronic toxicity models of ducks were established by feeding diets with different dosages of Mo or/and Cd. Data show that Mo or/and Cd cause oxidative stress by increasing MDA concentration, and decreasing T-AOC, CAT, GSH-Px and T-SOD activities, restrain PI3K/AKT axis by decreasing PI3K, AKT, p-AKT expression levels, which evokes pyroptosis and autophagy by elevating IL-1β, IL-18 concentrations and NLRP3, Caspase-1, ASC, GSDME, GSDMA, NEK7, IL-1β, IL-18 expression levels, promoting autophagosomes, LC3 puncta, Atg5, LC3A, LC3B, LC3II/LC3I and Beclin-1 expression levels, and reducing expression levels of P62 and Dynein. Furthermore, the variations of abovementioned indexes are most pronounced in co-treated group. Overall, results reveal that Mo or/and Cd may evoke pyroptosis and autophagy by PI3K/AKT axis in duck spleens. The association of Mo and Cd exacerbates the changes.

Profiling miRNAs of Teleost Fish in Responses to Environmental Stress: A Review

miRNAs are a class of endogenous and evolutionarily conserved noncoding short RNA molecules that post-transcriptionally regulate gene expression through sequence-specific interactions with mRNAs and are capable of controlling gene expression by binding to miRNA targets and interfering with the final protein output. The miRNAs of teleost were firstly reported in zebrafish development, but there are recent studies on the characteristics and functions of miRNAs in fish, especially when compared with mammals. Environmental factors including salinity, oxygen concentration, temperature, feed, pH, environmental chemicals and seawater metal elements may affect the transcriptional and posttranscriptional regulators of miRNAs, contributing to nearly all biological processes. The survival of aquatic fish is constantly challenged by the changes in these environmental factors. Environmental factors can influence miRNA expression, the functions of miRNAs and their target mRNAs. Progress of available information is reported on the environmental effects of the identified miRNAs, miRNA targets and the use of miRNAs in fish.

Melatonin administration alleviates 2,2,4,4-tetra-brominated diphenyl ether (PBDE-47)-induced necroptosis and secretion of inflammatory factors via miR-140-5p/TLR4/NF-κB axis in fish kidney cells

2,2,4,4-tetra-brominated diphenyl ether (PBDE-47)-the dominant homologue of polybrominated diphenyl ethers-is a toxic environmental pollutant in the aquatic environment that continuously exists and bioaccumulates in the aquatic food chain. In experimental disease models, melatonin (MEL) has been reported to attenuate necroptosis and inflammatory responses. To further explore the mechanism underlying PBDE-47 toxicity and the mitigative impact of MEL detoxification, in this study, fish kidney cell models of PBDE-47 poisoning and/or MEL treatment were developed. The Ctenopharyngodon idellus kidney (CIK) cell line was treated with PBDE-47 (100 μM) and/or MEL (60 μM) for 24 h. Experimental data suggest that PBDE-47 exposure resulted in the enhancement of cytoplasmic Ca²⁺ concentration, induction of calcium dysmetabolism, decrease in the miR-140-5p miRNA level, upregulation of Toll-like Receptor 4 (TLR4) and nuclear factor-kappaB (NF-κB), triggering of receptor interacting serine/threonine kinase-induced necroptosis, and NF-κB pathway mediated secretion of inflammatory factors in CIK cells. PBDE-47-induced CIK cell damage could be mitigated by MEL through the regulation of calcium channels and the restoration of disorders of the miR-140-5p/TLR4/NF-κB axis. Overall, MEL relieved PBDE-47-induced necroptosis and the secretion of inflammatory factors through the miR-140-5p/TLR4/NF-κB axis. These findings enrich the current understanding of the toxicological molecular mechanisms of the PBDE-47 as well as the detoxification mechanisms of the MEL.