Comparative analysis of two ferritin subunits from blunt snout bream (Megalobrama amblycephala): Characterization, expression, iron depriving and bacteriostatic activity

Possibility and challenge of plant-derived ferritin cages encapsulated polyphenols in the precise nutrition field

Polyphenols have attracted extensive attention due to their rich functional activities, such as antioxidant, anti-inflammatory and anti-tumor. However, the low solubility and poor stability limit their bioavailability and functional activities. Plant-derived ferritin cages have a unique hollow cage structure that can embed polyphenols to improve their unfavorable properties. Therefore, it is essential to adequately elaborate and summarize plant-derived ferritin cages to maximize their potential benefits in nutritional interventions. This review focuses on the fundamental properties of plant-derived ferritin cages, including the preparation process, purification technology, identification methods, and structural and functional properties. The relevant research on ferritin cages in polyphenol delivery has been summarized, including the delivery of water/lipid soluble polyphenols, modification of ferritin cages, and the interaction between polyphenols and ferritin cages. The research progress, shortcomings and prospects of plant-derived ferritin cages in precise nutrition are introduced. In addition, the relevant research on ferritin in immune response and protein engineering is also discussed to provide the theoretical basis for applying plant-derived ferritin cages in many frontier fields.

A novel antimicrobial peptide screened by a Bacillus subtilis expression system, derived from Larimichthys crocea Ferritin H, exerting bactericidal and parasiticidal activities

Antimicrobial peptides (AMPs) may be the most promising substitute for antibiotics due to their effective antimicrobial activities and multiple function mechanisms against pathogenic microorganisms. In this study, a novel AMP containing 51 amino acids, named Lc1687, was screened from the large yellow croaker (Larimichthys crocea) via a B. subtilis system. Bioinformatics and circular dichroism (CD) analyses showed that Lc1687 is a novel anionic amphiphilic α-helical peptide, which was derived from the C-terminal of a Ferritin heavy subunit. The recombinant Lc1687 (named rLc1687) purified from Escherichia coli exhibited strong activities against Gram-positive (Gram+) bacterium Staphylococcus aureus, Gram-negative (Gram-) bacteria Vibrio vulnificus, V. parahaemolyticus, and Scuticociliatida. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) revealed the possible function mechanisms of this peptide, which is to target and disrupt the bacterial cell membranes, including pore-forming, loss of fimbriae, and cytoplasm overflow, whereas gel retardation assay revealed that peptide Lc1687 cannot bind bacterial DNA. The peptide stability analysis showed that rLc1687 acts as a stable antimicrobial agent against Gram+ and Gram- bacteria at temperatures ranging from 25 to 100°C, pH 3-12, and UV radiation time ranging from 15 to 60 min. A hemolytic activity assay confirmed that this peptide may serve as a potential source for clinical medicine development. Taken together, Lc1687 is a novel AMP as it is a firstly confirmed Ferritin fragment with antimicrobial activity. It is also a promising agent for the development of peptide-based antibacterial and anti-parasitic therapy.

Molecular evolution and gene expression of ferritin family involved in immune defense of lampreys

Ferritin, one of the key regulators of iron homeostasis, is widely present throughout almost all species. The vertebrate ferritin family, which originates from a single gene in the ancestral invertebrates, contains the widest variety of ferritin subtypes among all animal species. However, the evolutionary history of the vertebrate ferritin family remains to be further clarified. In this study, genome-wide identification of the ferritin homologs is performed in lampreys, which are the extant representatives of jawless vertebrates that diverged from the future jawed vertebrates more than 500 million years ago. Molecular evolutionary analyses show that four members of the lamprey ferritin family, L-FT1-4, are derived from a common ancestor with jawed vertebrate ferritins prior to the divergence of the jawed vertebrate ferritin subtypes. The lamprey ferritin family shares evolutionarily conserved characteristics of the ferritin H subunit with higher vertebrates, but certain members such as L-FT1 additionally accumulate some features of the M or L subunits. Expression profiling reveals that lamprey ferritins are highly expressed in the liver. The transcription of L-FT1 is significantly induced in the liver and heart during lipopolysaccharide stimulation, indicating that L-FTs may play a role in the innate immune response to bacterial infection in lampreys. Furthermore, the transcriptional expression of L-FT1 in quiescent and LPS-activated leukocytes is up- and down-regulated by the lamprey TGF-β2, an essential regulator of the inflammatory response, respectively. Our results provide new insights into the origin and evolution of the vertebrate ferritin family and reveal that lamprey ferritins may be involved in immune regulation as target genes of the TGF-β signaling pathway.

Therapeutic potential of induced iron depletion using iron chelators in Covid-19

Ferritin, which includes twenty-four light and heavy chains in varying proportions in different tissues, is primarily responsible for maintaining the body's iron metabolism. Its normal value is between 10 and 200 ngmL^-1 in men and between 30 and 300 ngmL^-1 in women. Iron is delivered to the tissue via them, and they act as immunomodulators, signaling molecules, and inflammatory markers. When ferritin level exceeds 1000 µgL^-1, the patient is categorized as having hyperferritinemia. Iron chelators such as deferiprone, deferirox, and deferoxamine are currently FDA approved to treat iron overload. The inflammation cascade and poor prognosis of COVID-19 may be attributed to high ferritin levels. Critically ill patients can benefit from deferasirox, an iron chelator administered orally at 20-40 mgkg^-1 once daily, as well as intravenous deferoxamine at 1000 mg initially followed by 500 mg every 4 to 12 h. It can be combined with monoclonal antibodies, antioxidants, corticosteroids, and lactoferrin to make iron chelation therapy effective for COVID-19 victims. In this article, we analyze the antiviral and antifibrotic activity of iron chelators, thereby promoting iron depletion therapy as a potentially innovative treatment strategy for COVID-19.

A novel ferritin L (FerL) in hybrid crucian carp could participate in host defense against Aeromonas hydrophila infection and diminish inflammatory signals

FerL, a multifunctional iron-storage polypeptide, not only exhibited a regulatory role in iron metabolism, but also participated in the regulation of fish immunity. In this study, ORF sequence of WR-FerL was 522 bp, encoding 173 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-FerL was detected in spleen. A. hydrophila challenge and LPS stimulation could sharply enhance WR-FerL mRNA expression in tissues and fish cells, respectively. Purified WR-FerL fusion peptide exhibited in vitro binding activity to A. hydrophila and endotoxin, limited bacterial dissemination to tissues as well as attenuated A. hydrophila-induced production of pro-inflammatory cytokines. Moreover, WR-FerL overexpression could abrogate NF-κB and TNFα promoter activity in fish cells. These results indicated that WR-FerL could play an important role in host defense against A. hydrophila infection.

Ferritin H can counteract inflammatory response in hybrid fish and its parental species after Aeromonas hydrophila infection

Ferritin H can participate in the regulation of fish immunity. Tissue-specific analysis revealed that the highest expressions of Ferritin H in parental species were observed in spleen, while peaked level of Ferritin H mRNA in hybrid fish was observed in liver. In addition, A. hydrophila challenge could sharply enhance their Ferritin H mRNA expression in liver, kidney and spleen. To further investigate their roles in immune regulation, their Ferritin H fusion proteins were produced in vitro. Ferritin H fusion proteins could exhibit a direct binding activity to A. hydrophila and endotoxin in a dose-dependent manner, restrict dissemination of A. hydrophila to tissues and abrogate inflammatory cascades. Moreover, treatment with Ferritin H fusion proteins could reduce A. hydrophila-induced lipid peroxidation. These results indicated that Ferritin H in hybrid fish elicited a similar immune regulation of A. hydrophila-induced inflammatory signals in comparison with those of its parents.

Integrated analysis of lncRNA and mRNA in liver of Megalobrama amblycephala post Aeromonas hydrophila infection

Background

As non-coding RNA molecules of more than 200 bp in length, long non-coding RNAs (lncRNAs) play a variety of roles in biological processes, including regulating the immune responses to bacterial infections. In recent years, there have been many in-depth studies on mammalian lncRNAs, but the relevant studies in fish are very limited. Meanwhile, since lncRNAs are not conserved among species, it is difficult to apply the existing results directly to unstudied species.

Results

To obtain the information of lncRNAs in Megalobrama amblycephala, one of the most economically important freshwater fish in China, also to better understand the biological significance of lncRNAs in the immunity system, the fish liver at 0, 4, 12, 24, and 72 h post Aeromonas hydrophila infection (hpi) were obtained for lncRNA-sequencing (lncRNA-seq). A total of 14,849 lncRNAs were identified, and 2196 lncRNAs showed significant differences at different time points post A. hydrophila infection. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the target genes of the differentially expressed lncRNAs were enriched in several pathways related to immune such as apoptosis, inflammation, and immune response. Time-specific modules were then identified, using weighted correlation network analysis (WGCNA), and 28 modules significantly correlated with different time point after infection were found. Furthermore, four immune-related genes and six lncRNAs in the time-specific modules were subsequently verified by RT-qPCR.

Conclusions

The above findings reveal the discovery of widespread differentially expressed lncRNAs in the M. amblycephala liver post A. hydrophila infection, suggesting that lncRNAs might participate in the regulation of host response to bacterial infection, enriching the information of lncRNAs in teleost and providing a resources basis for further studies on the immune function of lncRNAs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07969-5.

Chimeric ferritin H in hybrid crucian carp exhibits a similar down-regulation in lipopolysaccharide-induced NF-κB inflammatory signal in comparison with Carassius cuvieri and Carassius auratus red var

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals.

Transferrin Receptor 1-Associated Iron Accumulation and Oxidative Stress Provides a Way for Grass Carp to Fight against Reovirus Infection

Iron is an essential element, closely linked with host immune responses. Nevertheless, the relationship between iron metabolism and virus infection is still unclear in aquatic vertebrates. To address this issue, we employed grass carp (Ctenopharyngodon idella) and its lethal virus, grass carp reovirus (GCRV), a double-strand RNA virus, as models. Our results demonstrate that GCRV infection increases the iron content and alters the expression of iron metabolism-related genes both in vivo and in vitro. Of note, the expression of C. idella transferrin receptor 1 (CiTfR1) rather than transferrin is upregulated upon GCRV infection. To clarify the implications of CiTfR1 upregulation for antiviral immunity, we proved that CiTfR1 was not a helper for GCRV invasion, but instead, it inhibited GCRV infection and promoted cell proliferation by facilitating the accumulation of intracellular labile iron pool (LIP), which increases intracellular oxidative stress. Interestingly, we found that CiTfR1 overexpression inhibited the mRNA expression of C. idella interferon 1 (CiIFN1) and CiIFN3. The present study reveals a novel antiviral defense mechanism in teleost where TfR1 induces the accumulation of LIP, leading to the suppression of virus infection and the proliferation of host cells, indicating that iron can be used as a medicated feed additive for the control of animal viral disease.