The FEBS journal最新文献

The pro-apoptotic BCL-2-interacting mediator of cell death [BIM; also known as Bcl-2-like protein 11 (BCL2L11)] is a crucial regulator of programmed cell death in immune cells, with roles in T-cell development, homeostasis, and immune response modulation. However, the precise molecular mechanisms that regulate BIM expression in these processes are not completely understood. One possible regulatory mechanism involves microRNAs, small noncoding RNAs that silence target messenger RNAs (mRNAs). The miR-17-92 cluster, which has been implicated in immune regulation, has nine predicted binding sites in the 3' untranslated region of the Bcl2l11 mRNA (thereafter referred to as Bim mRNA). To explore whether direct miR-17-92-mediated regulation of BIM controls apoptosis in T cells, a genetically modified mouse model with disrupted miR-17-92:Bim interactions specifically in T cells has been used. The results revealed that loss of miR-17-92:Bim binding, although leading to a modest increase of BIM protein in double-positive (DP) thymocytes and naïve CD8⁺ T cells, does not measurably affect early T-cell development or peripheral T-cell numbers. However, the absence of this interaction led to a moderate reduction in Th₁₇ CD4⁺ T cells at a steady state. Collectively, these findings suggest that miR-17-92-mediated regulation of BIM does not play major roles in T-cell apoptosis and homeostasis, highlighting the existence of alternative regulatory mechanisms controlling BIM pro-apoptotic activity.

We are delighted to present a selection of original articles, curated by FEBS Junior Section member, Dr Ignazio Restivo. These articles were published in The FEBS Journal in 2024 and 2025, and cover molecular aspects of developmental biology and cell biology, showcasing our advances in disease mechanisms and biotechnology. We invite you to join us in revisiting these gems, and we hope they will help you find scientific inspiration.

The iron-sulfur (Fe-S) cluster assembly homolog 1 (ISCA1) is a ubiquitous protein conserved in various organisms. Previous work has shown that a pigeon ISCA1 (clISCA1) forms columnar oligomers in the 2Fe-2S cluster-bound state, the length of which has been known to change in response to magnetic fields. However, whether this unique property is conserved in ISCA1 proteins of other species, particularly humans (hsISCA1), is unclear. Moreover, a recent study revealed that clISCA1 binds to not only Fe-S clusters but also mononuclear iron atoms, which may impart some magnetic properties to clISCA1. In this study, the electron spin resonance revealed that hsISCA1 also binds to mononuclear iron atoms. Moreover, the magnetic responses of Fe-S cluster-unbound ISCA1s (Fe-ISCA1s), which bind only mononuclear iron atoms, were inspected by small-angle X-ray scattering analyses for pigeon (Fe-clISCA1) and human (Fe-hsISCA1). The results indicated that Fe-hsISCA1 formed columnar oligomers under geomagnetic conditions, whereas Fe-clISCA1 formed dumbbell-like oligomers. When a magnetic field (180 mT) was applied, the Fe-hsISCA1 oligomer was shortened within 1 min and gradually elongated again after 10 min. This result indicates that mononuclear iron atoms contribute to the magnetically induced structural ordering of ISCA1, whereas the contribution of the Fe-S clusters to the columnarization of ISCA1 varies among species. Although the physiological role of the magnetic properties of ISCA1 is not yet elucidated, this study demonstrated that the magnetic field responsiveness of ISCA1 is conserved in humans. The magnetic field responsiveness may be a hidden fundamental property of ISCA1 that is maintained even if the Fe-S cluster is released.

Protein aggregation and transmission are hallmarks of neurodegenerative diseases. Praja1 E3 ubiquitin ligase has been shown to suppress the aggregation of causative proteins in amyotrophic lateral sclerosis, frontotemporal lobar degeneration, Parkinson's disease, Huntington's disease, and spinocerebellar degeneration, which include transactivation response DNA-binding protein of 43 kDa, fused in sarcoma, superoxide dismutase 1, α-synuclein, huntingtin, and ataxin-3. Aoki et al. demonstrated that Praja1 ubiquitinates and degrades tau, a key molecule in tauopathies such as Alzheimer's disease, Pick's disease, progressive supranuclear palsy, and corticobasal syndrome, furthering our understanding of the role of Praja1 in neurodegenerative diseases and potential therapeutic approaches.

Rickets, a disorder of bone formation, was originally known as nutritional rickets due to vitamin D deficiency. Advances in science have since identified various genetic forms, typically involving loss-of-function mutations in vitamin D activation or other mineral metabolism pathways. Recently, type 3 rickets was identified as a previously undescribed gain-of-function mutation in CYP3A4 (Ile301Thr). This mutant enzyme leverages the unique features of cytochrome P450 to produce an inactive vitamin D metabolite, 11α,25(OH)₂D₃, resulting in insufficient active vitamin D. The discovery of this unique gain-of-function aetiology and its associated metabolite opens a significant new direction in rickets research.

Long interspersed element-1 (LINE-1 or L1) is actively jumping in humans, notably in germ cells, neurons, and certain types of cancer. An active L1 is ~6.0 kb in length and encodes two proteins, designated ORF1p and ORF2p. L1 RNA binds with L1-encoded proteins and forms L1-ribonucleoprotein particles (L1-RNPs), the retrotransposition intermediate. Although cells that support L1 retrotransposition express both proteins, the detection of ORF2 protein (ORF2p) is extremely challenging due to its limited expression and unavailability of a suitable antibody. Here, we characterize an anti-ORF2p antibody and show the presence of endogenous L1-ORF2p in multiple cancer cell lines, among which the MCF-7 cell line showed notably high expression. Complexes purified by immunoprecipitation (IP) with anti-ORF2p or anti-ORF1p from MCF-7 or HEK293T cells contain ORF2p and ORF1p and show ORF2p-mediated reverse transcriptase (RT) activity on L1, Alu, and GAPDH RNA templates. The ORF2 IP complex was further purified by size exclusion chromatography (SEC), which showed three major peaks with molecular weights around 796, 427, and 239 kDa. All three peaks showed the presence of L1 proteins, RNA, and ORF2p-mediated RT activity. Although many proteins have been identified that interact with L1 proteins, it is unclear which of these belong to the core L1 RNP. Our novel anti-ORF2p will provide a valuable resource for future studies involving ORF2p IP followed by SEC to identify the protein components of core L1 RNPs. In summary, we report the detection of endogenous L1 ORF2 protein and partial purification of its complex by ORF2p antibody-coupled IP and SEC.

CML is primarily driven by the oncogenic BCR-ABL fusion kinase; however, tyrosine kinase inhibitor (TKI) resistance remains a significant clinical challenge. A study by Zang et al. identified USP8 as a critical mediator of this resistance. USP8, a deubiquitinase, stabilizes the stress-response regulator EIF2S1 (eIF2α) by removing K48-linked ubiquitin chains. This stabilization sustains PERK-EIF2S1-mediated unfolded protein response (UPR) signaling. The UPR suppresses general protein translation while promoting the expression of adaptive stress-response genes, allowing CML cells to survive TKI-induced stress. Consequently, targeting the USP8-EIF2S1 axis is proposed as a key therapeutic strategy to overcome resistance and enhance patient outcomes.

Quinolones are privileged scaffolds for drug discovery that are relatively rare in nature. Here, we characterise two promiscuous fungal polyketide synthases AthePKS and FerePKS, which we had previously found to produce 2-quinolones in vitro. We challenged the enzymes with several substituted anthranilic acid derivatives, revealing their ability to produce precursors of pharmaceutically relevant quinolones. We also discovered that AthePKS and FerePKS accept other 2-substituted benzoic acids, leading to the formation of coumarin and thiocoumarin scaffolds. We applied AthePKS in an artificial enzymatic cascade towards an antimicrobial 4-methoxy-1-methyl-2-quinolone and demonstrated its in vivo feasibility by successfully expressing the pathway in Escherichia coli. Lastly, we determined the crystal structure of AthePKS, suggesting hotspots for enhancing its catalytic efficiency by enzyme engineering. Our results provide a framework for further engineering of enzymatic routes towards privileged heteroaromatic scaffolds and derivatives thereof.

Hemocyanins are multifunctional soluble proteins found in most mollusks and some arthropods that may turn into a phenoloxidase-like enzyme (PO) associated with innate immune functions. To expand the structural understanding of gastropod hemocyanins and their physiological implications, here we report the single-particle cryogenic electron microscopy (cryo-EM) structure of Pomacea canaliculata snail hemocyanin (PcH) at 4.4 Å resolution along with its intrinsic and proteolytically induced PO activity. PcH shows a Megathura crenulata (giant keyhole limpet) hemocyanin (KLH)-type structure with a cylindrical shape, comprising 20 protomers assembled as di-pentamers of antiparallel asymmetric dimers, organized in a D5 symmetry. Each protomer comprises eight paralogous functional units (FUs) sharing conserved structural features typical of hemocyanins. The achieved map resolution allowed delineation of interaction networks among adjacent subunits across quaternary structure tiers-dimer, pentamer of dimers (decamer), and di-pentamer of dimers (di-decamer). Additionally, we identified six N-glycosylation sites per protomer, totaling 120 glycan trees in the overall structure. Kinetic analysis of intrinsic PO activity using catechol as substrate revealed a Michaelis constant (K_M) of 45.3 mm and a catalytic rate constant (k_cat) of 2.87 min^-1. This specific activity was enhanced by limited proteolysis using digestive and bacterial proteases. Potential protease cleavage sites were identified in silico, mapped onto the PcH model, and their accessibility assessed. Combined with molecular dynamics simulations, these findings suggest a structural basis for the PO induction mechanism. This study expands our knowledge of KLH-type hemocyanins and provides clues into their PO activation, which is triggered by endogenous and/or pathogen-associated proteases. This further underscores the role of molluscan hemocyanins in the innate immune system.

Hidden hearing loss (HHL) is an inner ear disorder that is characterized by synaptopathy despite normal hearing thresholds. In HHL mouse models, synaptopathy and decreased wave I amplitude were the key pathological and auditory features. However, the underlying molecular mechanisms of HHL remain unclear. We used gene-knockout mice to investigate the potential mechanisms underlying synaptopathy. The mice displayed pathological and auditory features consistent with HHL following glutamate-aspartate transporter [GLAST; also known as solute carrier family 1 member 3 (SLC1A3), or excitatory amino acid transporter 1] knockout (KO). In KO mice, surface expression of postsynaptic proteins was significantly decreased in the inner ear, and the cytoskeleton, especially intermediate filaments, was impaired. We also observed susceptibility to overt hearing loss in response to aging. Our findings indicate that GLAST KO induces synaptopathy, disrupts intermediate filament organization, and accelerates age-related hearing loss, providing insights into HHL development and its progression to overt hearing loss.