Protein and Peptide Letters - Online First
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Irisin Mitigates Myocardial Hypoxia/Reoxygenation Injury by Preserving Mitochondrial Redox Homeostasis via the UCP2-SOD2 Axis
Authors: Yizhen Xu, Huanqing Liu, Shuang Liu, Peng Wu, Rui Wang, You Li, Xiaona Wang, Qiuyu Cao, Lei Duan, Ruobai Qiao, Hao Tang and Zhen WangAvailable online: 02 March 2026More LessIntroductionMitochondrial redox homeostasis is of utmost significance in myocardial ischemia-reperfusion (I/R) injury. Irisin, a myokine, has drawn extensive attention in research regarding the protection against cardiovascular diseases.
MethodsThis study utilized in vitro Hypoxia/Reoxygenation (H/R) models in H9c2 cardiomyocytes to simulate I/R injury. Cells were pretreated with irisin (20 ng/mL) prior to reoxygenation. UCP2 knockdown was achieved via siRNA/shRNA transfection. Cell viability and apoptosis were assessed using CCK-8 and flow cytometry (Annexin V-FITC/PI staining), respectively. Intracellular calcium dynamics were monitored by Fluo-3/AM confocal imaging, while ROS levels were quantified via DCFH-DA flow cytometry. Key oxidative stress markers (LDH, MDA, GSH-Px, and CAT) and protein expression (ASC, NLRP3, SIRT1, UCP2, and SOD2) were evaluated using commercial kits and Western blotting. Protein interactions were analyzed by co-immunoprecipitation, and ubiquitination levels were measured under proteasomal/lysosomal inhibition (MG132/Leupeptin).
ResultsIrisin attenuated H/R injury in cardiomyocytes by suppressing apoptosis, calcium/ROS overload, and NLRP3 activation through a UCP2-dependent pathway. UCP2 knockdown significantly attenuated irisin’s protection and reduced SOD2 protein stability. Mechanistically, UCP2 bound SOD2 and inhibited its ubiquitin-proteasomal degradation.
DiscussionThis study reveals a novel mechanism where irisin enhances mitochondrial redox homeostasis by promoting UCP2’s function, which stabilizes SOD2 against ubiquitin-proteasomal degradation. This UCP2-SOD2 axis attenuates oxidative stress and inhibits NLRP3 inflammasome activation during cardiac injury, offering a promising dual-targeted therapeutic strategy for I/R injury.
ConclusionIrisin protects cardiomyocytes against H/R injury primarily via a novel UCP2-SOD2 axis.
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Proteome-Wide Acetylome Profiling Suggests Extensive Aspirin-Driven Remodeling of Networks Relevant to THP-1 Macrophage Differentiation
Authors: Zi-Hui Ma, Yuan-Qing Pan, Pir Tariq Shah and Li XingAvailable online: 25 February 2026More LessIntroductionAcetylsalicylic Acid (aspirin or ASA) is known to exhibit immunomodulatory effects not only through Cyclooxygenase (COX) inhibition but also through direct protein acetylation. However, its impact on innate immune cell differentiation remains unclear.
Materials and MethodsTo fill this gap, the study used quantitative acetyl-proteomics to track changes in the lysine acetylome during THP-1 monocyte differentiation into macrophages following ASA preconditioning.
ResultsOur results showed that preconditioning of THP-1 macrophages with 300 μg/ml ASA for 3 hours before differentiation induced persistent acetylation changes. We identified 5,199 differentially acetylated sites across 2,678 proteins, with 2,595 sites upregulated and 2,604 downregulated. The sequence analysis revealed a strong preference of ASA for acidic residues like E_K motifs and hydrophobic regions. The subcellular localization analysis showed notable enrichment in the nucleus (1,166 proteins), cytoplasm (850 proteins), and mitochondria (405 proteins), and frequently contained functional domains like PWWP, SET, RhoGEF, and RNA recognition motifs.
DiscussionThe Gene Ontology analysis linked these proteins to cellular metabolism, regulation, and stimulus response, while our KEGG analysis connected them to neurodegeneration, infection, and metabolic pathways. Furthermore, the protein-protein interaction networks further showed coordinated changes in ribosomal, signaling, and chromatin complexes.
ConclusionThe findings show that ASA preconditioning leaves a lasting acetylome signature during macrophage differentiation reprogramming regulatory networks relevant to macrophage differentiation and functional networks via motif-directed acetylation. The results provide a plausible COX-independent model in which structural motif-targeted acetylation may underlie ASA’s immunomodulatory role.
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The Dual Nature of Venom: Transforming Toxins into Therapeutic Peptides
Authors: Chloe Zi En Wong, Wei Hsum Yap, Adeline Yoke Yin Chia and Yin Quan TangAvailable online: 10 February 2026More LessVenom has been extracted from venomous animals since ancient times for use as hunting tools or biological weapons. In the modern era, the focus has shifted toward the biomedical potential of venom, particularly its rich composition of bioactive compounds. Among these, venom peptides are of particular interest due to their potent and selective biological activities. These peptides often constitute a significant portion of crude venom mixtures and have emerged as promising candidates for drug development. The growing body of research in this field has led to the establishment of “venomics,” a discipline that integrates proteomics, transcriptomics, and genomics to comprehensively characterize venom components. Technological advancements, such as high-throughput sequencing, mass spectrometry, and advanced computational tools, have revolutionized venomics, enabling deeper insights into venom composition, function, and evolutionary biology. These innovations have facilitated the discovery of venom-derived peptides with therapeutic applications, including treatments for chronic pain, cancer, cardiovascular diseases, and autoimmune disorders. However, despite these promising developments, challenges remain. These include the complexity of venom mixtures, ethical considerations in venom collection, and difficulties in translating in vitro findings into clinical applications. This review explores the evolution and technological progress of venomics, highlights key therapeutic applications of venom peptides, and discusses current limitations and future prospects in the field.
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Effective Plant-Derived Proteins and Peptides in Leukemia Treatment
Authors: Zahra Moghaddasi, Azam Bolhassani and Elnaz AgiAvailable online: 10 September 2025More LessLeukemia is one of the most prevalent malignancies worldwide that causes the unusual evolution of hematopoietic stem cells. The type of leukemia determines the optimal treatment plan and the patient's survival. However, finding safer and more effective medications and developing novel therapeutic strategies are still the most challenging research topics. Nowadays, over half of the medications used to treat cancer are derived from natural ingredients. Medicinal plants are a reliable natural source of anti-leukemic medications. Plant-derived biologically active compounds, including secondary metabolites, have long been considered extremely valuable for treating various human illnesses. However, the limitations of secondary metabolites have led scientists to seek alternative biologically active compounds. Plant-derived proteins and peptides have recently been explored as potential treatments for various human ailments, showing anti-microbial, anti-oxidant, anti-HIV, anti-cancer, ribosome-inactivating, and neuromodulatory properties. Until now, no review article has documented the biologically active proteins and peptides against leukemia. This review article explores the therapeutic properties of plant-derived proteins and peptides against leukemia.
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Antimicrobial Activity of a Defensin-Rich Fraction from Capsicum chinense Fruits: Insights for Biotechnological Applications against Fungal Infections
Available online: 16 July 2025More LessBackgroundThe increasing resistance of fungal pathogens to conventional antifungal treatments has led to a global rise in fungal infections, affecting human health (Candida spp.) and agricultural productivity (Colletotrichum and Fusarium spp.). Antimicrobial peptides (AMPs), such as defensins, have gained attention for their potential in controlling these infections due to their broad-spectrum activity.
ObjectivesThe aim of this study was to partially purify and characterize the antifungal activity of a defensin-enriched fraction (F3) from Capsicum chinense fruits. Specifically, we sought to evaluate its efficacy against pathogenic fungi and yeasts, and to assess the relative abundance of defensins in the fraction.
MethodsThe F3 fraction was obtained using ion exchange and molecular exclusion chromatography. Reverse-phase chromatography (HPLC) was then employed for further purification. The antifungal activity of F3 was tested against Colletotrichum, Fusarium, and Candida species. Mass spectrometry was used to identify and characterize the defensin (CcDef3) within the fraction. The presence of the defensin relative to other components was inferred from electrophoretic profiles and peptide analysis.
ResultsThe F3 fraction exhibited significant antifungal activity, with growth inhibition of Colletotrichum lindemuthianum of 51% and 60.9% at concentrations of 100 and 200 μg mL-1, respectively. The fraction also inhibited the growth of several Candida species, notably C. nivariensis (93.8%) and C. bracarensis (79.6%) at 100 μg mL-1. Cell viability analysis indicated a fungistatic effect. Fluorescence microscopy assays showed that F3 induced membrane permeabilization in C. parapsilosis and C. lindemuthianum, and increased ROS production in C. pelliculosa and F. solani. The defensin-rich H8 fraction, containing a 6.5 kDa protein (CcDef3), was identified as a major component via mass spectrometry.
DiscussionThe ongoing development of resistance in fungal strains, particularly Candida species, against traditional antibiotics and antifungals has turned into a significant medical concern and has increased the need for new treatment options.
ConclusionThese results suggest that the F3 fraction, particularly the defensin CcDef3, has potential as an antifungal agent for biotechnological and therapeutic applications. However, further studies are needed to quantify the contribution of CcDef3 relative to other components in the fraction and to fully isolate the defensin for in-depth analysis.
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Use of Plant Peptidases for the Production of Therapeutic Peptides
Available online: 11 April 2025More LessPeptidases play crucial roles in numerous physiological processes within living organisms. Therefore, they have been employed in various pharmaceutical applications. Plant peptidases have attracted considerable attention in various areas due to their specificity, stability across a diverse range of pH and temperatures, and safety profile. Here, we have focused on the use of plant peptidases, mostly papain and bromelain, to produce biologically active peptides, which confer various health advantages, including antioxidant, antimicrobial, antihypertensive, analgesic, antidiabetic, and anti-inflammatory effects. We have also discussed the importance of the action mechanism of peptidases for generating bioactive peptides with specific sequences and functions, the ecological and sustainability benefits of plant-derived peptidases compared to animal alternatives, digestive stability and bioavailability of peptides, as well as some obstacles to the commercialization of bioactive peptides and key challenges in peptidase-based industrial applications. Finally, we have examined enzyme immobilization as a viable method to enhance the production of bioactive peptides, offering numerous advantages in both research and industry contexts.
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Plant-derived Cyclotides in Immunomodulation and their Therapeutic Potential
Authors: Reema Mishra, Preeti Agarwal, Anshita Sharma, Meenal Mittal, Pooja Gulati and Aparajita MohantyAvailable online: 18 March 2025More LessThe incidences of immune-related disorders have drastically increased in recent years across the world population. Treatment and management of these diseases, especially autoimmune disorders, are complex and challenging. Available synthetic drugs are not completely effective and also pose serious side effects for the patients. Cyclotides are a class of plant-derived cyclic peptides (28-37 amino acids) with three conserved disulfide linkages establishing a cyclic cystine knot (CCK) motif that makes them very stable biomolecules. Their inherent stability, bioavailability and membrane-penetrating capabilities render them attractive potential pharmacological agents. Studies have demonstrated that cyclotides can either enhance or suppress immune responses, making them versatile candidates for treating various immune-related disorders. Of more than 1000 cyclotides discovered to date, only up to 15 native cyclotides (e.g. kalata B1, pase and caripe cyclotides) have been screened to demonstrate their immunomodulatory activity. Of special significance is the chemically synthesised lysine mutant of kalata B1 viz. [T20K], where preclinical studies have shown promise in the treatment of the autoimmune disorder, multiple sclerosis. In vivo studies in mice models have demonstrated that daily administration of 1mg/day of [T20K] led to a significant decrease in the level of cytokine secretion, lesser demyelination (<1%) and very low inflammatory index (<0.5), in the immunized mice. Moreover, when compared with other immunosuppressive drugs (azathioprine, prednisolone, and cyclosporine A) there was a notable drop in mortality and morbidity in mice administered with [T20K]. The cyclotides, kalata B1 and MCoTI-I have also been used as scaffolds to graft bioactive peptides with immunomodulatory activity. Subsequent in vitro and in vivo studies of these grafted cyclotides have demonstrated their therapeutic ability. Keeping in view the therapeutic potential of cyclotides as immunomodulatory peptides, the present review discusses its current research scenario and implications for the future in tackling immune-related disorders.
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