An in-situ peptide-antibody self-assembly to block CD47 and CD24 signaling enhances macrophage-mediated phagocytosis and anti-tumor immune responses.

Targeted immunomodulation for reactivating innate cells, especially macrophages, holds great promise to complement current adaptive immunotherapy. Nevertheless, there is still a lack of high-performance therapeutics for blocking macrophage phagocytosis checkpoint inhibitors in solid tumors. Herein, a peptide-antibody combo-supramolecular in situ assembled CD47 and CD24 bi-target inhibitor (PAC-SABI) is described, which undergoes biomimetic surface propagation on cancer cell membranes through ligand-receptor binding and enzyme-triggered reactions. By simultaneously blocking CD47 and CD24 signaling, PAC-SABI enhances the phagocytic ability of macrophages in vitro and in vivo, promoting anti-tumor responses in breast and pancreatic cancer mouse models. Moreover, building on the foundation of PAC-SABI-induced macrophage repolarization and increased CD8+ T cell tumor infiltration, sequential anti-PD-1 therapy further suppresses 4T1 tumor progression, prolonging survival rate. The in vivo construction of PAC-SABI-based nano-architectonics provides an efficient platform for bridging innate and adaptive immunity to maximize therapeutic potency.

The antiherpetic and anti-inflammatory activity of the frog-derived peptide Hylin-a1.

AIM: The high incidence of virus-related infections and the large diffusion of drug-resistant pathogens stimulate the search and identification of new antiviral agents with a broad spectrum of action. Antivirals can be designed to act on a single target by interfering with a specific step in the viral lifecycle. On the contrary, antiviral peptides (AVPs) are known for acting on a wide range of viruses, with a diversified mechanism of action targeting virus and/or host cell. In the present study, we evaluated the antiviral potential of the peptide Hylin-a1 secreted by the frog Hypsiobas albopunctatus against members of the Herpesviridae family. METHODS AND RESULTS: The inhibitory capacity of the peptide was evaluated in vitro by plaque assays in order to understand the possible mechanism of action. The results were also confirmed by real-time PCR and Western blot evaluating the expression of viral genes. Hylin-a1 acts to block the herpetic infection interfering at the early stages of both herpes simplex virus type 1 (HSV-1) and type 2 infection. Its mechanism is mainly directed on the membrane, probably by damaging the viral envelope. The same effect was also observed against HSV-1 strains resistant to acyclovir. CONCLUSIONS: The data presented in this study, such as the increased activity of the peptide when combined to acyclovir, a weak hemolytic profile, an anti-inflammatory effect, and a tolerable half-life in serum, indicates Hylin-a1 as a novel antiherpetic molecule with promising potential in the clinical setting.

Multilayered Computational Framework for Designing Peptide Inhibitors of HVEM-LIGHT Interaction.

The herpesvirus entry mediator (HVEM) and its ligand LIGHT play crucial roles in immune system regulation, including T-cell proliferation, B-cell differentiation, and immunoglobulin secretion. However, excessive T-cell activation can lead to chronic inflammation and autoimmune diseases. Thus, inhibiting the HVEM-LIGHT interaction emerges as a promising therapeutic strategy for these conditions and in preventing adverse reactions in organ transplantation. This study focused on designing peptide inhibitors, targeting the HVEM-LIGHT interaction, using molecular dynamics (MD) simulations of 65 peptides derived from HVEM. These peptides varied in length and disulfide-bond configurations, crucial for their interaction with the LIGHT trimer. By simulating 31 HVEM domain variants, including the full-length protein, we assessed conformational changes upon LIGHT binding to understand the influence of HVEM segments and disulfide bonds on the binding mechanism. Employing multitrajectory microsecond-scale, all-atom MD simulations and molecular mechanics with generalized Born and surface area (MM-GBSA) binding energy estimation, we identified promising CRD2 domain variants with high LIGHT affinity. Notably, point mutations in these variants led to a peptide with a single disulfide bond (C58-C73) and a K54E substitution, exhibiting the highest binding affinity. The importance of the CRD2 domain and Cys58-Cys73 disulfide bond for interrupting HVEM-LIGHT interaction was further supported by analyzing truncated CRD2 variants, demonstrating similar binding strengths and mechanisms. Further investigations into the binding mechanism utilized steered MD simulations at various pulling speeds and umbrella sampling to estimate the energy profile of HVEM-based inhibitors with LIGHT. These comprehensive analyses revealed key interactions and different binding mechanisms, highlighting the increased binding affinity of selected peptide variants. Experimental circular dichroism techniques confirmed the structural properties of these variants. This study not only advances our understanding of the molecular basis of HVEM-LIGHT interactions but also provides a foundation for developing novel therapeutic strategies for immune-related disorders. Furthermore, it sets a gold standard for peptide inhibitor design in drug development due to its systematic approach.

Design and synthesis of a nucleobase functionalized peptide hydrogel: in vitro assessment of anti-inflammatory and wound healing effects.

Over the past several years, a significant increase in the expanding field of biomaterial sciences has been observed due to the development of biocompatible materials based on peptide derivatives that have intrinsic therapeutic potential. In this report, we synthesized nucleobase functionalized peptide derivatives (NPs). Hydrogelation in the synthesized NPs was induced by increasing their hydrophobicity with an aromatic moiety. The aggregation behavior of the NPs was analyzed by performing molecular dynamics simulations and DOSY NMR experiments. We performed circular dichroism (CD), thioflavin-T binding and PXRD to characterize the supramolecular aggregation in the NP1 hydrogel. The mechanical strength of the NP1 hydrogel was tested by performing rheological experiments. TEM and SEM experiments were performed to investigate the morphology of the NP1 hydrogel. The biocompatibility of the newly synthesized NP1 hydrogel was investigated using McCoy and A549 cell lines. The hemolytic activity of the NP1 hydrogel was examined in human blood cells. The stability of the newly formed NP1 hydrogel was examined using proteinase K and α-chymotrypsin. The NP1 hydrogel was used for in vitro wound healing. Western blotting, qRT-PCR and DCFDA assay were performed to determine the anti-inflammatory activity of the NP1 hydrogel. The synthesized NP1 hydrogel also exhibits antibacterial efficacy.

High amphipathicity of α-helical peptides enhances unmethylated CpG DNA-induced activation of mouse macrophage-like RAW264.7 cells.

The α-helical antimicrobial peptide Kn2-7 enhances the activation of mouse macrophage-like RAW264.7 induced by DNA containing unmethylated cytosine-guanine motifs (CpG DNA). This enhancement is related to increased cellular uptake of DNA by Kn2-7, but the relevant properties of Kn2-7 are unknown. Physicochemical property analysis revealed that Kn2-7 has high amphipathicity. In contrast, the α-helical antimicrobial peptide L5, which increases the cellular uptake of CpG DNA but does not enhance CpG DNA-induced activation, has low amphipathicity. Kn2-7 derivatives with decreased amphipathicity but the same amino acid composition as Kn2-7 did not enhance CpG DNA-induced activation. On the other hand, L5 derivatives with high amphipathicity but the same amino acid composition as L5 enhanced CpG DNA-induced activation. Cellular uptake of DNA was not increased by the L5 derivatives, indicating that high amphipathicity does not affect DNA uptake. Furthermore, α-helical peptides with reversed sequences relative to the Kn2-7 and L5 derivatives with high amphipathicity were synthesized. The reversed-sequence peptides, which had the same amphipathicity but different amino acid sequences from their counterparts, enhanced CpG DNA-induced activation. Taken together, these observations indicate that the high amphipathicity of α-helical peptides enhances the CpG DNA-induced activation of RAW264.7.

Harmine and exendin-4 combination therapy safely expands human ß cell mass in vivo in a mouse xenograft system.

Five hundred thirty-seven million people globally suffer from diabetes. Insulin-producing ß cells are reduced in number in most people with diabetes, but most individuals still have some residual ß cells. However, none of the many diabetes drugs in common use increases human ß cell numbers. Recently, small molecules that inhibit dual tyrosine-regulated kinase 1A (DYRK1A) have been shown to induce immunohistochemical markers of human ß cell replication, and this is enhanced by drugs that stimulate the glucagon-like peptide 1 (GLP1) receptor (GLP1R) on ß cells. However, it remains to be demonstrated whether these immunohistochemical findings translate into an actual increase in human ß cell numbers in vivo. It is also unknown whether DYRK1A inhibitors together with GLP1R agonists (GLP1RAs) affect human ß cell survival. Here, using an optimized immunolabeling-enabled three-dimensional imaging of solvent-cleared organs (iDISCO+) protocol in mouse kidneys bearing human islet grafts, we demonstrate that combination of a DYRK1A inhibitor with exendin-4 increases actual human ß cell mass in vivo by a mean of four- to sevenfold in diabetic and nondiabetic mice over 3 months and reverses diabetes, without alteration in human α cell mass. The augmentation in human ß cell mass occurred through mechanisms that included enhanced human ß cell proliferation, function, and survival. The increase in human ß cell survival was mediated, in part, by the islet prohormone VGF. Together, these findings demonstrate the therapeutic potential and favorable preclinical safety profile of the DYRK1A inhibitor-GLP1RA combination for diabetes treatment.

Discovery of a peptide proteolysis-targeting chimera (PROTAC) drug of p300 for prostate cancer therapy.

BACKGROUND: The E1A-associated protein p300 (p300) has emerged as a promising target for cancer therapy due to its crucial role in promoting oncogenic signaling pathways in various cancers, including prostate cancer. This need is particularly significant in prostate cancer. While androgen deprivation therapy (ADT) has demonstrated promising efficacy in prostate cancer, its long-term use can eventually lead to the development of castration-resistant prostate cancer (CRPC) and neuroendocrine prostate cancer (NEPC). Notably, p300 has been identified as an important co-activator of the androgen receptor (AR), highlighting its significance in prostate cancer progression. Moreover, recent studies have revealed the involvement of p300 in AR-independent oncogenes associated with NEPC. Therefore, the blockade of p300 may emerge as an effective therapeutic strategy to address the challenges posed by both CRPC and NEPC. METHODS: We employed AI-assisted design to develop a peptide-based PROTAC (proteolysis-targeting chimera) drug that targets p300, effectively degrading p300 in vitro and in vivo utilizing nano-selenium as a peptide drug delivery system. FINDINGS: Our p300-targeting peptide PROTAC drug demonstrated effective p300 degradation and cancer cell-killing capabilities in both CRPC, AR-negative, and NEPC cells. This study demonstrated the efficacy of a p300-targeting drug in NEPC cells. In both AR-positive and AR-negative mouse models, the p300 PROTAC drug showed potent p300 degradation and tumor suppression. INTERPRETATION: The design of peptide PROTAC drug targeting p300 is feasible and represents an efficient therapeutic strategy for CRPC, AR-negative prostate cancer, and NEPC. FUNDING: The funding details can be found in the Acknowledgements section.

Enhancing Dental Pulp Stem Cell Proliferation and Odontogenic Differentiation with Protein Phosphatase 1-Disrupting Peptide: An In Vitro Study.

The reparative and regenerative capabilities of dental pulp stem cells (DPSCs) are crucial for responding to pulp injuries, with protein phosphatase 1 (PP1) playing a significant role in regulating cellular functions pertinent to tissue healing. Accordingly, this study aimed to explore the effects of a novel cell-penetrating peptide Modified Sperm Stop 1-MSS1, that disrupts PP1, on the proliferation and odontogenic differentiation of DPSCs. Employing MSS1 as a bioportide, DPSCs were cultured and characterized for metabolic activity, cell proliferation, and cell morphology alongside the odontogenic differentiation through gene expression and alkaline phosphatase (ALP) activity analysis. MSS1 exposure induced early DPSC proliferation, upregulated genes related to odontogenic differentiation, and increased ALP activity. Markers associated with early differentiation events were induced at early culture time points and those associated with matrix mineralization were upregulated at mid-culture stages. This investigation is the first to document the potential of a PP1-disrupting bioportide in modulating DPSC functionality, suggesting a promising avenue for enhancing dental tissue regeneration and repair.

The Use of Hexokinase 2-Displacing Peptides as an Anti-Neoplastic Approach for Malignant Peripheral Nerve Sheath Tumors.

Malignant Peripheral Nerve Sheath Tumors (MPNSTs) are aggressive sarcomas that can arise both sporadically and in patients with the genetic syndrome Neurofibromatosis type 1 (NF1). Prognosis is dismal, as large dimensions, risk of relapse, and anatomical localization make surgery poorly effective, and no therapy is known. Hence, the identification of MPNST molecular features that could be hit in an efficient and selective way is mandatory to envision treatment options. Here, we find that MPNSTs express high levels of the glycolytic enzyme Hexokinase 2 (HK2), which is known to shield cancer cells from noxious stimuli when it localizes at MAMs (mitochondria-associated membranes), contact sites between mitochondria and endoplasmic reticulum. A HK2-targeting peptide that dislodges HK2 from MAMs rapidly induces a massive death of MPNST cells. After identifying different matrix metalloproteases (MMPs) expressed in the MPNST microenvironment, we have designed HK2-targeting peptide variants that harbor cleavage sites for these MMPs, making such peptides activatable in the proximity of cancer cells. We find that the peptide carrying the MMP2/9 cleavage site is the most effective, both in inhibiting the in vitro tumorigenicity of MPNST cells and in hampering their growth in mice. Our data indicate that detaching HK2 from MAMs could pave the way for a novel anti-MPNST therapeutic strategy, which could be flexibly adapted to the protease expression features of the tumor microenvironment.

Biological Activity of Natural and Synthetic Peptides as Anticancer Agents.

Cancer is one of the leading causes of morbidity and death worldwide, making it a serious global health concern. Chemotherapy, radiotherapy, and surgical treatment are the most used conventional therapeutic approaches, although they show several side effects that limit their effectiveness. For these reasons, the discovery of new effective alternative therapies still represents an enormous challenge for the treatment of tumour diseases. Recently, anticancer peptides (ACPs) have gained attention for cancer diagnosis and treatment. ACPs are small bioactive molecules which selectively induce cancer cell death through a variety of mechanisms such as apoptosis, membrane disruption, DNA damage, immunomodulation, as well as inhibition of angiogenesis, cell survival, and proliferation pathways. ACPs can also be employed for the targeted delivery of drugs into cancer cells. With over 1000 clinical trials using ACPs, their potential for application in cancer therapy seems promising. Peptides can also be utilized in conjunction with imaging agents and molecular imaging methods, such as MRI, PET, CT, and NIR, improving the detection and the classification of cancer, and monitoring the treatment response. In this review we will provide an overview of the biological activity of some natural and synthetic peptides for the treatment of the most common and malignant tumours affecting people around the world.

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship.

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Inhibition of ACE2-S Protein Interaction by a Short Functional Peptide with a Boomerang Structure.

Considering the high evolutionary rate and great harmfulness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is imperative to develop new pharmacological antagonists. Human angiotensin-converting enzyme-2 (ACE2) functions as a primary receptor for the spike protein (S protein) of SARS-CoV-2. Thus, a novel functional peptide, KYPAY (K5), with a boomerang structure, was developed to inhibit the interaction between ACE2 and the S protein by attaching to the ACE2 ligand-binding domain (LBD). The inhibition property of K5 was evaluated via molecular simulations, cell experiments, and adsorption kinetics analysis. The molecular simulations showed that K5 had a high affinity for ACE2 but a low affinity for the cell membrane. The umbrella sampling (US) simulations revealed a significant enhancement in the binding potential of this functional peptide to ACE2. The fluorescence microscopy and cytotoxicity experiments showed that K5 effectively prevented the interaction between ACE2 and the S protein without causing any noticeable harm to cells. Further flow cytometry research indicated that K5 successfully hindered the interaction between ACE2 and the S protein, resulting in 78% inhibition at a concentration of 100 µM. This work offers an innovative perspective on the development of functional peptides for the prevention and therapy of SARS-CoV-2.

Human Milk Protein-Derived Bioactive Peptides from In Vitro-Digested Colostrum Exert Antimicrobial Activities against Common Neonatal Pathogens.

Human milk reduces risk for necrotizing enterocolitis in preterm infants. Necrotizing enterocolitis occurs in the ileocecal region where thousands of milk protein-derived peptides have been released from digestion. Digestion-released peptides may exert bioactivity, such as antimicrobial and immunomodulatory activities, in the gut. In this study, we applied mass spectrometry-based peptidomics to characterize peptides present in colostrum before and after in vitro digestion. Sequence-based computational modeling was applied to predict peptides with antimicrobial activity. We identified more peptides in undigested samples, yet the abundances were much higher in the digested samples. Heatmapping demonstrated highly different peptide profiles between undigested and digested samples. Four peptides (αS1-casein [157-163], αS1-casein [157-165], ß-casein [153-159] and plasminogen [591-597]) were selected, synthesized and tested against common pathogenic bacteria associated with necrotizing enterocolitis. All four exhibited bacteriostatic, though not bactericidal, activities against Klebsiella aerogenes, Citrobacter freundii and Serratia marcescens, but not Escherichia coli.

Screening of the Skin-Regenerative Potential of Antimicrobial Peptides: Clavanin A, Clavanin-MO, and Mastoparan-MO.

Skin wound healing is coordinated by a delicate balance between proinflammatory and anti-inflammatory responses, which can be affected by opportunistic pathogens and metabolic or vascular diseases. Several antimicrobial peptides (AMPs) possess immunomodulatory properties, suggesting their potential to support skin wound healing. Here, we evaluated the proregenerative activity of three recently described AMPs (Clavanin A, Clavanin-MO, and Mastoparan-MO). Human primary dermal fibroblasts (hFibs) were used to determine peptide toxicity and their capacity to induce cell proliferation and migration. Furthermore, mRNA analysis was used to investigate the modulation of genes associated with skin regeneration. Subsequently, the regenerative potential of the peptides was further confirmed using an ex vivo organotypic model of human skin (hOSEC)-based lesion. Our results indicate that the three molecules evaluated in this study have regenerative potential at nontoxic doses (i.e., 200 µM for Clavanin-A and Clavanin-MO, and 6.25 µM for Mastoparan-MO). At these concentrations, all peptides promoted the proliferation and migration of hFibs during in vitro assays. Such processes were accompanied by gene expression signatures related to skin regenerative processes, including significantly higher KI67, HAS2 and CXCR4 mRNA levels induced by Clavanin A and Mastoparan-MO. Such findings translated into significantly accelerated wound healing promoted by both Clavanin A and Mastoparan-MO in hOSEC-based lesions. Overall, the data demonstrate the proregenerative properties of these peptides using human experimental skin models, with Mastoparan-MO and Clavanin A showing much greater potential for inducing wound healing compared to Clavanin-MO.

Integrating In Silico and In Vitro Approaches to Identify Natural Peptides with Selective Cytotoxicity against Cancer Cells.

Anticancer peptides (ACPs) are bioactive compounds known for their selective cytotoxicity against tumor cells via various mechanisms. Recent studies have demonstrated that in silico machine learning methods are effective in predicting peptides with anticancer activity. In this study, we collected and analyzed over a thousand experimentally verified ACPs, specifically targeting peptides derived from natural sources. We developed a precise prediction model based on their sequence and structural features, and the model's evaluation results suggest its strong predictive ability for anticancer activity. To enhance reliability, we integrated the results of this model with those from other available methods. In total, we identified 176 potential ACPs, some of which were synthesized and further evaluated using the MTT colorimetric assay. All of these putative ACPs exhibited significant anticancer effects and selective cytotoxicity against specific tumor cells. In summary, we present a strategy for identifying and characterizing natural peptides with selective cytotoxicity against cancer cells, which could serve as novel therapeutic agents. Our prediction model can effectively screen new molecules for potential anticancer activity, and the results from in vitro experiments provide compelling evidence of the candidates' anticancer effects and selective cytotoxicity.

Differential potassium channel inhibitory activities of a novel thermostable degradation peptide BmKcug1a-P1 from scorpion medicinal material and its N-terminal truncated/restored peptides.

Thermally stable full-length scorpion toxin peptides and partially degraded peptides with complete disulfide bond pairing are valuable natural peptide resources in traditional Chinese scorpion medicinal material. However, their pharmacological activities are largely unknown. This study discovered BmKcug1a-P1, a novel N-terminal degraded peptide, in this medicinal material. BmKcug1a-P1 inhibited hKv1.2 and hKv1.3 potassium channels with IC50 values of 2.12 ± 0.27 µM and 1.54 ± 0.28 µM, respectively. To investigate the influence of N-terminal amino acid loss on the potassium channel inhibiting activities, three analogs (i.e., full-length BmKcug1a, BmKcug1a-P1-D2 and BmKcug1a-P1-D4) of BmKcug1a-P1 were prepared, and their potassium channel inhibiting activities on hKv1.3 channel were verified by whole-cell patch clamp technique. Interestingly, the potassium channel inhibiting activity of full-length BmKcug1a on the hKv1.3 channel was significantly improved compared to its N-terminal degraded form (BmKcug1a-P1), while the activities of two truncated analogs (i.e., BmKcug1a-P1-D2 and BmKcug1a-P1-D4) were similar to that of BmKcug1a-P1. Extensive alanine-scanning experiments identified the bonding interface (including two key functional residues, Asn30 and Arg34) of BmKcug1a-P1. Structural and functional dissection further elucidated whether N-terminal residues of the peptide are located at the bonding interface is important in determining whether the N-terminus significantly influences the potassium channel inhibiting activity of the peptide. Altogether, this research identified a novel N-terminal degraded active peptide, BmKcug1a-P1, from traditional Chinese scorpion medicinal material and elucidated how the N-terminus of peptides influences their potassium channel inhibiting activity, contributing to the functional identification and molecular truncation optimization of full-length and degraded peptides from traditional Chinese scorpion medicinal material Buthus martensii Karsch.

Effect of Short Peptides of Pregnancy-Specific ß1-Glycoprotein on Differentiation of Human Regulatory T Cells In Vitro and on Their Cytokine Profile.

Pregnancy-specific ß1-glycoprotein (PSG), one of the most important proteins of pregnancy, has a pronounced immunosuppressive effect. Short peptides of PSG, the so-called SLiMs (short linear motifs), are promising molecules for mild immunosuppression. We studied in vitro effect of short PSG peptides (YACS, YQCE, YVCS, and YECE) on differentiation and cytokine profile of human T-regulatory lymphocytes (Treg). T helpers isolated from the peripheral blood and polarized into the Treg phenotype with a T-cell activator (anti-CD2/3/28) and the cytokines IL-2 and transforming grown factor ß (TGFß) were used. PSG peptides were shown to have no direct modulatory effect on Treg differentiation in a culture of CD4+ cells polarized to the Treg phenotype. At the same time, PSG peptides had no effect on the viability and number of CD4+ cells in the in vitro culture. PSG peptides also had no effect on the levels of TNFα, IL-8, IL-2, macrophage inflammatory protein 1ß, IL-17, IL-10, IL-6, granulocyte-macrophage CSF, monocyte chemoattractant protein 1, IL-13, IL-5, IL-7, IL-12(p70), IL-1ß, granulocyte CSF, IL-4, but decreased IFNγ levels. The observed ability of the YQCE peptide to reduce the production of this proinflammatory Th1 cytokine by T helper cells can be interpreted as a positive effect. Our findings can be used for further development of safe peptide drugs based on SLiMs sequences.

Harnessing the Therapeutic Potential of Peptides for Synergistic Treatment of Alzheimer's Disease by Targeting Aß Aggregation, Metal-Mediated Aß Aggregation, Cholinesterase, Tau Degradation, and Oxidative Stress.

Alzheimer's disease (AD) is a progressive multifaceted neurodegenerative disease and remains a formidable global health challenge. The current medication for AD gives symptomatic relief and, thus, urges us to look for alternative disease-modifying therapies based on a multitarget directed approach. Looking at the remarkable progress made in peptide drug development in the last decade and the benefits associated with peptides, they offer valuable chemotypes [multitarget directed ligands (MTDLs)] as AD therapeutics. This review recapitulates the current developments made in harnessing peptides as MTDLs in combating AD by targeting multiple key pathways involved in the disease's progression. The peptides hold immense potential and represent a convincing avenue in the pursuit of novel AD therapeutics. While hurdles remain, ongoing research offers hope that peptides may eventually provide a multifaceted approach to combat AD.

Investigation of the Effect of Peptide p5 Targeting CDK5-p25 Hyperactivity on Munc18-1 (P67) Regulating Neuronal Exocytosis Using Molecular Simulations.

Munc18-1 is an SM (sec1/munc-like) family protein involved in vesicle fusion and neuronal exocytosis. Munc18-1 is known to regulate the exocytosis process by binding with closed- and open-state conformations of Syntaxin1, a protein belonging to the SNARE family established to be central to the exocytosis process. Our previous work studied peptide p5 as a promising drug candidate for CDK5-p25 complex, an Alzheimer's disease (AD) pathological target. Experimental in vivo and in vitro studies suggest that Munc18-1 promotes p5 to selectively inhibit the CDK5-p25 complex without affecting the endogenous CDK5 activity, a characteristic of remarkable therapeutic implications. In this paper, we identify several binding modes of p5 with Munc18-1 that could potentially affect the Munc18-1 binding with SNARE proteins and lead to off-target effects on neuronal communication using molecular dynamics simulations. Recent studies indicate that disruption of Munc18-1 function not only disrupts neurotransmitter release but also results in neurodegeneration, exhibiting clinical resemblance to other neurodegenerative conditions such as AD, causing diagnostic and treatment challenges. We characterize such interactions between p5 and Munc18-1, define the corresponding pharmacophores, and provide guidance for the in vitro validation of our findings to improve therapeutic efficacy and safety of p5.