Protein and Peptide Letters最新文献

Background: Aloperine (ALO) is a vital alkaloid present in the traditional Chinese herb Sophora alopecuroides, which has demonstrated effective anti-inflammatory activity. However, the effects and the mechanism of action of ALO on cisplatin (CDDP)-induced nephrotoxicity remain unclear.

Objective: This study aimed to investigate the effects of ALO on CDDP-induced nephrotoxicity and its potential mechanism of action in vitro.

Methods: Cell viability, lactate dehydrogenase cytotoxicity, apoptosis, activity of Caspase-Glo 3/7 and 1, in-cell western blotting, immunohistochemical staining, and enzyme-linked immunosorbent assay (ELISA) were performed to assess the influence of ALO on CDDP-treated kidney cells. Inhibitors of phosphatidylinositol 3-kinase (PI3K, LY294002), protein kinase B (Akt, AKT inhibitor VIII), and nuclear factor kappa B (NFκB, BAY 11-7082) were used to determine their potential mechanisms of action.

Results: The results indicated that ALO significantly reversed the inhibition of cell viability, cytotoxicity, apoptosis, and the release of inflammatory factors induced by CDDP in kidney cells. ALO attenuated the PI3K/AKT/NFκB-mediated pathway activated by CDDP treatment and downregulated the CDDP-induced nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome. Furthermore, the PI3K and AKT inhibitors diminished the effects of ALO on CDDP-treated kidney cells. Additionally, NFκB inhibitors reversed the effects of the PI3K and AKT inhibitors on ALO in CDDP-treated kidney cells.

Conclusion: These results suggest that ALO protects against CDDP-induced injury in kidney cells by modulating the PI3K/AKT/NFκB-mediated NLRP3 inflammasome.

Introduction: Endometrial carcinoma (EC) incidence and mortality continue to rise, and reliable therapeutic targets remain scarce. We aimed to define the oncogenic role and mechanism of tumor protein D52 (TPD52) in EC, focusing on epithelial-mesenchymal transition (EMT) and the PI3K/AKT and ERK/MAPK signaling pathways.

Methods: In this study, we assessed the expression levels of TPD52 in EC tissues and benign endometrial tissues using immunohistochemistry. To further investigate the role of TPD52, we performed experiments both in vitro and in vivo. We transfected siRNA and overexpression (OE) plasmids into Ishikawa and HEC-1-A cell lines to knock down (KD) or overexpress TPD52, respectively. We observed the effects of TPD52 knockdown on tumor growth and EMT through in vitro experiments.

Results: TPD52 was significantly upregulated in EC tissues compared with those of benign endometrial tissues. Silencing TPD52 significantly inhibited cell proliferation, migration, and invasion, whereas TPD52 overexpression produced the opposite effects. TPD52 facilitates epithelial-mesenchymal transition (EMT). Moreover, TPD52 stimulates the PI3K/AKT and ERK/MAPK signaling pathways.

Discussion: These data position TPD52 as a bona fide EC oncoprotein that drives EMT via dual PI3K/AKT-ERK/MAPK signaling. Limitations include the modest patient cohort and the lack of clinical-pathological correlation analyses.

Conclusion: TPD52 promotes EC progression through EMT and PI3K/AKT and ERK/MAPK activation, offering a promising therapeutic target whose clinical utility warrants further investigation.

Scorpion venom compounds are known to contain nucleotides, polypeptides, mucoproteins, lipids, biogenic amines, and other unidentified macromolecules. Several peptides in scorpion fluids have demonstrated a wide range of biological activities with strong specificity for their targeted sites. Margatoxin, isolated from the venom of the scorpion, exhibits desirable properties, including high selectivity, good permeability, and stability in cancer cells, which can be achieved at picomolar doses, thereby blocking voltage-gated K⁺ channels. This narrative review consolidates results from an extensive literature search conducted in major electronic databases up to September 2024. Important studies were identified using keywords associated with scorpion venom peptides, Kv1.3 channels, cancer treatment, and neurodegenerative disorders. The amino acids that make up Margatoxin have an effective molecular function in blocking voltage-gated K⁺ channels 1.3. Due to the abnormally high expression of voltage-gated K⁺ channel 1.3 in various types of cancers, blockers of this channel can inhibit apoptosis, metabolic changes, tumor angiogenesis, invasion, and migration. On the other hand, these channel blockers have emerged as a promising therapeutic approach for neurological disorders, such as Alzheimer's and Parkinson's diseases. The strong efficacy and targeted action of margatoxin further position it as a promising drug candidate. As the number of individuals affected by cancer and neurological conditions continues to rise, research into scorpion venom peptides like margatoxin may lead to innovative therapeutic options for future treatments.

With the emergence of the precision medicine era, targeting specific proteins has emerged as a pivotal breakthrough in tumor diagnosis and treatment. Apurinic/apyrimidinic Endonuclease 1 (APE1) is a multifunctional protein that plays a crucial role in DNA repair and cellular redox regulation. This article comprehensively explores the fundamental mechanisms of APE1 as a multifunctional enzyme in biology, with particular emphasis on its potential significance in disease diagnosis and strategies for tumor treatment. Firstly, this article meticulously analyzes the intricate biological functions of APE1 at a molecular level, establishing a solid theoretical foundation for subsequent research endeavors. In terms of diagnostic applications, the presence of APE1 can be detected in patient serum samples, biopsy tissues, and through cellular in situ testing. The precise detection methods enable changes in APE1 levels to serve as reliable biomarkers for predicting tumor occurrence, progression, and patient prognosis. Moreover, this article focuses on elucidating the potential role of APE1 in tumor treatment by exploring various inhibitors, including nucleic acid-based inhibitors and small molecule drug inhibitors categories, and revealing their unique advantages in disrupting DNA repair function and modulating oxidative-reduction activity. Finally, the article provides an outlook on future research directions for APE1 while acknowledging major technical difficulties and clinical challenges that need to be overcome despite its immense potential as a target for tumor therapy.

Introduction: Gastric cancer has emerged as one of the major diseases threatening human health. Our previous studies indicated that the anti-cancer bioactive peptide (ACBP) inhibits the initiation and progression of gastric cancer through apoptosis and cell cycle arrest, yet the mechanisms remain unclear. To elucidate the relationships between the effects of ACBP and the levels of cell differentiation, as well as the functional mechanisms of ACBP, we conducted a study using three human gastric cancer cell lines: NCI-N87, MGC-803, and another unspecified line.

Methods: We investigated the impact of ACBP on the survival and morphology of these cancer cell lines, examined apoptosis and cell cycle progression, and detected the expression of TP53, TP63, and TP73 in cancer cells, as well as the expression of Bax, PUMA, and Mcl-1 in a xenograft mouse model. ACBP inhibited the proliferation of all three cancer cell lines in a dose-dependent manner, similar to the positive control and 5-fluorouracil (5-FU). The effect of ACBP correlated with the degree of differentiation of the cancer cells; the lower the differentiation degree, the stronger the inhibitory effect.

Results: After ACBP treatment, the expression of TP53, TP63, and TP73 increased in all cell lines. In the xenograft mouse model, ACBP inhibited the growth of MGC-803 cells in vivo. The apoptotic-related genes Bax and PUMA were upregulated, while Mcl-1 was downregulated. ACBP inhibited tumor cell growth by inducing apoptosis through the TP53 signaling cascade, upregulating TP53, TP63, and TP73 and their downstream apoptosis-promoting genes Bax and PUMA while downregulating the anti-apoptotic gene Mcl-1.

Conclusion: Notably, after ACBP treatment, Mcl-1 expression was significantly reduced in the tumor tissue of the xenograft model, indicating that ACBP induced apoptosis through the TP53 signaling cascade. This project provides a scientific basis for exploring the antitumor mechanism of ACBP in gastric cancer therapy.

Introduction: Tritrpticin (TRP3) is a peptide belonging to the cathelicidin family and has a broad spectrum of antimicrobial activity. However, this class of biomolecules can be easily degraded in the body, making it necessary to use an efficient transport system. The ability to form stable nanostructures from the interaction of glycyrrhizin saponin with the pluronic polymer F127 was demonstrated, forming mixed biopolymeric micelles, highly promising as drug carriers.

Objective: The present work sought to understand the physicochemical interaction of the antimicrobial peptide TRP3 with the mixed polymeric micelle made from pluronic F127 and the saponin glycyrrhizin.

Methods: The interaction of tritrpticin with mixed nanostructured micelles was evaluated through fluorescence spectroscopy and fluorescence quenching with acrylamide. The experiments were performed at room temperature (25 ± 1°C), adopting an excitation wavelength set to 280 nm and emission between 300 and 500 nm, with a slit of 5 nm.

Results: The interaction of the cationic peptide tritrpticin with the mixed biopolymeric micelles was observed through the blue shift of the fluorescence emission to shorter wavelengths, proving the change of tryptophan to a more hydrophobic environment. Through the fluorescence suppression technique, it was possible to indicate the location of the peptide in the mixed micelles, proving tritrpticin to be partially inserted inside them.

Conclusion: It was concluded that tritrpticin interacted with mixed nanostructured micelles, forming a promising system for biotechnological applications.

Introduction: Diminazene aceturate (DIZE) was described as an angiotensin-converting enzyme 2 (ACE2) activator. ACE2/Angiotensin-(1-7)/Mas receptor axis presents protective actions on cardiovascular diseases and plays an important modulatory role in the neurobiology of mood and anxiety disorders.

Objectives: To evaluate the effects of chronic intracerebroventricular (ICV) treatment with DIZE on blood pressure, anxiety- and depression-like behaviors in hypertensive transgenic (mRen2)27 rats (TGR).

Methods: Male TGR and Sprague-Dawley rats (10-12 weeks old) were subjected to chronic ICV infusion of DIZE (1.0 μg/h for 7 days). Blood pressure and heart rate were measured by tail plethysmography and anxiety- and depression-like behaviors were evaluated through elevated plus maze, marble burying and forced swim tests, respectively.

Results: Treatment with DIZE induced a significant reduction in mean arterial pressure in both TGR and SD rats. A decrease in heart rate was only observed in the hypertensive animals. Additionally, treatment with DIZE attenuated the anxiety- and depression-like behaviors that were observed in TGR.

Conclusion: DIZE has central anti-hypertensive, anxiolytic, and anti-depressive effects.

Introduction: Numerous X-ray crystal structures of the c-Src SH3 domain have provided a large sampling of atomic-level information for this important signaling domain. Multiple crystal forms have been reported, with variable crystal lattice contacts and chemical crystallization conditions.

Materials and methods: We crystallized the c-Src SH3 domain in a crystallization buffer containing NiCl₂.

Results: A unique crystal structure of the Src SH3 domain in the trigonal space group H32 is determined to 1.45 Å resolution. Crystal packing and anomalous scattering reveal that this crystal form is mediated by two ordered nickel ions provided by the crystallization buffer. Nickel coordination occurs in a 2:2 stoichiometry, which dimerizes two SH3 domain monomers across a pseudo-twofold rotation axis and involves the native N-terminal c-Src SH3 amino acid sequence, a surface-exposed histidine residue, and ordered water molecules.

Discussion: This study provides an example of metal-mediated crystallization and metal binding by N-terminal protein residues, contrasting with the Amino-Terminal Copper and Nickel Binding (ATCUN) motif.

Conclusion: Alternative avenues help widen the potential for future crystallography-based studies of the c-Src SH3 domain.

Background: Human papillomavirus type 16 (HPV16) is implicated in various malignancies. The virus enters host cells through endocytosis, during which the minor capsid protein L2 interacts with the S100A10 subunit of the annexin A2 heterotetramer (A2t) on the host cell membrane. This interaction is critical for facilitating HPV entry and subsequent infection of human cells. Therefore, examining the interaction between the L2 protein and S100A10 is crucial for advancing our understanding of the mechanisms by which HPV16 infiltrates cells.

Objective: The cell-free expression (CFE) system was investigated for L2 purification. The structure of L2 was characterized and its interaction with S100A10 was explored.

Methods: The L2 protein was expressed using a CFE expression system, and its expression was verified via Western blotting. L2 was further purified through size-exclusion chromatography (SEC), and its structural features were preliminarily assessed using transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy. Additionally, surface plasmon resonance (SPR) was employed to analyze the interaction between L2 and S100A10.

Results: Western blotting confirmed the successful expression of L2. TEM and CD provided preliminary structural observations of L2, and SPR measurements yielded precise kinetic parameters for the interaction between L2 and S100A10.

Conclusion: In this study, we successfully expressed the HPV16 L2 protein using a cell-free protein expression system. Preliminary structural analysis using TEM and CD revealed key structural features of L2. Furthermore, SPR analysis provided detailed kinetic parameters for its interaction with S100A10. These findings provide more details on understanding L2's structural features, with broader implications for antipathogen studies.