Extensive characterization and differential analysis of endogenous peptides from Bombyx batryticatus using mass spectrometric approach

Protective Effects of Bombyx batryticatus Protein-Rich Extract Against Cisplatin-Induced Nephrotoxicity in HEK293 Cells and a Mouse Model

Cisplatin, a potent and prominent chemotherapeutic drug, has considerable side effects, including nephrotoxicity, which limits its therapeutic application and efficacy. Therefore, the development of agents that protect normal cells while preserving cisplatin's chemotherapeutic properties is of utmost importance. This study aimed to explore the protective effects of Bombyx batryticatus protein-rich extract (BBPE) against cisplatin-induced nephrotoxicity in a cisplatin-treated mouse model and human embryonic kidney (HEK293) cells. Apoptosis was assessed in HEK293 cells to determine the cytoprotective effects of BBPE and its effects on the generation of cisplatin-induced reactive oxygen species (ROS) and mitochondrial transmembrane potential (MTP) collapse. Although cisplatin induced nephrotoxicity in HEK293 cells, pretreatment with BBPE showed significant protective effects against cisplatin-induced nephrotoxicity by regulating the expression levels of pro- and antiapoptotic proteins. The cytoprotective effects of BBPE were mediated by decreased ROS production and MTP loss in cisplatin-treated HEK293 cells. The in vitro results were confirmed in the cisplatin-treated mouse model. Pretreatment with BBPE protected against cisplatin-induced nephrotoxicity by restoring malondialdehyde, superoxide dismutase, and catalase levels in kidney tissue and blood urea nitrogen and creatinine serum levels. Furthermore, histopathological assessment and terminal dUTP nick end-labeling staining showed that BBPE mitigated cisplatin-induced nephrotoxicity in kidney tissues. Overall, BBPE may act as a potent agent for alleviating cisplatin-induced nephrotoxicity, thereby increasing the safety of cisplatin-based chemotherapy.

Characterization of the natural peptidome of four leeches by integrated proteogenomics and pseudotargeted peptidomics

Animal-derived drugs are an indispensable part of folk medicine worldwide. However, their chemical constituents are poorly approached, which leads to the low level of the quality standard system of animal-derived drugs and further causes a chaotic market. Natural peptides are ubiquitous throughout the organism, especially in animal-derived drugs. Thus, in this study, we used multi-source leeches, including Hirudo nipponica (HN), Whitmania pigra (WP), Whitmania acranulata (WA), and Poecilobdella manillensis (PM), as a model. A strategy integrating proteogenomics and novel pseudotargeted peptidomics was developed to characterize the natural peptide phenotype and screen for signature peptides of four leech species. First, natural peptides were sequenced against an in-house annotated protein database of closely related species constructed from RNA-seq data from the Sequence Read Archive (SRA) website, which is an open-sourced public archive resource. Second, a novel pseudotargeted peptidomics integrating peptide ion pair extraction and retention time transfer was established to achieve high coverage and quantitative accuracy of the natural peptides and to screen for signature peptides for species authentication. In all, 2323 natural peptides were identified from four leech species whose databases were poorly annotated. The strategy was shown to significantly improve peptide identification. In addition, 36 of 167 differential peptides screened by pseudotargeted proteomics were identified, and about one-third of them came from the leucine-rich repeat domain (LRR) proteins, which are widely distributed in organisms. Furthermore, six signature peptides were screened with good specificity and stability, and four of them were validated by synthetic standards. Finally, a dynamic multiple reaction monitoring (dMRM) method based on these signature peptides was established and revealed that one-half of the commercial samples and all of the Tongxinluo capsules were derived from WP. All in all, the strategy developed in this study was effective for natural peptide characterization and signature peptide screening, which could also be applied to other animal-derived drugs, especially for modelless species that are less studied in protein database annotation.

In situ detection and mass spectrometry imaging of protein-related metabolites in Bombyx batryticatus before and after frying with wheat bran

Bombyx batryticatus is derived from the dried larva of Bombyx mori Linnaeus infected by Beauveria bassiana (Bals.) Vuillant. Raw Bombyx batryticatus should be stir-fried before oral administration due to its irritation to the gastrointestinal tract. Nevertheless, it is still an arduous task to uncover the intrinsic mechanism of Bombyx batryticatus processing. In this study, we collected two types of Bombyx batryticatus, one being stir-fried and the other serving as a control. Then, an informative approach, which integrated matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) with chemometrics analysis, was established to screen processing-associated markers and reveal in situ spatial distribution patterns of protein-related metabolites. After optimization of experimental conditions, 21 ions were initially detected from Bombyx batryticatus, including amino acids and peptides. In addition, 15 differential markers were screened by orthogonal projection to potential structure discriminant analysis (OPLS-DA), which were localized and visualized in the transverse section of Bombyx batryticatus by MSI. Eventually, it can be demonstrated that the stir-frying process reduces toxicity while potentially boosting specific biological activities of Bombyx batryticatus. In summary, the established strategy could not only clarify the chemical transformation of protein-related metabolites from Bombyx batryticatus before and after frying with wheat bran, but also reveal the significance of Chinese medicine processing technology.

Purification, Identification and Neuroprotective Effects of Proteins from Bombyx batryticatus in Glu-Stimulated PC12 Cells

Bombyx batryticatus (BB) is one of the most commonly used Traditional Chinese Medicines (TCMs) in the treatment of convulsions and epilepsy. The antiepileptic effects of total proteins from BB (BBPs) have been proven in our previous research. In this study, BBPs were further purified, the neuroprotective effects were evaluated in Glu-stimulated PC12 cells, and the structure was identified by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Six subfractions (PF-1 to PF-6) were obtained by DEAE-52 Sepharose FF ion-exchange chromatography. It was found that PF-1, PF-2, and PF-3, with similar protein compositions, possessed neuroprotective effects in Glu-stimulated PC12 cells by significantly increasing the GABA level, and decreasing the levels of IL-1β and TNF-α. The most active fraction (PF-2) was further separated by Sephadex G-75 gel filtration chromatography, and an effective protein component named PF-2-2 was obtained. Fluorescein isothiocyanate-labeled PF-2-2 (FITC-PF-2-2) was prepared, and the binding of FITC-F-2-2 to the PC12 cells was directly observed with a confocal microscope. PF-2-2 was found to first bind to the surface of PC12 cells and then internalize into the cells. The main band of PF-2-2 was then analyzed by MALDI-TOF/TOF-MS and searched in the MASCOT database; finally a protein named Low molecular mass 30 kDa lipoprotein 21G1 was identified. In conclusion, PF-2-2 and purified proteins isolated from BBPs have potential application prospects in the treatment of epilepsy.

Quinetides: diverse posttranslational modified peptides of ribonuclease-like storage protein from Panax quinquefolius as markers for differentiating ginseng species

Background

Peptides have diverse and important physiological roles in plants and are ideal markers for species identification. It is unclear whether there are specific peptides in Panax quinquefolius L. (PQ). The aims of this study were to identify Quinetides, a series of diverse posttranslational modified native peptides of the ribonuclease-like storage protein (ginseng major protein), from PQ to explore novel peptide markers and develop a new method to distinguish PQ from Panax ginseng.

Methods

We used different fragmentation modes in the LTQ Orbitrap analysis to identify the enriched Quinetide targets of PQ, and we discovered Quinetide markers of PQ and P. ginseng using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis. These "peptide markers" were validated by simultaneously monitoring Rf and F11 as standard ginsenosides.

Results

We discovered 100 Quinetides of PQ with various post-translational modifications (PTMs), including a series of glycopeptides, all of which originated from the protein ginseng major protein. We effectively distinguished PQ from P. ginseng using new "peptide markers." Four unique peptides (Quinetides TP6 and TP7 as markers of PQ and Quinetides TP8 and TP9 as markers of P. ginseng) and their associated glycosylation products were discovered in PQ and P. ginseng.

Conclusion

We provide specific information on PQ peptides and propose the clinical application of peptide markers to distinguish PQ from P. ginseng.

The Effect of Protein-Rich Extract from Bombyx Batryticatus against Glutamate-Damaged PC12 Cells Via Regulating γ-Aminobutyric Acid Signaling Pathway

Bombyx Batryticatus (BB) is a known traditional Chinese medicine (TCM) utilized to treat convulsions, epilepsy, cough, asthma, headaches, etc. in China for thousands of years. This study is aimed at investigating optimum extraction of protein-rich extracts from BB (BBPs) using response surface methodology (RSM) and exploring the protective effects of BBPs against nerve growth factor (NGF)-induced PC12 cells injured by glutamate (Glu) and their underlying mechanisms. The results indicated optimum process of extraction was as follows: extraction time 1.00 h, ratio of liquid to the raw material 3.80 mL/g and ultrasonic power 230.0 W. The cell viability of PC12 cells stimulated by Glu was determined by CCK-8 assay. The levels of γ-aminobutyric (GABA), interleukin-1β (IL-1β), interleukin-4 (IL-4), tumor necrosis factor-α (TNF-α), 5-hydroxytryptamine (5-HT) and glucocorticoid receptor alpha (GR) in PC12 cells were assayed by ELISA. Furthermore, the Ca²⁺ levels in PC12 cells were determined by flow cytometry analysis. Protein and mRNA expressions of GABAA-Rα1, NMDAR1, GAD 65, GAD 67, GAT 1 and GAT 3 in PC12 cells were evaluated by real-time polymerase chain reaction (RT-PCR) and Western blotting assays. Results revealed that BBPs decreased toxic effects due to Glu treatment and decreased Ca²⁺ levels in PC12 cells. After BBPs treatments, levels of GABA and 5-HT were increased and contents of TNF-α, IL-4 and IL-1β were decreased in NGF-induced PC12 cells injured by Glu. Moreover, BBPs up-regulated the expressions of GABAA-Rα1, GAD 65 and GAD 67, whereas down-regulated that of NMDAR1 GAT 1 and GAT 3. These findings suggested that BBPs possessed protective effects on NGF-induced PC12 cells injured by Glu via γ-Aminobutyric Acid (GABA) signaling pathways, which demonstrated that BBPs has potential anti-epileptic effect in vitro. These findings may be useful in the development of novel medicine for the treatment of epilepsy.

Development of an LC-MS multivariate nontargeted methodology for differential analysis of the peptide profile of Asian hornet venom (Vespa velutina nigrithorax): application to the investigation of the impact of collection period variation

Insect venom is a highly complex mixture of bioactive compounds, containing proteins, peptides, and small molecules. Environmental factors can alter the venom composition and lead to intraspecific variation in its bioactivity properties. The investigation of discriminating compounds caused by variation impacts can be a key to manage sampling and explore the bioactive compounds. The present study reports the development of a peptidomic methodology based on UHPLC-ESI-QTOF-HRMS analysis followed by a nontargeted multivariate analysis to reveal the profile variance of Vespa velutina venom collected in different conditions. The reliability of the approach was enhanced by optimizing certain XCMS data processing parameters and determining the sample peak threshold to eliminate the interfering features. This approach demonstrated a good repeatability and a criterion coefficient of variation (CV) > 30% was set for deleting nonrepeatable features from the matrix. The methodology was then applied to investigate the impact of collection period variation. PCA and PLS-DA models were used and validated by cross-validation and permutation tests. A slight discrimination was found between winter and summer hornet venom in two successive years with 10 common discriminating compounds. Graphical abstract.