Bioactive peptides attenuate cardiac apoptosis in spontaneously hypertensive rat hearts through activation of autophagy and mitochondrial biogenesis pathway

New Insights into Antioxidant Peptides: An Overview of Efficient Screening, Evaluation Models, Molecular Mechanisms, and Applications

Antioxidant peptides are currently a hotspot in food science, pharmaceuticals, and cosmetics. In different fields, the screening, activity evaluation, mechanisms, and applications of antioxidant peptides are the pivotal areas of research. Among these topics, the efficient screening of antioxidant peptides stands at the forefront of cutting-edge research. To this end, efficient screening with novel technologies has significantly accelerated the research process, gradually replacing the traditional approach. After the novel antioxidant peptides are screened and identified, a time-consuming activity evaluation is another indispensable procedure, especially in in vivo models. Cellular and rodent models have been widely used for activity evaluation, whilst non-rodent models provide an efficient solution, even with the potential for high-throughput screening. Meanwhile, further research of molecular mechanisms can elucidate the essence underlying the activity, which is related to several signaling pathways, including Keap1-Nrf2/ARE, mitochondria-dependent apoptosis, TGF-β/SMAD, AMPK/SIRT1/PGC-1α, PI3K/Akt/mTOR, and NF-κB. Last but not least, antioxidant peptides have broad applications in food manufacture, therapy, and the cosmetics industry, which requires a systematic review. This review introduces novel technologies for the efficient screening of antioxidant peptides, categorized with a new vision. A wide range of activity evaluation assays, encompassing cellular models, as well as rodent and non-rodent models, are provided in a comprehensive manner. In addition, recent advances in molecular mechanisms are analyzed with specific cases. Finally, the applications of antioxidant peptides in food production, therapy, and cosmetics are systematically reviewed.

Afzelin protects against doxorubicin-induced cardiotoxicity by promoting the AMPKα/SIRT1 signaling pathway

BACKGROUND

Doxorubicin (DOX), a chemotherapeutic drug, could relieve the progressions of various diseases. However, its clinical application is limited due to its cardiotoxicity. This study aimed to investigate the effects of afzelin (a flavonol glycoside found in Houttuynia cordata) on the cardiotoxicity induced by DOX.

METHODS

In ex-vivo, H9C2 cells were incubated with 20, 40, or 80 μM afzelin for 12 h, followed by the treatment with 1 μM DOX for 12 h. In vivo, C57BL/6 J mice were intraperitoneally injected with 4 mg/kg/day DOX on days 1, 7, and 14. Meanwhile, starting from day 1, mice were intragastrically administrated with 5 mg/kg/day or 10 mg/kg/day afzelin for 20 days. The cardiac function of mice was evaluated by detecting hemodynamic parameters using the M-mode echocardiography.

RESULTS

DOX decreased the cell survival rate, and elevated apoptotic rate, as well as induced the oxidative stress and mitochondrial dysfunction in H9C2 cells. All these changes were alleviated by afzelin treatment in a concentration-dependent manner. The results were further proven by the mitigation of cardiac injury in vivo, as evidenced by the elevation of fractional shortening, heart weight/tibia length, and the rate of the increase/decrease of left ventricular pressure in mice subjected to DOX-induced cardiotoxicity. Furthermore, afzelin upregulated the expression of p-AMP-activated protein kinase alpha (AMPKα) and sirtuin1 (SIRT1). Dorsomorphin (an AMPKα inhibitor) abrogated the anti-cardiotoxicity effects of afzelin in H9C2 cells induced by DOX.

CONCLUSION

Afzelin protected against DOX-induced cardiotoxicity by promoting the AMPKα/SIRT1 signaling pathway.

Angiotensin II-induced calcium overload affects mitochondrial functions in cardiac hypertrophy by targeting the USP2/MFN2 axis

Ubiquitination, a common type of post-translational modification, is known to affect various diseases, including cardiac hypertrophy. Ubiquitin-specific peptidase 2 (USP2) plays a crucial role in regulating cell functions, but its role in cardiac functions remains elusive. The present study aims to investigate the mechanism of USP2 in cardiac hypertrophy. Animal and cell models of cardiac hypertrophy were established using Angiotensin II (Ang II) induction. Our experiments revealed that Ang II induced USP2 downregulation in the in vitro and in vivo models. USP2 overexpression suppressed the degree of cardiac hypertrophy (decreased ANP, BNP, and β-MHC mRNA levels, cell surface area, and ratio of protein/DNA), calcium overload (decreased Ca²⁺ concentration and t-CaMKⅡ and p-CaMKⅡ, and increased SERCA2), and mitochondrial dysfunction (decreased MDA and ROS and increased MFN1, ATP, MMP, and complex Ⅰ and II) both in vitro and in vivo. Mechanically, USP2 interacted with MFN2 and improved the protein level of MFN2 through deubiquitination. Rescue experiments confirmed that MFN2 downregulation neutralized the protective role of USP2 overexpression in cardiac hypertrophy. Overall, our findings suggested that USP2 overexpression mediated deubiquitination to upregulate MFN2, thus alleviating calcium overload-induced mitochondrial dysfunction and cardiac hypertrophy.

Cardiac changes in spontaneously hypertensive rats: Modulation by aerobic exercise

Systemic arterial hypertension is a multifactorial clinical condition characterized by high and sustained levels of blood pressure. For a better understanding of the pathophysiology of hypertension, studies are conducted with spontaneously hypertensive animals, which allow the investigation of physiological changes that in most cases cannot be studied in humans. In these animals, myocardial remodeling, increased pro-inflammatory markers, redox imbalance and contractile dysfunctions that lead to changes in cardiac function can be observed. However, it can be inferring that aerobic training improves cardiac function and cardiomyocyte contractility, in addition to controlling inflammation and reducing oxidative stress in cardiac muscle, despite this, the precise mechanisms by which physical exercise improves cardiovascular control are not fully understood. In this review, we provide an overview of the pathophysiological changes that affect the heart of spontaneously hypertensive animals and their modulation by aerobic exercise.

Dipeptide IF and Exercise Training Attenuate Hypertension in SHR Rats by Inhibiting Fibrosis and Hypertrophy and Activating AMPKα1, SIRT1, and PGC1α

Bioactive peptides are physiologically active peptides produced from proteins by gastrointestinal digestion, fermentation, or hydrolysis by proteolytic enzymes. Bioactive peptides are resorbed in their whole form and have a preventive effect against various disease conditions, including hypertension, dyslipidemia, inflammation, and oxidative stress. In recent years, there has been a growing body of evidence showing that physiologically active peptides may have a function in sports nutrition. The present study aimed to evaluate the synergistic effect of dipeptide (IF) from alcalase potato protein hydrolysates and exercise training in hypertensive (SHR) rats. Animals were divided into five groups. Bioactive peptide IF and swimming exercise training normalized the blood pressure and decreased the heart weight. Cardiac, hepatic, and renal functional markers also normalized in SHR rats. The combined administration of IF peptide and exercise offer better protection in SHR rats by downregulating proteins associated with myocardial fibrosis, hypertrophy, and inflammation. Remarkably, peptide treatment alongside exercise activates the PI3K/AKT cell survival pathway in the myocardial tissue of SHR animals. Further, the mitochondrial biogenesis pathway (AMPKα1, SIRT1, and PGC1α) was synergistically activated by the combinatorial treatment of IF and exercise. Exercise training along with IF administration could be a possible approach to alleviating hypertension.

Bioactive Peptides and Exercise Modulate the AMPK/SIRT1/PGC-1α/FOXO3 Pathway as a Therapeutic Approach for Hypertensive Rats

Peptides are fragments of fundamental protein sequences that may have health benefits in addition to basic dietary benefits. Recently, we have reported on the pharmacological benefits of alcalase potato protein hydrolysate (APPH) and bioactive peptides isolated from APPH. The aim was to evaluate the synergistic effect of exercise along with DIKTNKPVIF (DF) peptides in ameliorating hypertension in spontaneously hypertensive rat (SHR) rats. We examined ECG parameters, lipid profiles, cardiac markers, and histology, and quantified the proteins associated with fibrosis, hypertrophy, apoptosis, mitochondrial biogenesis, and longevity pathways. DF peptide administration, along with exercise, reduced the blood pressure and cardiac marker levels in serum. Furthermore, it also suppressed the expression of fibrosis markers COL1A1, CTGF, and uPA and downregulated cardiac-hypertrophy-associated markers such as calcineurin, NFATC3, GATA4, pGATA4 and BNP. Exercise synergistically increases the expression of IFG1, PI3K, and AKT cell-survival pathway proteins, along with DF administration. Moreover, AMPK/SIRT1/PGC-1α/FOXO3 pathway protein expression was increased with the combinatorial administration of DF and exercise. Our data suggest that exercise, along with DF peptides, act synergistically in alleviating hypertension by activating the mitochondrial biogenesis pathway.

Decapeptide from Potato Hydrolysate Induces Myogenic Differentiation and Ameliorates High Glucose-Associated Modulations in Protein Synthesis and Mitochondrial Biogenesis in C2C12 Cells

Sarcopenia is characterized as an age-related loss of muscle mass that results in negative health consequences such as decreased strength, insulin resistance, slowed metabolism, increased body fat mass, and a substantially diminished quality of life. Additionally, conditions such as high blood sugar are known to further exacerbate muscle degeneration. Skeletal muscle development and regeneration following injury or disease are based on myoblast differentiation. Bioactive peptides are biologically active peptides found in foods that could have pharmacological functions. The aim of this paper was to investigate the effect of decapeptide DI-10 from the potato alcalase hydrolysate on myoblast differentiation, muscle protein synthesis, and mitochondrial biogenesis in vitro. The treatment of C2C12 myoblasts with DI-10 (10 µg/mL) did not induce cell death. DI-10 treatment in C2C12 myoblast cells accelerates the phosphorylation of promyogenic kinases such as ERK, Akt and mTOR proteins in a dose-dependent manner. DI-10 improves myotubes differentiation and upregulates the expression of myosin heavy chain (MyHC) protein in myoblast cells under differentiation medium with high glucose. DI-10 effectively increased the phosphorylation of promyogenic kinases Akt, mTOR, and mitochondrial-related transcription factors AMPK and PGC1α expression under hyperglycemic conditions. Further, decapeptide DI-10 decreased the expression of Murf1 and MAFbx proteins, which are involved in protein degradation and muscle atrophy. Our reports support that decapeptide DI-10 could be potentially used as a therapeutic candidate for preventing muscle degeneration in sarcopenia.

Role of bioactive peptides derived from food proteins in programmed cell death to treat inflammatory diseases and cancer

Bioactive peptides are specific peptide which usually contains 2-20 amino acid residues and actively exerts various functions and biological activities and ultimately affect health. Programmed cell deaths are some styles of cell death discovered in recent years, which is the key to tissue development and balance, eliminating excess, damaged or aging cells. More importantly, programmed cell death is a potential way to treat inflammatory diseases and cancer. In this review, through screening references from 2015 to present, we introduce the effect of bioactive peptides derived from food proteins on inflammatory diseases or cancer through regulating programmed cell deaths, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. And this review also introduces the targets of these bioactive peptides to regulate programmed cell death. The purpose of this review is to help to expand the prospective applications of bioactive peptides in the field of inflammatory disease and cancer to provide some guidance.

In situ observation of mitochondrial biogenesis as the early event of apoptosis

Mitochondrial biogenesis is a cell response to external stimuli which is generally believed to suppress apoptosis. However, during the process of apoptosis, whether mitochondrial biogenesis occurs in the early stage of the apoptotic cells remains unclear. To address this question, we constructed the COX8-EGFP-ACTIN-mCherry HeLa cells with recombinant fluorescent proteins respectively tagged on the nucleus and mitochondria and monitored the mitochondrial changes in the living cells exposed to gamma-ray radiation. Besides in situ detection of mitochondrial fluorescence changes, we also examined the cell viability, nuclear DNA damage, reactive oxygen species (ROS), mitochondrial superoxide, citrate synthase activity, ATP, cytoplasmic and mitochondrial calcium, mitochondrial mass, mitochondrial morphology, and protein expression related to mitochondrial biogenesis, as well as the apoptosis biomarkers. As a result, we confirmed that significant mitochondrial biogenesis took place preceding the radiation-induced apoptosis, and it was closely correlated with the apoptotic cells at late stage. The involved mechanism was also discussed.

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Dual fluorescence approach was used for in situ observation of living cell processes

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Radiation-induced effects of mitochondrial biogenesis and apoptosis were observed

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Relationship between mitochondrial biogenesis and apoptosis was revisited

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Assessing early mitochondrial biogenesis is critical for predicting later fate of cells

Sirtuins-Mediated System-Level Regulation of Mammalian Tissues at the Interface between Metabolism and Cell Cycle: A Systematic Review

Sirtuins are a family of highly conserved NAD+-dependent proteins and this dependency links Sirtuins directly to metabolism. Sirtuins' activity has been shown to extend the lifespan of several organisms and mainly through the post-translational modification of their many target proteins, with deacetylation being the most common modification. The seven mammalian Sirtuins, SIRT1 through SIRT7, have been implicated in regulating physiological responses to metabolism and stress by acting as nutrient sensors, linking environmental and nutrient signals to mammalian metabolic homeostasis. Furthermore, mammalian Sirtuins have been implicated in playing major roles in mammalian pathophysiological conditions such as inflammation, obesity and cancer. Mammalian Sirtuins are expressed heterogeneously among different organs and tissues, and the same holds true for their substrates. Thus, the function of mammalian Sirtuins together with their substrates is expected to vary among tissues. Any therapy depending on Sirtuins could therefore have different local as well as systemic effects. Here, an introduction to processes relevant for the actions of Sirtuins, such as metabolism and cell cycle, will be followed by reasoning on the system-level function of Sirtuins and their substrates in different mammalian tissues. Their involvement in the healthy metabolism and metabolic disorders will be reviewed and critically discussed.

Bioactive Peptides and Dietary Polyphenols: Two Sides of the Same Coin

The call for health-promoting nutraceuticals and functional foods containing bioactive compounds is growing. Among the great diversity of functional phytochemicals, polyphenols and, more recently, bioactive peptides have stood out as functional compounds. The amount of an ingested nutrient able to reach the bloodstream and exert the biological activity is a critical factor, and is affected by several factors, such as food components and food processing. This can lead to unclaimed interactions and/or reactions between bioactive compounds, which is particularly important for these bioactive compounds, since some polyphenols are widely known for their ability to interact and/or precipitate proteins/peptides. This review focuses on this important topic, addressing how these interactions could affect molecules digestion, absorption, metabolism and (biological)function. At the end, it is evidenced that further research is needed to understand the true effect of polyphenol-bioactive peptide interactions on overall health outcomes.