Ox-Lp(a) transiently induces HUVEC autophagy via an ROS-dependent PAPR-1-LKB1-AMPK-mTOR pathway

Lipoprotein (a)-Related Inflammatory Imbalance: A Novel Horizon for the Development of Atherosclerosis

PURPOSE OF REVIEW

The primary objective of this review is to explore the pathophysiological roles and clinical implications of lipoprotein(a) [Lp(a)] in the context of atherosclerotic cardiovascular disease (ASCVD). We seek to understand how Lp(a) contributes to inflammation and arteriosclerosis, aiming to provide new insights into the mechanisms of ASCVD progression.

RECENT FINDINGS

Recent research highlights Lp(a) as an independent risk factor for ASCVD. Studies show that Lp(a) not only promotes the inflammatory processes but also interacts with various cellular components, leading to endothelial dysfunction and smooth muscle cell proliferation. The dual role of Lp(a) in both instigating and, under certain conditions, mitigating inflammation is particularly noteworthy. This review finds that Lp(a) plays a complex role in the development of ASCVD through its involvement in inflammatory pathways. The interplay between Lp(a) levels and inflammatory responses highlights its potential as a target for therapeutic intervention. These insights could pave the way for novel approaches in managing and preventing ASCVD, urging further investigation into Lp(a) as a therapeutic target.

Anti-hypertensive effect and potential mechanism of gastrodia-uncaria granules based on network pharmacology and experimental validation

Hypertension has become a major contributor to the morbidity and mortality of cardiovascular diseases worldwide. Despite the evidence of the anti-hypertensive effect of gastrodia-uncaria granules (GUG) in hypertensive patients, little is known about its potential therapeutic targets as well as the underlying mechanism. GUG components were sourced from TCMSP and HERB, with bioactive ingredients screened. Hypertension-related targets were gathered from DisGeNET, OMIM, GeneCards, CTD, and GEO. The STRING database constructed a protein-protein interaction network, visualized by Cytoscape 3.7.1. Core targets were analyzed via GO and KEGG using R package ClusterProfiler. Molecular docking with AutodockVina 1.2.2 revealed favorable binding affinities. In vivo studies on hypertensive mice and rats validated network pharmacology findings. GUG yielded 228 active ingredients and 1190 targets, intersecting with 373 hypertension-related genes. PPI network analysis identified five core genes: AKT1, TNF-α, GAPDH, IL-6, and ALB. Top enriched GO terms and KEGG pathways associated with the anti-hypertensive properties of GUG were documented. Molecular docking indicated stable binding of core components to targets. In vivo study showed that GUG could improve vascular relaxation, alleviate vascular remodeling, and lower blood pressure in hypertensive animal models possibly through inhibiting inflammatory factors such as AKT1, mTOR, and CCND1. Integrated network pharmacology and in vivo experiment showed that GUG may exert anti-hypertensive effects by inhibiting inflammation response, which provides some clues for understanding the effect and mechanisms of GUG in the treatment of hypertension.

Curcumin and its anti-colorectal cancer potential: From mechanisms of action to autophagy

Colorectal cancer (CRC) development and progression, one of the most common cancers globally, is supported by specific mechanisms to escape cell death despite chemotherapy, including cellular autophagy. Autophagy is an evolutionarily highly conserved degradation pathway involved in a variety of cellular processes, such as the maintenance of cellular homeostasis and clearance of foreign bodies, and its imbalance is associated with many diseases. However, the role of autophagy in CRC progression remains controversial, as it has a dual function, affecting either cell death or survival, and is associated with cellular senescence in tumor therapy. Indeed, numerous data have been presented that autophagy in cancers serves as an alternative to cell apoptosis when the latter is ineffective or in apoptosis-resistant cells, which is why it is also referred to as programmed cell death type II. Curcumin, one of the active constituents of Curcuma longa, has great potential to combat CRC by influencing various cellular signaling pathways and epigenetic regulation in a safe and cost-effective approach. This review discusses the efficacy of curcumin against CRC in vitro and in vivo, particularly its modulation of autophagy and apoptosis in various cellular pathways. While clinical studies have assessed the potential of curcumin in cancer prevention and treatment, none have specifically examined its role in autophagy. Nonetheless, we offer an overview of potential correlations to support the use of this polyphenol as a prophylactic or co-therapeutic agent in CRC.

Arsenic disturbs neural tube closure involving AMPK/PKB-mTORC1-mediated autophagy in mice

Arsenic exposure is a significant risk factor for folate-resistant neural tube defects (NTDs), but the potential mechanism is unclear. In this study, a mouse model of arsenic-induced NTDs was established to investigate how arsenic affects early neurogenesis leading to malformations. The results showed that in utero exposure to arsenic caused a decline in the normal embryos, an elevated embryo resorption, and a higher incidence of malformed embryos. Cranial and spinal deformities were the main malformation phenotypes observed. Meanwhile, arsenic-induced NTDs were accompanied by an oxidant/antioxidant imbalance manifested by elevated levels of reactive oxygen species (ROS) and decreased antioxidant activities. In addition, changes in the expression of autophagy-related genes and proteins (ULK1, Atg5, LC3B, p62) as well as an increase in autophagosomes were observed in arsenic-induced aberrant brain vesicles. Also, the components of the upstream pathway regulating autophagy (AMPK, PKB, mTOR, Raptor) were altered accordingly after arsenic exposure. Collectively, our findings propose a mechanism for arsenic-induced NTDs involving AMPK/PKB-mTORC1-mediated autophagy. Blocking autophagic cell death due to excessive autophagy provides a novel strategy for the prevention of folate-resistant NTDs, especially for arsenic-exposed populations.

M1 linear ubiquitination of LKB1 inhibits vascular endothelial cell injury in atherosclerosis through activation of AMPK

Endothelial cell injury is confirmed to be the initial step in the atherosclerosis (AS) process. Here, we tried to elucidate the role of liver kinase B1 (LKB1) and adenosine phosphate protein kinase (AMPK) in modulating vascular endothelial cells (VECs) in AS. High-fat feed (HFD)-induced AS rat models were prepared and treated with AMPK activator A-769662 alone or combined with chloroquine. An analysis of VEC injury, inflammation response, and autophagy followed it. The M1 linear ubiquitination of LKB1 was assessed by co-immunoprecipitation. The interaction between LKB1 and AMPK was analyzed. Primary aortic VECs were isolated and induced by LPS to verify the effects of LKB1 and AMPK on VEC injury in AS. Activation of AMPK reduced the VEC injury and inflammatory response of VECs and promoted autophagy caused by AS. LKB1 could regulate the activation of AMPK in AS. M1 linear ubiquitination enhanced LKB1 activity and increased AMPK activation to protect against VEC injury in AS, which was validated by in vitro experiments. Our current study highlighted that M1 linear ubiquitination of LKB1 may induce the activation of LKB1 to activate AMPK, which inhibited VEC injury in AS.

VdTps2 Modulates Plant Colonization and Symptom Development in Verticillium dahliae

The trehalose biosynthesis pathway is a potential target for antifungal drugs development. Trehalose phosphate synthase (TPS) and phosphatase are widely conserved components of trehalose biosynthesis in fungi. However, the role of trehalose biosynthesis in the vascular plant-pathogenic fungus Verticillium dahliae remains unclear. Here, we investigated the functions of the TPS complex, including VdTps1, VdTps2, and VdTps3 in V. dahliae. Unlike VdTps2, deletion of VdTps1 or VdTps3 did not alter any phenotypes compared with the wild-type strain. In contrast, the ΔVdTps2 strain showed severely depressed radial growth due to the abnormal swelling of the hyphal tips. Further, deletion of VdTps2 increased microsclerotia formation, melanin biosynthesis, and resistance to cell-wall perturbation and high-temperature stress. Virulence assays and quantification of fungal biomass revealed that deletion of VdTps2 delayed disease symptom development, as evident by the reduced virulence and decreased biomass of the ΔVdTps2 strain in plant stem tissue following inoculation. Additionally, increases in penetration peg formation observed in the ΔVdTps2 strain in the presence of H2O2 suggested that VdTps2 suppresses initial colonization. Our results also revealed the role of VdTps2 as a regulator of autophagy. Together, these results indicate that VdTps2 contributes to plant colonization and disease development. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

APN Expression in Serum and Corpus Luteum: Regulation of Luteal Steroidogenesis Is Possibly Dependent on the AdipoR2/AMPK Pathway in Goats

Adiponectin (APN) is an essential adipokine for a variety of reproductive processes. To investigate the role of APN in goat corpora lutea (CLs), CLs and sera from different luteal phases were collected for analysis. The results showed that the APN structure and content had no significant divergence in different luteal phases both in CLs and sera; however, high molecular weight APN was dominant in serum, while low molecular weight APN was more present in CLs. The luteal expression of both AdipoR1/2 and T-cadherin (T-Ca) increased on D11 and 17. APN and its receptors (AdipoR1/2 and T-Ca) were mainly expressed in goat luteal steroidogenic cells. The steroidogenesis and APN structure in pregnant CLs had a similar model as in the mid-cycle CLs. To further explore the effects and mechanisms of APN in CLs, steroidogenic cells from pregnant CLs were isolated to detect the AMPK-mediated pathway by the activation of APN (AdipoRon) and knockdown of APN receptors. The results revealed that P-AMPK in goat luteal cells increased after incubation with APN (1 μg/mL) or AdipoRon (25 μM) for 1 h, and progesterone (P4) and steroidogenic proteins levels (STAR/CYP11A1/HSD3B) decreased after 24 h. APN did not affect the steroidogenic protein expression when cells were pretreated with Compound C or SiAMPK. APN increased P-AMPK and reduced the CYP11A1 expression and P4 levels when cells were pretreated with SiAdipoR1 or SiT-Ca, while APN failed to affect P-AMPK, the CYP11A1 expression or the P4 levels when pretreated with SiAdipoR2. Therefore, the different structural forms of APN in CLs and sera may possess distinct functions; APN might regulate luteal steroidogenesis through AdipoR2 which is most likely dependent on AMPK.

Ellagic acid induces apoptosis and autophagy in colon cancer through the AMPK/mTOR pathway

Ellagic acid (EA), found in fruits and foods, has been shown to be effective in the treatment of breast, colon and bladder cancer. However, due to the complexity of colon cancer, the therapeutic mechanism of EA for colon cancer is still unclear. Cell Counting Kit-8 (CCK-8) assay were employed to investigate the cell proliferation. Western blotting and flow cytometry assays were utilized to investigate apoptosis and autophagy in CRC cells (HCT116), respectively. Moreover, western blotting and luciferase reporter assays were evaluated the effect of EA on AMPK/mTOR pathway. Through flow cytometry analysis, EA could promote the apoptosis of HCT116 cells. In addition, EA can reduce the phosphorylation of mTOR, promoted phosphorylation of AMPK, and induced autophagy in HCT116 cells. Also, Dorsomorphin pretreatment can reduce the expression of autophagy protein, which indicates that EA induces autophagy through AMPK/mTOR pathway. These results suggest that EA inhibits the growth of colon cancer through AMPK/mTOR pathway and induces apoptosis and protective autophagy.

Hotspots and trends in liver kinase B1 research: A bibliometric analysis

Introduction

In the past 22 years, a large number of publications have reported that liver kinase B1 (LKB1) can regulate a variety of cellular processes and play an important role in many diseases. However, there is no systematic bibliometric analysis on the publications of LKB1 to reveal the research hotspots and future direction.

Methods

Publications were retrieved from the Web of Science Core Collection (WoSCC), Scopus, and PubMed databases. CiteSpace and VOSviewer were used to analysis the top countries, institutions, authors, source journals, discipline categories, references, and keywords.

Results

In the past 22 years, the number of LKB1 publications has increased gradually by year. The country, institution, author, journals that have published the most articles and cited the most frequently were the United States, Harvard University, Prof. Benoit Viollet, Journal of Biochemistry and Plos One. The focused research hotspot was the molecular functions of LKB1. The emerging hotspots and future trends are the clinical studies about LKB1 and co-mutated genes as biomarkers in tumors, especially in lung adenocarcinoma.

Conclusions

Our research could provide knowledge base, frontiers, emerging hotspots and future trends associated with LKB1 for researchers in this field, and contribute to finding potential cooperation possibilities.

The Molecular Mechanisms of Phytophthora infestans in Response to Reactive Oxygen Species Stress

Reactive oxygen species (ROSs) are critical for the growth, development, proliferation, and pathogenicity of microbial pathogens; however, excessive levels of ROSs are toxic. Little is known about the signaling cascades in response to ROS stress in oomycetes such as Phytophthora infestans, the causal agent of potato late blight. Here, P. infestans was used as a model system to investigate the mechanism underlying the response to ROS stress in oomycete pathogens. Results showed severe defects in sporangium germination, mycelium growth, appressorium formation, and virulence of P. infestans in response to H₂O₂ stress. Importantly, these phenotypes mimic those of P. infestans treated with rapamycin, the inhibitor of target of rapamycin (TOR, 1-phosphatidylinositol-3-kinase). Strong synergism occurred when P. infestans was treated with a combination of H₂O₂ and rapamycin, suggesting that a crosstalk exists between ROS stress and the TOR signaling pathway. Comprehensive analysis of transcriptome, proteome, and phosphorylation omics showed that H₂O₂ stress significantly induced the operation of the TOR-mediated autophagy pathway. Monodansylcadaverine staining showed that in the presence of H₂O₂ and rapamycin, the autophagosome level increased in a dosage-dependent manner. Furthermore, transgenic potatoes containing double-stranded RNA of TOR in P. infestans (PiTOR) displayed high resistance to P. infestans. Therefore, TOR is involved in the ROS response and is a potential target for control of oomycete diseases, because host-mediated silencing of PiTOR increases potato resistance to late blight.

Role of reactive oxygen species in tumors based on the 'seed and soil' theory: A complex interaction (Review)

Tumor microenvironment (TME) can serve as the 'soil' for the growth and survival of tumor cells and function synergically with tumor cells to mediate tumor progression and therapeutic resistance. Reactive oxygen species (ROS) is somewhat of a double‑edged sword for tumors. Accumulating evidence has reported that regulating ROS levels can serve an anti‑tumor role in the TME, including the promotion of cancer cell apoptosis, inhibition of angiogenesis, preventing immune escape, manipulating tumor metabolic reorganization and improving drug resistance. In the present review, the potential role of ROS in anti‑tumor therapy was summarized, including the possibility of directly or indirectly targeting the TME.

Role of PARP1-mediated autophagy in EGFR-TKI resistance in non-small cell lung cancer

Resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) has become the main clinical challenge of advanced lung cancer. This research aimed to explore the role of PARP1-mediated autophagy in the progression of TKI therapy. PARP1-mediated autophagy was evaluated in vitro by CCK-8 assay, clonogenic assay, immunofluorescence, and western blot in the HCC-827, H1975, and H1299 cells treated with icotinib (Ico), rapamycin, and AZD2281 (olaparib) alone or in combination. Our results and GEO dataset analysis confirmed that PARP1 is expressed at lower levels in TKI-sensitive cells than in TKI-resistant cells. Low PARP1 expression and high p62 expression were associated with good outcomes among patients with NSCLC after TKI therapy. AZD2281 and a lysosomal inhibitor reversed resistance to Ico by decreasing PARP1 and LC3 in cells, but an mTOR inhibitor did not decrease Ico resistance. The combination of AZD2281 and Ico exerted a markedly enhanced antitumor effect by reducing PARP1 expression and autophagy in vivo. Knockdown of PARP1 expression reversed the resistance to TKI by the mTOR/Akt/autophagy pathway in HCC-827IR, H1975, and H1299 cells. PARP1-mediated autophagy is a key pathway for TKI resistance in NSCLC cells that participates in the resistance to TKIs. Olaparib may serve as a novel method to overcome the resistance to TKIs.

Lipoprotein(a) the Insurgent: A New Insight into the Structure, Function, Metabolism, Pathogenicity, and Medications Affecting Lipoprotein(a) Molecule

Lipoprotein(a) [Lp(a)], aka “Lp little a”, was discovered in the 1960s in the lab of the Norwegian physician Kåre Berg. Since then, we have greatly improved our knowledge of lipids and cardiovascular disease (CVD). Lp(a) is an enigmatic class of lipoprotein that is exclusively formed in the liver and comprises two main components, a single copy of apolipoprotein (apo) B-100 (apo-B100) tethered to a single copy of a protein denoted as apolipoprotein(a) apo(a). Plasma levels of Lp(a) increase soon after birth to a steady concentration within a few months of life. In adults, Lp(a) levels range widely from <2 to 2500 mg/L. Evidence that elevated Lp(a) levels >300 mg/L contribute to CVD is significant. The improvement of isoform-independent assays, together with the insight from epidemiologic studies, meta-analyses, genome-wide association studies, and Mendelian randomization studies, has established Lp(a) as the single most common independent genetically inherited causal risk factor for CVD. This breakthrough elevated Lp(a) from a biomarker of atherosclerotic risk to a target of therapy. With the emergence of promising second-generation antisense therapy, we hope that we can answer the question of whether Lp(a) is ready for prime-time clinic use. In this review, we present an update on the metabolism, pathophysiology, and current/future medical interventions for high levels of Lp(a).

LncRNA DYNLRB2-2 inhibits THP-1 macrophage foam cell formation by enhancing autophagy

The aim of this study was to investigate whether long non-coding RNA (lncRNA) DYNLRB2-2 can inhibit foam cell formation by activating autophagy. The location of DYNLRB2-2 in THP-1-derived macrophages was analyzed by fluorescence in situ hybridization (FISH). Oxidized-low-density lipoprotein (ox-LDL) was used to induce the formation of foam cells, Oil Red O (ORO) staining and high-performance liquid chromatography (HPLC) were performed to detect accumulation of lipid droplets and the level of cholesterol concentration, respectively. The mRNA and protein level of ATP-binding cassette transporter A1 (ABCA1) were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. Relative protein levels of (p-) liver kinase B1 (LKB1), (p-) AMP-activated protein kinase (AMPK), (p-) the mammalian target of rapamycin (mTOR) and autophagy markers (LC3 II, Beclin-1 and p62) in THP-1 macrophage-derived foam cells were analyzed by Western blotting. The levels of inflammatory factors [tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β] in THP-1 macrophage-derived foam cells were detected by enzyme-linked immunosorbent assay (ELISA). 3-MA and compound C were used to block autophagy. Our data show that DYNLRB2-2 inhibited the formation of THP-1 macrophage-derived foam cells and promotes cholesterol efflux (CE) by activating autophagy. DYNLRB2-2 caused autophagy by activating the signaling pathway of LKB1/AMPK/mTOR in foam cells. DYNLRB2-2 activated the LKB1/AMPK/mTOR signaling pathway via the miR-298/Sirtuin 3 (SIRT3) axis. Our data indicated that DYNLRB2-2 enhanced CE by regulating the LKB1/AMPK/mTOR autophagy signaling pathway through the miR-298/SIRT3 axis, thereby blocking the formation of foam cells from THP-1 macrophages.

Adrenomedullin alleviates the pyroptosis of Leydig cells by promoting autophagy via the ROS-AMPK-mTOR axis

Adrenomedullin (ADM) exerts anti-oxidant, anti-inflammatory and anti-apoptotic effects in Leydig cells. However, the role and mechanism of ADM in the pyroptosis of Leydig cells are poorly understood. This study first showed the protective effects of ADM on the pyroptosis and biological functions of Leydig cells exposed to lipopolysaccharide (LPS) by promoting autophagy. Primary rat Leydig cells were treated with various concentrations of LPS and ADM, together with or without N-acetyl-L-cysteine (NAC) or 3-methyladenine (3-MA). Cell proliferation was detected through CCK-8 and BrdU incorporation assays, and ROS level was measured with the DCFDA assay. Real-time PCR, western blot, immunofluorescence, transmission electron microscopy, TUNEL and flow cytometry were performed to examine ADM's effect on the pyroptosis, autophagy and steroidogenic enzymes of Leydig cells and AMPK/mTOR signalling. Like NAC, ADM dose-dependently reduced LPS-induced cytotoxicity and ROS overproduction. ADM also dose-dependently ameliorated LPS-induced pyroptosis by reversing the increased expression of NLRP3, ASC, caspase-1, IL-1β, IL-18, GSDMD, caspase-3, caspase-7, TUNEL-positive and PI and active caspase-1 double-stained positive rate, DNA fragmentation and LDH concentration, which could be rescued via co-incubation with 3-MA. ADM dose-dependently increased autophagy in LPS-induced Leydig cells, as confirmed by the increased expression of LC3-I/II, Beclin-1 and ATG-5; decreased expression of p62 and autophagosomes formation; and increased LC3-II/LC3-I ratio. However, co-treatment with 3-MA evidently decreased autophagy. Furthermore, ADM dose-dependently rescued the expression of steroidogenic enzymes, including StAR, P450scc, 3β-HSD and CYP17, and testosterone production in LPS-induced Leydig cells. Like rapamycin, ADM dose-dependently enhanced AMPK phosphorylation but reduced mTOR phosphorylation in LPS-induced Leydig cells, which could be rescued via co-incubation with 3-MA. In addition, pyroptosis was further decreased, and autophagy was further promoted in LPS-induced Leydig cells upon co-treatment with ADM and rapamycin. ADM may protect the steroidogenic functions of Leydig cells against pyroptosis by activating autophagy via the ROS-AMPK-mTOR axis.

α-hederin induces autophagic cell death in colorectal cancer cells through reactive oxygen species dependent AMPK/mTOR signaling pathway activation

α-hederin, a monodesmosidic triterpenoid saponin, had previously demonstrated strong anticancer effects. In the current study, the pharmacological mechanism of autophagic cell death induced by α-hederin was investigated in human colorectal cancer cells. First, through cell counting kit-8 and colony formation assays, it was demonstrated that α-hederin could inhibit the proliferation of HCT116 and HCT8 cell. Results of flow cytometry using fluorescein isothiocyanate Annexin V/propidium iodide and Hoechst 33258 staining indicated that α-hederin could induce apoptosis. Western blotting demonstrated that α-hederin could activate mitochondrial apoptosis signal pathway. Then, using light chain 3 lentiviral and electron microscope assay, it was demonstrated that α-hederin could induce autophagy in colorectal cancer cells. In addition, immunohistochemistry results from in vivo experiments also demonstrated that α-hederin could induce autophagy. AMP-activated protein kinase (AMPK)/mechanistic target of rapamycin (mTOR) signaling was demonstrated to be activated by α-hederin, which could be blocked by reactive oxygen species (ROS) inhibitor NAC. Furthermore, NAC could inhibit apoptosis and autophagy induced by α-hederin. Finally, 3-MA (autophagy inhibitor) reduced the inhibition of α-hederin on cell activity, but it had no significant effect on apoptosis. In conclusion, α-hederin triggered apoptosis through ROS-activated mitochondrial signaling pathway and autophagic cell death through ROS dependent AMPK/mTOR signaling pathway activation in colorectal cancer cells.

Autophagy promotes angiogenesis via AMPK/Akt/mTOR signaling during the recovery of heat-denatured endothelial cells

Our previous study demonstrated that angiogenesis increased during the recovery of heat-denatured endothelial cells. However, the mechanism is still unclear. This study aimed to investigate the relation of autophagy and angiogenesis during the recovery of heat-denatured endothelial cells. A rat deep partial-thickness burn model and heat-denatured human umbilical vein endothelial cells (HUVECs) model (52 °C for 35 s) were used. Autophagy increased significantly in the dermis and HUVECs in a time-dependent manner after heat denaturation and recovery for 2-5 days. Rapamycin-mediated autophagy enhanced the pro-angiogenic effect, evidenced by increased proliferation and migration of HUVECs, and formation of tube-like structures. Autophagy inhibition by 3-Methyladenine (3-MA) abolished the angiogenesis in heat-denatured HUVECs after recovery for 3-5 days. Moreover, heat denaturation augmented the phosphorylation of AMP-activated protein kinase (AMPK) but reduced the phosphorylation of Akt and mTOR in HUVECs. Furthermore, autophagy inhibition by antioxidant NAC, compound C or AMPK siRNA impaired cell proliferation, migration and tube formation heat-denatured HUVECs. At last, the in vivo experiments also showed that inhibition of autophagy by bafilomycin A1 could suppress angiogenesis and recovery of heat-denatured dermis.Taken together, we firstly revealed that autophagy promotes angiogenesis via AMPK/Akt/mTOR signaling during the recovery of heat-denatured endothelial cells and may provide a potential therapeutic target for the recovery of heat-denatured dermis.

Genistein protects against ox-LDL-induced senescence through enhancing SIRT1/LKB1/AMPK-mediated autophagy flux in HUVECs

The anti-senescence activity of genistein is associated with inducing autophagy; however, the underlying mechanisms are not fully understood. In this study, human umbilical vein endothelial cells (HUVECs) were pretreated with genistein (1000 nM) for 30 min and then exposed to ox-LDL (50 mg/L) for another 12 h. The study found that genistein inhibited the ox-LDL-induced senescence (reducing the levels of P16 and P21 protein, and the activity of SA-β-gal); meanwhile, the effect of genistein was bound up with enhancing autophagic flux (increasing LC3-II, and decreasing the level of P62, p-mTOR and p-P70S6K). Moreover, SIRT1/LKB1/AMPK pathway was involved in genistein accelerating autophagic flux and mitigating senescence in HUVECs. The present study illustrated that genistein was a promising therapeutic agent to delay aging process and extend longevity.

Sodium butyrate induces autophagy in colorectal cancer cells through LKB1/AMPK signaling

Butyrate is produced by the fermentation of undigested dietary fibers and acts as the promising candidate for cancer treatment. However, the mechanism underlying sodium butyrate (NaB)-induced autophagy in colorectal cancer is not yet completely understood. The expressions of LC3-II protein and mRNA were detected by western blot and quantitative RT-PCR in colorectal cancer (CRC) cell lines HCT-116 and HT-29, respectively. Autolysosome formation was observed by transmission electron microscope. AMPK and LKB1 were inhibited by chemical inhibitor or siRNAs and confirmed by western blot. NaB elevated the protein and mRNA expressions of LC3 in a dose-dependent manner. NaB treatment increased the formation of autolysosome and expression of phosphorylated liver kinase B1 (LKB1), AMP-activated protein kinase (AMPK), and acetyl-CoA carboxylase (ACC). Treatment with compound C (an inhibitor of AMPK) and siRNA-mediated knockdown of AMPK and LKB1 significantly attenuated NaB-induced autophagy in CRC cells. Collectively, these findings indicated that LKB1 and AMPK are critical for NaB-mediated autophagy and may act as the novel targets for colorectal cancer therapy in the future.

Septin4 as a novel binding partner of PARP1 contributes to oxidative stress induced human umbilical vein endothelial cells injure

Oxidative stress induced vascular endothelial cell injure is one of the key and initial event in the development of atherosclerosis. Septin4, as a member of GTP binding protein family, is widely expressed in the eukaryotic cells and considered to be an essential component of the cytoskeleton which is involved in many important physiological processes. However, whether Septin4 is involved in cardiovascular diseases, such as oxidative stress inducted endothelial cell injury still unclear. PARP1 as a DNA repair enzyme can be activated by identifying DNA damaged fragments, which consumes high levels of energy and leads to vascular endothelial cell apoptosis. Here, our results first found that Septin4 is involved in oxidative stress induced endothelial cell ROS production and apoptosis through knock-down and over-expression Septin4 approaches. Furthermore, to explore how Septin4 is involved in oxidative stress induced endothelial cells injure, we first identified that Septin4 is a novel PARP1 interacting protein and the interaction is enhanced under oxidative stress. In conclusions, our founding indicates that Septin4 is a novel essential factor involved in oxidative stress induced vascular endothelial cell injury by interacting with apoptosis-related protein PARP1.

Resveratrol ameliorates autophagic flux to promote functional recovery in rats after spinal cord injury

Resveratrol is known to improve functional recovery after spinal cord injury, but the exact mechanism involved is yet unclear. The aim of this study was to clarify whether resveratrol can exert neuroprotective effects via activating neuronal autophagic flux, in view of the underlying role of the autophagic flux mediated by resveratrol on neuronal apoptosis after spinal cord injury, and identify the role of the liver kinase B1(LKB1)/adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/ p70 ribosomal protein S6 kinase (p70s6k) signal pathway in the autophagic flux mediated by resveratrol. The results obtained strongly indicate that resveratrol improved functional recovery in Sprague–Dawley rats after acute spinal cord injury, preserved their motor neurons, alleviated the neuronal apoptosis, and ameliorated neuronal autophagic flux. After blocking the autophagic flux, the neuroprotective effects of resveratrol were eliminated. Furthermore, it was proved that resveratrol can activate the LKB1/AMPK/mTOR/p70s6k pathway in vivo and in vitro, and the LKB1/AMPK/mTOR/p70s6k pathway plays a vital role in activating the autophagic flux mediated by resveratrol in PC12 cells. Thus, resveratrol enables to ameliorate neuronal autophagic flux via the LKB1/AMPK/mTOR/p70s6k pathway to alleviate apoptosis, and finally ameliorating functional recovery after acute SCI in SD rats.

Catalpol attenuates oxidative stress and promotes autophagy in TNF-α-exposed HAECs by up-regulating AMPK

Catalpol attenuates oxidative stress and promotes autophagy in TNF-α-exposed HAECs through up-regulating AMPK.

CLIC1 Inhibition Attenuates Vascular Inflammation, Oxidative Stress, and Endothelial Injury

Endothelial dysfunction, which includes endothelial oxidative damage and vascular inflammation, is a key initiating step in the pathogenesis of atherosclerosis (AS) and an independent risk factor for this disorder. Intracellular chloride channel 1 (CLIC1), a novel metamorphic protein, acts as a sensor of cell oxidation and is involved in inflammation. In this study, we hypothesize that CLIC1 plays an important role in AS. Apolipoprotein E-deficient mice were supplied with a normal diet or a high-fat and high-cholesterol diet for 8 weeks. Overexpressed CLIC1 was associated with the accelerated atherosclerotic plaque development, amplified oxidative stress, and in vivo release of inflammatory cytokines. We subsequently examined the underlying molecular mechanisms through in vitro experiments. Treatment of cultured human umbilical vein endothelial cells (HUVECs) with H2O2 induced endothelial oxidative damage and enhanced CLIC1 expression. Suppressing CLIC1 expression through gene knocked-out (CLIC1-/-) or using the specific inhibitor indanyloxyacetic acid-94 (IAA94) reduced ROS production, increased SOD enzyme activity, and significantly decreased MDA level. CLIC1-/- HUVECs exhibited significantly reduced expression of TNF-α and IL-1β as well as ICAM-1 and VCAM-1 at the protein levels. In addition, H2O2 promoted CLIC1 translocation to the cell membrane and insertion into lipid membranes, whereas IAA94 inhibited CLIC1 membrane translocation induced by H2O2. By contrast, the majority of CLIC1 did not aggregate on the cell membrane in normal HUVECs, and this finding is consistent with the changes in cytoplasmic chloride ion concentration. This study demonstrates for the first time that CLIC1 is overexpressed during AS development both in vitro and in vivo and can regulate the accumulation of inflammatory cytokines and production of oxidative stress. Our results also highlight that deregulation of endothelial functions may be associated with the membrane translocation of CLIC1 and active chloride-selective ion channels in endothelial cells.

RecQL4 regulates autophagy and apoptosis in U2OS cells

RecQL4, one of the 5 human RecQ helicases, is a key mediator of genomic stability and its deficiency can cause premature aging phenotypes. Here, by using CRISPR/Cas and RNAi technology, we demonstrated that autophagy level was elevated in both RecQL4 knockdown and knockout cells compared with those of the control cells. Surprisingly, mitochondrial content was increased and LC3 co-localization with mitochondria was partially lost in RecQL4 knockout cells compared with the control cells, suggesting that RecQL4 deficiency impaired mitophagic processes in U2OS cells. Furthermore, we found that knockout of RecQL4 destabilized PINK1. In addition, RecQL4 knockout cells were more susceptible to apoptosis under mitochondrial stress than the control cells. In conclusion, our findings indicated a novel role of RecQL4 in the regulation of autophagy/mitophagy in U2OS cells.

Calorie restriction as an intervention in ageing

Ageing causes loss of function in tissues and organs, is accompanied by a chronic inflammatory process and affects life- and healthspan. Calorie restriction (CR) is a non-genetic intervention that prevents age-associated diseases and extends longevity in most of the animal models studied so far. CR produces a pleiotropic effect and improves multiple metabolic pathways, generating benefits to the whole organism. Among the effects of CR, modulation of mitochondrial activity and a decrease in oxidative damage are two of the hallmarks. Oxidative damage is reduced by the induction of endogenous antioxidant systems and modulation of the peroxidability index in cell membranes. Mitochondrial activity changes are regulated by inhibition of IGF-1 and Target of Rapamycin (TOR)-dependent activities and activation of AMP-dependent kinase (AMPK) and the sirtuin family of proteins. The activity of PGC-1α and FoxO is regulated by these systems and is involved in mitochondria biogenesis, oxidative metabolism activity and mitochondrial turnover. The use of mimetics and the regulation of common factors have demonstrated that these molecular pathways are essential to explain the effect of CR in the organism. Finally, the anti-inflammatory effect of CR is an interesting emerging factor to be taken into consideration. In the present revision we focus on the general effect of CR and other mimetics in longevity, focusing especially on the cardiovascular system and skeletal muscle.