Targeting SIK3 to modulate hippocampal synaptic plasticity and cognitive function by regulating the transcription of HDAC4 in a mouse model of Alzheimer's disease

Cognitive deterioration and memory decline associated with the progression of Alzheimer's disease (AD) primarily results from synaptic failure. However, current understanding of the upstream regulatory mechanisms controlling synaptic plasticity remains limited. Salt-inducible kinase 3 (SIK3) is central to the signal pathway and is involved in neuronal regulation of sleep duration in mice. We speculated that the SIK3 cascade signaling pathway might contribute to the pathogenesis of AD. Thus, the present study employed AD transgenic mouse models, Morris Water Maze, virus-mediated gene transfer, electrophysiology, co-immunoprecipitation, western blotting, quantitative polymerase chain reaction, immunofluorescence, ChIP-qPCR, Golgi-Cox staining and dendritic spine analysis to investigate this connection. Our results revealed that SIK3 mRNA/protein expression was significantly reduced in middle-aged AD transgenic mouse models and AD patients. Conditional deletion of SIK3 gene in dorsal hippocampal neurons of 5×FAD mice further accelerated cognitive deterioration and impaired synaptic plasticity. In hippocampal neuronal cultures, SIK3 formed a complex with HDAC4, directly phosphorylated HDAC4 and regulated its nuclear cytoplasmic shuttle. Overexpression of SIK3 could facilitate the expression of synaptic plasticity-related genes by directly repressing mef2c or involving the recruitment of histone deacetylase to promoter regions of target genes through regulation of p-HDAC4, and vice versa. Moreover, up-regulation of SLP-S, the truncated fragment of SIK3, in dorsal hippocampal neurons, restored the synaptic plasticity and alleviates the cognitive impairment in 5×FAD mice. Collectively, these findings revealed a novel and important role of SIK3-HDAC4 regulation of synaptic plasticity and propose a new target for therapeutic approaches of cognitive deficits associated with AD.

Saracatinib prompts hemin-induced K562 erythroid differentiation but suppresses erythropoiesis of hematopoietic stem cells

Human myeloid leukemia cells (such as K562) could be used for the study of erythropoiesis, and mature erythroid markers and globins could be induced during leukemia cell differentiation; however, the pathways involved are different compared with those of hematopoietic stem cells (HSCs).We identified the differentially expressed genes (DEGs) of K562 cells and HSCs associated with stem cells and erythroid differentiation. Furthermore, we showed that hemin-induced differentiation of K562 cells could be induced by serum starvation or treatment with the tyrosine kinase inhibitor saracatinib. However, erythroid differentiation of HSCs was inhibited by the deprivation of the important serum component erythropoietin (EPO) or treatment with saracatinib. Finally, we found that the mRNA expression of K562 cells and HSCs was different during saracatinib-treated erythroid differentiation, and the DEGs of K562 cells and HSCs associated with tyrosine-protein kinase were identified.These findings elucidated the cellular phenomenon of saracatinib induction during erythroid differentiation of K562 cells and HSCs, and the potential mechanism is the different mRNA expression profile of tyrosine-protein kinase in K562 cells and HSCs.

An evolutionarily conserved phosphoserine-arginine salt bridge in the interface between ribosomal proteins uS4 and uS5 regulates translational accuracy in Saccharomyces cerevisiae

Protein-protein and protein-rRNA interactions at the interface between ribosomal proteins uS4 and uS5 are thought to maintain the accuracy of protein synthesis by increasing selection of cognate aminoacyl-tRNAs. Selection involves a major conformational change-domain closure-that stabilizes aminoacyl-tRNA in the ribosomal acceptor (A) site. This has been thought a constitutive function of the ribosome ensuring consistent accuracy. Recently, the Saccharomyces cerevisiae Ctk1 cyclin-dependent kinase was demonstrated to ensure translational accuracy and Ser238 of uS5 proposed as its target. Surprisingly, Ser238 is outside the uS4-uS5 interface and no obvious mechanism has been proposed to explain its role. We show that the true target of Ctk1 regulation is another uS5 residue, Ser176, which lies in the interface opposite to Arg57 of uS4. Based on site specific mutagenesis, we propose that phospho-Ser176 forms a salt bridge with Arg57, which should increase selectivity by strengthening the interface. Genetic data show that Ctk1 regulates accuracy indirectly; the data suggest that the kinase Ypk2 directly phosphorylates Ser176. A second kinase pathway involving TORC1 and Pkc1 can inhibit this effect. The level of accuracy appears to depend on competitive action of these two pathways to regulate the level of Ser176 phosphorylation.

Luteolin-7-O-β-d-glucuronide Ameliorates Cerebral Ischemic Injury: Involvement of RIP3/MLKL Signaling Pathway

Luteolin-7-O-β-d-glucuronide (LGU) is a major active flavonoid glycoside compound that is extracted from Ixeris sonchifolia (Bge.) Hance, and it is a Chinese medicinal herb mainly used for the treatment of coronary heart disease, angina pectoris, cerebral infarction, etc. In the present study, the neuroprotective effect of LGU was investigated in an oxygen glucose deprivation (OGD) model and a middle cerebral artery occlusion (MCAO) rat model. In vitro, LGU was found to effectively improve the OGD-induced decrease in neuronal viability and increase in neuronal death by a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and a lactate dehydrogenase (LDH) leakage rate assay, respectively. LGU was also found to inhibit OGD-induced intracellular Ca2+ overload, adenosine triphosphate (ATP) depletion, and mitochondrial membrane potential (MMP) decrease. By Western blotting analysis, LGU significantly inhibited the OGD-induced increase in expressions of receptor-interacting serine/threonine-protein kinase 3 (RIP3) and mixed lineage kinase domain-like protein (MLKL). Moreover, molecular docking analysis showed that LGU might bind to RIP3 more stably and firmly than the RIP3 inhibitor GSK872. Immunofluorescence combined with confocal laser analyses disclosed that LGU inhibited the aggregation of MLKL to the nucleus. Our results suggest that LGU ameliorates OGD-induced rat primary cortical neuronal injury via the regulation of the RIP3/MLKL signaling pathway in vitro. In vivo, LGU was proven, for the first time, to protect the cerebral ischemia in a rat middle cerebral artery occlusion (MCAO) model, as shown by improved neurological deficit scores, infarction volume rate, and brain water content rate. The present study provides new insights into the therapeutic potential of LGU in cerebral ischemia.

The relationship of ALPK1, hyaluronic acid and M1 macrophage polarization in the temporomandibular joint synovitis

M1 macrophage polarization and synovitis play an important role in the pathogenesis of temporomandibular joint osteoarthritis (TMJOA). Reduced molecular weight of hyaluronic acid (HA) in synovial fluid of patients with TMJOA. In addition, high molecular weight hyaluronic acid (HMW-HA) is often used clinically to treat TMJ inflammation. As a pattern recognition receptor of the cytoplasm, ALPK1 was found to be pro-inflammatory in a variety of diseases. However, the relationship of ALPK1, HA and M1 macrophage polarization in TMJ synovitis remains unclear. We aimed to investigate the role of ALPK1 and HA in macrophage polarization and TMJ synovitis and the underlying mechanisms. The results demonstrated that ALPK1 was highly upregulated in the synovial macrophages in the inflamed TMJ synovium of patients. Low molecular weight hyaluronic acid (LMW-HA) promoted the expression of ALPK1 and M1 macrophage-associated genes. Besides, rhALPK1 promoted the expression of M1 macrophage-associated factors and the nuclear translocation of PKM2. Furthermore, ALPK1 knockout mice exhibited limited infiltration of macrophages and decreased expression levels of M1 macrophage-associated genes in CFA-induced TMJ synovitis. While HMW-HA inhibited the expression of ALPK1 and M1 macrophage polarization. Our results elucidated that ALPK1 promoted TMJ synovitis by promoting nuclear PKM2-mediated M1 macrophage polarization, whereas HMW-HA inhibited the expression of ALPK1 as well as M1 macrophage polarization.

Ethanol-Induced Hepatic Ferroptosis Is Mediated by PERK-Dependent MAMs Formation: Preventive Role of Quercetin

SCOPE

Iron deposition is frequently observed in alcoholic liver disease (ALD), which indicates a potential role of ferroptosis in its development. This study aims to explore the effects of quercetin on ferroptosis in ALD and elucidates the underlying mechanism involving the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs) mediated by protein kinase RNA-like endoplasmic reticulum kinase (PERK).

METHODS AND RESULTS

C57BL/6J mice are fed either a regular or an ethanol-containing liquid diet (with 28% energy form ethanol) with or without quercetin supplementation (100 mg kg-1 BW) for 12 weeks. Ethanol feeding or treatment induced ferroptosis in mice and AML12 cells, which is associated with increased MAMs formation and PERK expression within MAMs. Quercetin attenuates these changes and protects against ethanol-induced liver injury. The antiferroptotic effect of quercetin is abolished by ferroptosis inducers, but mimicked by ferroptosis inhibitors and PERK knockdown. The study demonstrates that PERK structure, rather than its kinase activity (transfected with the K618A site mutation that inhibits kinase activity-ΔK plasmid or protein C terminal knockout-ΔC plasmid of PERK), mediates the enhanced MAMs formation and ferroptosis during the ethanol exposure.

CONCLUSION

Quercetin ameliorates ethanol-induced liver injury by inhibiting ferroptosis via modulating PERK-dependent MAMs formation.

DDIT3/CHOP promotes LPS/ATP-induced pyroptosis in osteoblasts via mitophagy inhibition

Inflammatory environments can trigger endoplasmic reticulum (ER) stress and lead to pyroptosis in various tissues and cells, including liver, brain, and immune cells. As a key factor of ER stress, DNA damage-inducible transcript 3 (DDIT3)/CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) is upregulated in osteoblasts during inflammatory stimulation. DDIT3/CHOP may therefore regulate osteoblast pyroptosis in inflammatory conditions. During this investigation, we found that lipopolysaccharides (LPS)/adenosine 5'-triphosphate (ATP) stimulation in vitro induced osteoblasts to undergo pyroptosis, and the expression of DDIT3/CHOP was increased during this process. The overexpression of DDIT3/CHOP further promoted osteoblast pyroptosis as evidenced by the increased expression of the inflammasome NLR family pyrin domain containing 3 (NLRP3) and ratios of caspase-1 p20/caspase-1 and cleaved gasdermin D (GSDMD)/GSDMD. To explore the specific mechanism of this effect, we found through fluorescence imaging and Western blot analysis that LPS/ATP stimulation promoted PTEN-induced kinase 1 (PINK1)/E3 ubiquitin-protein ligase parkin (Parkin)-mediated mitophagy in osteoblasts, and this alteration was suppressed by the DDIT3/CHOP overexpression, resulting in increased ratio of pyroptosis compared with the control groups. The impact of DDIT3/CHOP on pyroptosis in osteoblasts was reversed by the application of carbonyl cyanide 3-chlorophenylhydrazone (CCCP), a specific mitophagy agonist. Therefore, our data demonstrated that DDIT3/CHOP promotes osteoblast pyroptosis by inhibiting PINK1/Parkin-mediated mitophagy in an inflammatory environment.

Precise Readout of MEK1 Proteoforms upon MAPK Pathway Modulation by Individual Ion Mass Spectrometry

The functions of proteins bearing multiple post-translational modifications (PTMs) are modulated by their modification patterns, yet precise characterization of them is difficult. MEK1 (also known as MAP2K1) is one such example that acts as a gatekeeper of the mitogen-activating protein kinase (MAPK) pathway and propagates signals via phosphorylation by upstream kinases. In principle, top-down mass spectrometry can precisely characterize whole MEK1 proteoforms, but fragmentation methods that would enable the site-specific characterization of labile modifications on 43 kDa protein ions result in overly dense tandem mass spectra. By using the charge-detection method called individual ion mass spectrometry, we demonstrate how complex mixtures of phosphoproteoforms and their fragment ions can be reproducibly handled to provide a "bird's eye" view of signaling activity through mapping proteoform landscapes in a pathway. Using this approach, the overall stoichiometry and distribution of 0-4 phosphorylations on MEK1 was determined in a cellular model of drug-resistant metastatic melanoma. This approach can be generalized to other multiply modified proteoforms, for which PTM combinations are key to their function and drug action.

CDK12 is a potential biomarker for diagnosis, prognosis and immunomodulation in pan-cancer

Cell cycle-dependent protein kinase 12 (CDK12) plays a key role in a variety of carcinogenesis processes and represents a promising therapeutic target for cancer treatment. However, to date, there have been no systematic studies addressing its diagnostic, prognostic and immunological value across cancers. Here, we found that CDK12 was significantly upregulated in various types of cancers, and it expression increased with progression in ten cancer types, including breast cancer, cholangiocarcinoma and colon adenocarcinoma. Moreover, the ROC curves indicated that CDK12 showed diagnostic value in eight cancer types. High CDK12 expression was associated with poor prognosis in eight types of cancer, including low-grade glioma, mesothelioma, melanoma and pancreatic cancer. Furthermore, we conducted immunoassays to explore the exact mechanisms underlying CDK12-induced carcinogenesis, which revealed that increased expression of CDK12 allowed tumours to evade immune surveillance and upregulate immune checkpoint genes. Additionally, mutational studies have shown that amplification and missense mutations are the predominant mutational events affecting CDK12 across cancers. These findings establish CDK12 as a significant biological indicator of cancer diagnosis, prognosis, and immunotherapeutic targeting. Early surveillance and employment of CDK12 inhibitors, along with concomitant immunotherapy interventions, may enhance the clinical outcomes of cancer patients.

Mitophagy protects against silver nanoparticle-induced hepatotoxicity by inhibiting mitochondrial ROS and the NLRP3 inflammasome

Silver nanoparticles (AgNPs) have wide clinical applications because of their excellent antibacterial properties; however, they can cause liver inflammation in animals. Macrophages are among the main cells mediating inflammation and are also responsible for the phagocytosis of nanomaterials. The NLRP3 inflammasome is a major mechanism of inflammation, and its activation both induces cytokine release and triggers inflammatory cell death (i.e., pyroptosis). In previous studies, we demonstrated that mitophagy activation plays a protective role against AgNP-induced hepatotoxicity. However, the exact molecular mechanisms underlying these processes are not fully understood. In this study, we demonstrate that AgNP exposure induces NLRP3 inflammasome activation, mitochondrial damage and pyroptosis in vivo and in vitro. NLRP3 silencing or inhibiting mitochondrial reactive oxygen species (ROS) overproduction reduces PINK1-Parkin-mediated mitophagy. Meanwhile, the inhibition of mitophagy ROS production, mitochondrial, NLRP3-mediated inflammation, and pyroptosis in RAW264.7 cells were more pronounced than in the control group. These results suggest that PINK1-Parkin-mediated mitophagy plays a protective role by reducing AgNP-induced mitochondrial ROS and subsequent NLRP3 inflammasome activation.

The effect of PK gene overexpression on content and antioxidant properties of carotenoids in marine microalga Dunaliella parva

Dunaliella parva can extensively accumulate carotenoids, which is a promising raw material for carotenoids production. Carotenoids have important medicinal value. D. parva is an ideal organism for studying the mechanism of carotenoid synthesis. Our previous study identified a transcription factor DpAP2 which could regulate carotenoid synthesis in D. parva. In addition, DpAP2 could interact with three proteins with different activities (DNA binding transcription factor activity, protein kinase activity, and alpha-D-phosphohexomutase). To investigate the function of PK gene encoding interacting protein of DpAP2 with protein kinase activity in D. parva, PK gene was cloned into vector pBI221-GFP-UbiΩ-CAT and transformed into D. parva in this study. The results showed that overexpression of PK gene enhanced the contents of carotenoids, total sugars, proteins, and antioxidant activities of carotenoid extract such as superoxide radical scavenging activity, reducing power, hydroxyl radical scavenging activity in transgenic D. parva with overexpression of PK gene. This study explored the function of PK gene, and improved the medicinal value of D. parva.

Rapid translocation of NGR proteins driving polarization of PIN-activating D6 protein kinase during root gravitropism

Root gravitropic bending represents a fundamental aspect of terrestrial plant physiology. Gravity is perceived by sedimentation of starch-rich plastids (statoliths) to the bottom of the central root cap cells. Following gravity perception, intercellular auxin transport is redirected downwards leading to an asymmetric auxin accumulation at the lower root side causing inhibition of cell expansion, ultimately resulting in downwards bending. How gravity-induced statoliths repositioning is translated into asymmetric auxin distribution remains unclear despite PIN auxin efflux carriers and the Negative Gravitropic Response of roots (NGR) proteins polarize along statolith sedimentation, thus providing a plausible mechanism for auxin flow redirection. In this study, using a functional NGR1-GFP construct, we visualized the NGR1 localization on the statolith surface and plasma membrane (PM) domains in close proximity to the statoliths, correlating with their movements. We determined that NGR1 binding to these PM domains is indispensable for NGR1 functionality and relies on cysteine acylation and adjacent polybasic regions as well as on lipid and sterol PM composition. Detailed timing of the early events following graviperception suggested that both NGR1 repolarization and initial auxin asymmetry precede the visible PIN3 polarization. This discrepancy motivated us to unveil a rapid, NGR-dependent translocation of PIN-activating AGCVIII kinase D6PK towards lower PMs of gravity-perceiving cells, thus providing an attractive model for rapid redirection of auxin fluxes following gravistimulation.

Genetic architecture of the structural connectome

Myelinated axons form long-range connections that enable rapid communication between distant brain regions, but how genetics governs the strength and organization of these connections remains unclear. We perform genome-wide association studies of 206 structural connectivity measures derived from diffusion magnetic resonance imaging tractography of 26,333 UK Biobank participants, each representing the density of myelinated connections within or between a pair of cortical networks, subcortical structures or cortical hemispheres. We identify 30 independent genome-wide significant variants after Bonferroni correction for the number of measures studied (126 variants at nominal genome-wide significance) implicating genes involved in myelination (SEMA3A), neurite elongation and guidance (NUAK1, STRN, DPYSL2, EPHA3, SEMA3A, HGF, SHTN1), neural cell proliferation and differentiation (GMNC, CELF4, HGF), neuronal migration (CCDC88C), cytoskeletal organization (CTTNBP2, MAPT, DAAM1, MYO16, PLEC), and brain metal transport (SLC39A8). These variants have four broad patterns of spatial association with structural connectivity: some have disproportionately strong associations with corticothalamic connectivity, interhemispheric connectivity, or both, while others are more spatially diffuse. Structural connectivity measures are highly polygenic, with a median of 9.1 percent of common variants estimated to have non-zero effects on each measure, and exhibited signatures of negative selection. Structural connectivity measures have significant genetic correlations with a variety of neuropsychiatric and cognitive traits, indicating that connectivity-altering variants tend to influence brain health and cognitive function. Heritability is enriched in regions with increased chromatin accessibility in adult oligodendrocytes (as well as microglia, inhibitory neurons and astrocytes) and multiple fetal cell types, suggesting that genetic control of structural connectivity is partially mediated by effects on myelination and early brain development. Our results indicate pervasive, pleiotropic, and spatially structured genetic control of white-matter structural connectivity via diverse neurodevelopmental pathways, and support the relevance of this genetic control to healthy brain function.

METTL3/YTHDF2 m6A axis mediates the progression of diabetic nephropathy through epigenetically suppressing PINK1 and mitophagy

AIMS

This research aimed to investigate the specific mechanism of methyltransferase like 3 (METTL3) in the progression of diabetic kidney disease (DKD).

MATERIALS AND METHODS

The model of diabetic kidney disease was established with HK-2 cells and mice in vitro and in vivo. The N6 methyladenosine (m6A) contents in the cells and tissues were detected with a commercial kit and the m6A levels of PTEN induced putative kinase 1 (PINK2) were detected with a MeRIP kit. The mRNA and protein levels were determined with RT-qPCR and western blot. The ROS, TNF-α, and IL-6 levels were assessed with ELISA. The cell proliferative ability was measured by a CCK-8 assay and cell apoptosis was determined with TUNEL staining. The HE and Masson staining was performed to observe the renal morphology. The RIP assay was conducted to detect the interaction between METTL3/YTHDF2 and PINK1.

RESULTS

The m6A content and METTL3 levels were prominently elevated in diabetic kidney disease. METTL3 silencing promoted the cell growth and the expression of LC3 II, PINK1, and Parkin, while inhibiting the cell apoptosis and the expression of LC3 I and p62 in the high glucose (HG) stimulated HK-2 cells. METTL3 silencing also decreased the ROS, TNF-α, and IL-6 levels in diabetic kidney disease. PINK1 silencing neutralized the function of sh-METTL3 in the HG stimulated HK-2 cells. The HE and Masson staining showed that METTL3 silencing alleviated the kidney injury induced by DKD. METTL3 silencing decreased the m6A levels of PINK1, while increased the mRNA levels of PINK1 which depended on YTHDF2.

CONCLUSIONS

METTL3 silencing could inhibit the progression of diabetic nephropathy in vivo and in vitro by regulating the m6A modification of PINK1, which depends on YTHDF2. Our research lays the theoretical foundation for the precise treatment of diabetic kidney disease and the development of targeted drugs in the future.

Regulation of Aerobic Succinate Transporter dctA of E. coli by cAMP-CRP, DcuS-DcuR, and EIIAGlc: Succinate as a Carbon Substrate and Signaling Molecule

INTRODUCTION

C4-dicarboxylates (C4-DC) have emerged as significant growth substrates and signaling molecules for various Enterobacteriaceae during their colonization of mammalian hosts. Particularly noteworthy is the essential role of fumarate respiration during colonization of pathogenic bacteria. To investigate the regulation of aerobic C4-DC metabolism, the study explored the transcriptional control of the main aerobic C4-DC transporter, dctA, under different carbohydrate conditions. In addition, mutants related to carbon catabolite repression (CCR) and C4-DC regulation (DcuS-DcuR) were examined to better understand the regulatory integration of aerobic C4-DC metabolism into CCR. For initial insight into posttranslational regulation, the interaction between the aerobic C4-DC transporter DctA and EIIAGlc from the glucose-specific phosphotransferase system was investigated.

METHODS

The expression of dctA was characterized in the presence of various carbohydrates and regulatory mutants affecting CCR. This was accomplished by fusing the dctA promoter (PdctA) to the lacZ reporter gene. Additionally, the interaction between DctA and EIIAGlc of the glucose-specific phosphotransferase system was examined in vivo using a bacterial two-hybrid system.

RESULTS

The dctA promoter region contains a class I cAMP-CRP-binding site at position -81.5 and a DcuR-binding site at position -105.5. DcuR, the response regulator of the C4-DC-activated DcuS-DcuR two-component system, and cAMP-CRP stimulate dctA expression. The expression of dctA is subject to the influence of various carbohydrates via cAMP-CRP, which differently modulate cAMP levels. Here we show that EIIAGlc of the glucose-specific phosphotransferase system strongly interacts with DctA, potentially resulting in the exclusion of C4-DCs when preferred carbon substrates, such as sugars, are present. In contrast to the classical inducer exclusion known for lactose permease LacY, inhibition of C4-DC uptake into the cytoplasm affects only its role as a substrate, but not as an inducer since DcuS detects C4-DCs in the periplasmic space ("substrate exclusion"). The work shows an interplay between cAMP-CRP and the DcuS-DcuR regulatory system for the regulation of dctA at both transcriptional and posttranslational levels.

CONCLUSION

The study highlights a hierarchical interplay between global (cAMP-CRP) and specific (DcuS-DcuR) regulation of dctA at the transcriptional and posttranslational levels. The integration of global and specific transcriptional regulation of dctA, along with the influence of EIIAGlc on DctA, fine-tunes C4-DC catabolism in response to the availability of other preferred carbon sources. It attributes DctA a central role in the control of aerobic C4-DC catabolism and suggests a new role to EIIAGlc on transporters (control of substrate uptake by substrate exclusion).

Adrenoreceptor phylogeny and novel functions of nitric oxide in ascidian immune cells

Nitric oxide (NO) is a simple molecule involved in many biological processes and functions in the cardiovascular, neural, and immune systems. In recent years, NO has also been recognized as a crucial messenger in communication between the nervous and immune systems. Together with NO, catecholamines are the main group of neurotransmitters involved in cross-talk between the nervous and immune systems. Catecholamines such as noradrenaline, can act on immune cells through adrenoreceptors (ARs) present on the cell surface, and NO can cross the cell membrane and interact with secondary messengers, modulating catecholamine production. Here, we analyzed the mutual modulation by noradrenaline and NO in Phallusia nigra immune cells for specific subtypes of ARs. We also investigated the involvement of protein kinases A and C as secondary messengers to these specific subtypes of ARs in the adrenergic signaling pathway that culminates in NO modulation, and the phylogenetic distribution of ARs in deuterostome genomes. This analysis provided evidence for single-copy orthologs of α1, α2 and β-AR in ascidian genomes, suggesting that NO and NA act on a less diverse set of ARs in urochordates. Pharmacological assays showed that high levels of NO can induce ascidian immune cells to produce catecholamines. We also observed that protein kinases A and C are the secondary messengers involved in downstream modulation of NO production through an ancestral β-AR. Taken together, these results provide new information on NO as a modulator of immune cells, and reveal the molecules involved in the signaling pathway of ARs. The results also indicate that ARs may participate in NO modulation. Finally, our results suggest that the common ancestor of urochordates possessed a less complex system of ARs required for immune action and diverse pharmacological responses, since the α-ARs are phylogenetically more related to D1-receptors than are the β-ARs.

Steady State and Time-Dependent Fluorescent Peptide Assays for Protein Kinases

Protein kinases catalyze the phosphorylation of proteins most commonly on Ser, Thr, and Tyr residues and regulate many cellular events in eukaryotic cells, such as cell cycle progression, transcription, metabolism, and apoptosis. Protein kinases each have a conserved ATP-binding site and one or more substrate-binding site(s) that exhibit recognition features for different protein substrates. By bringing ATP and a substrate into proximity, each protein kinase can transfer the γ phosphate of the ATP molecule to a hydroxyl group of the target residue on the substrate. In such a way, signaling pathways downstream from the substrate can be regulated based on the phosphorylated versus dephosphorylated status of the substrate. Although there are a number of ways to assay the activity of protein kinases, most of them are technically cumbersome and/or are indirect or based on quenched reactions. This protocol describes an assay employing a fluorescent peptide substrate to detect phosphorylation by protein kinases in real time. The assay is based on the principle that the phosphorylation of the peptide substrate leads to an increase in the fluorescence emission intensity of an appended fluorophore. We extend the application of this assay to an example of how to assess time-dependent covalent inhibition of kinases as well. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Measuring protein kinase activity using fluorescent peptides Alternate Protocol: Measuring protein kinase activity using a fluorescence plate reader Support Protocol: Labeling peptides with sox fluorophore Basic Protocol 2: Measuring time-dependent ATP-competitive inhibition of protein kinases using fluorescent peptides.

Immunomodulatory and clinical effects of receptor-interacting protein kinase 1 (RIPK1) inhibitor eclitasertib (SAR443122) in patients with severe COVID-19: a phase 1b, randomized, double-blinded, placebo-controlled study

BACKGROUND

Targeting receptor-interacting serine/threonine protein kinase 1 could mitigate the devastating sequelae of the hyperinflammatory state observed in severe cases of COVID-19. This study explored the immunomodulatory and clinical effects of the receptor-interacting serine/threonine protein kinase 1 inhibitor SAR443122 (eclitasertib) in patients with severe COVID-19.

METHODS

In this Phase 1b, double-blinded, placebo-controlled study (NCT04469621) a total of 82 patients were screened, of whom 68 patients were eligible and randomized (2:1) to receive eclitasertib 600 mg (300 mg twice daily) or placebo up to 14 days. Primary outcome was relative change in C-reactive protein from baseline to Day 7. Time to clinical improvement using 7-point ordinal scale, ventilator/respiratory failure-free days, change in SpO2/FiO2 ratio, and biomarkers of severe COVID-19 were explored.

RESULTS

Geometric mean ratio (point estimate [90% confidence interval]) of the relative change from baseline in C-reactive protein with eclitasertib vs. placebo on Day 7 was 0.85 (0.49-1.45; p = 0.30). Median time to 50% decrease in C-reactive protein from baseline was 3 days vs. 5 days (p = 0.056) with eclitasertib vs. placebo. Median time to ≥ 2-point improvement on 7-point clinical symptoms scale was 8 days vs. 10 days with eclitasertib vs. placebo (p = 0.38). Mean ventilator/respiratory failure-free days, change in baseline-adjusted SpO2/FiO2 ratio, and clinical biomarkers showed consistent numerical improvements with eclitasertib vs. placebo. The most frequently reported treatment-emergent adverse events were gastrointestinal disorders and condition aggravated/worsened COVID-19 pneumonia.

CONCLUSIONS

Eclitasertib was well tolerated with consistent trends toward more rapid resolution of inflammatory biomarkers and clinical improvement in severe COVID-19 patients than placebo.

CLINICALTRIALS

GOV IDENTIFIER

NCT04469621, first posted on clinicaltrials.gov on July 14, 2020.

XRN1 deletion induces PKR-dependent cell lethality in interferon-activated cancer cells

Emerging data suggest that induction of viral mimicry responses through activation of double-stranded RNA (dsRNA) sensors in cancer cells is a promising therapeutic strategy. One approach to induce viral mimicry is to target molecular regulators of dsRNA sensing pathways. Here, we show that the exoribonuclease XRN1 is a negative regulator of the dsRNA sensor protein kinase R (PKR) in cancer cells with high interferon-stimulated gene expression. XRN1 deletion causes PKR pathway activation and consequent cancer cell lethality. Disruption of interferon signaling with the JAK1/2 inhibitor ruxolitinib can decrease cellular PKR levels and rescue sensitivity to XRN1 deletion. Conversely, interferon-β stimulation can increase PKR levels and induce sensitivity to XRN1 inactivation. Lastly, XRN1 deletion causes accumulation of endogenous complementary sense/anti-sense RNAs, which may represent candidate PKR ligands. Our data demonstrate how XRN1 regulates PKR and how this interaction creates a vulnerability in cancer cells with an activated interferon cell state.

Protective effect against toxoplasmosis in BALB/C mice vaccinated with recombinant Toxoplasma gondii CDPK3, GRA35, and ROP46 protein cocktail vaccine

Toxoplasma gondii (T. gondii) is one of the most common pathogenic protozoa in the world, and causes toxoplasmosis, which in varying degrees causes significant economic losses and poses a serious public health challenge globally. To date, the development of an effective vaccine for human toxoplasmosis remains a challenge. Given that T.gondii calcium-dependent protein kinase 3 (CDPK3), dense granule protein 35 (GRA35) and rhoptry organelle protein 46 (ROP46) play key roles during Toxoplasma gondii invasion of host cells, we developed a protein vaccine cocktail including these proteins and validated its protective efficacy. The specific protective effects of vaccine on mice were analyzed by measuring serum antibodies, cytokines, splenocyte proliferation, the percentage of CD4+ and CD8+ T-lymphocytes, survival rate, and parasite cyst burden. The results showed that mice vaccinated with a three-protein cocktail produced the highest levels of immune protein antibodies to IgG, and high levels of IFN-γ, IL-2, IL-4, and IL-10 compared to other mice vaccinated with two proteins. In addition, CD4+ and CD8+ T cell percentages were significantly elevated. Compared to the control groups, mice vaccinated with the three-protein cocktail survived significantly longer after acute infection with T. gondii and had significantly fewer cysts after chronic infection. These results demonstrated that a cocktail vaccine of TgCDPK3, TgGRA35, and TgROP46 can effectively induce cellular and humoral immune responses with good protective effects in mice, indicating its potential as vaccine candidates for toxoplasmosis.

Effect of electroacupuncture on neuronal programmed necrosis by regulating RIP1/RIP3/MLKL pathway in rats with cerebral ischemia reperfusion injury

OBJECTIVES

To investigate the neuroprotective effect of electroacupuncture (EA) at "Quchi"(LI11) and "Zusanli"(ST36) in the rats with cerebral ischemia reperfusion injury and its influence on programmed necrosis of cerebral cortical neurons.

METHODS

Sixty male SD rats were randomly divided into sham-operation group, model group, EA group and inhibitor group, with 15 rats in each group. Left middle cerebral artery occlusion model was established using the modified thread embolism method. In the sham-operation group, the carotid artery was exposed and dissociated in each rat. EA was applied to "Quchi"(LI11) and "Zusanli"(ST36) on the right side for 30 min each time, once daily for 7 days in the rats of the EA group. The rats in the inhibitor group were intraperitoneally injected with norstatin-1 (0.6 mg/kg) for consecutive 7 days. The neurological deficit score of rats in each group was observed. HE staining was adopted to detect the degree of pathological damage of the cerebral cortex in the infarction area. Using TUNEL staining, the apoptosis of cortical neurons in the infarction area was determined；the contents of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 were detected by ELISA；the mRNA and protein expression of the receptor interacting protein-1 (RIP1), the receptor interacting protein-3 (RIP3) and the substrate mixed lineage kinase like protein (MLKL) were detected by fluorescence quantitative PCR and Western blot, respectively.

RESULTS

In comparison with the sham-operation group, the neurological deficit score in the model group was higher(P<0.01)；HE staining showed that there was the pathological damage in the infarction area；the neuron apoptosis rate, the contents of TNF-α, IL-1β and IL-6, and the mRNA and protein expressions of RIP1, RIP3 and MLKL increased(P<0.01) in the model group. In the EA group, the neurological deficit score was reduced(P<0.01)；HE staining showed that the pathological damage was ameliorated in the infarction area；the neuron apoptosis rate, the contents of TNF-α, IL-1β and IL-6, and the mRNA and protein expressions of RIP1, RIP3, MLKL decreased(P<0.05, P<0.01) when compared with those in the model group.

CONCLUSIONS

EA can attenuate cerebral ischemia reperfusion injury and display its neuroprotective effect probably through inhibiting programmed necrosis of cerebral cortical neurons in the rats.

Serodiagnosis of multiple cancers using an extracellular protein kinase A autoantibody-based lateral flow platform

Extracellular protein kinase A autoantibody (ECPKA-AutoAb) has been suggested as a universal cancer biomarker due to its higher amounts in serum of several types of cancer patients than that of normal individuals. Herein, we first developed a lateral flow immunoassay (LFIA) tool, using a sandwich format, toward ECPKA-AutoAb in human serum. For this format, 3G2 as a capture antibody was identified using hybridoma technique and a series of screenings where it showed superior capacity to recognize Enzo PKA catalytic subunit alpha (Cα), compared to other PKA antibodies and antigens. Using these components, we performed sandwich ELISA toward a mimic and real sample of ECPKA-AutoAb. As per the results, limit of detection (LOD) was found to be 135 ng/mL and ECPKA-AutoAb levels were higher in various cancer patients than in normal individuals like previous studies. Based on these results, we applied this sandwich format into LFIA tool and found that the LOD of the fabricated LFIA tool showed about 3.8 ng/mL using spiked PKA-Ab, which is significantly improved compared to the LOD of sandwich ELISA. Also, the developed LFIA tool demonstrated a remarkable ability to detect significant differences in ECPKA-AutoAb levels between normal and cancer patients within 15 min, showing a potential for point-of-care (PoC) detection. One interesting point is that our LFIA strip contains an additional conjugation pad II, named because of its position behind the conjugation pad, in which PKA Cα is dried, enabling a sandwich format.

Receptor-interacting Protein Kinase 2 Is an Immunotherapy Target in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal malignancy because of its aggressive nature and the paucity of effective treatment options. Almost all registered drugs have proven ineffective in addressing the needs of patients with PDAC. This is the result of a poor understanding of the unique tumor-immune microenvironment (TME) in PDAC. To identify druggable regulators of immunosuppressive TME, we performed a kinome- and membranome-focused CRISPR screening using orthotopic PDAC models. Our data showed that receptor-interacting protein kinase 2 (RIPK2) is a crucial driver of immune evasion of cytotoxic T-cell killing and that genetic or pharmacologic targeting of RIPK2 sensitizes PDAC to anti-programmed cell death protein 1 (anti-PD-1) immunotherapy, leading to prolonged survival or complete regression. Mechanistic studies revealed that tumor-intrinsic RIPK2 ablation disrupts desmoplastic TME and restores MHC class I (MHC-I) surface levels through eliminating NBR1-mediated autophagy-lysosomal degradation. Our results provide a rationale for a novel combination therapy consisting of RIPK2 inhibition and anti-PD-1 immunotherapy for PDAC.

SIGNIFICANCE

PDAC is resistant to almost all available therapies, including immune checkpoint blockade. Through in vivo CRISPR screen, we identified that RIPK2 plays a crucial role in facilitating immune evasion by impeding antigen presentation and cytotoxic T-cell killing. Targeting tumor-intrinsic RIPK2 either genetically or pharmacologically improves PDAC to anti-PD-1 immunotherapy. See related commentary by Liu et al., p. 208 . This article is featured in Selected Articles from This Issue, p. 201.

RNA recognition by PKR during DNA virus infection

Protein kinase R (PKR) is a double-stranded RNA (dsRNA) binding protein that plays a crucial role in innate immunity during viral infection and can restrict both DNA and RNA viruses. The potency of its antiviral function is further reflected by the large number of viral-encoded PKR antagonists. However, much about the regulation of dsRNA accumulation and PKR activation during viral infection remains unknown. Since DNA viruses do not have an RNA genome or RNA replication intermediates like RNA viruses do, PKR-mediated dsRNA detection in the context of DNA virus infection is particularly intriguing. Here, we review the current state of knowledge regarding the regulation of PKR activation and its antagonism during infection with DNA viruses.

Vagus nerve stimulation inhibits cortical spreading depression via glutamate-dependent TrkB activation mechanism in the nucleus tractus solitarius

BACKGROUND

Vagus nerve stimulation (VNS) was recently found to inhibit cortical spreading depression (CSD), the underlying mechanism of migraine aura, through activation of the nucleus tractus solitarius (NTS), locus coeruleus (LC) and dorsal raphe nucleus (DRN). The molecular mechanisms underlying the effect of VNS on CSD in these nuclei remain to be explored. We hypothesized that VNS may activate glutamate receptor-mediated tropomyosin kinase B (TrkB) signaling in the NTS, thereby facilitating the noradrenergic and serotonergic neurotransmission to inhibit CSD.

METHODS

To investigate the role of TrkB and glutamate receptors in non-invasive VNS efficacy on CSD, a validated KCl-evoked CSD rat model coupled with intra-NTS microinjection of selective antagonists, immunoblot and immunohistochemistry was employed.

RESULTS

VNS increased TrkB phosphorylation in the NTS. Inhibition of intra-NTS TrkB abrogated the suppressive effect of VNS on CSD and CSD-induced cortical neuroinflammation. TrkB was found colocalized with glutamate receptors in NTS neurons. Inhibition of glutamate receptors in the NTS abrogated VNS-induced TrkB activation. Moreover, the blockade of TrkB in the NTS attenuated VNS-induced activation of the LC and DRN.

CONCLUSIONS

VNS induces the activation of glutamate receptor-mediated TrkB signaling in the NTS, which might modulate serotonergic and norepinephrinergic innervation to the cerebral cortex to inhibit CSD and cortical inflammation.

Effect of diminazene on cardiac hypertrophy through mitophagy in rat models with hyperthyroidism induced by levothyroxine

Hyperthyroidism is associated with the alteration in molecular pathways involved in the regulation of mitochondrial mass and apoptosis, which contribute to the development of cardiac hypertrophy. Diminazene (DIZE) is an animal anti-infection drug that has shown promising effects on improving cardiovascular disease. The aim of the present study was to investigate the therapeutic effect of DIZE on cardiac hypertrophy and the signaling pathways involved in this process in the hyperthyroid rat model. Twenty male Wistar rats were equally divided into four groups: control, hyperthyroid, DIZE, and hyperthyroid + DIZE. After 28 days of treatment, serum thyroxine (T4) and thyroid stimulating hormone (TSH) level, cardiac hypertrophy indices, cardiac damage markers, cardiac malondialdehyde (MDA), and superoxide dismutase (SOD) level, the mRNA expression level of mitochondrial and apoptotic genes were evaluated. Hyperthyroidism significantly decreased the cardiac expression level of SIRT1/PGC1α and its downstream involved in the regulation of mitochondrial biogenesis, mitophagy, and antioxidant enzyme activities including TFAM, PINK1/MFN2, Drp1, and Nrf2, respectively, as well as stimulated mitochondrial-dependent apoptosis by reducing Bcl-2 expression and increasing Bax expression. Treatment with DIZE significantly reversed the downregulation of SIRT1, PGC1α, PINK1, MFN2, Drp1, and Nrf2 but did not significantly change the TFAM expression. Moreover, DIZE suppressed apoptosis by normalizing the cardiac expression levels of Bax and Bcl-2. DIZE is effective in attenuating hyperthyroidism-induced cardiac hypertrophy by modulating the mitophagy-related pathway, suppressing apoptosis and oxidative stress.

Properties of FDA-approved small molecule protein kinase inhibitors: A 2024 update

Owing to the dysregulation of protein kinase activity in many diseases including cancer, this enzyme family has become one of the most important drug targets in the 21st century. There are 80 FDA-approved therapeutic agents that target about two dozen different protein kinases and seven of these drugs were approved in 2023. Of the approved drugs, thirteen target protein-serine/threonine protein kinases, four are directed against dual specificity protein kinases (MEK1/2), twenty block nonreceptor protein-tyrosine kinases, and 43 inhibit receptor protein-tyrosine kinases. The data indicate that 69 of these drugs are prescribed for the treatment of neoplasms. Six drugs (abrocitinib, baricitinib, deucravacitinib, ritlecitinib, tofacitinib, upadacitinib) are used for the treatment of inflammatory diseases (atopic dermatitis, rheumatoid arthritis, psoriasis, alopecia areata, and ulcerative colitis). Of the 80 approved drugs, nearly two dozen are used in the treatment of multiple diseases. The following seven drugs received FDA approval in 2023: capivasertib (HER2-positive breast cancer), fruquintinib (metastatic colorectal cancer), momelotinib (myelofibrosis), pirtobrutinib (mantle cell lymphoma, chronic lymphocytic leukemia, small lymphocytic lymphoma), quizartinib (Flt3-mutant acute myelogenous leukemia), repotrectinib (ROS1-positive lung cancer), and ritlecitinib (alopecia areata). All of the FDA-approved drugs are orally effective with the exception of netarsudil, temsirolimus, and trilaciclib. This review summarizes the physicochemical properties of all 80 FDA-approved small molecule protein kinase inhibitors including the molecular weight, number of hydrogen bond donors/acceptors, polar surface area, potency, solubility, lipophilic efficiency, and ligand efficiency.

Combinatorial regulation by ERK1/2 and CK1δ protein kinases leads to HIF-1α association with microtubules and facilitates its symmetrical distribution during mitosis

Hypoxia-inducible factor-1 (HIF-1) is the key transcriptional mediator of the cellular response to hypoxia and is also involved in cancer progression. Regulation of its oxygen-sensitive HIF-1α subunit involves post-translational modifications that control its stability, subcellular localization, and activity. We have previously reported that phosphorylation of the HIF-1α C-terminal domain by ERK1/2 promotes HIF-1α nuclear accumulation and stimulates HIF-1 activity while lack of this modification triggers HIF-1α nuclear export and its association with mitochondria. On the other hand, modification of the N-terminal domain of HIF-1α by CK1δ impairs HIF-1 activity by obstructing the formation of a HIF-1α/ARNT heterodimer. Investigation of these two antagonistic events by expressing double phospho-site mutants in HIF1A-/- cells under hypoxia revealed independent and additive phosphorylation effects that can create a gradient of HIF-1α subcellular localization and transcriptional activity. Furthermore, modification by CK1δ caused mitochondrial release of the non-nuclear HIF-1α form and binding to microtubules via its N-terminal domain. In agreement, endogenous HIF-1α could be shown to co-localize with mitotic spindle microtubules and interact with tubulin, both of which were inhibited by CK1δ silencing or inhibition. Moreover, CK1δ expression was necessary for equal partitioning of mother cell-produced HIF-1α to the daughter cell nuclei at the end of mitosis. Overall, our results suggest that phosphorylation by CK1δ stimulates the association of non-nuclear HIF-1α with microtubules, which may serve as a means to establish a symmetric distribution of HIF-1α during cell division under low oxygen conditions.

Protein kinase D1 - A targetable mediator of pancreatic cancer development

Members of the Protein kinase D (PKD) kinase family each play important cell-specific roles in the regulation of normal pancreas functions. In pancreatic diseases PKD1 is the most widely characterized isoform with roles in pancreatitis and in induction of pancreatic cancer and its progression. PKD1 expression and activation increases in pancreatic acinar cells through macrophage secreted factors, Kirsten rat sarcoma viral oncogene homolog (KRAS) signaling, and reactive oxygen species (ROS), driving the formation of precancerous lesions. In precancerous lesions PKD1 regulates cell survival, growth, senescence, and generation of doublecortin like kinase 1 (DCLK1)-positive cancer stem cells (CSCs). Within tumors, regulation by PKD1 includes chemoresistance, apoptosis, proliferation, CSC features, and the Warburg effect. Thus, PKD1 plays a critical role throughout pancreatic disease initiation and progression.

Hypoxic Preconditioning Attenuates Neuroinflammation via Inhibiting NF-κB/NLRP3 Axis Mediated by p-MLKL after Transient Global Cerebral Ischemia

Hypoxic preconditioning (HPC) has been reported to alleviate neuronal damage and microglial activation in hippocampal CA1 after transient global cerebral ischemia (tGCI). However, the molecular mechanism is unclear. Recent studies identified that nuclear factor-kappa-B (NF-κB)/oligomerization domain-like receptors protein (NLRP) 3 inflammasome pathway is mainly involved in the activation of microglia and that phosphorylated (p)-mixed lineage kinase domain-like (MLKL) is related to the regulation of NF-κB/NLRP3 axis. Hence, in this study, we set out to investigate whether HPC attenuates neuronal damage and microglial activation through inhibiting NF-κB/NLRP3 axis mediated by p-MLKL after tGCI in CA1 of male rats. We found that HPC decreased NLRP3 inflammasome in microglia and inhibited M1 polarization of microglia in CA1 after tGCI. Mechanistically, HPC inhibited the activation of NF-κB signaling pathway and reduced the mRNA and protein levels of NLRP3 inflammasome after tGCI. Additionally, the knockdown of p-MLKL by short hairpin RNA (shRNA) administration inhibited the activation of the NF-κB signaling pathway and reduced the formation of NLRP3 inflammasome, thus attenuating M1 polarization of microglia and decreasing the release of interleukin 1 beta (IL-1β) and necrosis factor alpha (TNF-α) in CA1 post ischemia. We consider that p-MLKL in microglia may be derived from necroptotic neurons after tGCI. In conclusion, the new finding in this study is that HPC-induced neuroprotection against tGCI through inhibiting NF-κB/NLRP3 pathway mediated by p-MLKL.

Sheng Mai Yin shows anti-fatigue, anti-hypoxia and cardioprotective potential in an experimental joint model of fatigue and acute myocardial infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiovascular disease (CVD) and fatigue are two common diseases endangering human life and health that may interact and reinforce one another. Myocardial infarction survivors frequently experience fatigue, and acute myocardial infarction (AMI) is one of the most common cardiovascular diseases that cause fatigue-induced sudden death. Sheng Mai Yin (SMY), a Chinese medicine prescription, is traditionally used for the treatment of diabetes and cardiovascular disease, and has been demonstrated to reduce fatigue and safeguard cardiac function.

AIM OF THE STUDY

This study aims to investigate the effects and underlying mechanisms of SMY in treating fatigue and AMI.

MATERIALS AND METHODS

The pharmacological mechanisms of SMY in treating fatigue and AMI were predicted by bioinformatics and network pharmacology methods. After administering SMY at high, medium and low doses, the swimming time to exhaustion, hemoglobin level, serological parameters and hypoxia tolerance time were detected in C57BL/6N mice, and the left ventricular ejection fractions (LVEF), left ventricular fractional shortening (LVFS), grasp strength, cardiac histopathology, serological parameters and the expression of PINK1 and Parkin proteins were examined in Wistar rats.

RESULTS

371 core targets for SMY and 282 disease targets for fatigue and AMI were obtained using bioinformatics and network pharmacology methods. Enrichment analysis of target genes revealed that SMY might interfere with fatigue and AMI through biological processes such as mitochondrial autophagy, apoptosis, and oxidative stress. For in vivo experiments, SMY showed significant anti-fatigue and hypoxia tolerance effects in mice; It also improved the cardiac function and grasp strength, decreased their cardiac index, myocardial injury and fibrosis degree, and induced serological parameters levels and the expression of PTEN-induced putative kinase 1 (PINK1) and Parkin proteins in myocardium, suggesting that SMY may exert cardioprotective effects in a joint rat model of fatigue and AMI by inhibiting excessive mitochondrial autophagy.

CONCLUSION

This study revealed the anti-fatigue, anti-hypoxia and cardioprotective effects of SMY in a joint model of fatigue-AMI, and the pharmacological mechanism may be related to the inhibition of mitochondrial autophagy in cardiomyocytes through the PINK1/Parkin pathway. The discoveries may provide new ideas for the mechanism study of traditional Chinese medicine, especially complex prescriptions, in treating fatigue and AMI.

Effects of carbamazepine on BDNF expression in trigeminal ganglia and serum in rats with trigeminal neuralgia

OBJECTIVES

Trigeminal neuralgia (TN) is a severe chronic neuropathic pain that mainly affects the distribution area of the trigeminal nerve with limited treating efficacy. There are numerous treatments for TN, but currently the main clinical approach is to suppress pain by carbamazepine (CBZ). Brain-derived neurotrophic factor (BDNF) is closely related to chronic pain. This study aims to determine the effects of CBZ treatment on BDNF expression in both the trigeminal ganglion (TG) and serum of TN via a chronic constriction injury of the infraorbital nerve (ION-CCI) rat model.

METHODS

The ION-CCI models were established in male Sprague-Dawley rats and were randomly divided into a sham group, a TN group, a TN+low-dose CBZ treatment group (TN+20 mg/kg CBZ group), a TN+medium-dose CBZ treatment group (TN+40 mg/kg CBZ group), and a TN+high-dose CBZ treatment group (TN+80 mg/kg CBZ group). The mechanical pain threshold in each group of rats was measured regularly before and after surgery. The expressions of BDNF and tyrosine kinase receptor B (TrkB) mRNA in TGs of rats in different groups were determined by real-time PCR, and the expression of BDNF protein on neurons in TGs was observed by immunofluorescence. Western Blotting was used to detect the protein expression of BDNF, TrkB, extracellular regulated protein kinases (ERK), and phospho-extracellular regulated protein kinases (p-ERK) in TGs of rats in different groups. The expression of BDNF in the serum of rats in different groups was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results of mechanical pain sensitivity showed that there was no significant difference in the mechanical pain threshold in the right facial sensory area of the experimental rats in each group before surgery (all P>0.05). From the 3rd day after operation, the mechanical pain threshold of rats in the TN group was significantly lower than that in the sham group (all P<0.01), and the mechanical pain threshold of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 CBZ mg/kg group was higher than that in the TN group (all P<0.05). The BDNF and TrkB mRNA and protein expressions in TGs of rats in the TN group were higher than those in the sham group (all P<0.05), and those in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than the TN group (all P<0.05). The p-ERK levels in TG of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were significantly decreased compared with the TN group (all P<0.05). The BDNF and neuron-specific nuclear protein (NeuN) were mainly co-expressed in neuron of TGs in the TN group and they were significantly higher than those in the sham group (all P<0.05). The co-labeled expressions of BDNF and NeuN in TGs of the TN+ 80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). The results of ELISA showed that the level of BDNF in the serum of the TN group was significantly higher than that in the sham group (P<0.05). The levels of BDNF in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). Spearman correlation analysis showed that the BDNF level in serum was negatively correlated with mechanical pain threshold (r=-0.650, P<0.01).

CONCLUSIONS

CBZ treatment can inhibit the expression of BDNF and TrkB in the TGs of TN rats, reduce the level of BDNF in serum of TN rats and the phosphorylation of ERK signaling pathway, so as to inhibit TN. The serum level of BDNF can be considered as an indicator for the diagnosis and prognosis of TN.

Homogeneous and Label-Free Detection and Monitoring of Protein Kinase Activity Using the Impact Electrochemistry of Silver Nanoparticles

Protein kinase activity correlates closely with that of many human diseases. However, the existing methods for quantifying protein kinase activity often suffer from limitations such as low sensitivity, harmful radioactive labels, high cost, and sophisticated detection procedures, underscoring the urgent need for sensitive and rapid detection methods. Herein, we present a simple and sensitive approach for the homogeneous detection of protein kinase activity based on nanoimpact electrochemistry to probe the degree of aggregation of silver nanoparticles (AgNPs) before and after phosphorylation. Phosphorylation, catalyzed by protein kinases, introduces two negative charges into the substrate peptide, leading to alterations in electrostatic interactions between the phosphorylated peptide and the negatively charged AgNPs, which, in turn, affects the aggregation status of AgNPs. Via direct electro-oxidation of AgNPs in nanoimpact electrochemistry experiments, protein kinase activity can be quantified by assessing the impact frequency. The present sensor demonstrates a broad detection range and a low detection limit for protein kinase A (PKA), along with remarkable selectivity. Additionally, it enables monitoring of PKA-catalyzed phosphorylation processes. In contrast to conventional electrochemical sensing methods, this approach avoids the requirement of complex labeling and washing procedures.

TrkB-dependent regulation of molecular signaling across septal cell types

The lateral septum (LS), a GABAergic structure located in the basal forebrain, is implicated in social behavior, learning, and memory. We previously demonstrated that expression of tropomyosin kinase receptor B (TrkB) in LS neurons is required for social novelty recognition. To better understand molecular mechanisms by which TrkB signaling controls behavior, we locally knocked down TrkB in LS and used bulk RNA-sequencing to identify changes in gene expression downstream of TrkB. TrkB knockdown induces upregulation of genes associated with inflammation and immune responses, and downregulation of genes associated with synaptic signaling and plasticity. Next, we generated one of the first atlases of molecular profiles for LS cell types using single nucleus RNA-sequencing (snRNA-seq). We identified markers for the septum broadly, and the LS specifically, as well as for all neuronal cell types. We then investigated whether the differentially expressed genes (DEGs) induced by TrkB knockdown map to specific LS cell types. Enrichment testing identified that downregulated DEGs are broadly expressed across neuronal clusters. Enrichment analyses of these DEGs demonstrated that downregulated genes are uniquely expressed in the LS, and associated with either synaptic plasticity or neurodevelopmental disorders. Upregulated genes are enriched in LS microglia, associated with immune response and inflammation, and linked to both neurodegenerative disease and neuropsychiatric disorders. In addition, many of these genes are implicated in regulating social behaviors. In summary, the findings implicate TrkB signaling in the LS as a critical regulator of gene networks associated with psychiatric disorders that display social deficits, including schizophrenia and autism, and with neurodegenerative diseases, including Alzheimer's.

α-Ketoglutarate improves cardiac insufficiency through NAD+-SIRT1 signaling-mediated mitophagy and ferroptosis in pressure overload-induced mice

BACKGROUND

In heart failure (HF), mitochondrial dysfunction and metabolic remodeling lead to a reduction in energy productivity and aggravate cardiomyocyte injury. Supplementation with α-ketoglutarate (AKG) alleviated myocardial hypertrophy and fibrosis in mice with HF and improved cardiac insufficiency. However, the myocardial protective mechanism of AKG remains unclear. We verified the hypothesis that AKG improves mitochondrial function by upregulating NAD+ levels and activating silent information regulator 2 homolog 1 (SIRT1) in cardiomyocytes.

METHODS

In vivo, 2% AKG was added to the drinking water of mice undergoing transverse aortic constriction (TAC) surgery. Echocardiography and biopsy were performed to evaluate cardiac function and pathological changes. Myocardial metabolomics was analyzed by liquid chromatography‒mass spectrometry (LC‒MS/MS) at 8 weeks after surgery. In vitro, the expression of SIRT1 or PINK1 proteins was inhibited by selective inhibitors and siRNA in cardiomyocytes stimulated with angiotensin II (AngII) and AKG. NAD+ levels were detected using an NAD test kit. Mitophagy and ferroptosis levels were evaluated by Western blotting, qPCR, JC-1 staining and lipid peroxidation analysis.

RESULTS

AKG supplementation after TAC surgery could alleviate myocardial hypertrophy and fibrosis and improve cardiac function in mice. Metabolites of the malate-aspartate shuttle (MAS) were increased, but the TCA cycle and fatty acid metabolism pathway could be inhibited in the myocardium of TAC mice after AKG supplementation. Decreased NAD+ levels and SIRT1 protein expression were observed in heart of mice and AngII-treated cardiomyocytes. After AKG treatment, these changes were reversed, and increased mitophagy, inhibited ferroptosis, and alleviated damage in cardiomyocytes were observed. When the expression of SIRT1 was inhibited by a selective inhibitor and siRNA, the protective effect of AKG was suppressed.

CONCLUSION

Supplementation with AKG can improve myocardial hypertrophy, fibrosis and chronic cardiac insufficiency caused by pressure overload. By increasing the level of NAD+, the SIRT-PINK1 and SIRT1-GPX4 signaling pathways are activated to promote mitophagy and inhibit ferroptosis in cardiomyocytes, which ultimately alleviates cardiomyocyte damage.

Selective turn-on sensing of adenosine diphosphate and phosphate anions by ruthenium (II) polypyridine anchored p-tert-butylcalix[4]arene platform

BACKGROUND

Nucleoside polyphosphate (NPP) anions are important for enzymatic activity and should be monitored by scientists in industry and medicine. By elucidating enzyme kinetics and processes, it aids in the discovery of effective inhibitors and activators. Nucleoside polyphosphate (NPP) anions are used by kinases, GTPases, and glycosyltransferases (GTs). Phosphorylation of certain amino acid residues (Ser, Thr, and Tyr) on proteins requires the breakdown of ATP by protein kinases, which produces ADP. Protein kinases, breakdown of ATP, and NPP are the focus of oncology drug development because the aberrant control of kinase activity is a common cause of cancer.

RESULTS

However, a discriminative turn-on fluorescent property is exhibited by non-fluorescent p-tertbutylcalix[4]arene modified 1,2,3-triazole containing bis-ruthenium polypyridyl complex (RL) upon the addition of phosphate anions such as (dihydrogen pyrophosphate (H2P2O72-) and dihydrogen phosphate (H2PO4-)) in CH3CN solvent and Adenosine Diphosphate (ADP) in CH3CN/HEPES (pH = 7.4) buffer (9/1, v/v). The probe RL shows a better-recognizing ability with pyrophosphate anion (H2P2O72-) than dihydrogen phosphate anion (H2PO4-). With H2P2O72- and H2PO4- anions, the RL detection limit was calculated to be as low as 83 nM and 198 nM, respectively.

SIGNIFICANCE

The calix[4]arene macrocycle's excellent size and binding cone conformation make it a good host-guest interface for the pyrophosphate anion and ADP. The bis-ruthenium polypyridyl complex's connection to the p-tertbutyl calix[4]arene moiety creates the ADP selectivity turn-on sensor. When moving from mono-nuclear to bi-nuclear ruthenium complex anchored on p-tertbutyl calix[4]arene, the probe can differentiate ADP, ATP, and AMP. Furthermore, this platform is a great resource for creating devices to simultaneously assess phosphate anions in environmental samples.

Hugan Qingzhi tablets attenuates endoplasmic reticulum stress in nonalcoholic fatty liver disease rats by regulating PERK and ATF6 pathways

BACKGROUND

Endoplasmic reticulum (ER) stress, promoting lipid metabolism disorders and steatohepatitis, contributes significantly to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Hugan Qingzhi tablets (HQT) has a definite effect in the clinical treatment of NAFLD patients, but its mechanism is still unclear. This study aims to investigate the effects of HQT on ER stress in the liver tissues of NAFLD rats and explore the underlying mechanism.

METHODS

The NAFLD rat model was managed with high-fat diet (HFD) for 12weeks. HQT was administrated in a daily basis to the HFD groups. Biochemical markers, pro-inflammatory cytokines, liver histology were assayed to evaluate HQT effects in HFD-induced NAFLD rats. Furthermore, the expression of ER stress-related signal molecules including glucose regulating protein 78 (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), p-PERK, eukaryotic translation initiation factor 2α (EIF2α), p-EIF2α, activating transcription factor 4 (ATF4), acetyl-coenzyme A-carboxylase (ACC), activating transcription factor (ATF6), and nuclear factor-kappa B-p65 (NF-κB-p65) were detected by western blot and/or qRT-PCR.

RESULTS

The histopathological characteristics and biochemical data indicated that HQT exhibited protective effects on HFD-induced NAFLD rats. Furthermore, it caused significant reduction in the expression of ERS markers, such as GRP78, PERK, p-PERK, and ATF6, and subsequently downregulated the expression of EIF2α, p-EIF2α ATF4, ACC, and NF-κB-p65.

CONCLUSIONS

The results suggested that HQT has protective effect against hepatic steatosis and inflammation in NAFLD rats by attenuating ER stress, and the potential mechanism is through inhibition of PERK and ATF6 pathways.

Location, location, location: Protein kinase nanoclustering for optimised signalling output

Protein kinases (PKs) are proteins at the core of cellular signalling and are thereby responsible for most cellular physiological processes and their regulations. As for all intracellular proteins, PKs are subjected to Brownian thermal energy that tends to homogenise their distribution throughout the volume of the cell. To access their substrates and perform their critical functions, PK localisation is therefore tightly regulated in space and time, relying upon a range of clustering mechanisms. These include post-translational modifications, protein-protein and protein-lipid interactions, as well as liquid-liquid phase separation, allowing spatial restriction and ultimately regulating access to their substrates. In this review, we will focus on key mechanisms mediating PK nanoclustering in physiological and pathophysiological processes. We propose that PK nanoclusters act as a cellular quantal unit of signalling output capable of integration and regulation in space and time. We will specifically outline the various super-resolution microscopy approaches currently used to elucidate the composition and mechanisms driving PK nanoscale clustering and explore the pathological consequences of altered kinase clustering in the context of neurodegenerative disorders, inflammation, and cancer.

ErZhiTianGui Decoction alleviates age-related ovarian aging by regulating mitochondrial homeostasis and inhibiting ferroptosis

AIM

This study was designed to investigate the pharmacological effects and mechanisms of ErZhiTianGui Decoction (EZTG) for age-related ovarian aging in mice.

METHODS

This study used naturally aging mice as a model, and EZTG was used for intragastric administration. Ovarian pathological changes, as well as follicular reserve were assessed by hematoxylin and eosin staining, and serum hormone levels (anti-mullerian hormone, follicle-stimulating hormone), mitochondrial reactive oxygen species (ROS) and mitochondrial DNA (mtDNA) damage marker 8-hydroxy-2'-deoxyguanosine(8-OHdG), and lipid peroxidation markers glutathione(GSH) and malondialdehyde(MDA) were determined by enzyme-linked immunosorbent assay. Mitochondrial membrane potential (MMP) levels in ovaries were determined using flow cytometry. The levels of PINK1 and Parkin were observed using immunofluorescence staining. Mitochondrial-derived vesicles (MDVs) and mitochondrial morphology were observed using electron microscopy. Prussian blue staining was used to observe iron ion aggregation in ovarian tissue. The Iron assay kits detected total iron levels. Western blot was used to detect the expression of proteins related to mitochondrial and ferroptosis related genes.

RESULTS

After EZTG treatment, aged mice showed increased ovarian reserve, improved serum hormone levels, increased MMP, GSH levels, and decreased mitochondrial ROS, 8-OHdG, and MDA levels. Immunofluorescence staining showed decreased levels of PINK1 and Parkin, and the same trend was observed for the Western blot. Meanwhile, electron microscopy showed that EZTG improved the mitochondrial morphology in the ovaries of aged mice. EZTG also decreased the total iron and protein levels of Acyl-CoA synthetase long-chain family4 (ACSL4) and increased the protein level of glutathione peroxidase 4 (GPX4) in the ovaries of aged mice.

CONCLUSIONS

EZTG can maintain PINK1/Parkin-mediated mitochondrial homeostasis, reduce the lipid peroxidation caused by the accumulation of ROS, and inhibit the occurrence of ferroptosis and delaying ovarian aging. These findings suggest that EZTG may be a promising drug for treating age-related ovarian aging in females.

A revised nomenclature for the lemur family of protein kinases

The lemur family of protein kinases has gained much interest in recent years as they are involved in a variety of cellular processes including regulation of axonal transport and endosomal trafficking, modulation of synaptic functions, memory and learning, and they are centrally placed in several intracellular signalling pathways. Numerous studies have also implicated role of the lemur kinases in the development and progression of a wide range of cancers, cystic fibrosis, and neurodegenerative diseases. However, parallel discoveries and inaccurate prediction of their kinase activity have resulted in a confusing and misleading nomenclature of these proteins. Herein, a group of international scientists with expertise in lemur family of protein kinases set forth a novel nomenclature to rectify this problem and ultimately help the scientific community by providing consistent information about these molecules.

Varicella zoster virus glycoprotein E facilitates PINK1/Parkin-mediated mitophagy to evade STING and MAVS-mediated antiviral innate immunity

Viruses have evolved to control mitochondrial quality and content to facilitate viral replication. Mitophagy is a selective autophagy, in which the damaged or unnecessary mitochondria are removed, and thus considered an essential mechanism for mitochondrial quality control. Although mitophagy manipulation by several RNA viruses has recently been reported, the effect of mitophagy regulation by varicella zoster virus (VZV) remains to be fully determined. In this study, we showed that dynamin-related protein-1 (DRP1)-mediated mitochondrial fission and subsequent PINK1/Parkin-dependent mitophagy were triggered during VZV infection, facilitating VZV replication. In addition, VZV glycoprotein E (gE) promoted PINK1/Parkin-mediated mitophagy by interacting with LC3 and upregulating mitochondrial reactive oxygen species. Importantly, VZV gE inhibited MAVS oligomerization and STING translocation to disrupt MAVS- and STING-mediated interferon (IFN) responses, and PINK1/Parkin-mediated mitophagy was required for VZV gE-mediated inhibition of IFN production. Similarly, carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-mediated mitophagy induction led to increased VZV replication but attenuated IFN production in a three-dimensional human skin organ culture model. Our results provide new insights into the immune evasion mechanism of VZV gE via PINK1/Parkin-dependent mitophagy.

Melatonin enhances captopril mediated cardioprotective effects and improves mitochondrial dynamics in male Wistar rats with chronic heart failure

Mitochondrial dysfunction is a recent emerging research scope that proved to be involved in many cardiovascular diseases culminating in chronic heart failure (CHF), which remains one of the primary causes of morbidity and mortality. This study investigated the added cardio-protective effects of exogenous melatonin administration to conventional captopril therapy in isoproterenol (ISO) exposed rats with CHF. Five groups of Wistar rats were recruited; (I): Control group, (II): (ISO group), (III): (ISO + captopril group), (IV): (ISO + melatonin group) and (V): (ISO + melatonin/captopril group). Cardiac function parameters and some oxidant, inflammatory and fibrotic markers were investigated. Moreover; mRNA expression of mitochondrial mitophagy [parkin & PTEN induced kinase 1 (PINK1)], biogenesis [Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)], fusion [mitofusin 2 (Mfn2)] and fission [dynamin-related protein 1 (DRP-1)] parameters in rat's myocardium were evaluated. Rats' myocardium was histo-pathologically and immunohistochemically evaluated for Beclin1 and Sirt3 expression. The present study revealed that captopril and melatonin ameliorated cardiac injury, oxidative stress biomarkers, and pro-inflammatory cytokines in ISO-exposed rats. These protective effects could be attributed to mitochondrial dynamic proteins control (i.e. enhanced the mRNA expression of parkin, PINK1, PGC-1α and Mfn2, while reduced DRP-1 mRNA expression). Also, Beclin1 and Sirt3 cardiac immunoreactivity were improved. Combined captopril and melatonin therapy showed a better response than either agent alone. Melatonin enhanced myocardial mitochondrial dynamics and Sirt3 expression in CHF rats and may represent a promising upcoming therapy added to conventional heart failure treatment.

p-tau Ser356 is associated with Alzheimer's disease pathology and is lowered in brain slice cultures using the NUAK inhibitor WZ4003

Tau hyperphosphorylation and aggregation is a common feature of many dementia-causing neurodegenerative diseases. Tau can be phosphorylated at up to 85 different sites, and there is increasing interest in whether tau phosphorylation at specific epitopes, by specific kinases, plays an important role in disease progression. The AMP-activated protein kinase (AMPK)-related enzyme NUAK1 has been identified as a potential mediator of tau pathology, whereby NUAK1-mediated phosphorylation of tau at Ser356 prevents the degradation of tau by the proteasome, further exacerbating tau hyperphosphorylation and accumulation. This study provides a detailed characterisation of the association of p-tau Ser356 with progression of Alzheimer's disease pathology, identifying a Braak stage-dependent increase in p-tau Ser356 protein levels and an almost ubiquitous presence in neurofibrillary tangles. We also demonstrate, using sub-diffraction-limit resolution array tomography imaging, that p-tau Ser356 co-localises with synapses in AD postmortem brain tissue, increasing evidence that this form of tau may play important roles in AD progression. To assess the potential impacts of pharmacological NUAK inhibition in an ex vivo system that retains multiple cell types and brain-relevant neuronal architecture, we treated postnatal mouse organotypic brain slice cultures from wildtype or APP/PS1 littermates with the commercially available NUAK1/2 inhibitor WZ4003. Whilst there were no genotype-specific effects, we found that WZ4003 results in a culture-phase-dependent loss of total tau and p-tau Ser356, which corresponds with a reduction in neuronal and synaptic proteins. By contrast, application of WZ4003 to live human brain slice cultures results in a specific lowering of p-tau Ser356, alongside increased neuronal tubulin protein. This work identifies differential responses of postnatal mouse organotypic brain slice cultures and adult human brain slice cultures to NUAK1 inhibition that will be important to consider in future work developing tau-targeting therapeutics for human disease.

Pleiotropic functions of TAO kinases and their dysregulation in neurological disorders

Thousand and one amino acid kinases (TAOKs) are relatively understudied and functionally pleiotropic protein kinases that have emerged as important regulators of neurodevelopment. Through their conserved amino-terminal catalytic domain, TAOKs mediate phosphorylation at serine/threonine residues in their substrates, but it is their divergent regulatory carboxyl-terminal domains that confer both exquisite functional specification and cellular localization. In this Review, we discuss the physiological roles of TAOKs and the intricate signaling pathways, molecular interactions, and cellular behaviors they modulate-from cell stress responses, division, and motility to tissue homeostasis, immunity, and neurodevelopment. These insights are then integrated into an analysis of the known and potential impacts of disease-associated variants of TAOKs, with a focus on neurodevelopmental disorders, pain and addiction, and neurodegenerative diseases. Translating this foundation into clinical benefits for patients will require greater structural and functional differentiation of the TAOKs afforded by their individually specialized domains.

Polyphyllin I induces ferroptosis in castration-resistant prostate cancer cells through the ERK/DNMT1/ACSL4 axis

BACKGROUND

Castration-resistant prostate cancer (CRPC) inevitably arises after androgen deprivation therapy (ADT). Therefore, there is an urgent need to search for novel treatment strategies for CRPC. Polyphyllin I (PPI), one of the steroidal saponins in paris polyphylla, has been shown to have an anticancer effect. This study investigated the role and mechanism of PPI in CRPC cell ferroptosis.

METHODS

Protein levels of GPX4, p-extracellular regulated protein kinases (ERK), ERK, DNMT1, and ACSL4 were measured by Western blot. DNMT1 and ACSL4 mRNA expression was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Prostate cancer cells (DU145, PC3) were treated with PPI. Cell viability was assessed utilizing Cell Counting Kit-8 (CCK-8) assay. The role of PPI in regulating ferroptosis was determined by analyzing lipid reactive oxygen species (ROS), malonyl dialdehyde (MDA), iron (Fe2+ ), and glutathione (GSH) content. Chromatin immunoprecipitation (ChIP) assay verified the effect of DNMT1 on the ACSL4 promoter. The methylation level of ACSL4 promoter was assessed utilizing MSP. A nude mice xenograft was adopted to detect the effect of PPI in vivo.

RESULTS

PPI inhibited CRPC cell proliferation, reduced levels of GSH and GPX4, and increased levels of MDA, Fe2+ , and ROS, while ERK inhibitor reversed the effect of PPI on ferroptosis. PPI repressed the methylation level of ACSL4 promoter by inhibiting DNMT1. DNMT1 knockdown promoted CRPC cell ferroptosis by regulating ACSL4. PPI induced ferroptosis and suppressed CRPC growth in nude mice.

CONCLUSION

PPI can be used as a ferroptosis inducer to induce ferroptosis in CRPC cells via the ERK/DNMT1/ACSL4 axis, suggesting that PPI may be a new strategy for CRPC treatment.

The crosstalk between PTEN-induced kinase 1-mediated mitophagy and the inflammasome in the pathogenesis of alopecia areata

Alopecia areata (AA) is a T-cell-mediated autoimmune disease that causes chronic, relapsing hair loss; however, its precise pathogenesis remains to be elucidated. Recent studies have provided compelling evidence of crosstalk between inflammasomes and mitophagy-a process that contributes to the removal of damaged mitochondria. Our previous studies showed that the NLR family pyrin domain containing 3 (NLRP3) inflammasome is important for eliciting and progressing inflammation in AA. In this study, we detected mitochondrial DNA damage in AA-affected scalp tissues and IFNγ and poly(I:C) treated outer root sheath (ORS) cells. In addition, IFNγ and poly(I:C) treatment increased mitochondrial reactive oxygen species (ROS) levels in ORS cells. Moreover, we showed that mitophagy induction alleviates IFNγ and poly(I:C)-induced NLRP3 inflammasome activation in ORS cells. Lastly, PTEN-induced kinase 1 (PINK1) knockdown increased NLRP3 inflammasome activation, indicating that PINK1-mediated mitophagy plays a critical role in NLRP3 inflammasome activation in ORS cells. This study supports previous studies showing that oxidative stress disrupts immune privilege status and promotes autoimmunity in AA. The results emphasize the significance of crosstalk between mitophagy and inflammasomes in the pathogenesis of AA. Finally, mitophagy factors regulating mitochondrial dysfunction and inhibiting inflammasome activation could be novel therapeutic targets for AA.

Ovarian cancer relies on the PDGFRβ-fibronectin axis for tumorsphere formation and metastatic spread

High-grade serous ovarian cancer (HGSOC) is the deadliest gynecological malignancy. The most common form of metastatic spread of HGSOC is transcoelomic dissemination. In this process, detached cells from the primary tumor aggregate as tumorspheres and promote the accumulation of peritoneal ascites. This represents an early event in HGSOC development and is indicative of poor prognosis. In this study, based on tumorspheres isolated from ascitic liquid samples from HGSOC patients, ovarian cancer spheroid 3D cultures, and in vivo models, we describe a key signal for tumorsphere formation in HGSOC. We report that platelet-derived growth factor receptor beta (PDGFRβ) is essential for fibronectin-mediated cell clustering of ovarian cancer cells into tumorspheres. This effect is mediated by the kinase NUAK family SNF1-like kinase 1 (NUAK1) and blocked by PDGFRβ pharmacological or genetic inhibition. In the absence of PDGFRβ, ovarian cancer cells can be provided with fibronectin by cancer-associated fibroblasts to generate chimeric spheroids. This work provides new insights that uncover potential targets to prevent peritoneal dissemination, the main cause of advanced disease in HGSOC patients.

Identification of Azalamellarin N as a Pyroptosis Inhibitor

Pyroptosis is a form of regulated cell death that promotes inflammation; it attracts much attention because its dysregulation leads to various inflammatory diseases. To help explore the precise mechanisms by which pyroptosis is regulated, in this study, we searched for chemical compounds that inhibit pyroptosis. From our original compound library, we identified azalamellarin N (AZL-N), a hexacyclic pyrrole alkaloid, as an inhibitor of pyroptosis induced by R837 (also called imiquimod), which is an agonist of the intracellular multiprotein complex nucleotide-binding and oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome. However, whereas the effect of AZL-N on R837-induced pyroptosis was relatively weak, AZL-N strongly inhibited pyroptosis induced by extracellular ATP or nigericin, which are different types of NLRP3 inflammasome agonists. This was in contrast with the results that MCC950, a well-established NLRP3 inhibitor, consistently inhibited pyroptosis irrespective of the type of stimulus. We also found that AZL-N inhibited activation of caspase-1 and apoptosis-associated speck-like proteins containing a caspase activation and recruitment domain (ASC), which are components of the NLRP3 inflammasome. Analysis of the structure-activity relationship revealed that a lactam ring of AZL-N, which has been shown to contribute to the strong binding of AZL-N to its known target protein kinases, is required for its inhibitory effects on pyroptosis. These results suggest that AZL-N inhibits pyroptosis by targeting molecule(s), which may be protein kinase(s), that act upstream of NLRP3 inflammasome activation, rather than by directly targeting the components of the NLRP3 inflammasome. Further identification and analysis of target molecule(s) of AZL-N will shed light on the regulatory mechanisms of pyroptosis, particularly those depending on proinflammatory stimuli.

An investigation of the distributions of ferroptosis and necroptosis mediators in the maternal-fetal interface at different days of rat pregnancy

Ferroptosis and necroptosis are recognized as playing major roles in the regulation of various physiological processes. However, the physiological role of the cell death mediated by these two pathways in the developmental process has not yet been clearly established. This study investigated ferroptosis and necroptosis signalling pathways in maternal-fetal tissue in the different gestational days (GD) of rat pregnancy using immunohistochemical and western blot methods in order to fill this gap. Twenty-four female Wistar albino rats were mated and divided into three groups. Maternal-fetal tissue samples were collected on GD 5, 12 and 19 of pregnancy. Expression and total protein levels of the markers glutathione peroxidase-4, soluble transporter family 7 member 11, transferrin receptor, receptor-interacting serine/threonine-protein kinase 1, receptor-interacting serine/threonine-protein kinase 3 and mixed lineage kinase domain-like protein were investigated on both the maternal and fetal surfaces of the placenta using immunohistochemical and western blot methods. The results showed varying levels of protein expression of both ferroptosis and necroptosis mediators in the GD 5, 12 and 19 of pregnancy. Immunohistochemical analyses revealed that these mediators were located on both the maternal (decidua and metrial gland) and fetal surfaces (labyrinth zone, yolk sac and basal zone) and that their expression levels changed in the different GD. The findings revealed the existence of important ferroptosis and necroptosis pathway mediators in rat maternal-fetal tissue. These results may provide a molecular framework for a better understanding of the communication between the placenta, decidua and fetus during the developmental process.