Protein Lactylation and Metabolic Regulation of the Zoonotic Parasite Toxoplasma gondii

Protein lactylation in broiler breast: Insights on occurrence mechanisms and the correlations with meat quality

This study investigated the effects of lactate levels in broiler breast on protein lactylation modification, meat quality, and their correlation. High lactate injections led to increased lactate levels in both serum and breast muscle, and significantly reduced the values of pH0, pH45min and pH24h. Additionally, the lactylation levels in breast muscle were increased both post-slaughter and post-mortem. Protein lactylation in breast muscle occurred through enzymatic and non-enzymatic pathways at these stages, with the underlying mechanisms varying according to lactate levels and the muscle aging process. Correlation analysis revealed that post-slaughter lactylation contributed to breast muscle morphometry, whereas post-mortem lactylation was associated with meat quality and texture profile. These findings could demonstrate the presence and dynamic patterns of protein lactylation in broiler breast muscles, offering new insights into the role of lactate accumulation in meat quality variation.

The emerging role of protein L-lactylation in metabolic regulation and cell signalling

L-Lactate has emerged as a crucial metabolic intermediate, moving beyond its traditional view as a mere waste product. The recent discovery of L-lactate-driven protein lactylation as a post-translational modification has unveiled a pathway that highlights the role of lactate in cellular signalling. In this Perspective, we explore the enzymatic and metabolic mechanisms underlying protein lactylation and its impacts on both histone and non-histone proteins in the contexts of physiology and diseases. We discuss growing evidence suggesting that this modification regulates a wide range of cellular functions and is involved in various physiological and pathological processes, such as cell-fate determination, development, cardiovascular diseases, cancer and autoimmune disorders. We propose that protein lactylation acts as a pivotal mechanism, integrating metabolic and signalling pathways to enable cellular adaptation, and highlight its potential as a therapeutic target in various diseases.

Lactylation: a promising therapeutic target in ischemia-reperfusion injury management

Ischemia-reperfusion injury (IRI) is a critical condition that poses a significant threat to patient safety. The production of lactate increases during the process of IRI, and lactate serves as a crucial indicator for assessing the severity of such injury. Lactylation, a newly discovered post-translational modification in 2019, is induced by lactic acid and predominantly occurs on lysine residues of histone or nonhistone proteins. Extensive studies have demonstrated the pivotal role of lactylation in the pathogenesis and progression of various diseases, including melanoma, myocardial infarction, hepatocellular carcinoma, Alzheimer's disease, and nonalcoholic fatty liver disease. Additionally, a marked correlation between lactylation and inflammation has been observed. This article provides a comprehensive review of the mechanism underlying lactylation in IRI to establish a theoretical foundation for better understanding the interplay between lactylation and IRI.

The TgAMPK-TgPFKII axis essentially regulates protein lactylation in the zoonotic parasite Toxoplasma gondii

Toxoplasma gondii infects nucleated cells of warm-blooded animals and cause zoonotic toxoplasmosis. Lysine lactylation, as a novel post-translational modification, is essential for epigenetic regulation and cellular processes, and proteomic analyses have shown that lactylated proteins are involved in a wide range of biological processes including energy metabolism, gene regulation, and protein biosynthesis. Additionally, protein lactylation is prevalent in T. gondii, while its regulatory mechanisms have not been fully understood. In this study, we investigated the role of T. gondii phosphofructokinase-2 (TgPFKII) and the adenosine-5'-monophosphate-activated protein kinase (AMPK) signaling pathway in the invasion, replication, and lactylation regulation of T. gondii. We localized TgPFKII in the cytoplasm of T. gondii tachyzoites and demonstrated its necessity for parasite growth and protein lactylation through auxin-induced degradation. Our results showed that inhibition of the AMPK pathway led to decreased TgPFKII expression and reduced protein lactylation levels. Furthermore, AMPK-specific inhibitors significantly impaired parasite invasion and proliferation. These findings highlight TgPFKII as a crucial regulator of lactylation and underscore the importance of the AMPK pathway in T. gondii's pathogenic mechanisms, offering potential targets for therapeutic intervention.IMPORTANCEUnderstanding the intricate mechanisms by which Toxoplasma gondii invades and proliferates within host cells is essential for developing novel therapeutic strategies against toxoplasmosis. This study focuses on the pivotal roles of T. gondii phosphofructokinase-2 (TgPFKII) and the adenosine-5'-monophosphate-activated protein kinase (AMPK) signaling pathway in regulating protein lactylation in association with parasite invasion and growth. By elucidating the cellular localization and functional importance of TgPFKII, as well as its regulation through AMPK-specific inhibitors, we provide comprehensive insights into the metabolic and signaling networks that underpin T. gondii pathogenicity. Our findings reveal that TgPFKII is a critical regulator of lactylation and that the AMPK pathway significantly influences T. gondii's ability to invade and replicate within host cells. These insights pave the way for targeted interventions aimed at disrupting key metabolic and signaling pathways in T. gondii, potentially leading to more effective treatments for toxoplasmosis.

Functional mechanisms and potential therapeutic strategies for lactylation in liver diseases

Lactylation, a novel form of lactate-mediated protein post-translational modification (PTM), has been identified as a crucial regulator of gene expression and protein function through the modification of both histone and non-histone proteins. Liver disease is frequently characterized by a reprogramming of glucose metabolism and subsequent lactate accumulation. Recent research has implicated lactylation in a diverse array of hepatic pathologies, including liver injury, non-alcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Consequently, lactylation has emerged as a pivotal regulatory mechanism in liver disease pathogenesis. This review aims to elucidate the intricate regulatory and functional mechanisms underlying lactylation, synthesize recent advancements in its role in various liver diseases, and highlight its potential as a therapeutic target for future interventions in hepatic disorders.

Characterization of the Activities of Vorinostat Against Toxoplasma gondii

Toxoplasma gondii is a globally widespread pathogen of significant veterinary and medical importance, causing abortion or congenital disease in humans and other warm-blooded animals. Nevertheless, the current treatment options are restricted and sometimes result in toxic side effects. Hence, it is essential to discover drugs that demonstrate potent anti-Toxoplasma activity. Herein, we found that vorinostat, a pan-HDAC inhibitor, exhibited an IC50 value of 260.1 nM against the T. gondii RH strain and a selectivity index (SI) > 800 with respect to HFF cells. Vorinostat disrupted the entire lytic cycle of T. gondii in vitro. Proteome analysis indicated that vorinostat remarkably perturbed the protein expression of T. gondii, and proteins involved in "DNA replication" and "membrane" were significantly dysregulated. Furthermore, we found that vorinostat significantly enhanced ROS production and induced parasite apoptosis. Importantly, vorinostat could prolong survival in a murine model. Our findings reveal that vorinostat is effective against T. gondii both in vitro and in vivo, suggesting its potential as a therapeutic option for human toxoplasmosis.

Key Regulators of Parasite Biology Viewed Through a Post-Translational Modification Repertoire

Parasites are the leading causes of morbidity and mortality in both humans and animals, imposing substantial socioeconomic burdens worldwide. Controlling parasitic diseases has become one of the key issues in achieving "One Health". Most parasites have sophisticated life cycles exhibiting progressive developmental stages, morphologies, and host-switching, which are controlled by various regulatory machineries including protein post-translational modifications (PTMs). PTMs have emerged as a key mechanism by which parasites modulate their virulence, developmental transitions, and environmental adaptations. PTMs are enzyme-mediated additions or removals of chemical groups that dynamically regulate the stability and functions of proteins and confer novel properties, playing vital roles in a variety of biological processes and cellular functions. In this review, we circumscribe how parasites utilize various PTMs to regulate their intricate lives, with a focus on the biological role of PTMs in parasite biology and pathogenesis.

Functional dissection of prenyltransferases reveals roles in endocytosis and secretory vacuolar sorting in type 2-ME49 strain of Toxoplasma gondii

Prenyltransferases act essential roles in the prenylation modification, which is significant for proteins, like small GTPases to execute various important activities in Toxoplasma gondii (T.gondii). The structures and partial functions of prenyltransferases (FTase, GGTase-I, and GGTase-II) in prenylation process have been dissected in T. gondii. However, the cellular effects of prenyltransferases on type 2-ME49 strain of Toxoplasma are largely unknown. To address this gap, CRISPR/Cas9-based gene-editing technology was employed to construct conditional knockdown strains of prenyltransferases in ME49 strain. Subsequent observation of ingestion ability of host cytosolic molecules (e.g, green fluorescent protein [GFP]) and status of secretory vacuolar sorting post-knockdown of prenyltransferases revealed significant findings. Our study demonstrated that degradation of FTase and GGTase-II notably affected the trafficking of endocytic GFP and vacuolar secretory trafficking to rhoptry bulb. Additionally, depletion of GGTase-II led to disordered endoplasmic reticulum and microtubules, as well as impaired gliding motility. The integrity of mitochondrion was damaged after degradation of GGTase-I. These findings underscore the critical functions of prenyltransferases in endocytosis and secretory vacuolar sorting in ME49 strain of T. gondii, thereby enhancing our understanding of prenyltransferases as potential drug targets.

Systematic analysis of lysine lactylation in nucleus pulposus cells

Nucleus pulposus (NP) resides in hypoxic microenvironment and NP cells (NPCs), primarily reply on glycolysis and producing high levels of lactate. Intracellular lactate drives lysine lactylation (Kla) as a newly epigenetic modification. However, the impact of Kla on NPCs remains unknown. Here, single-cell RNA sequencing (scRNA-seq) data suggested an altered balance between glycolysis and aerobic oxidation in intervertebral disc degeneration (IDD). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis displayed 3510 lactylation sites on 1052 non-histone proteins of NPCs isolated from rat cultured in normoxia and hypoxia. Moreover, there are 18 proteins with 129 Kla sites and 117 Kla sites in 27 proteins exclusively detected in normoxia and hypoxia group, respectively. Bioinformatics analysis displayed that these lactylated proteins are tightly related to ribosome, spliceosome and the VEGFA-VEGFA2 signaling pathway. Together, our study reveals that Kla may play an important role in regulating cellular metabolism of NPCs.

The impact of histone lactylation on the tumor microenvironment and metabolic pathways and its potential in cancer therapy

BACKGROUND

The complexity of cancer is intricately linked to its multifaceted biological processes, including the roles of the tumor microenvironment (TME) as well as genetic and metabolic regulation. Histone lactylation has recently emerged as a novel epigenetic modification mechanism that plays a pivotal role in regulating cancer initiation, proliferation, invasion, and metastasis.

OBJECTIVE

This review aims to elucidate the role of histone lactylation in modulating various aspects of tumor biology, including DNA repair mechanisms, glycolytic metabolic abnormalities, functions of non-tumor cells in the TME, and the promotion of tumor inflammatory responses and immune escape. Additionally, the review explores potential therapeutic strategies targeting histone lactylation.

METHODS

A comprehensive literature review was performed, analyzing recent findings on histone lactylation and its impact on cancer biology. This involved a systematic examination of studies focusing on biochemical pathways, cellular interactions, and clinical implications related to histone lactylation.

RESULTS

Histone lactylation was identified as a critical regulator of tumor cell DNA repair mechanisms and glycolytic metabolic abnormalities. It also significantly influences the functions of non-tumor cells within the TME, promoting tumor inflammatory responses and immune escape. Moreover, histone lactylation acts as a multifunctional biological signaling molecule impacting immune responses within the TME. Various cell types within the TME, including T cells and macrophages, were found to regulate tumor growth and immune escape mechanisms through lactylation.

CONCLUSION

Histone lactylation offers a novel perspective on tumor metabolism and its role in cancer development. It presents promising opportunities for the development of innovative cancer therapies. This review underscores the potential of histone lactylation as a therapeutic target, paving the way for new strategies in cancer treatment.

Altered neuronal lactate dehydrogenase A expression affects cognition in a sex- and age-dependent manner

The astrocyte-neuron lactate shuttle (ANLS) model posits that astrocyte-generated lactate is transported to neurons to fuel memory processes. However, neurons express high levels of lactate dehydrogenase A (LDHA), the rate-limiting enzyme of lactate production, suggesting a cognitive role for neuronally generated lactate. It was hypothesized that lactate metabolism in neurons is critical for learning and memory. Here transgenic mice were generated to conditionally induce or knockout (KO) the Ldha gene in CNS neurons of adult mice. High pattern separation memory was enhanced by neuronal Ldha induction in young females, and by neuronal Ldha KO in aged females. In older mice, Ldha induction caused cognitive deficits whereas Ldha KO caused cognitive improvements. Genotype-associated cognitive changes were often only observed in one sex or oppositely in males and females. Thus, neuronal-generated lactate has sex-specific cognitive effects, is largely indispensable at young age, and may be detrimental to learning and memory with aging.

SOD3 suppresses early cellular immune responses to parasite infection

Host immune responses are tightly controlled by various immune factors during infection, and protozoan parasites also manipulate the immune system to evade surveillance, leading to an evolutionary arms race in host‒pathogen interactions; however, the underlying mechanisms are not fully understood. We observed that the level of superoxide dismutase 3 (SOD3) was significantly elevated in both Plasmodium falciparum malaria patients and mice infected with four parasite species. SOD3-deficient mice had a substantially longer survival time and lower parasitemia than control mice after infection, whereas SOD3-overexpressing mice were much more vulnerable to parasite infection. We revealed that SOD3, secreted from activated neutrophils, bound to T cells, suppressed the interleukin-2 expression and concomitant interferon-gamma responses crucial for parasite clearance. Overall, our findings expose active fronts in the arms race between the parasites and host immune system and provide insights into the roles of SOD3 in shaping host innate immune responses to parasite infection.

Integration of Epigenome and Lactylome Reveals the Regulation of Lipid Production in Nannochloropsis oceanica

Lysine lactylation (Kla) is a kind of novel post-translational modification (PTM) that participates in gene expression and various metabolic processes. Nannochloropsis has a remarkable capacity for triacylglycerol (TAG) production under nitrogen stress. To elucidate the involvement of lactylation in lipid synthesis, we conducted chromatin immunoprecipitation sequencing (ChIP-seq) and mRNA-seq analyses to monitor lactylation modifications and transcriptome alterations in Nannochloropsis oceanica. In all, 2057 genes showed considerable variation between nitrogen deprivation (ND) and nitrogen repletion (NR) conditions. Moreover, a total of 5375 differential Kla peaks were identified, including 5331 gain peaks and 44 loss peaks under ND vs NR. The differential Kla peaks were primarily distributed in the promoter (≤1 kb) (71.07%), 5'UTR (22.64%), and exon (4.25%). Integrative analysis of ChIP-seq, transcriptome, and previous proteome and lactylome data elucidates the potential mechanism by which lactylation promotes lipid accumulation under ND. Lactylation facilitates autophagy and protein degradation, leading to the recycling of carbon into the tricarboxylic acid (TCA) cycle, thereby providing carbon precursors for lipid synthesis. Additionally, lactylation induces the redirection of carbon from membrane lipids to TAG by upregulating lipases and enhancing the TCA cycle and β-oxidation pathways. This research offers a new perspective for the investigation of lipid biosynthesis in Nannochloropsis.

Ubiquitous protein lactylation in health and diseases

For decades, lactate has been considered a byproduct of glycolysis. The lactate shuttle hypothesis shifted the lactate paradigm, demonstrating that lactate not only plays important roles in cellular metabolism but also cellular communications, which can transcend compartment barriers and can occur within and among different cells, tissues and organs. Recently, the discovery that lactate can induce a novel post-translational modification, named lysine lactylation (Kla), brings forth a new avenue to study nonmetabolic functions for lactate, which has inspired a 'gold rush' of academic and commercial interest. Zhang et al. first showed that Kla is manifested in histones as epigenetic marks, and then mounting evidences demonstrated that Kla also occurs in diverse non-histone proteins. The widespread Kla faithfully orchestrates numerous biological processes, such as transcription, metabolism and inflammatory responses. Notably, dysregulation of Kla touches a myriad of pathological processes. In this review, we comprehensively reviewed and curated the existing literature to retrieve the new identified Kla sites on both histones and non-histone proteins and summarized recent major advances toward its regulatory mechanism. We also thoroughly investigated the function and underlying signaling pathway of Kla and comprehensively summarize how Kla regulates various biological processes in normal physiological states. In addition, we also further highlight the effects of Kla in the development of human diseases including inflammation response, tumorigenesis, cardiovascular and nervous system diseases and other complex diseases, which might potentially contribute to deeply understanding and interpreting the mechanism of its pathogenicity.

Proteomic analysis identifies PFKP lactylation in SW480 colon cancer cells

Aerobic glycolysis is a pivotal hallmark of cancers, including colorectal cancer. Evidence shows glycolytic enzymes are regulated by post-translational modifications (PTMs), thereby affecting the Warburg effect and reprograming cancer metabolism. Lysine lactylation is a PTM reported in 2019 in histones. In this study, we identified protein lactylation in FHC cells and SW480 colon cancer cells through mass spectrometry. Totally, 637 lysine lactylation sites in 444 proteins were identified in FHC and SW480 cells. Lactylated proteins were enriched in the glycolysis pathway, and we identified lactylation sites in phosphofructokinase, platelet (PFKP) lysine 688 and aldolase A (ALDOA) lysine 147. We also showed that PFKP lactylation directly attenuated enzyme activity. Collectively, our study presented a resource to investigate proteome-wide lactylation in SW480 cells and found PFKP lactylation led to activity inhibition, indicating that lactic acid and lactylated PFKP may form a negative feedback pathway in glycolysis and lactic acid production.

Global profiling of protein lactylation in Caenorhabditis elegans

Lactylation, as a novel posttranslational modification, is essential for studying the functions and regulation of proteins in physiological and pathological processes, as well as for gaining in-depth knowledge on the occurrence and development of many diseases, including tumors. However, few studies have examined the protein lactylation of one whole organism. Thus, we studied the lactylation of global proteins in Caenorhabditis elegans to obtain an in vivo lactylome. Using an MS-based platform, we identified 1836 Class I (localization probabilities > 0.75) lactylated sites in 487 proteins. Bioinformatics analysis showed that lactylated proteins were mainly located in the cytoplasm and involved in the tricarboxylic acid cycle (TCA cycle) and other metabolic pathways. Then, we evaluated the conservation of lactylation in different organisms. In total, 41 C. elegans proteins were lactylated and homologous to lactylated proteins in humans and rats. Moreover, lactylation on H4K80 was conserved in three species. An additional 238 lactylated proteins were identified in C. elegans for the first time. This study establishes the first lactylome database in C. elegans and provides a basis for studying the role of lactylation.