Chiral Posttranslational Modification to Lysine ε-Amino Groups

Turning sour into sweet: Lactylation modification as a promising target in cardiovascular health

Lactylation, a recently identified posttranslational modification (PTM), has emerged as a critical regulatory mechanism in cardiovascular diseases (CVDs). This PTM involves the addition of lactyl groups to lysine residues on histones and nonhistone proteins, influencing gene expression and cellular metabolism. The discovery of lactylation has revealed new directions for understanding metabolic and immune processes, particularly in the context of CVDs. This review describes the intricate roles of specific lactylated proteins and enzymes, such as H3K18, HMGB1, MCT1/4, and LDH, in the regulation of cardiovascular pathology. This study also highlights the unique impact of lactylation on myocardial hypertrophy and distinguishes it from other PTMs, such as SUMOylation and acetylation, underscoring its potential as a therapeutic target. Emerging drugs targeting lactate transporters and critical enzymes involved in lactylation offer promising avenues for novel CVD therapies. This review calls for further research to elucidate the mechanisms linking lactylation to CVDs, emphasizing the need for comprehensive studies at the molecular, cellular, and organismal levels to pave the way for innovative preventive, diagnostic, and treatment strategies in cardiovascular medicine.

The role of protein lactylation in brain health and disease: current advances and future directions

Lactate, the end product of glycolysis, plays a crucial role in cellular signaling and metabolism. The discovery of lactylation, a novel post-translational modification, has uncovered the role of lactate in regulating diseases, especially in the brain. Lactylation connects genetic encoding with protein function, thereby influencing key biological processes. Increasing evidence supports lactate-mediated lactylation as a critical modulator in neurological disorders. This review offers an overview of lactate metabolism and lactylation, highlighting recent advances in understanding the regulatory enzymes of lactylation and their role in the central nervous system. We investigate the impact of lactylation on brain dysfunctions, including neurodegenerative diseases, cerebrovascular disorders, neuroinflammation, brain tumors, and psychiatric conditions. Moreover, we highlight the therapeutic potential of targeting lactylation in treating brain disorders and outline key research gaps and future directions needed to advance this promising field.

Dynamic changes in lactate-related genes in microglia and their role in immune cell interactions after ischemic stroke

Objectives

This study aims to elucidate the dynamic changes in lactate-related genes (LRGs) in microglia following ischemic stroke (IS) and their associations with immune cells.

Methods

We performed differential expression analysis on bulk-sequencing (GSE30655 and GSE35338) and scRNA-seq data (GSE174574) to identify differentially expressed genes. These genes were intersected with lactate genes from MSigDB to identify post-stroke LRGs. We used t-SNE to visualize LRG distribution across cell types and selected microglia for cell-cell communication, pseudo time, and functional enrichment analyses. These findings were integrated with the GSE225948 scRNA-seq dataset to examine LRG trends in the chronic phase of IS. Finally, CIBERSORT was used to explore immune cell infiltration changes and LRG-immune cell associations post-IS.

Results

Nine LRGs were identified, including Spp1, Per2, Col4a1, Sfxn4, C1qbp, Myc, Apln, Cdo1, and Cav1, with Spp1, C1qbp, and Myc highly expressed in microglia. C1qbp and Myc are crucial in the acute phase, while Spp1 impacts both acute and chronic phases of IS. Microglia subcluster analysis revealed four subclusters (MG0-MG3). Immune cell infiltration analysis showed significant associations between these genes and immune cells.

Conclusion

In summary, Spp1, C1qbp, and Myc are LRGs that are predominantly expressed in microglia and play regulatory roles in various stages of IS.

The role of lactylation in virology

Lactylation, a novel post-translational protein modification, is increasingly recognized for its widespread occurrence on lysine residues in both histone and non-histone proteins. Recent research has primarily focused on its implications in specific human diseases, particularly cancer progression, metabolic disorders, neurodegenerative diseases, and immune responses. However, it is crucial to acknowledge the significant roles played by viruses as pathogens in both clinical and veterinary medicine, as well as in zoological and phytopathological studies. This review highlights the latest advancements in understanding the mechanisms underlying lactylation and its regulation, emphasizing the role of lactylation in certain viruses. We discuss its involvement in essential biological functions, the pathogenic mechanisms of various viruses, host-virus interactions, and practical applications, including the potential for lactylation to serve as a therapeutic target in disease pathogenesis. Exploring the interactions between viruses and lactylation presents a promising research direction that may help refine the emerging concept of lactylation.

L- and D-Lactate: unveiling their hidden functions in disease and health

Lactate, once considered a mere byproduct of anaerobic metabolism, is now recognized as a critical signaling molecule with diverse roles in physiology and pathology. There are two stereoisomers of lactate: L- and D-lactate. Recent studies have shown that disruptions in these two lactate stereoisomers have distinct effects on health and disease. L-lactate is central to glycolysis and energy transfer through the Cori cycle but also acts as the dominant lactylation isomer induced by glycolysis, influencing metabolism and cell survival. Although less studied, D-lactate is linked to metabolic disorders and plays a role in mitochondrial dysfunction and oxidative stress. This review focuses on both L- and D-lactate and examines their biosynthesis, transport, and expanding roles in physiological and pathological processes, particularly their functions in cancer, immune regulation, inflammation, neurodegeneration and other diseases. Finally, we assess the therapeutic prospects of targeting lactate metabolism, highlighting emerging strategies for intervention in clinical settings. Our review synthesizes the current understanding of L- and D-lactate, offering insights into their potential as targets for therapeutic innovation.

Dynamic investigation of hypoxia-induced L-lactylation

The recently identified histone modification lysine lactylation can be stimulated by L-lactate and glycolysis. Although the chemical group added upon lysine lactylation was originally proposed to be the L-enantiomer of lactate (KL-la), two isomeric modifications, lysine D-lactylation (KD-la) and N-ε-(carboxyethyl) lysine (Kce), also exist in cells, with their precursors being metabolites of glycolysis. The dynamic regulation and differences among these three modifications in response to hypoxia remain poorly understood. In this study, we demonstrate that intracellular KL-la, but not KD-la or Kce, is up-regulated in response to hypoxia. Depletion of glyoxalase enzymes, GLO1 and GLO2, had minimal impact on KD-la, Kce, or hypoxia-induced KL-la. Conversely, blocking glycolytic flux to L-lactate under hypoxic conditions by knocking out lactate dehydrogenase A/B completely abolished the induction of KL-la but increased KD-la and Kce. We further observed a correlation between the level of KL-la and hypoxia-inducible factor 1 alpha (HIF-1α) expression under hypoxic conditions and when small molecules were used to stabilize HIF-1α in the normoxia condition. Our result demonstrated that there is a strong correlation between HIF-1α and KL-la in lung cancer tissues and that patient samples with higher grade tend to have higher KL-la levels. Using a proteomics approach, we quantified 66 KL-la sites that were up-regulated by hypoxia and demonstrated that p300/CBP contributes to hypoxia-induced KL-la. Collectively, our study demonstrates that KL-la, rather than KD-la or Kce, is the prevailing lysine lactylation in response to hypoxia. Our results therefore demonstrate a link between KL-la and the hypoxia-induced adaptation of tumor cells.

Protein lactylation in cancer: mechanisms and potential therapeutic implications

Increased glycolysis, which leads to high lactate production, is a common feature of cancer cells. Recent evidence suggests that lactate plays a role in the post-translational modification of histone and nonhistone proteins via lactylation. In contrast to genetic mutations, lactylation in cancer cells is reversible. Thus, reversing lactylation can be exploited as a pharmacological intervention for various cancers. Here we discuss recent advances in histone and nonhistone lactylation in cancer, including L-, D- and S-lactylation, as well as alanyl-tRNA synthetase as a novel lactyltransferase. We also discuss potential approaches for targeting lactylation as a therapeutic opportunity in cancer treatment.

Exploring Alternative Zinc-Binding Groups in Histone Deacetylase (HDAC) Inhibitors Uncovers as a Potent Ethylhydrazide-Based HDAC Inhibitor with Chemosensitizing Properties

In this work, we synthesized a series of peptoid-based histone deacetylase (HDAC) inhibitors with variations in the linker region and zinc-binding groups. All compounds were investigated for their HDAC inhibition, antiplasmodial activity, and cytotoxicity against native and cisplatin-resistant carcinoma cell lines. The ethylhydrazide 20 (DS-103) proved to be the most effective compound in these primary screenings. DS-103 showed nanomolar inhibition of class I HDACs and of HDAC6 (class IIb). To further investigate the binding mode of DS-103, a crystal structure of DS-103 in complex with HDAC6 was obtained, which represents the first reported crystal structure of an alkylhydrazide in complex with an HDAC enzyme. Importantly, DS-103 completely reversed cisplatin resistance in two different platinum-resistant solid cancer cell lines and demonstrated strong synergism with cisplatin. The synergistic anticancer effects are mediated by increased DNA damage and p21 expression, resulting in caspase-mediated apoptosis and cell death.

Nonenzymatic lysine D-lactylation induced by glyoxalase II substrate SLG dampens inflammatory immune responses

Immunometabolism is critical in the regulation of immunity and inflammation; however, the mechanism of preventing aberrant activation-induced immunopathology remains largely unclear. Here, we report that glyoxalase II (GLO2) in the glycolysis branching pathway is specifically downregulated by NF-κB signaling during innate immune activation via tristetraprolin (TTP)-mediated mRNA decay. As a result, its substrate S-D-lactoylglutathione (SLG) accumulates in the cytosol and directly induces D-lactyllysine modification of proteins. This nonenzymatic lactylation by SLG is greatly facilitated by a nearby cysteine residue, as it initially reacts with SLG to form a reversible S-lactylated thiol intermediate, followed by SN-transfer of the lactyl moiety to a proximal lysine. Lactylome profiling identifies 2255 lactylation sites mostly in cytosolic proteins of activated macrophages, and global protein structure analysis suggests that proximity to a cysteine residue determines the susceptibility of lysine to SLG-mediated D-lactylation. Furthermore, lactylation is preferentially enriched in proteins involved in immune activation and inflammatory pathways, and D-lactylation at lysine 310 (K310) of RelA attenuates inflammatory signaling and NF-κB transcriptional activity to restore immune homeostasis. Accordingly, TTP-binding site mutation or overexpression of GLO2 in vivo blocks this feedback lactylation in innate immune cells and promotes inflammation, whereas genetic deficiency or pharmacological inhibition of GLO2 restricts immune activation and attenuates inflammatory immunopathology both in vitro and in vivo. Importantly, dysregulation of the GLO2/SLG/D-lactylation regulatory axis is closely associated with human inflammatory phenotypes. Overall, our findings uncover an immunometabolic feedback loop of SLG-induced nonenzymatic D-lactylation and implicate GLO2 as a promising target for combating clinical inflammatory disorders.

Insight into the roles of lactylation in macrophages: functions and clinical implications

Lactylation, a post-translational modification, has been linked to gene transcription regulation through epigenetic modulation in various pathophysiological processes. The lactylation regulatory proteins, known as writers, erasers, and readers, govern their dynamics by adding, removing, and recognizing lactyl groups on proteins. Macrophages, as cells of the immune system, maintain homeostasis, responding dynamically to diverse internal and external stimuli. Emerging researches unveil that lactylation, through inducing macrophage activation and polarization, affects their functionality in pathological conditions such as inflammation, tumor microenvironment, and fibrosis. Evidence progressively indicates that lactate-driven alterations in lactylation levels within macrophages can influence the pathogenesis of numerous diseases. This review aims to systematically summarize the research progress of lactylation in macrophages, explore its functions and mechanisms by which lactylation contributes to the pathology of different disease phenotypes, and propose future research directions along with potential diagnostic and therapeutic strategies.

Lysine L-lactylation is the dominant lactylation isomer induced by glycolysis

Lysine L-lactylation (Kl-la) is a novel protein posttranslational modification (PTM) driven by L-lactate. This PTM has three isomers: Kl-la, N-ε-(carboxyethyl)-lysine (Kce) and D-lactyl-lysine (Kd-la), which are often confused in the context of the Warburg effect and nuclear presence. Here we introduce two methods to differentiate these isomers: a chemical derivatization and high-performance liquid chromatography analysis for efficient separation, and isomer-specific antibodies for high-selectivity identification. We demonstrated that Kl-la is the primary lactylation isomer on histones and dynamically regulated by glycolysis, not Kd-la or Kce, which are observed when the glyoxalase system was incomplete. The study also reveals that lactyl-coenzyme A, a precursor in L-lactylation, correlates positively with Kl-la levels. This work not only provides a methodology for distinguishing other PTM isomers, but also highlights Kl-la as the primary responder to glycolysis and the Warburg effect.

miR-1458 is inhibited by low concentrations of Vitamin B6 and targets TBX6 to promote the formation of spermatogonial stem cells in Rugao Yellow Chicken

Spermatogonial stem cells (SSCs) have vast application prospects in livestock and poultry production, genetic engineering, and medical research. However, the scarcity of SSCs and the complexity of their development limit the elucidation and verification of the mechanism of SSCs in vitro. Although miRNAs have been identified as critical players in germ cell development, upstream regulatory mechanisms by which miRNAs regulate SSCs formation are rarely reported. In this study, miR-1458, which was differentially expressed during SSCs formation, was selected by transcriptomic sequencing. We found that miR-1458, inhibited in an in vitro SSCs induction model, significantly upregulated the expression of germline marker genes (Cvh and integrin β1). Further analysis using Immunofluorescence and Flow Cytometry confirmed that miR-1458 inhibition promotes the formation of spermatogonial stem-like cells (SSCLCs). Immunohistochemical significantly increased the number of SSCs in the testis in vivo. However, significant upregulation of miR-1458 showed opposite results. High-throughput sequencing results showed that miR-1458 interacted with TBX6, one of the target genes of miR-1458, involved in affecting cell differentiation, and dual-luciferase reporter vectors confirmed the targeting relationship between the two. TBX6 overexpression and knockdown in vitro and in vivo have validated its function in SSCs formation. We found that overexpression of TBX6 promoted SSCs formation. Additionally, we identified Vitamin B6, a key metabolite affecting SSCs formation, as an upstream regulator of miR-1458 expression. The results showed that low concentrations of Vitamin B6 led to low expression of miR-1458 by decreasing histone demethylation levels. Overall, our findings suggest that miR-1458 is involved in SSCs formation, which is inhibited by low concentrations of Vitamin B6 and subsequently regulates the formation of SSCs by targeting TBX6, an essential gene involved in embryonic stem cell differentiation. Our study demonstrates the critical role of the Vitamin B6-miR-1458-TBX6 regulatory axis in spermatogonial stem cell formation in Rugao Yellow Chicken, providing new insights into the regulatory mechanisms by which miRNAs affect SSCs formation. It should be noted that most of the germline findings related to miRNAs were obtained by in vitro studies, and in vivo studies are needed to validate our results for clinical applications.

Histone deacetylases: potential therapeutic targets in cisplatin-induced acute kidney injury

Aim: Chemotherapy has been well shown to enhance life expectancy in patients with malignancy. However, conventional chemotherapy drugs, particularly cisplatin, are highly associated with nephrotoxicity, which limits therapeutic efficacy and impairs quality of life. Histone deacetylases (HDACs) are proteases that play significant roles in diseases by influencing protein post-translational modification and gene expression. Agents that inhibit HDAC enzymes have been developed and approved by the FDA as anticancer drugs. It is worth noting that in certain preclinical studies with tumour cell lines, the integration of HDAC modulators and cisplatin not only exerts synergistic or additive tumour-killing effects but also alleviates cisplatin nephrotoxicity. The aim of this review is to discuss the role of HDACs in cisplatin nephrotoxicity.

Methods: After searching in PubMed and Web of Science databases using 'Histone deacetylase', 'nephrotoxicity', 'cisplatin', and 'onconpehrology' as keywords, studies related was compiled and examined.

Results: HDAC inhibitors exert renal protective effects by inhibiting inflammation, apoptosis, oxidative stress, and promoting autophagy; whereas sirtuins play a renal protective role by regulating lipid metabolism, inhibiting inflammation and apoptosis, and protecting mitochondrial biosynthesis and mitochondrial dynamics. These potential interactions provide clues concerning targets for molecular treatment.

Conclusion: This review encapsulates the function and molecular mechanisms of HDACs in cisplatin nephrotoxicity, providing the current view by which HDACs induce different biological signaling in the regulation of chemotherapy-associated renal injury. More importantly, this review exhaustively elucidates that HDACs could be targeted to develop a new therapeutic strategy in treating cisplatin nephrotoxicity, which will extend the knowledge of the biological impact and clinical implications of HDACs.

Friend or foe: Lactate in neurodegenerative diseases

Lactate, a byproduct of glycolysis, was considered as a metabolic waste until identified by studies on the Warburg effect. Increasing evidence elucidates that lactate functions as energy fuel, signaling molecule, and donor for protein lactylation. Altered lactate utilization is a common metabolic feature of the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease and Huntington's disease. This review offers an overview of lactate metabolism from the perspective of production, transportation and clearance, and the role of lactate in neurodegenerative progression, as well as a summary of protein lactylation and the signaling function of lactate in neurodegenerative diseases. Besides, this review delves into the dual roles of changed lactate metabolism during neurodegeneration and explores prospective therapeutic methods targeting lactate. We propose that elucidating the correlation between lactate and neurodegeneration is pivotal for exploring innovative therapeutic interventions for neurodegenerative diseases.

New insights into the roles of lactylation in cancer

Lactylation, a novel discovered posttranslational modification, is a vital component of lactate function and is prevalent in a wide range of cells, interacting with both histone and non-histone proteins. Recent studies have confirmed that lactylation as a new contributor to epigenetic landscape is involved in multiple pathological processes. Accumulating evidence reveals that lactylation exists in different pathophysiological states and leads to inflammation and cancer; however, few mechanisms of lactylation have been elaborated. This review summarizes the biological processes and pathophysiological roles of lactylation in cancer, as well as discusses the relevant mechanisms and potential therapeutic targets, aiming to provide new insights for targeted cancer therapy.

TRAP1 drives smooth muscle cell senescence and promotes atherosclerosis via HDAC3-primed histone H4 lysine 12 lactylation

BACKGROUND AND AIMS

Vascular smooth muscle cell (VSMC) senescence is crucial for the development of atherosclerosis, characterized by metabolic abnormalities. Tumour necrosis factor receptor-associated protein 1 (TRAP1), a metabolic regulator associated with ageing, might be implicated in atherosclerosis. As the role of TRAP1 in atherosclerosis remains elusive, this study aimed to examine the function of TRAP1 in VSMC senescence and atherosclerosis.

METHODS

TRAP1 expression was measured in the aortic tissues of patients and mice with atherosclerosis using western blot and RT-qPCR. Senescent VSMC models were established by oncogenic Ras, and cellular senescence was evaluated by measuring senescence-associated β-galactosidase expression and other senescence markers. Chromatin immunoprecipitation (ChIP) analysis was performed to explore the potential role of TRAP1 in atherosclerosis.

RESULTS

VSMC-specific TRAP1 deficiency mitigated VSMC senescence and atherosclerosis via metabolic reprogramming. Mechanistically, TRAP1 significantly increased aerobic glycolysis, leading to elevated lactate production. Accumulated lactate promoted histone H4 lysine 12 lactylation (H4K12la) by down-regulating the unique histone lysine delactylase HDAC3. H4K12la was enriched in the senescence-associated secretory phenotype (SASP) promoter, activating SASP transcription and exacerbating VSMC senescence. In VSMC-specific Trap1 knockout ApoeKO mice (ApoeKOTrap1SMCKO), the plaque area, senescence markers, H4K12la, and SASP were reduced. Additionally, pharmacological inhibition and proteolysis-targeting chimera (PROTAC)-mediated TRAP1 degradation effectively attenuated atherosclerosis in vivo.

CONCLUSIONS

This study reveals a novel mechanism by which mitonuclear communication orchestrates gene expression in VSMC senescence and atherosclerosis. TRAP1-mediated metabolic reprogramming increases lactate-dependent H4K12la via HDAC3, promoting SASP expression and offering a new therapeutic direction for VSMC senescence and atherosclerosis.

Lactylation: A Novel Post-Translational Modification with Clinical Implications in CNS Diseases

Lactate, an important metabolic product, provides energy to neural cells during energy depletion or high demand and acts as a signaling molecule in the central nervous system. Recent studies revealed that lactate-mediated protein lactylation regulates gene transcription and influences cell fate, metabolic processes, inflammation, and immune responses. This review comprehensively examines the regulatory roles and mechanisms of lactylation in neurodevelopment, neuropsychiatric disorders, brain tumors, and cerebrovascular diseases. This analysis indicates that lactylation has multifaceted effects on central nervous system function and pathology, particularly in hypoxia-induced brain damage. Highlighting its potential as a novel therapeutic target, lactylation may play a significant role in treating neurological diseases. By summarizing current findings, this review aims to provide insights and guide future research and clinical strategies for central nervous system disorders.

Lactate and lactylation in cardiovascular diseases: current progress and future perspectives

Cardiovascular diseases (CVDs) are often linked to structural and functional impairments, such as heart defects and circulatory dysfunction, leading to compromised peripheral perfusion and heightened morbidity risks. Metabolic remodeling, particularly in the context of cardiac fibrosis and inflammation, is increasingly recognized as a pivotal factor in the pathogenesis of CVDs. Metabolic syndromes further predispose individuals to these conditions, underscoring the need to elucidate the metabolic underpinnings of CVDs. Lactate, a byproduct of glycolysis, is now recognized as a key molecule that connects cellular metabolism with the regulation of cellular activity. The transport of lactate between different cells is essential for metabolic homeostasis and signal transduction. Disruptions to lactate dynamics are implicated in various CVDs. Furthermore, lactylation, a novel post-translational modification, has been identified in cardiac cells, where it influences protein function and gene expression, thereby playing a significant role in CVD pathogenesis. In this review, we summarized recent advancements in understanding the role of lactate and lactylation in CVDs, offering fresh insights that could guide future research directions and therapeutic interventions. The potential of lactate metabolism and lactylation as innovative therapeutic targets for CVD is a promising avenue for exploration.

Reversible Conjugation of Polypeptides and Proteins Utilizing a [3.3.1] Scaffold under Mild Conditions

An investigation of reversible protein conjugation and deconjugation is presented. Despite numerous available protein conjugation methods, there has been limited documentation of achieving protein conjugation in a controlled and reversible manner. This report introduces a protocol that enables protein modification in a multicomponent fashion under aqueous buffer and mild conditions. A readily available mercaptobenzaldehyde derivative can modify the primary amine of peptides and proteins with a distinctive [3.3.1] scaffold. This modification can be reversed under mild conditions in a controlled fashion, restoring the original protein motif. The effectiveness of this approach has been demonstrated in the modification and quantifiable regeneration of insulin protein.

Lactate and Lactylation in Sepsis: A Comprehensive Review

Sepsis is a disorder of the immune response to infection or infectious factors with high morbidity and mortality in clinical settings. The lactylation of lysine residues, fueled by lactate, plays a pivotal role in its pathophysiology. In conducting a literature review on sepsis-related research, we employed a systematic approach to ensure comprehensiveness and accuracy. Initially, we conducted an extensive literature search through the PubMed database, utilizing a range of keywords including "sepsis", "lactate", "lactylation", and "epigenetic modification". The aim was to capture the most recent research related to the pathophysiological mechanisms of sepsis, metabolic disorders, and the role of lactylation. The results of the literature review revealed a close link between sepsis and metabolic dysfunction, particularly the pivotal role of lactylation in regulating immune responses and inflammatory processes. Lactate, not only an energy metabolic byproduct produced during glycolysis, affects the activity of various proteins, including those involved in immune regulation and cell signaling, through lactylation. In the context of sepsis, changes in the levels of lactylation may be closely associated with the severity and prognosis of the disease. In summary, lactylation, as an emerging type of epigenetic modification, provides a new perspective for the diagnosis and treatment of sepsis. Future research needs to further elucidate the exact mechanisms of lactylation in sepsis and explore its potential as a therapeutic target.

Dichloroacetate for Cancer Treatment: Some Facts and Many Doubts

Rarely has a chemical elicited as much controversy as dichloroacetate (DCA). DCA was initially considered a dangerous toxic industrial waste product, then a potential treatment for lactic acidosis. However, the main controversies started in 2008 when DCA was found to have anti-cancer effects on experimental animals. These publications showed contradictory results in vivo and in vitro such that a thorough consideration of this compound's in cancer is merited. Despite 50 years of experimentation, DCA's future in therapeutics is uncertain. Without adequate clinical trials and health authorities' approval, DCA has been introduced in off-label cancer treatments in alternative medicine clinics in Canada, Germany, and other European countries. The lack of well-planned clinical trials and its use by people without medical training has discouraged consideration by the scientific community. There are few thorough clinical studies of DCA, and many publications are individual case reports. Case reports of DCA's benefits against cancer have been increasing recently. Furthermore, it has been shown that DCA synergizes with conventional treatments and other repurposable drugs. Beyond the classic DCA target, pyruvate dehydrogenase kinase, new target molecules have also been recently discovered. These findings have renewed interest in DCA. This paper explores whether existing evidence justifies further research on DCA for cancer treatment and it explores the role DCA may play in it.

Regulation of newly identified lysine lactylation in cancer

Metabolic reprogramming is a typical hallmark of cancer. Enhanced glycolysis in tumor cells leads to the accumulation of lactate, which is traditionally considered metabolic waste. With the development of high-resolution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), the lactate-derived, lysine lactylation(Kla), has been identified. Kla can alter the spatial configuration of chromatin and regulate the expression of corresponding genes. Metabolic reprogramming and epigenetic remodeling have been extensively linked. Accumulating studies have subsequently expanded the framework on the key roles of this protein translational modification (PTM) in tumors and have provided a new concept of cancer-specific regulation by Kla.

Protein Post-Translational Modifications Based on Proteomics: A Potential Regulatory Role in Animal Science

Genomic studies in animal breeding have provided a wide range of references; however, it is important to note that genes and mRNA alone do not fully capture the complexity of living organisms. Protein post-translational modification, which involves covalent modifications regulated by genetic and environmental factors, serves as a fundamental epigenetic mechanism that modulates protein structure, activity, and function. In this review, we comprehensively summarize various phosphorylation and acylation modifications on metabolic enzymes relevant to energy metabolism in animals, including acetylation, succinylation, crotonylation, β-hydroxybutylation, acetoacetylation, and lactylation. It is worth noting that research on animal energy metabolism and modification regulation lags behind the demands for growth and development in animal breeding compared to human studies. Therefore, this review provides a novel research perspective by exploring unreported types of modifications in livestock based on relevant findings from human or animal models.

Revealing chromatin-specific functions of histone deacylases

Histone deacylases are erasers of Nε-acyl-lysine post-translational modifications and have been targeted for decades for the treatment of cancer, neurodegeneration and other disorders. Due to their relatively promiscuous activity on peptide substrates in vitro, it has been challenging to determine the individual targets and substrate identification mechanisms of each isozyme, and they have been considered redundant regulators. In recent years, biochemical and biophysical studies have incorporated the use of reconstituted nucleosomes, which has revealed a diverse and complex arsenal of recognition mechanisms by which histone deacylases may differentiate themselves in vivo. In this review, we first present the peptide-based tools that have helped characterize histone deacylases in vitro to date, and we discuss the new insights that nucleosome tools are providing into their recognition of histone substrates within chromatin. Then, we summarize the powerful semi-synthetic approaches that are moving forward the study of chromatin-associated factors, both in vitro by detailed single-molecule mechanistic studies, and in cells by live chromatin modification. We finally offer our perspective on how these new techniques would advance the study of histone deacylases. We envision that such studies will help elucidate the role of individual isozymes in disease and provide a platform for the development of the next generation of therapeutics.

Protein Lactylation and Metabolic Regulation of the Zoonotic Parasite Toxoplasma gondii

The biology of Toxoplasma gondii, the causative pathogen of one of the most widespread parasitic diseases (toxoplasmosis), remains poorly understood. Lactate, which is derived from glucose metabolism, is not only an energy source in a variety of organisms, including T. gondii, but also a regulatory molecule that participates in gene activation and protein function. Lysine lactylation (Kla) is a type of post-translational modifications (PTMs) that has been recently associated with chromatin remodeling; however, Kla of histone and non-histone proteins has not yet been studied in T. gondii. To examine the prevalence and function of lactylation in T. gondii parasites, we mapped the lactylome of proliferating tachyzoite cells and identified 1964 Kla sites on 955 proteins in the T. gondii RH strain. Lactylated proteins were distributed in multiple subcellular compartments and were closely related to a wide variety of biological processes, including mRNA splicing, glycolysis, aminoacyl-tRNA biosynthesis, RNA transport, and many signaling pathways. We also performed a chromatin immunoprecipitation sequencing (ChIP-seq) analysis using a lactylation-specific antibody and found that the histones H4K12la and H3K14la were enriched in the promoter and exon regions of T. gondii associated with microtubule-based movement and cell invasion. We further confirmed the delactylase activity of histone deacetylases TgHDAC2-4, and found that treatment with anti-histone acetyltransferase (TgMYST-A) antibodies profoundly reduced protein lactylation in T. gondii. This study offers the first dataset of the global lactylation proteome and provides a basis for further dissecting the functional biology of T. gondii.

Dynamic patterns of histone lactylation during early tooth development in mice

Histone lactylation on its lysine (K) residues has been reported to have indispensable roles in lung fibrosis, embryogenesis, neural development, inflammation, and tumors. However, little is known about the lactylation activity towards histone lysine residue during tooth development. We investigated the dynamic patterns of lactate-derived histone lysine lactylation (Kla) using a pan-Kla antibody during murine tooth development, including lower first molar and lower incisor. The results showed that pan-Kla exhibited temporo-spatial patterns in both dental epithelium and mesenchyme cells during development. Notably, pan-Kla was identified in primary enamel knot (PEK), stratum intermedium (SI), stellate reticulum (SR), dental follicle cells, odontoblasts, ameloblasts, proliferating cells in dental mesenchyme, as well as osteoblasts around the tooth germ. More importantly, pan-Kla was also identified to be co-localized with neurofilament during tooth development, suggesting histone lysine lactylation may be involved in neural invasion during tooth development. These findings suggest that histone lysine lactylation may play important roles in regulating tooth development.

Lactate and Lactylation: Clinical Applications of Routine Carbon Source and Novel Modification in Human Diseases

Cell metabolism generates numerous intermediate metabolites that could serve as feedback and feed-forward regulation substances for posttranslational modification. Lactate, a metabolic product of glycolysis, has recently been conceptualized to play a pleiotropic role in shaping cell identities through metabolic rewiring and epigenetic modifications. Lactate-derived carbons, sourced from glucose, mediate the crosstalk among glycolysis, lactate, and lactylation. Furthermore, the multiple metabolic fates of lactate make it an ideal substrate for metabolic imaging in clinical application. Several studies have identified the crucial role of protein lactylation in human diseases associated with cell fate determination, embryonic development, inflammation, neoplasm, and neuropsychiatric disorders. Herein, this review will focus on the metabolic fate of lactate-derived carbon to provide useful information for further research and therapeutic approaches in human diseases. We comprehensively discuss its role in reprogramming and modification during the regulation of glycolysis, the clinical translation prospects of the hyperpolarized lactate signal, lactyl modification in human diseases, and its application with other techniques and omics.

Lactate-induced protein lactylation: A bridge between epigenetics and metabolic reprogramming in cancer

Lactate is not only an endpoint of glycolysis but is gradually being discovered to play the role of a universal metabolic fuel for energy via the 'lactate shuttle' moving between cells and transmitting signals. The glycolytic-dependent metabolism found in tumours and fast-growing cells has made lactate a pivotal player in energy metabolism reprogramming, which enables cells to obtain abundant energy in a short time. Moreover, lactate can provide favourable conditions for tumorigenesis by shaping the acidic tumour microenvironment, recruiting immune cells, etc. and the recently discovered lactate-induced lactylation moves even further on pro-tumorigenesis mechanisms of lactate production, circulation and utilization. As with other epigenetic modifications, lactylation can modify histone proteins to alter the spatial configuration of chromatin, affect DNA accessibility and regulate the expression of corresponding genes. What's more, the degree of lactylation is inseparable from the spatialized lactate concentration, which builds a bridge between epigenetics and metabolic reprogramming. Here, we review the important role of lactate in energy reprogramming, summarize the latest finding of lactylation in tumorigenesis and try to explore therapeutic strategies in oncotherapy that can kill two birds with one stone.

The crosstalking of lactate-Histone lactylation and tumor

Lactate was once considered to be a by-product of energy metabolism, but its unique biological value was only gradually explored with the advent of the Warburg effect. As an end product of glycolysis, lactate can act as a substrate for energy metabolism, a signal transduction molecule, a regulator of the tumor microenvironment and immune cells, and a regulator of the deubiquitination of specific enzymes, and is involved in various biological aspects of tumor regulation, including energy shuttling, growth and invasion, angiogenesis and immune escape. Furthermore, we describe a novel lactate-dependent epigenetic modification, namely histone lactylation modification, and review the progress of its study in tumors, mainly involving the reprogramming of tumor phenotypes, regulation of related gene expression, mediation of the glycolytic process in tumor stem cells (CSCs) and influence on the tumor immune microenvironment. The study of epigenetic regulation of tumor genes by histone modification is still in its infancy, and we expect that by summarizing the effects of lactate and histone modification on tumor and related gene regulation, we will clarify the scientific significance of future histone modification studies and the problems to be solved, and open up new fields for targeted tumor therapy.

Functions and mechanisms of lactylation in carcinogenesis and immunosuppression

As critical executors regulating many cellular operations, proteins determine whether living activities can be performed in an orderly and efficient manner. Precursor proteins are inert and must be modified posttranslationally to enable a wide range of protein types and functions. Protein posttranslational modifications (PTMs) are well recognized as being directly associated with carcinogenesis and immune modulation and have emerged as important targets for cancer detection and treatment. Lactylation (Kla), a novel PTM associated with cellular metabolism found in a wide range of cells, interacts with both histone and nonhistone proteins. Unlike other epigenetic changes, Kla has been linked to poor tumor prognosis in all current studies. Histone Kla can affect gene expression in tumors and immunological cells, thereby promoting malignancy and immunosuppression. Nonhistone proteins can also regulate tumor progression and treatment resistance through Kla. In this review, we aimed to summarize the role of Kla in the onset and progression of cancers, metabolic reprogramming, immunosuppression, and intestinal flora regulation to identify new molecular targets for cancer therapy and provide a new direction for combined targeted therapy and immunotherapy.

Lactate and Lactylation in the Brain: Current Progress and Perspectives

As the final product of glycolysis, lactate features not only as an energy substrate, a metabolite, and a signaling molecule in a variety of diseases-such as cancer, inflammation, and sepsis-but also as a regulator of protein lactylation; this is a newly proposed epigenetic modification that is considered to be crucial for energy metabolism and signaling in brain tissues under both physiological and pathological conditions. In this review, evidence on lactylation from studies on lactate metabolism and disease has been summarized, revealing the function of lactate and its receptors in the regulation of brain function and summarizing the levels of lactylation expression in various brain diseases. Finally, the function of lactate and lactylation in the brain and the potential mechanisms of intervention in brain diseases are presented and discussed, providing optimal perspectives for future research on the role of lactylation in the brain.

Post-translational modifications of histones: Mechanisms, biological functions, and therapeutic targets

Histones are DNA-binding basic proteins found in chromosomes. After the histone translation, its amino tail undergoes various modifications, such as methylation, acetylation, phosphorylation, ubiquitination, malonylation, propionylation, butyrylation, crotonylation, and lactylation, which together constitute the "histone code." The relationship between their combination and biological function can be used as an important epigenetic marker. Methylation and demethylation of the same histone residue, acetylation and deacetylation, phosphorylation and dephosphorylation, and even methylation and acetylation between different histone residues cooperate or antagonize with each other, forming a complex network. Histone-modifying enzymes, which cause numerous histone codes, have become a hot topic in the research on cancer therapeutic targets. Therefore, a thorough understanding of the role of histone post-translational modifications (PTMs) in cell life activities is very important for preventing and treating human diseases. In this review, several most thoroughly studied and newly discovered histone PTMs are introduced. Furthermore, we focus on the histone-modifying enzymes with carcinogenic potential, their abnormal modification sites in various tumors, and multiple essential molecular regulation mechanism. Finally, we summarize the missing areas of the current research and point out the direction of future research. We hope to provide a comprehensive understanding and promote further research in this field.

Metabolomics analysis in rat hearts with ischemia/reperfusion injury after diazoxide postconditioning

Background: Diazoxide is a selective mitochondrial-sensitive potassium channel opening agent that has a definite effect on reducing myocardial ischemia/reperfusion injury (MIRI). However, the exact effects of diazoxide postconditioning on the myocardial metabolome remain unclear, which might contribute to the cardioprotective effects of diazoxide postconditioning. Methods: Rat hearts subjected to Langendorff perfusion were randomly assigned to the normal (Nor) group, ischemia/reperfusion (I/R) group, diazoxide (DZ) group and 5-hydroxydecanoic acid + diazoxide (5-HD + DZ) group. The heart rate (HR), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), and maximum left ventricular pressure (+dp/dtmax) were recorded. The mitochondrial Flameng scores were analysed according to the ultrastructure of the ventricular myocardial tissue in the electron microscopy images. Rat hearts of each group were used to investigate the possible metabolic changes relevant to MIRI and diazoxide postconditioning. Results: The cardiac function indices in the Nor group were better than those in the other groups at the end point of reperfusion, and the HR, LVDP and +dp/dt_max of the Nor group at T2 were significantly higher than those of the other groups. Diazoxide postconditioning significantly improved cardiac function after ischaemic injury, and the HR, LVDP and +dp/dt_max of the DZ group at T2 were significantly higher than those of the I/R group, which could be abolished by 5-HD. The HR, LVDP and +dp/dt_max of the 5-HD + DZ group at T2 were significantly lower than those of the DZ group. The myocardial tissue in the Nor group was mostly intact, while it exhibited considerable damage in the I/R group. The ultrastructural integrity of the myocardium in the DZ group was higher than that in the I/R and 5-HD + DZ groups. The mitochondrial Flameng score in the Nor group was lower than that in the I/R, DZ and 5-HD + DZ groups. The mitochondrial Flameng score in the DZ group was lower than that in the I/R and 5-HD + DZ groups. Five metabolites, namely, L-glutamic acid, L-threonine, citric acid, succinate, and nicotinic acid, were suggested to be associated with the protective effects of diazoxide postconditioning on MIRI. Conclusion: Diazoxide postconditioning may improve MIRI via certain metabolic changes. This study provides resource data for future studies on metabolism relevant to diazoxide postconditioning and MIRI.

Global proteomic analysis reveals lysine succinylation contributes to the pathogenesis of aortic aneurysm and dissection

Protein lysine succinylation is a recently discovered posttranslational modification. This study examined the role of protein lysine succinylation in the pathogenesis of aortic aneurysm and dissection (AAD). 4D label-free LC-MS/MS analysis was used to perform the global profiles of succinylation in aortas obtained from 5 heart transplant donors, 5 patients with thoracic aortic aneurysm (TAA), and 5 patients with thoracic aortic dissection (TAD). In comparison to normal controls, we detected 1138 succinylated sites from 314 proteins in TAA, and 1499 sites from 381 proteins in TAD. Among these, 120 differentially succinylated sites from 76 proteins overlapped between TAA and TAD (|log2FC| > 0.585, p < 0.05). These differentially modified proteins were mainly localized in the mitochondria and cytoplasm, and were primarily involved in diverse energy metabolic processes, including carbon metabolism, amino acid catabolism, and β-oxidation of fatty acids. By establishing an in vitro model of lysine succinylation in vascular smooth muscle cells, we observed changes in the activities of three key metabolic enzymes (PKM, LDHA, and SDHA). These findings suggest that succinylation potentially contributes to the pathogenesis of aortic diseases, and presents a valuable resource for investigating the functional roles and regulatory mechanisms of succinylation in AAD. SIGNIFICANCE: AAD are interrelated life-threatening diseases associated with high morbidity and mortality. Although we discovered that lysine succinylation was significantly up-regulated in the aorta tissues of patients with AAD, its role in the progression of aortic diseases is largely unknown. We conducted a 4D label-free LC-MS/MS analysis and identified 120 differentially succinylated sites on 76 proteins that overlapped between TAA and TAD as compared to normal controls. Lysine succinylation may contribute to the pathogenesis of AAD by regulating energy metabolism pathways. The proteins containing succinylated sites could be served as potential diagnostic markers and therapeutic targets for aortic diseases.

Function and mechanism of histone β-hydroxybutyrylation in health and disease

Histone post-translational modifications (HPTMs) are essential epigenetic mechanisms that affect chromatin-associated nuclear processes without altering the DNA sequence. With the application of mass spectrometry-based proteomics, novel histone lysine acylation, such as propionylation, butyrylation, crotonylation, malonylation, succinylation, glutarylation, and lactoylation have been successively discovered. The emerging diversity of the lysine acylation landscape prompted us to investigate the function and mechanism of these novel HPTMs in health and disease. Recently, it has been reported that β-hydroxybutyrate (BHB), the main component of the ketone body, has various protective roles beyond alternative fuel provision during starvation. Histone lysine β-hydroxybutyrylation (Kbhb) is a novel HPTMs identified by mass spectrometry, which regulates gene transcription in response to carbohydrate restriction or elevated BHB levels in vivo and vitro. Recent studies have shown that histone Kbhb is strongly associated with the pathogenesis of metabolic cardiovascular diseases, kidney diseases, tumors, neuropsychiatric disorders, and metabolic diseases suggesting it has different functions from histone acetylation and methylation. This review focuses on the writers, erasers, sites, and underlying functions of histone Kbhb, providing a glimpse into their complex regulation mechanism.

The role and mechanism of histone lactylation in health and diseases

Whether under anaerobic or aerobic conditions, glycolysis results in production of lactate. Increasing evidence suggests that lactate serves as a multifunctional signaling molecule that develops non-metabolic activities in addition to serving as a key metabolite to link glycolysis and oxidative phosphorylation. Histone posttranslational modification patterns (HPTMs) are essential epigenetic processes controlling a variety of biological activities. Proteomics based on mass spectrometry (MS) has been used to progressively reveal new HPTMs. Recent discoveries of histone lactylation modification mediated by lactate and subsequent research demonstrating its involvement in cancer, inflammation, lung fibrosis, and other conditions suggest that it plays a significant role in immune regulation and homeostasis maintenance. This review provides a brief overview of the complicated control of histone lactylation modification in both pathological and physiological conditions.