Lactate regulates autophagy through ROS-mediated activation of ERK1/2/m-TOR/p-70S6K pathway in skeletal muscle

Histone lactylation-induced premature senescence contributes to 1-nitropyrene-Induced chronic obstructive pulmonary disease

Our previous study revealed that mice exposed to 1-nitropyrene (1-NP) develop pulmonary fibrosis and senescent alveolar cells. However, the impacts of chronic 1-NP on chronic obstructive pulmonary disease (COPD) and the underlying mechanism are unclear. Our research suggested that chronic 1-NP evoked alveolar structure damage, inflammatory cell infiltration, and pulmonary function decline in mice. Moreover, 1-NP increased p53 and p21 expression, the number of β-galactosidase-positive cells, and cell cycle arrest in mouse lungs and MLE-12 cells. Moreover, 1-NP promoted glycolysis and upregulated lactic dehydrogenase A (LDHA) and lactate production in mouse lungs and MLE-12 cells. Elevated glycolysis provoked histone lactylation, but not histone acetylation in pulmonary epithelial cells. Mechanistically, histone H3 lysine 14 lactylation (H3K14la) was upregulated in pulmonary epithelial cells. P53 knockdown mitigated 1-NP-induced cell cycle arrest and senescence in MLE-12 cells. CUT&Tag and ChIP-qPCR experiments confirmed that increased H3K14la directly upregulated p53 transcription in pulmonary epithelial cells. As expected, LDHA knockdown alleviated 1-NP-triggered cell cycle arrest and senescence in MLE-12 cells. In addition, supplementation with oxamate, an inhibitor of LDH, attenuated 1-NP-incurred premature senescence and the COPD-like phenotype in mice. These data revealed for the first time that histone lactylation-induced the increase in p53 transcription contributes to pulmonary epithelial cell senescence during 1-NP-induced COPD progression. Our results provide a basis for repressing lactate production as a promising therapeutic strategy for COPD.

The reciprocal effects of autophagy and the Warburg effect in pancreatic ductal adenocarcinoma: an in vitro study

Autophagy and the Warburg effect are two common pathways in pancreatic ductal adenocarcinoma (PDAC). To date, the reciprocal effects of these pathways have not yet been elucidated. Therefore, this study was designed to investigate the relationship between these factors in vitro and may provide therapeutic targets in the future. The Mia-Paca-2 and AsPc-1 cell lines were cultured under normal conditions. To achieve autophagy, starvation was induced by Hank's balanced salt solution (HBSS), whereas autophagy was inhibited by 3-methyladenine (3-MA). The Warburg effect is mimicked by lactic acid, and the Warburg effect is inhibited by oxamate, the main inhibitor of lactate dehydrogenase. Cell viability was checked through the MTT assay method. Autophagy was checked via evaluation of Beclin-1 via western blotting. The amount of lactic acid was also measured with a lactate dehydrogenase (LDH) assay kit. The cells were incubated with different concentrations of 3-MA, lactic acid and oxamate. The viability of AsPc-1 cells decreased, and the IC50 values were 1195 µM, 23.06 mM and 8.617 mM for 3-MA, lactic acid and oxamate, respectively. Similarly, the IC50 values of Mia-Paca-2 were 873.9 µM, 35.9 mM and 26.74 mM for 3-MA, lactic acid and oxamate, respectively. Our data revealed that starvation increased the expression of the autophagy-related protein Beclin-1 (P value < 0.05); however, 3-MA significantly reduced its expression (P value < 0.05). In addition, lactic acid alone did not affect the expression level of Beclin-1 (P value > 0.05), but oxamate treatment increased its expression (P value < 0.05). We also showed that starvation reduced lactic acid levels, but an autophagy inhibitor, 3MA, significantly increased lactic acid production (P value < 0.05). Our findings showed that lactic acid alone has no significant effect on autophagy and that oxamate induces autophagy, possibly because of caloric restriction. On the other hand, autophagy inhibits lactic acid production, whereas the inhibition of autophagy leads to increased lactic acid production.

A first-in-class selective inhibitor of ERK1/2 and ERK5 overcomes drug resistance with a single-molecule strategy

Despite significant advancements in kinase-targeted therapy, the emergence of acquired drug resistance to targets such as KRAS and MEK remains a challenge. Extracellular-regulated kinase 1/2 (ERK1/2), positioned at the terminus of this pathway, is highly conserved and less susceptible to mutations, thereby garnering attention as a crucial therapeutical target. However, attempts to use monotherapies that target ERK1/2 have achieved only limited clinical success, mainly due to the issues of limited efficacy and the emergence of drug resistance. Herein, we present a proof of concept that extracellular-regulated kinase 5 (ERK5) acts as a compensatory pathway after ERK1/2 inhibition in triple-negative breast cancer (TNBC). By utilizing the principle of polypharmacology, we computationally designed SKLB-D18, a first-in-class molecule that selectively targets ERK1/2 and ERK5, with nanomolar potency and high specificity for both targets. SKLB-D18 demonstrated excellent tolerability in mice and demonstrated superior in vivo anti-tumor efficacy, not only exceeding the existing clinical ERK1/2 inhibitor BVD-523, but also the combination regimen of BVD-523 and the ERK5 inhibitor XMD8-92. Mechanistically, we showed that SKLB-D18, as an autophagy agonist, played a role in mammalian target of rapamycin (mTOR)/70 ribosomal protein S6 kinase (p70S6K) and nuclear receptor coactivator 4 (NCOA4)-mediated ferroptosis, which may mitigate multidrug resistance.

Recycle, repair, recover: the role of autophagy in modulating skeletal muscle repair and post-exercise recovery

Skeletal muscle is a highly plastic tissue that can adapt relatively rapidly to a range of stimuli. In response to novel mechanical loading, e.g. unaccustomed resistance exercise, myofibers are disrupted and undergo a period of ultrastructural remodeling to regain full physiological function, normally within 7 days. The mechanisms that underpin this remodeling are believed to be a combination of cellular processes including ubiquitin-proteasome/calpain-mediated degradation, immune cell infiltration, and satellite cell proliferation/differentiation. A relatively understudied system that has the potential to be a significant contributing mechanism to repair and recovery is the autophagolysosomal system, an intracellular process that degrades damaged and redundant cellular components to provide constituent metabolites for the resynthesis of new organelles and cellular structures. This review summarizes our current understanding of the autophagolysosomal system in the context of skeletal muscle repair and recovery. In addition, we also provide hypothetical models of how this system may interact with other processes involved in skeletal muscle remodeling and provide avenues for future research to improve our understanding of autophagy in human skeletal muscle.

The role of histone lactylation genes in hepatocellular carcinoma prognostic models and their immune cell infiltration features: a comprehensive analysis of single-cell, spatial transcriptome, Mendelian randomization and experiment

INTRODUCTION

With the increasing impact of hepatocellular carcinoma (HCC) on society, there is an urgent need to propose new HCC diagnostic biomarkers and identification models. Histone lysine lactylation (Kla) affects the prognosis of cancer patients and is an emerging target in cancer treatment. However, the potential of Kla-related genes in HCC is poorly understood.

METHODS

A variety of machine learning methods were used to construct and validate a model of differentially expressed Kla genes with comprehensive evaluations included ROC, Kaplan‒Meier curve, Cox regression, decision curve. Immune infiltration gathered with spatial transcriptome was performed using integrated data from multiple databases. Furthermore, single-cell analysis was used to discover the cell-cell communication and Mendelian randomization was used to study the causal relationships between immune cell and HCC. Lastly, qRT-PCR was used to verify the expression of Kla genes.

RESULTS

We established a model consisting of 12 genes that had well prognostic performance and were identified as independent prognostic factors. Single-cell analysis showed that CD8 T+ cells and conventional dendritic cells were enriched in HCC patients. Spatial transcriptomics analysis indicated that the Kla genes influenced the immune characteristics of HCC. Mendelian randomization results showed that TBNK and monocytes were the main risk factors. qRT-PCR validation results indicated that the expression of multiple genes in Huh7 cells was significantly higher than in LO2 cells.

CONCLUSION

Overall, a Kla-related model was established, which may provide new strategies and insights for the treatment and diagnosis of HCC.

Exercise-driven cellular autophagy: A bridge to systematic wellness

BACKGROUND

Exercise enhances health by supporting homeostasis, bolstering defenses, and aiding disease recovery. It activates autophagy, a conserved cellular process essential for maintaining balance, while dysregulated autophagy contributes to disease progression. Despite extensive research on exercise and autophagy independently, their interplay remains insufficiently understood.

AIM OF REVIEW

This review explores the molecular mechanisms of exercise-induced autophagy in various tissues, focusing on key transduction pathways. It examines how different types of exercise trigger specific autophagic responses, supporting cellular balance and addressing systemic dysfunctions. The review also highlights the signaling pathways involved, their roles in protecting organ function, reducing disease risk, and promoting longevity, offering a clear understanding of the link between exercise and autophagy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Exercise-induced autophagy is governed by highly coordinated and dynamic pathways integrating direct and indirect mechanical forces and biochemical signals, linking physical activity to cellular and systemic health across multiple organ systems. Its activation is influenced by exercise modality, intensity, duration, and individual biological characteristics, including age, sex, and muscle fiber composition. Aerobic exercises primarily engage AMPK and mTOR pathways, supporting mitochondrial quality and cellular homeostasis. Anaerobic training activates PI3K/Akt signaling, modulating molecules like FOXO3a and Beclin1 to drive muscle autophagy and repair. In pathological contexts, exercise-induced autophagy enhances mitochondrial function, proteostasis, and tissue regeneration, benefiting conditions like sarcopenia, neurodegeneration, myocardial ischemia, metabolic disorders, and cancer. However, excessive exercise may lead to autophagic overactivation, leading to muscle atrophy or pathological cardiac remodeling. This underscores the critical need for balanced exercise regimens to maximize therapeutic efficacy while minimizing risks. Future research should prioritize identifying reliable biomarkers, optimizing exercise protocols, and integrating exercise with pharmacological strategies to enhance therapeutic outcomes.

GsMTx4 Combined with Exercise Exerts Neuroprotective Effects by Regulating Neuronal Autophagy in Rats with Spinal Cord Injury

A sharp increase in intramedullary pressure after spinal cord injury (SCI) can aggravate secondary injury and lead to severe neurological deficits. Unfortunately, effective treatment options are currently lacking. The mechanosensitive ion channel Piezo1 plays an important role in the pathological process of SCI by transducing mechanical stress. The Piezo1 inhibitor GsMTx4 has been shown to have neuroprotective effects and may hold therapeutic potential for SCI. Given that single drug treatment strategy has limited effect on functional recovery after SCI, we explored the efficacy of combining GsMTx4 with exercise training in treating SCI in rats and investigated the underlying mechanisms. We used the T10 SCI rat model, administered GsMTx4 immediately after injury, and performed 4 weeks of body weight supported treadmill training starting (BWSTT) 2 weeks post injury. Subsequently, HE and LFB staining were used to observe the morphology of spinal cord tissue, WB was used to detect autophagy and apoptosis-related proteins, biochemical detection of calcium ion concentration and CTSD activity, IHC detection of LAMP1 expression, immunofluorescence labeling of NeuN and ChAT-positive motor neurons, as well as MBP and GFAP, and BBB scores were used to evaluate rat motor function. We found that the combined treatment of GsMTx4 drug and exercise training was more effective than single treatment alone. The combined treatment reduced calcium ion concentration, improved lysosomal function, enhanced autophagic flux, reduced cell apoptosis, and significantly improved the motor function of rats. This combined treatment regimen may pave the way for developing more comprehensive treatment strategies for SCI in the future.

Curcumin inhibits oxidative stress and autophagy in C17.2 neural stem cell through ERK1/2 signaling pathways

Objectives

This study investigates curcumin's neuroprotective role and its potential in promoting neurogenesis in progenitor cells within the brain. Notably, curcumin's antioxidant properties have been implicated in Alzheimer's disease treatment. However, the association between curcumin's antioxidative effects and its impact on neural stem cells (NSCs) remains to be elucidated.

Methods

C17.2 neural stem cells were utilized as a model to simulate oxidative stress, induced by hydrogen peroxide (H2O2). We quantified the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and intracellular reactive oxygen species (ROS), alongside the gene expression of SOD1 and SOD2, to assess intracellular oxidative stress. Additionally, Western blot analysis was conducted to measure the expressions of LC3-II, Beclin-1, and phosphorylated ERK (p-ERK), thereby evaluating autophagy and ERK signaling pathway activation.

Results

Treatment with curcumin resulted in a reduction of MDA and ROS levels, suggesting a protective effect on NSCs against oxidative damage induced by H2O2. Furthermore, a decrease in the relative expressions of LC3-II, Beclin-1, and p-ERK was observed post-curcumin treatment.

Conclusions

The findings suggest that curcumin may confer protection against oxidative stress by attenuating autophagy and deactivating the ERK1/2 signaling pathways, which could contribute to therapeutic strategies for Alzheimer's disease.

Lactate Contributes to Remote Ischemic Preconditioning-Mediated Protection Against Myocardial Ischemia Reperfusion Injury by Facilitating Autophagy via the AMP-Activated Protein Kinase-Mammalian Target of Rapamycin-Transcription Factor EB-Connexin 43 Axis

Remote ischemic preconditioning (RIPC) exerts a protective role on myocardial ischemia/reperfusion (I/R) injury by the release of various humoral factors. Lactate is a common metabolite in ischemic tissues. Nevertheless, little is known about the role lactate plays in myocardial I/R injury and its underlying mechanism. This investigation revealed that RIPC elevated the level of lactate in blood and myocardium. Furthermore, AZD3965, a selective monocarboxylate transporter 1 inhibitor, and 2-deoxy-d-glucose, a glycolysis inhibitor, mitigated the effects of RIPC-induced elevated lactate in the myocardium and prevented RIPC against myocardial I/R injury. In an in vitro hypoxia/reoxygenation model, lactate markedly mitigated hypoxia/reoxygenation-induced cell damage in H9c2 cells. Further studies suggested that lactate contributed to RIPC, rescuing I/R-induced autophagy deficiency by promoting transcription factor EB (TFEB) translocation to the nucleus through activating the AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) pathway without influencing the phosphatidylinositol 3-kinase-Akt pathway, thus reducing cardiomyocyte damage. Interestingly, lactate up-regulated the mRNA and protein expression of connexin 43 (CX43) by facilitating the binding of TFEB to CX43 promoter in the myocardium. Functionally, silencing of TFEB attenuated the protective effect of lactate on cell damage, which was reversed by overexpression of CX43. Further mechanistic studies suggested that lactate facilitated CX43-regulated autophagy via the AMPK-mTOR-TFEB signaling pathway. Collectively, this research demonstrates that RIPC protects against myocardial I/R injury through lactate-mediated myocardial autophagy via the AMPK-mTOR-TFEB-CX43 axis.

Lactate induces C2C12 myoblasts differentiation by mediating ROS/p38 MAPK signalling pathway

Lactate serves not merely as an energy substrate for skeletal muscle but also regulates myogenic differentiation, leading to an elevation of reactive oxygen species (ROS) levels. The present study was focused on exploring the effects of lactate and ROS/p38 MAPK in promoting C2C12 myoblasts differentiation. Our results demonstrated that lactate increased C2C12 myoblasts differentiation at a range of physiological concentrations, accompanied by enhanced ROS contents. We used n-acetylcysteine (NAC, a ROS scavenger) pretreatment and found that it delayed lactate-induced C2C12 myoblast differentiation by upregulating Myf5 expression on days 5 and 7 and lowering MyoD and MyoG expression. The finding implies that lactate accompanies ROS-dependent manner to promote C2C12 myoblast differentiation. Additionally, lactate significantly increased p38 MAPK phosphorylation to promote C2C12 cell differentiation, but pretreatment with SB203580 (p38 MAPK inhibitor) reduced lactate-induced C2C12 myoblasts differentiation. whereas lactate pretreatment with NAC inhibited p38 MAPK phosphorylation in C2C12 cells, demonstrating that lactate mediated ROS and regulated the p38 MAPK signalling pathway to promote C2C12 cell differentiation. In conclusion, our results suggest that the promotion of C2C12 myoblasts differentiation by lactate is dependent on ROS and the p38 MAPK signalling pathway. These observations reveal a beneficial role for lactate in increasing myogenesis through ROS-sensitive mechanisms as well as providing new ideas regarding the positive impact of ROS in improving the function of skeletal muscle.

Potential nutritional strategies to prevent and reverse sarcopenia in aging process: Role of fish oil-derived ω-3 polyunsaturated fatty acids, wheat oligopeptide and their combined intervention

INTRODUCTION

Nutritional support is potentially considered an essential step to prevent muscle loss and enhance physical function in older adults.

OBJECTIVES

This study aimed to assess the role of potential nutritional strategies, i.e., fish oil-derived ω-3 polyunsaturated fatty acids (PUFAs), wheat oligopeptide and their combined intervention, in preventing and reversing sarcopenia in aging process.

METHODS

One hundred 25-month-old Sprague-Dawley rats were randomly divided into 10 groups, and 10 newly purchased 6-month-old rats were included in young control group (n = 10). Fish oil (200, 400 or 800 mg/kg body weight), wheat oligopeptide (100, 200 or 400 mg/kg body weight), fish oil + wheat oligopeptide (800 + 100, 400 + 200 or 200 + 400 mg/kg body weight) or the equal volume of solvent were administered daily by gavage for 10 weeks. The effects of these interventions on natural aging rats were evaluated.

RESULTS

All intervention groups had a significant increase in muscle mass and grip strength and reduction in perirenal fat weight when compared to the aged control group (P < 0.05). The results of biochemical parameters, magnetic resonance imaging, proteomics and western blot suggested that the combination of wheat oligopeptide and fish oil-derived ω-3 PUFA, especially group WFM 2 (400 + 200 mg/kg body weight fish oil + wheat oligopeptide), was found to be more effective against aging-associated muscle loss than single intervention. Additionally, the interventions ameliorated fatty infiltration, muscle atrophy, and congestion in the intercellular matrix, and inflammatory cell infiltration in muscle tissue. The interventions also improved oxidative stress, anabolism, hormone levels, and inflammatory levels of skeletal muscle.

CONCLUSIONS

The combination of fish oil-derived ω-3 PUFA and wheat oligopeptide was found to be a promising nutritional support to prevent and reverse sarcopenia. The potential mechanism involved the promotion of protein synthesis and muscle regeneration, as well as the enhancement of muscle strength.

Resistance training does not increase myocellular garbage dumps: A pilot study on lipofuscin in skeletal muscle fibers of resistance trained young men

Lipofuscin (LF) is an intracellular aggregate associated with proteostatic impairments, especially prevalent in nondividing skeletal muscle fibers. Reactive oxygen species (ROS) drive LF-formation. Resistance training (RT) improves muscle performance but also increases ROS production, potentially promoting LF-formation. Thus, we aimed to investigate if RT of a mesocycle duration increases LF-formation in type-I and II muscle fibers and whether RT increases the antioxidant capacity (AOC) in terms of SOD1 and SOD2 content. An intervention group (IG) performed 14 eccentrically accented RT-sessions within 7 weeks. Vastus lateralis muscle biopsies were collected before and after the intervention from IG as well as from a control group (CG) which refrained from RT for the same duration. LF was predominantly found near nuclei, followed by membrane-near and a minor amount in the fiber core, with corresponding spot sizes. Overall, LF-content was higher in type-I than type-II fibers (p < 0.05). There was no increase in LF-content in type-I or IIA fibers, neither for the IG following RT nor for the CG. The same is valid for SOD1/2. We conclude that, in healthy subjects, RT can be safely performed, without adverse effects on increased LF-formation.

Lactate-induced autophagy activation: unraveling the therapeutic impact of high-intensity interval training on insulin resistance in type 2 diabetic rats

Impaired autophagy is a hallmark of diabetes. The current study proposed to investigate if high intensity interval training (HIIT) induced lactate accumulation could stimulate autophagy in type 2 diabetic male rats. 28 male Wistar rats were randomly assigned into four groups: Healthy Control (CO), Diabetes Control (T2D), Exercise (EX), and Diabetes + Exercise (T2D + EX). Diabetes was induced by feeding high-fat diet and administrating single dose of streptozotocin (35 mg/kg). After becoming diabetic, the animals in the exercise groups (EX and T2D + EX) performed an eight-week HIIT (4-10 interval, 80-100% Vmax, 5 days per week). Serum levels of lactate, glucose and insulin as well as the levels of lactate, pyruvate, lactate transporter monocarboxylate transporter 1 (MCT1), phosphorylated mitogen-activated protein kinases (p-MAP 1 and 2), phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ERK 1 and 2), mammalian target of rapamycin (p-mTOR), ribosomal protein S6 kinase beta-1 (p-70S6k), p90 ribosomal S6 kinases (p-90RSK), autophagy related 7 (ATG7), Beclin-1, microtubule-associated protein 1A/1B, and 2A/2B -light chain 3 levels (LC3-I), (LC3- II), (LC3I/LC3II) in soleus muscle were measured. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and serum glucose was lower in T2D + EX compared to T2D group (P < 0.0001). While serum and soleus muscle levels of lactate was not different between T2D and T2D + Ex, the levels of Pyruvate (P < 0.01), MCT1, p-ERK1/2, p-mTOR, p70S6k, P-90RSK, ATG7, LC3-II, and LC3-II/LC3I ratios were higher in T2D + EX compared to T2D group (P < 0.0001). We concluded that eight weeks of high-intensity interval training could activated ERK/P90SRK while inhibiting mTOR/P70S6K signaling pathway in lactate dependent manner. It means increased autophagy which resulted in improve insulin resistance (IR) and reduce blood glucose.

Lactate activates the mitochondrial electron transport chain independently of its metabolism

Lactate has long been considered a cellular waste product. However, we found that as extracellular lactate accumulates, it also enters the mitochondrial matrix and stimulates mitochondrial electron transport chain (ETC) activity. The resulting increase in mitochondrial ATP synthesis suppresses glycolysis and increases the utilization of pyruvate and/or alternative respiratory substrates. The ability of lactate to increase oxidative phosphorylation does not depend on its metabolism. Both L- and D-lactate are effective at enhancing ETC activity and suppressing glycolysis. Furthermore, the selective induction of mitochondrial oxidative phosphorylation by unmetabolized D-lactate reversibly suppressed aerobic glycolysis in both cancer cell lines and proliferating primary cells in an ATP-dependent manner and enabled cell growth on respiratory-dependent bioenergetic substrates. In primary T cells, D-lactate enhanced cell proliferation and effector function. Together, these findings demonstrate that lactate is a critical regulator of the ability of mitochondrial oxidative phosphorylation to suppress glucose fermentation.

Insights on the role of L-lactate as a signaling molecule in skin aging

L-lactate is a catabolite from the anaerobic metabolism of glucose, which plays a paramount role as a signaling molecule in various steps of the cell survival. Its activity, as a master tuner of many mechanisms underlying the aging process, for example in the skin, is still presumptive, however its crucial position in the complex cross-talk between mitochondria and the process of cell survival, should suggest that L-lactate may be not a simple waste product but a fine regulator of the aging/survival machinery, probably via mito-hormesis. Actually, emerging evidence is highlighting that ROS are crucial in the signaling of skin health, including mechanisms underlying wound repair, renewal and aging. The ROS, including superoxide anion, hydrogen peroxide, and nitric oxide, play both beneficial and detrimental roles depending upon their levels and cellular microenvironment. Physiological ROS levels are essential for cutaneous health and the wound repair process. Aberrant redox signaling activity drives chronic skin disease in elderly. On the contrary, impaired redox modulation, due to enhanced ROS generation and/or reduced levels of antioxidant defense, suppresses wound healing via promoting lymphatic/vascular endothelial cell apoptosis and death. This review tries to elucidate this issue.

Lactate activates the mitochondrial electron transport chain independent of its metabolism

Lactate has long been considered a cellular waste product. However, we found that as extracellular lactate accumulates, it also enters the mitochondrial matrix and stimulates mitochondrial electron transport chain (ETC) activity. The resulting increase in mitochondrial ATP synthesis suppresses glycolysis and increases the utilization of pyruvate and/or alternative respiratory substrates. The ability of lactate to increase oxidative phosphorylation does not depend on its metabolism. Both L- and D-lactate are effective at enhancing ETC activity and suppressing glycolysis. Furthermore, the selective induction of mitochondrial oxidative phosphorylation by unmetabolized D-lactate reversibly suppressed aerobic glycolysis in both cancer cell lines and proliferating primary cells in an ATP-dependent manner and enabled cell growth on respiratory-dependent bioenergetic substrates. In primary T cells, D-lactate enhanced cell proliferation and effector function. Together, these findings demonstrate that lactate is a critical regulator of the ability of mitochondrial oxidative phosphorylation to suppress glucose fermentation.

Lactate, histone lactylation and cancer hallmarks

Histone lactylation, an indicator of lactate level and glycolysis, has intrinsic connections with cell metabolism that represents a novel epigenetic code affecting the fate of cells including carcinogenesis. Through delineating the relationship between histone lactylation and cancer hallmarks, we propose histone lactylation as a novel epigenetic code priming cells toward the malignant state, and advocate the importance of identifying novel therapeutic strategies or dual-targeting modalities against lactylation toward effective cancer control. This review underpins important yet less-studied area in histone lactylation, and sheds insights on its clinical impact as well as possible therapeutic tools targeting lactylation.

Lactate protects against oxidative stress-induced retinal degeneration by activating autophagy

Age-related macular degeneration is a common cause of blindless among the aged, which can mainly be attributed to oxidative stress and dysregulated autophagy in retinal pigment epithelium cells. Lactate was reported to act as a signaling molecule and exerted beneficial effect against oxidative stress. This study aims to investigate the protective effect of lactate against oxidative stress-induced retinal degeneration. Here, H₂O₂-induced oxidative stress cell model and sodium iodate-induced mice retinal degeneration model were established. It was found that H₂O₂ inhibited cell viability in ARPE-19 cells and sodium iodate induced deterioration of retinal pigment epithelium as well as apoptosis in retina. Pretreatment with lactate alleviated oxidative stress-induced cell death and retinal degeneration. Molecularly, lactate activated autophagy by up-regulating the ratio of LC3II/I, increased formation of LC3 puncta and autophagic vacuole. Further, lactate prevented H₂O₂-induced mitochondrial fission and maintained mitochondrial function by alleviating H₂O₂-induced mitochondrial membrane potential disruption and intracellular ROS generation. In contrast, application of 3-methyladenine, an inhibitor of autophagy, effectively weakened the protective effect of lactate against oxidative stress in vivo and in vitro. Taken together, all data in this study indicate that lactate protects against oxidative stress-induced retinal degeneration and preserves mitochondrial function by activating autophagy.

New insights into the interplay between autophagy and oxidative and endoplasmic reticulum stress in neuronal cell death and survival

Autophagy is a dynamic process that maintains the normal homeostasis of cells by digesting and degrading aging proteins and damaged organelles. The effect of autophagy on neural tissue is still a matter of debate. Some authors suggest that autophagy has a protective effect on nerve cells, whereas others suggest that autophagy also induces the death of nerve cells and aggravates nerve injury. In mammals, oxidative stress, autophagy and endoplasmic reticulum stress (ERS) constitute important defense mechanisms to help cells adapt to and survive the stress conditions caused by physiological and pathological stimuli. Under many pathophysiological conditions, oxidative stress, autophagy and ERS are integrated and amplified in cells to promote the progress of diseases. Over the past few decades, oxidative stress, autophagy and ERS and their interactions have been a hot topic in biomedical research. In this review, we summarize recent advances in understanding the interactions between oxidative stress, autophagy and ERS in neuronal cell death and survival.

Aerobic Adaptations to Resistance Training: The Role of Time under Tension

Generally, skeletal muscle adaptations to exercise are perceived through a dichotomous lens where the metabolic stress imposed by aerobic training leads to increased mitochondrial adaptations while the mechanical tension from resistance training leads to myofibrillar adaptations. However, there is emerging evidence for cross over between modalities where aerobic training stimulates traditional adaptations to resistance training (e.g., hypertrophy) and resistance training stimulates traditional adaptations to aerobic training (e.g., mitochondrial biogenesis). The latter is the focus of the current review in which we propose high-volume resistance training (i.e., high time under tension) leads to aerobic adaptations such as angiogenesis, mitochondrial biogenesis, and increased oxidative capacity. As time under tension increases, skeletal muscle energy turnover, metabolic stress, and ischemia also increase, which act as signals to activate the peroxisome proliferator-activated receptor gamma coactivator 1-alpha, which is the master regulator of mitochondrial biogenesis. For practical application, the acute stress and chronic adaptations to three specific forms of high-time under tension are also discussed: Slow-tempo, low-intensity resistance training, and drop-set resistance training. These modalities of high-time under tension lead to hallmark adaptations to resistance training such as muscle endurance, hypertrophy, and strength, but little is known about their effect on traditional aerobic training adaptations.

Trophoblast-derived Lactic Acid Orchestrates Decidual Macrophage Differentiation via SRC/LDHA Signaling in Early Pregnancy

Lactic acid (LA) metabolism in the tumor microenvironment contributes to the establishment and maintenance of immune tolerance. This pathway is characterized in tumor associated macrophages. However, the role and pathway of LA metabolism at maternal-fetal interface during early pregnancy, especially in decidual macrophage differentiation, are still unclear. Herein, for the first time, we discovered that LA can trigger either M2 or M1 macrophage polarization via oxidative phosphorylation and glycolysis regulation under normoxia or hypoxia, respectively. Also, LA metabolism played a vital role in decidual macrophages-mediated recurrent pregnancy loss (RPL), through HIF-1α/SRC/LDHA pathway. Moreover, blockade of LA intake with AZD3965 (MCT-1 inhibitor) could rescue pregnancy in an abortion-prone mouse model, suggesting a potential therapeutic target in RPL. Collectively, the present study identifies the previously unknown functions of LA metabolism in the differentiation of decidual macrophages in early normal pregnancy and RPL, and provides a potential therapeutic strategy in RPL by manipulating decidual macrophages' functions through LA metabolic pathway.

Aerobic Exercise Ameliorates Cancer Cachexia-Induced Muscle Wasting through Adiponectin Signaling

Cachexia is a multifactorial syndrome characterized by muscle loss that cannot be reversed by conventional nutritional support. To uncover the molecular basis underlying the onset of cancer cachectic muscle wasting and establish an effective intervention against muscle loss, we used a cancer cachectic mouse model and examined the effects of aerobic exercise. Aerobic exercise successfully suppressed muscle atrophy and activated adiponectin signaling. Next, a cellular model for cancer cachectic muscle atrophy using C2C12 myotubes was prepared by treating myotubes with a conditioned medium from a culture of colon-26 cancer cells. Treatment of the atrophic myotubes with recombinant adiponectin was protective against the thinning of cells through the increased production of p-mTOR and suppression of LC3-II. Altogether, these findings suggest that the activation of adiponectin signaling could be part of the molecular mechanisms by which aerobic exercise ameliorates cancer cachexia-induced muscle wasting.