Dichloroacetate (DCA), a pyruvate dehydrogenase kinase inhibitor, is often used to treat lactic acidosis and malignant tumors. Increasing studies have shown that DCA has neuroprotective effects. Here, we explored the role and mechanism of DCA in Sepsis associated encephalopathy (SAE). Single-cell analysis was used to determine the important role of PDK4 in SAE and identify the cell type. GO and GSEA analysis were used to determine the correlation between DCA and pyroptosis. Through LPS + ATP stimulation, a microglia pyroptosis model was established to observe the expression level of intracellular pyroptosis-related proteins under DCA intervention, and further detect the changes in intracellular ROS and JC-1. Additionally, a co-culture environment of microglia and neuron was simply constructed to evaluate the effect of DCA on activated microglia-mediated neuronal apoptosis. Finally, Novel object recognition test and the Morris water maze were used to explore the effect of DCA on cognitive function in mice from different groups after intervention. Based on the above experiments, this study concludes that DCA can improve the ratio of peripheral and central M1 macrophages, inhibit NLRP3-mediated pyroptosis through ROS and mitochondrial membrane potential (MMP). DCA can reduce neuron death caused by SAE and improve cognitive function in LPS mice. In SAE, DCA may be a potential candidate drug for the treatment of microglia-mediated neuroinflammation.

暂无摘要。

More than 650 reversible and irreversible post-translational modifications (PTMs) of proteins have been listed so far. Canonical PTMs of proteins consist of the covalent addition of functional or chemical groups on target backbone amino-acids or the cleavage of the protein itself, giving rise to modified proteins with specific properties in terms of stability, solubility, cell distribution, activity, or interactions with other biomolecules. PTMs of protein contribute to cell homeostatic processes, enabling basal cell functions, allowing the cell to respond and adapt to variations of its environment, and globally maintaining the constancy of the milieu interieur (the body\'s inner environment) to sustain human health. Abnormal protein PTMs are, however, associated with several disease states, such as cancers, metabolic disorders, or neurodegenerative diseases. Abnormal PTMs alter the functional properties of the protein or even cause a loss of protein function. One example of dramatic PTMs concerns the cellular prion protein (PrPC), a GPI-anchored signaling molecule at the plasma membrane, whose irreversible post-translational conformational conversion (PTCC) into pathogenic prions (PrPSc) provokes neurodegeneration. PrPC PTCC into PrPSc is an additional type of PTM that affects the tridimensional structure and physiological function of PrPC and generates a protein conformer with neurotoxic properties. PrPC PTCC into PrPSc in neurons is the first step of a deleterious sequence of events at the root of a group of neurodegenerative disorders affecting both humans (Creutzfeldt-Jakob diseases for the most representative diseases) and animals (scrapie in sheep, bovine spongiform encephalopathy in cow, and chronic wasting disease in elk and deer). There are currently no therapies to block PrPC PTCC into PrPSc and stop neurodegeneration in prion diseases. Here, we review known PrPC PTMs that influence PrPC conversion into PrPSc. We summarized how PrPC PTCC into PrPSc impacts the PrPC interactome at the plasma membrane and the downstream intracellular controlled protein effectors, whose abnormal activation or trafficking caused by altered PTMs promotes neurodegeneration. We discussed these effectors as candidate drug targets for prion diseases and possibly other neurodegenerative diseases.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) represents a prevalent malignant tumor, with approximately 40% of patients encountering treatment challenges or relapse attributed to rituximab resistance, primarily due to diminished or absent CD20 expression. Our prior research identified PDK4 as a key driver of rituximab resistance through its negative regulation of CD20 expression. Further investigation into PDK4\'s resistance mechanism and the development of advanced exosome nanoparticle complexes may unveil novel resistance targets and pave the way for innovative, effective treatment modalities for DLBCL.
METHODS: We utilized a DLBCL-resistant cell line with high PDK4 expression (SU-DHL-2/R). We infected it with short hairpin RNA (shRNA) lentivirus for RNA sequencing, aiming to identify significantly downregulated mRNA in resistant cells. Techniques including immunofluorescence, immunohistochemistry, and Western blotting were employed to determine PDK4\'s localization and expression in resistant cells and its regulatory role in phosphorylation of Histone deacetylase 8 (HDAC8). Furthermore, we engineered advanced exosome nanoparticle complexes, aCD20@ExoCTX/siPDK4, through cellular, genetic, and chemical engineering methods. These nanoparticles underwent characterization via Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM), and their cellular uptake was assessed through flow cytometry. We evaluated the nanoparticles\' effects on apoptosis in DLBCL-resistant cells and immune cells using CCK-8 assays and flow cytometry. Additionally, their capacity to counteract resistance and exert anti-tumor effects was tested in a resistant DLBCL mouse model.
RESULTS: We found that PDK4 initiates HDAC8 activation by phosphorylating the Ser-39 site, suppressing CD20 protein expression through deacetylation. The aCD20@ExoCTX/siPDK4 nanoparticles served as effective intracellular delivery mechanisms for gene therapy and monoclonal antibodies, simultaneously inducing apoptosis in resistant DLBCL cells and triggering immunogenic cell death in tumor cells. This dual action effectively reversed the immunosuppressive tumor microenvironment, showcasing a synergistic therapeutic effect in a subcutaneous mouse tumor resistance model.
CONCLUSIONS: This study demonstrates that PDK4 contributes to rituximab resistance in DLBCL by modulating CD20 expression via HDAC8 phosphorylation. The designed exosome nanoparticles effectively overcome this resistance by targeting the PDK4/HDAC8/CD20 pathway, representing a promising approach for drug delivery and treating patients with Rituximab-resistant DLBCL.

OBJECTIVE: The xanthone dimer 12-O-deacetyl-phomoxanthone A (12-ODPXA) was extracted from the secondary metabolites of the endophytic fungus Diaporthe goulteri. The 12-ODPXA compound exhibited anticancer properties in murine lymphoma; however, the anti-ovarian cancer (OC) mechanism has not yet been explored. Therefore, the present study evaluated whether 12-ODPXA reduces OC cell proliferation, metastasis, and invasion by downregulating pyruvate dehydrogenase kinase (PDK)4 expression.
METHODS: Cell counting kit-8, colony formation, flow cytometry, wound healing, and transwell assays were performed to examine the effects of 12-ODPXA on OC cell proliferation, apoptosis, migration, and invasion. Transcriptome analysis was used to predict the changes in gene expression. Protein expression was determined using western blotting. Glucose, lactate, and adenosine triphosphate (ATP) test kits were used to measure glucose consumption and lactate and ATP production, respectively. Zebrafish xenograft models were constructed to elucidate the anti-OC effects of 12-ODPXA.
RESULTS: The 12-ODPXA compound inhibited OC cell proliferation, migration, invasion, and glycolysis while inducing cell apoptosis via downregulation of PDK4. In vivo experiments showed that 12-ODPXA suppressed tumor growth and migration in zebrafish.
CONCLUSIONS: Our data demonstrate that 12-ODPXA inhibits ovarian tumor growth and metastasis by downregulating PDK4, revealing the underlying mechanisms of action of 12-ODPXA in OC.

BACKGROUND: Targeting ferroptosis mediated by autophagy presents a novel therapeutic approach to breast cancer, a mortal neoplasm on the global scale. Pyruvate dehydrogenase kinase isozyme 4 (PDK4) has been denoted as a determinant of breast cancer metabolism. The target of this study was to untangle the functional mechanism of PDK4 in ferroptosis dependent on autophagy in breast cancer.
METHODS: RT-qPCR and western blotting examined PDK4 mRNA and protein levels in breast cancer cells. Immunofluorescence staining appraised light chain 3 (LC3) expression. Fe (2 +) assay estimated total iron level. Relevant assay kits and C11-BODIPY (591/581) staining evaluated lipid peroxidation level. DCFH-DA staining assayed intracellular reactive oxygen species (ROS) content. Western blotting analyzed the protein levels of autophagy, ferroptosis and apoptosis-signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway-associated proteins.
RESULTS: PDK4 was highly expressed in breast cancer cells. Knockdown of PDK4 induced the autophagy of breast cancer cells and 3-methyladenine (3-MA), an autophagy inhibitor, countervailed the promoting role of PDK4 interference in ferroptosis in breast cancer cells. Furthermore, PDK4 knockdown activated ASK1/JNK pathway and ASK1 inhibitor (GS-4997) partially abrogated the impacts of PDK4 absence on the autophagy and ferroptosis in breast cancer cells.
CONCLUSIONS: To sum up, deficiency of PDK4 activated ASK1/JNK pathway to stimulate autophagy-dependent ferroptosis in breast cancer.

BACKGROUND: Ginsenoside Rh2 (G-Rh2), a steroidal compound extracted from roots of ginseng, has been extensively studied in tumor therapy. However, its specific regulatory mechanism in non-small cell lung cancer (NSCLC) is not well understood. Pyruvate dehydrogenase kinase 4 (PDK4), a central regulator of cellular energy metabolism, is highly expressed in various malignant tumors. We investigated the impact of G-Rh2 on the malignant progression of NSCLC and how it regulated PDK4 to influence tumor aerobic glycolysis and mitochondrial function.
METHODS: We examined the inhibitory effect of G-Rh2 on NSCLC through I proliferation assay, migration assay and flow cytometry in vitro. Subsequently, we verified the ability of G-Rh2 to inhibit tumor growth and metastasis by constructing subcutaneous tumor and metastasis models in nude mice. Proteomics analysis was conducted to analyze the action pathways of G-Rh2. Additionally, we assessed glycolysis and mitochondrial function using seahorse, PET-CT, Western blot, and RT-qPCR.
RESULTS: Treatment with G-Rh2 significantly inhibited tumor proliferation and migration ability both in vitro and in vivo. Furthermore, G-Rh2 inhibited the tumor\'s aerobic glycolytic capacity, including glucose uptake and lactate production, through the HIF1-α/PDK4 pathway. Overexpression of PDK4 demonstrated that G-Rh2 targeted the inhibition of PDK4 expression, thereby restoring mitochondrial function, promoting reactive oxygen species (ROS) accumulation, and inducing apoptosis. When combined with sodium dichloroacetate, a PDK inhibitor, it complemented the inhibitory capacity of PDKs, acting synergistically as a detoxifier.
CONCLUSIONS: G-Rh2 could target and down-regulate the expression of HIF-1α, resulting in decreased expression of glycolytic enzymes and inhibition of aerobic glycolysis in tumors. Additionally, by directly targeting mitochondrial PDK, it elevated mitochondrial oxidative phosphorylation and enhanced ROS accumulation, thereby promoting tumor cells to undergo normal apoptotic processes.

BACKGROUND: Stevioside (SV) with minimal calories is widely used as a natural sweetener in beverages due to its high sweetness and safety. However, the effects of SV on glucose uptake and the pyruvate dehydrogenase kinase isoenzyme (PDK4) as an important protein in the regulation of glucose metabolism, remain largely unexplored. In this study, we used C2C12 skeletal muscle cells that was induced by palmitic acid (PA) to assess the effects and mechanisms of SV on glucose uptake and PDK4.
METHODS: The glucose uptake of C2C12 cells was determined by 2-NBDG; expression of the Pdk4 gene was measured by quantitative real-time PCR; and expression of the proteins PDK4, p-AMPK, TBC1D1 and GLUT4 was assessed by Western blotting.
RESULTS: In PA-induced C2C12 myotubes, SV could significantly promote cellular glucose uptake by decreasing PDK4 levels and increasing p-AMPK and TBC1D1 levels. SV could promote the translocation of GLUT4 from the cytoplasm to the cell membrane in cells. Moreover, in Pdk4-overexpressing C2C12 myotubes, SV decreased the level of PDK4 and increased the levels of p-AMPK and TBC1D1.
CONCLUSIONS: SV was found to ameliorate PA-induced abnormal glucose uptake via the PDK4/AMPK/TBC1D1 pathway in C2C12 myotubes. Although these results warranted further investigation for validation, they may provide some evidence of SV as a safe natural sweetener for its use in sugar-free beverages to prevent and control T2DM.

BACKGROUND: Accumulation studies found that tumor-associated macrophages (TAMs) are a predominant cell in tumor microenvironment (TME), which function essentially during tumor progression. By releasing bioactive molecules, including circRNA, small extracellular vesicles (sEV) modulate immune cell functions in the TME, thereby affecting non-small cell lung cancer (NSCLC) progression. Nevertheless, biology functions and molecular mechanisms of M2 macrophage-derived sEV circRNAs in NSCLC are unclear.
METHODS: Cellular experiments were conducted to verify the M2 macrophage-derived sEV (M2-EV) roles in NSCLC. Differential circRNA expression in M0 and M2-EV was validated by RNA sequencing. circFTO expression in NSCLC patients and cells was investigated via real-time PCR and FISH. The biological mechanism of circFTO in NSCLC was validated by experiments. Our team isolated sEV from M2 macrophages (M2Ms) and found that M2-EV treatment promoted NSCLC CP, migration, and glycolysis.
RESULTS: High-throughput sequencing found that circFTO was highly enriched in M2-EV. FISH and RT-qPCR confirmed that circFTO expression incremented in NSCLC tissues and cell lines. Clinical studies confirmed that high circFTO expression correlated negatively with NSCLC patient survival. Luciferase reporter analysis confirmed that miR-148a-3p and PDK4 were downstream targets of circFTO. circFTO knockdown inhibited NSCLC cell growth and metastasis in in vivo experiments. Downregulating miR-148a-3p or overexpressing PDK4 restored the malignancy of NSCLC, including proliferation, migration, and aerobic glycolysis after circFTO silencing.
CONCLUSIONS: The study found that circFTO from M2-EV promoted NSCLC cell progression and glycolysis through miR-148a-3p/PDK4 axis. circFTO is a promising prognostic and diagnostic NSCLC biomarker and has the potential to be a candidate NSCLC therapy target.

Mitochondrial dysfunction is considered one of the major pathogenic mechanisms of sepsis-induced cardiomyopathy (SIC). Pyruvate dehydrogenase kinase 4 (PDK4), a key regulator of mitochondrial metabolism, is essential for maintaining mitochondrial function. However, its specific role in SIC remains unclear. To investigate this, we established an in vitro model of septic cardiomyopathy using lipopolysaccharide (LPS)-induced H9C2 cardiomyocytes. Our study revealed a significant increase in PDK4 expression in LPS-treated H9C2 cardiomyocytes. Inhibiting PDK4 with dichloroacetic acid (DCA) improved cell survival, reduced intracellular lipid accumulation and calcium overload, and restored mitochondrial structure and respiratory capacity while decreasing lactate accumulation. Similarly, Oxamate, a lactate dehydrogenase inhibitor, exhibited similar effects to DCA in LPS-treated H9C2 cardiomyocytes. To further validate whether PDK4 causes cardiomyocyte and mitochondrial damage in SIC by promoting lactate production, we upregulated PDK4 expression using PDK4-overexpressing lentivirus in H9C2 cardiomyocytes. This resulted in elevated lactate levels, impaired mitochondrial structure, and reduced mitochondrial respiratory capacity. However, inhibiting lactate production reversed the mitochondrial dysfunction caused by PDK4 upregulation. In conclusion, our study highlights the pathogenic role of PDK4 in LPS-induced cardiomyocyte and mitochondrial damage by promoting lactate production. Therefore, targeting PDK4 and its downstream product lactate may serve as promising therapeutic approaches for treating SIC.