PDK4-mediated metabolic reprogramming is a potential therapeutic target for neovascular age-related macular degeneration.

Age-related macular degeneration (AMD) causes severe blindness in the elderly due to choroidal neovascularization (CNV), which results from the dysfunction of the retinal pigment epithelium (RPE). While normal RPE depends exclusively on mitochondrial oxidative phosphorylation for energy production, the inflammatory conditions associated with metabolic reprogramming of the RPE play a pivotal role in CNV. Although mitochondrial pyruvate dehydrogenase kinase (PDK) is a central node of energy metabolism, its role in the development of CNV in neovascular AMD has not been investigated. In the present study, we used a laser-induced CNV mouse model to evaluate the effects of Pdk4 gene ablation and treatment with pan-PDK or specific PDK4 inhibitors on fluorescein angiography and CNV lesion area. Among PDK isoforms, only PDK4 was upregulated in the RPE of laser-induced CNV mice, and Pdk4 gene ablation attenuated CNV. Next, we evaluated mitochondrial changes mediated by PDK1-4 inhibition using siRNA or PDK inhibitors in inflammatory cytokine mixture (ICM)-treated primary human RPE (hRPE) cells. PDK4 silencing only in ICM-treated hRPE cells restored mitochondrial respiration and reduced inflammatory cytokine secretion. Likewise, GM10395, a specific PDK4 inhibitor, restored oxidative phosphorylation and decreased ICM-induced upregulation of inflammatory cytokine secretion. In a laser-induced CNV mouse model, GM10395 significantly alleviated CNV. Taken together, we demonstrate that specific PDK4 inhibition could be a therapeutic strategy for neovascular AMD by preventing mitochondrial metabolic reprogramming in the RPE under inflammatory conditions.

Identification of programmed cell death-related genes and diagnostic biomarkers in endometriosis using a machine learning and Mendelian randomization approach.

Background: Endometriosis (EM) is a prevalent gynecological disorder frequently associated with irregular menstruation and infertility. Programmed cell death (PCD) is pivotal in the pathophysiological mechanisms underlying EM. Despite this, the precise pathogenesis of EM remains poorly understood, leading to diagnostic delays. Consequently, identifying biomarkers associated with PCD is critical for advancing the diagnosis and treatment of EM. Methods: This study used datasets from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs) following preprocessing. By cross-referencing these DEGs with genes associated with PCD, differentially expressed PCD-related genes (DPGs) were identified. Enrichment analyses for KEGG and GO pathways were conducted on these DPGs. Additionally, Mendelian randomization and machine learning techniques were applied to identify biomarkers strongly associated with EM. Results: The study identified three pivotal biomarkers: TNFSF12, AP3M1, and PDK2, and established a diagnostic model for EM based on these genes. The results revealed a marked upregulation of TNFSF12 and PDK2 in EM samples, coupled with a significant downregulation of AP3M1. Single-cell analysis further underscored the potential of TNFSF12, AP3M1, and PDK2 as biomarkers for EM. Additionally, molecular docking studies demonstrated that these genes exhibit significant binding affinities with drugs currently utilized in clinical practice. Conclusion: This study systematically elucidated the molecular characteristics of PCD in EM and identified TNFSF12, AP3M1, and PDK2 as key biomarkers. These findings provide new directions for the early diagnosis and personalized treatment of EM.

Hypoxia-induced downregulation of PGK1 crotonylation promotes tumorigenesis by coordinating glycolysis and the TCA cycle.

Protein post-translational modifications (PTMs) are crucial for cancer cells to adapt to hypoxia; however, the functional significance of lysine crotonylation (Kcr) in hypoxia remains unclear. Herein we report a quantitative proteomics analysis of global crotonylome under normoxia and hypoxia, and demonstrate 128 Kcr site alterations across 101 proteins in MDA-MB231 cells. Specifically, we observe a significant decrease in K131cr, K156cr and K220cr of phosphoglycerate kinase 1 (PGK1) upon hypoxia. Enoyl-CoA hydratase 1 (ECHS1) is upregulated and interacts with PGK1, leading to the downregulation of PGK1 Kcr under hypoxia. Abolishment of PGK1 Kcr promotes glycolysis and suppresses mitochondrial pyruvate metabolism by activating pyruvate dehydrogenase kinase 1 (PDHK1). A low PGK1 K131cr level is correlated with malignancy and poor prognosis of breast cancer. Our findings show that PGK1 Kcr is a signal in coordinating glycolysis and the tricarboxylic acid (TCA) cycle and may serve as a diagnostic indicator for breast cancer.

PDK4-mediated Nrf2 inactivation contributes to oxidative stress and diabetic kidney injury.

Diabetic kidney disease (DKD) is often featured with redox dyshomeostatis. Pyruvate dehydrogenase kinase 4 (PDK4) is the hub for DKD development. However, the mechanism by which PDK4 mediates DKD is poorly understood. The current work aimed to elucidate the relationship between PDK4 and DKD from the perspective of redox manipulation. Oxidative stress was observed in the human proximal tubular cell line (HK-2 cells) treated with a high concentration of glucose and palmitic acid (HGL). The mechanistic study showed that PDK4 could upregulate Kelch-like ECH-associated protein 1 (Keap1) in HGL-treated HK-2 cells through the suppression of autophagy, resulting in the depletion of nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of redox homeostasis. At the cellular level, pharmacological inhibition or genetic knockdown of PDK4 could boost Nrf2, followed by the increase of a plethora of antioxidant enzymes and ferroptosis-suppression enzymes. Meanwhile, the inhibition or knockdown of PDK4 remodeled iron metabolism, further mitigating oxidative stress and lipid peroxidation. The same trend was observed in the DKD mice model. The current work highlighted the role of PDK4 in the development of DKD and suggested that PDK4 might be a promising target for the management of DKD.

Unveiling the PDK4-centered rituximab-resistant mechanism in DLBCL: the potential of the "Smart" exosome nanoparticle therapy.

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.

Inhibition of the ubiquitin-proteasome system reduces the abundance of pyruvate dehydrogenase kinase 1 in cultured myotubes.

Pyruvate dehydrogenase kinase (PDK), which phosphorylates the pyruvate dehydrogenase complex, regulates glucose metabolism in skeletal muscle. PDK1, an isozyme whose expression is controlled by hypoxia-inducible factor-1α (HIF-1α), is thought to play a role in muscle adaptation to hypoxia. While transcriptional upregulation of PDK1 by HIF-1α is well characterised, mechanisms controlling proteolysis of PDK1 in skeletal muscle have not been thoroughly investigated. Proteasome inhibitor MG132 paradoxically reduced the abundance of PDK1 in human cancer cells and rat L6 myotubes, suggesting that MG132 might direct PDK1 towards autophagic degradation. The objectives of our current study were to determine (1) whether MG132 suppresses PDK1 levels in primary human myotubes, (2) whether chloroquine, an inhibitor of autophagy, prevents MG132-induced suppression of PDK1 in L6 myotubes, and (3) whether PYR-41, an inhibitor of ubiquitination, suppresses PDK1 in L6 myotubes. Using qPCR and/or immunoblotting, we found that despite markedly upregulating HIF-1α protein, MG132 did not alter the PDK1 expression in cultured primary human myotubes, while it suppressed both PDK1 mRNA and protein in L6 myotubes. The PDK1 levels in L6 myotubes were suppressed also during co-treatment with chloroquine and MG132. PYR-41 markedly increased the abundance of HIF-1α in primary human and L6 myotubes, while reducing the abundance of PDK1. In L6 myotubes treated with PYR-41, chloroquine increased the abundance of the epidermal growth factor receptor, but did not prevent the suppression of PDK1. Collectively, our results suggest that cultured myotubes degrade PDK1 via a pathway that cannot be inhibited by MG132, PYR-41, and/or chloroquine.

Decreased AMPK/SIRT1/PDK4 induced by androgen excess inhibits human endometrial stromal cell decidualization in PCOS.

Polycystic ovary syndrome (PCOS) is a complex common endocrine disorder affecting women of reproductive age. Ovulatory dysfunction is recognized as a primary infertile factor, however, even when ovulation is medically induced and restored, PCOS patients continue to experience reduced cumulative pregnancy rates and a higher spontaneous miscarriage rate. Hyperandrogenism, a hallmark feature of PCOS, affects ovarian folliculogenesis, endometrial receptivity, and the establishment and maintenance of pregnancy. Decidualization denotes the transformation that the stromal compart of the endometrium must undergo to accommodate pregnancy, driven by the rising progesterone levels and local cAMP production. However, studies on the impact of hyperandrogenism on decidualization are limited. In this study, we observed that primary endometrial stromal cells from women with PCOS exhibit abnormal responses to progesterone during in vitro decidualization. A high concentration of testosterone inhibits human endometrial stromal cells (HESCs) decidualization. RNA-Seq analysis demonstrated that pyruvate dehydrogenase kinase 4 (PDK4) expression was significantly lower in the endometrium of PCOS patients with hyperandrogenism compared to those without hyperandrogenism. We also characterized that the expression of PDK4 is elevated in the endometrium stroma at the mid-secretory phase. Artificial decidualization could enhance PDK4 expression, while downregulation of PDK4 leads to abnormal decidualization both in vivo and in vitro. Mechanistically, testosterone excess inhibits IGFBP1 and PRL expression, followed by phosphorylating of AMPK that stimulates PDK4 expression. Based on co-immunoprecipitation analysis, we observed an interaction between SIRT1 and PDK4, promoting glycolysis to facilitate decidualization. Restrain of AR activation resumes the AMPK/SIRT1/PDK4 pathway suppressed by testosterone excess, indicating that testosterone primarily acts on decidualization through AR stimulation. Androgen excess in the endometrium inhibits decidualization by disrupting the AMPK/SIRT1/PDK4 signaling pathway. These data demonstrate the critical roles of endometrial PDK4 in regulating decidualization and provide valuable information for understanding the underlying mechanism during decidualization.

Design and synthesis of novel fluorene derivatives as inhibitors of pyruvate dehydrogenase kinase.

Activation of pyruvate dehydrogenase (PDH) by inhibition of pyruvate dehydrogenase kinase (PDHK) has the potential for the treatment of diabetes mellitus and its complications, caused by the malfunction of the glycolytic system and glucose oxidation. In this paper, we describe the identification of novel PDHK inhibitors with a fluorene structure. High-throughput screening using our in-house library provided compound 6 as a weak inhibitor that occupied the allosteric lipoyl group binding site in PDHK2. Structure-based drug design (SBDD) while addressing physicochemical properties succeeded in boosting inhibitory activity approximately 700-fold. Thus obtained compound 32 showed favorable pharmacokinetics profiles supported by high membrane permeability and metabolic stability, and exhibited activation of PDH in rat livers and a glucose lowering effect in Zucker fatty rats.

Inhibition of glycolysis enhances the efficacy of immunotherapy via PDK-mediated upregulation of PD-L1.

BACKGROUND: Immunotherapy for gastric cancer remains a challenge due to its limited efficacy. Metabolic reprogramming toward glycolysis has emerged as a promising avenue for enhancing the sensitivity of tumors to immunotherapy. Pyruvate dehydrogenase kinases (PDKs) play pivotal roles in regulating glycolysis. The importance of PDKs in the context of gastric cancer immunotherapy and their potential as therapeutic targets have not been fully explored. METHODS: PDK and PD-L1 expression was analyzed using data from the GSE66229 and The Cancer Genome Atlas (TCGA) cohorts. Additionally, the Immune Checkpoint Blockade Therapy Atlas (ICBatlas) database was utilized to assess PDK expression in an immune checkpoint blockade (ICB) therapy group. Subsequently, the upregulation of PD-L1 and the enhancement of anticancer effects achieved by targeting PDK were validated through in vivo and in vitro assays. The impact of PDK on histone acetylation was investigated using ChIP‒qPCR to detect changes in histone acetylation levels. RESULTS: Our analysis revealed a notable negative correlation between PD-L1 and PDK expression. Downregulation of PDK led to a significant increase in PD-L1 expression. PDK inhibition increased histone acetylation levels by promoting acetyl-CoA generation. The augmentation of acetyl-CoA production and concurrent inhibition of histone deacetylation were found to upregulate PD-L1 expression in gastric cancer cells. Additionally, we observed a significant increase in the anticancer effect of PD-L1 antibodies following treatment with a PDK inhibitor. CONCLUSIONS: Downregulation of PDK in gastric cancer cells leads to an increase in PD-L1 expression levels, thus potentially improving the efficacy of PD-L1 immune checkpoint blockade therapy.

FOXK2 amplification promotes breast cancer development and chemoresistance.

Oncogene activation through DNA amplification or overexpression is a crucial driver of cancer initiation and progression. The FOXK2 gene, located on chromosome 17q25, encodes a transcription factor with a forkhead DNA-binding domain. Analysis of genomic datasets reveals that FOXK2 is frequently amplified and overexpressed in breast cancer, correlating with poor patient survival. Knockdown of FOXK2 significantly inhibited breast cancer cell proliferation, migration, anchorage-independent growth, and delayed tumor growth in a xenograft mouse model. Additionally, inhibiting FOXK2 sensitized breast cancer cells to chemotherapy. Co-overexpression of FOXK2 and mutant PI3KCA transformed non-tumorigenic MCF-10A cells, suggesting a role for FOXK2 in PI3KCA-driven tumorigenesis. CCNE2, PDK1, and ESR1 were identified as transcriptional targets of FOXK2 in MCF-7 cells. Small-molecule inhibitors of CCNE2/CDK2 (dinaciclib) and PDK1 (dichloroacetate) exhibited synergistic anti-tumor effects with PI3KCA inhibitor (alpelisib) in vitro. Inhibition of FOXK2 by dinaciclib synergistically enhanced the anti-tumor effects of alpelisib in a xenograft mouse model. Collectively, these findings highlight the oncogenic function of FOXK2 and suggest that FOXK2 and its downstream genes represent potential therapeutic targets in breast cancer.

Deletion of pyruvate dehydrogenase kinases reduces susceptibility to deep vein thrombosis in mice.

ABSTRACT: Neutrophils contribute to deep vein thrombosis (DVT) by releasing prothrombotic neutrophil extracellular traps (NETs). NET formation (known as NETosis) is an energy-intensive process that requires an increased rate of aerobic glycolysis. The metabolic enzymes pyruvate dehydrogenase kinases (PDKs) inhibit the pyruvate dehydrogenase complex to divert the pyruvate flux from oxidative phosphorylation toward aerobic glycolysis. Herein, we identified that the combined deletion of PDK2 and PDK4 (PDK2/4-/-) renders mice less susceptible to DVT (measured by thrombus incidence, weight, and length) in the inferior vena cava-stenosis model at day 2 after surgery. Compared with wild-type (WT) mice, the venous thrombus obtained from PDK2/4-/- mice exhibited reduced citrullinated histone content, a known marker of NETs. In line with in vivo observations, phorbol 12-myristate 13-acetate (PMA)-stimulated PDK2/4-/- neutrophils displayed reduced NETosis and secretion of cathepsin G and elastase compared with PMA-stimulated WT neutrophils. The formation of platelet aggregates mediated by PMA-stimulated PDK2/4-/- neutrophils were significantly reduced compared with PMA-stimulated WT neutrophils. Finally, PDK2/4-/- neutrophils exhibited reduced levels of intracellular Ca2+ concentration, extracellular signal-regulated kinase 1/2 (Erk1/2) phosphorylation, and glycolytic proton efflux rate (a measure of aerobic glycolysis), known to facilitate NETosis. Together, these findings elucidate, to our knowledge, for the first time, the fundamental role of PDK2/4 in regulating NETosis and acute DVT.

12-O-deacetyl-phomoxanthone A inhibits ovarian tumor growth and metastasis by downregulating PDK4.

AIMS: 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. CONCLUSION: 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.

Biological impact and therapeutic potential of a novel camptothecin derivative (FLQY2) in pancreatic cancer through inactivation of the PDK1/AKT/mTOR pathway.

BACKGROUND: Camptothecin (CPT), a pentacyclic alkaloid with antitumor properties, is derived from the Camptotheca acuminata. Topotecan and irinotecan (CPT derivatives) were first approved by the Food and Drug Administration for cancer treatment over 25 years ago and remain key anticancer drugs today. However, their use is often limited by clinical toxicity. Despite extensive development efforts, many of these derivatives have not succeeded clinically, particularly in their effectiveness against pancreatic cancer which remains modest. AIM OF THE STUDY: This study aimed to evaluate the therapeutic activity of FLQY2, a CPT derivative synthesized in our laboratory, against pancreatic cancer, comparing its efficacy and mechanism of action with those of established clinical drugs. METHODS: The cytotoxic effects of FLQY2 on cancer cells were assessed using an MTT assay. Patient-derived organoid (PDO) models were employed to compare the sensitivity of FLQY2 to existing clinical drugs across various cancers. The impact of FLQY2 on apoptosis and cell cycle arrest in Mia Paca-2 pancreatic cancer cells was examined through flow cytometry. Transcriptomic and proteomic analyses were conducted to explore the underlying mechanisms of FLQY2's antitumor activity. Western blotting was used to determine the levels of proteins regulated by FLQY2. Additionally, the antitumor efficacy of FLQY2 in vivo was evaluated in a pancreatic cancer xenograft model. RESULTS: FLQY2 demonstrated (1) potent cytotoxicity; (2) superior tumor-suppressive activity in PDO models compared to current clinical drugs such as gemcitabine, 5-fluorouracil, cisplatin, paclitaxel, ivosidenib, infinitinib, and lenvatinib; (3) significantly greater tumor inhibition than paclitaxel liposomes in a pancreatic cancer xenograft model; (4) robust antitumor effects, closely associated with the inhibition of the TOP I and PDK1/AKT/mTOR signaling pathways. In vitro studies revealed that FLQY2 inhibited cell proliferation, colony formation, induced apoptosis, and caused cell cycle arrest at nanomolar concentrations. Furthermore, the combination of FLQY2 and gemcitabine exhibited significant inhibitory and synergistic effects. CONCLUSION: The study confirmed the involvement of topoisomerase I and the PDK1/AKT/mTOR pathways in mediating the antitumor activity of FLQY2 in treating Mia Paca-2 pancreatic cancer. Therefore, FLQY2 has potential as a novel therapeutic option for patients with pancreatic cancer.

Long non-coding RNA NEAT1 promotes aerobic glycolysis and progression of cervical cancer through WNT/ß-catenin/PDK1 axis.

BACKGROUND: Cervical cancer is one of the most common gynecological cancers. Accumulated evidence shows that long non-coding RNAs (lncRNAs) play essential roles in cervical cancer occurrence and progression, but their specific functions and mechanisms remain to be further explored. METHODS: The RT-qPCR assay was used to detect the expression of NEAT1 in cervical cancer tissues and cell lines. CCK-8, colony formation, flow cytometry, western blotting, and Transwell assays were used to evaluate the impact of NEAT1 on the malignant behavior of cervical cancer cells. Glucose consumption, lactate production, ATP levels, ROS levels, MMP levels, and the mRNA expressions of glycolysis-related genes and tricarboxylic acid cycle-related genes were detected to analyze the effect of NEAT1 on metabolism reprograming in cervical cancer cells. The expressions of PDK1, ß-catenin and downstream molecules of the WNT/ß-catenin signaling pathway in cervical cancer cells and tissues were detected by western blotting, RT-qPCR, immunofluorescence and immunohistochemistry assays. RESULTS: This study investigated the role and possible molecular mechanism of lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) in cervical cancer. Our results showed that NEAT1 was highly expressed in cervical cancer tissues and cell lines. Downregulation of NEAT1 inhibited the proliferation, migration, invasion and glycolysis of cervical cancer cells, while overexpression of NEAT1 led to the opposite effects. Mechanistically, NEAT1 upregulated pyruvate dehydrogenase kinase (PDK1) through the WNT/ß-catenin signaling pathway, which enhanced glycolysis and then facilitated cervical cancer metastasis. Furthermore, NEAT1 maintained the protein stability of ß-catenin but did not affect its mRNA level. We also excluded the direct binding of NEAT1 to the ß-catenin protein via RNA pull-down assay. The suppressive impact of NEAT1 knockdown on cell proliferation, invasion, and migration was rescued by ß-catenin overexpression. The WNT inhibitor iCRT3 attenuated the carcinogenic effect induced by NEAT1 overexpression. CONCLUSION: In summary, these findings indicated that NEAT1 may contribute to the progression of cervical cancer by activating the WNT/ß-catenin/PDK1 signaling axis.

Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction in tafazzin-deficient cells.

Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.

Elucidation of the anti-gastric cancer mechanism of Guiqi Baizhu Formula by integrative approach of chemical bioinformatics.

Gastric cancer (GC) has posed a great threat to the lives of people around the world. To date, safer and more cost-effective therapy for GC is lacking. Traditional Chinese medicine (TCM) may provide some new options for this. Guiqi Baizhu Formula (GQBZF), a classic TCM formula, has been extensively used to treat GC, while its bioactive components and therapeutic mechanisms remain unclear. In this study, we evaluated the underlying mechanisms of GQBZF in treating GC by integrative approach of chemical bioinformatics. GQBZF lyophilized powder (0.0625 mg/mL, 0.125 mg/mL) significantly attenuated the expression of p-IGF1R, PI3K, p-PDK1, p-VEGFR2 to inhibit the proliferation, migration and induce apoptosis of gastric cancer cells, which was consistent with the network pharmacology. Additionally, atractylenolide Ⅰ, quercetin, glycyrol, physcione and aloe-emodin, emodin, kaempferol, licoflavone A were found to be the key compounds of GQBZF regulating IGF1R and VEGFR2, respectively. And among which, glycyrol and emodin were determined as key active compounds against GC by farther vitro experiments and LC/MS. Meanwhile, we also found that glycyrol inhibited MKN-45 cells proliferation and enhanced apoptosis, which might be related to the inhibition of IGF1R/PI3K/PDK1, and emodin could significantly attenuate the MKN-45 cells migration, which might be related to the inhibition of VEGFR2-related signaling pathway. These results were verified again by molecular dynamics simulation and binding interaction pattern. In summary, this study suggested that GQBZF and its key active components (glycyrol and emodin) can suppress IGF1R/PI3K/PDK1 and VEGFR2-related signaling pathway, thereby inhibiting tumor cell proliferation and migration and inducing apoptosis. These findings provided an important strategy for developing new agents and facilitated clinical use of GQBZF against GC.

The effect of PDK1 in maintaining immune cell development and function.

3-phosphoinositide-dependent protein kinase 1 (PDK1) exhibits a substantial influence on immune cell development by establishing a vital connection between PI3K and downstream mTOR signaling cascades. However, it remains unclear whether PDK1 signaling affects the homeostasis and functionality of immune cells. To explore the impact of PDK1 on different immune cells within immune organs, transgenic mouse strains with lymphocyte-specific PDK1 knockout (PDK1fl/fl CD2-Cre) were generated. Unlike wild-type (WT) mice, lymphocyte-specific PDK1 knockout (KO) mice exhibited thymic atrophy, elevated percentages of CD8+ T cells and neutrophils, and reduced proportions of γδ T cells, B cells, and NK cells in the spleen. Functional analysis revealed elevated release of IFN-γ and IL-17A by T cells in PDK1 KO mice, contrasting with diminished levels observed in γδ T cells and Treg cells. Furthermore, the activation, cytotoxicity, and migratory potential of γδ T cells in PDK1 KO mice are heightened, indicating a potential association with the regulation of the mTOR signaling pathway. To conclude, the findings of this research demonstrated that specific knockout of PDK1 in lymphocytes hindered T cell development in the thymus and exhibited a substantial influence on immune cell homeostasis in the spleen and lymph nodes.

Phosphorylation of FOXK2 at Thr13 and Ser30 by PDK2 sustains glycolysis through a positive feedback manner in ovarian cancer.

Ovarian cancer is one of the most common gynecological malignant tumors with insidious onset, strong invasiveness, and poor prognosis. Metabolic alteration, particularly aerobic glycolysis, which is tightly regulated by transcription factors, is associated with the malignant behavior of OC. We screened FOXK2 in this study as a key transcription factor that regulates glycolysis in OC. FOXK2 is overly expressed in OC, and poor prognosis is predicted by overexpression. FOXK2 promotes OC cell proliferation both in vitro and in vivo and cell migration in vitro. Further studies showed that PDK2 directly binds to the forkhead-associated (FHA) domain of FOXK2 to phosphorylate FOXK2 at Thr13 and Ser30, thereby enhancing the transcriptional activity of FOXK2. FOXK2 transcriptionally regulates the expression of PDK2, thus forming positive feedback to sustain glycolysis in OC cells.

Decidual stromal cell-derived exosomes deliver miR-22-5p_R-1 to suppress trophoblast metabolic switching from mitochondrial respiration to glycolysis by targeting PDK4 in unexplained recurrent spontaneous abortion.

INTRODUCTION: Studies have shown that EMT (epithelial-mesenchymal transition) and energy metabolism influence each other, and it is unclear whether the trophoblast energy metabolism phenotype is dominated by glycolysis or mitochondrial respiration, and the relationship between trophoblast energy metabolism and EMT is still unclear. METHODS: Exosomes were isolated from the DSC of URSA patients and their miRNA profile was characterized by miRNA sequencing. Wound healing assays and transwell assays were used to assess the invasion and migration ability of trophoblasts. Mitochondrial stress and glycolysis stress test were used to evaluate energy metabolism phenotype of trophoblast. Luciferase reporter assays, qRT-PCR and WB were conducted to uncover the underlying mechanism. Finally, animal experiments were employed to explore the effect of DSC-exos on embryo absorption in mice. RESULTS: Our results showed that URSA-DSC-exos suppressed trophoblast EMT to reduce their migration and invasion, miR-22-5p_R-1 was the most upregulated miRNAs. URSA-DSC-exos can suppress trophoblast MGS (metabolic switch from mitochondrial respiration to glycolysis) and inhibit trophoblast migration and invasion by transferring miR-22-5p_R-1. Mechanistically, miR-22-5p_R-1 suppress trophoblast MGS and inhibit trophoblast EMT by directly suppressing PDK4 expression at the post-transcriptional level. Furthermore, in vivo experiment suggested that URSA-DSC-exos aggravated embryo absorption in mice. Clinically, PDK4 and EMT molecule were aberrant in villous of URSA patients, and negative correlations were found between miR-22-5p_R-1 and PDK4. DISCUSSION: Our findings indicated that URSA-DSC-exos induced MGS obstacle playing an important role in intercellular communication between trophoblast and DSC, illuminating a novel mechanism in DSC regulation of trophoblasts and their role in URSA.

Nirmatrelvir has detrimental effects on sperm function by altering the PI3K/PDK1/AKT signaling pathway.

Nirmatrelvir (NMV) is a recently developed selective inhibitor of the main protease of Sars-Cov-2 that reduces the severity of infection. Despite its widespread use and various side effects, NMV's effect on male fertility is still unclear. This study was thus established to investigate how NMV affects male fertility. For experiments, Duroc spermatozoa were incubated with various concentrations of NMV (0, 0.1, 1, 10, 50, and 100 µM). Then, sperm motility, motion kinematics, capacitation status, intracellular ATP level, and cell viability were evaluated. In addition, the expression levels of phospho-PKA substrates, tyrosine-phosphorylated proteins, and PI3K/PDK1/AKT signaling pathway-related proteins were measured by western blotting. Our results showed that sperm motility, motion kinematics, proportion of capacitated spermatozoa, and intracellular ATP level were significantly decreased by NMV in a dose-dependent manner. Moreover, PKA activation was significantly suppressed by NMV, and expression levels of PI3K, phospho-PDK1, AKT, and phospho-AKT (Thr308 and Ser473) were significantly increased in a dose-dependent manner. Combining these findings, it is suggested that NMV has detrimental effects on sperm function by inducing abnormal changes in the PI3K/PDK1/AKT signaling pathway, resulting in PKA deactivation. Therefore, there is a need to pay particular attention to its male reproductive toxicity when NMV is administered.