American journal of physiology. Cell physiology最新文献

We have reported that an endogenous aryl hydrocarbon receptor (AhR) ligand, 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), inhibits functions of human umbilical vein endothelial cells (HUVECs) and induces preeclampsia (PE)-like symptoms in rats. Herein, we tested the hypothesis that ITE impairs endothelial functions via disturbing transcriptome and phosphoproteome in HUVECs. We measured AhR activity in human maternal and umbilical vein sera from PE and normotensive (NT) pregnancies. The serum-induced changes in CYP1A1/B1 mRNA (indexes of AhR activation) in HUVECs were quantified using RT-qPCR. ITE's effects on endothelial proliferation and monolayer integrity in female and male HUVECs were determined. We profiled ITE-induced changes in transcriptome and phosphoproteome in HUVECs using RNA-seq and bottom-up phosphoproteomics, respectively. After 12 hr of treatment, umbilical vein sera from PE increased CYP1A1 mRNA (1.7-fold of NT) HUVECs, which was blocked by CH223191, an AhR antagonist. ITE dose-dependently inhibited endothelial proliferation (76%-87% of control) and time-dependently reduced endothelial integrity with a maximum inhibition (~ 10%) at 40 hr. ITE induced 140 and 80 differentially expressed genes in female and male HUVECs, respectively. ITE altered phosphorylation of 92 and 105 proteins at 4 and 24 hr, respectively, in HUVECs. These ITE-dysregulated genes and phosphoproteins were enriched in biological functions and pathways are relevant to heart, liver, and kidney diseases, vascular functions, and inflammatory responses. Thus, endogenous AhR ligands may impair endothelial functions by disturbing transcriptome and phosphoproteome. These AhR ligand-dysregulated genes and phosphoproteins may be therapeutic and cell sex-specific targets for PE-induced endothelial dysfunction.

Though γ-aminobutyric acid (GABA) serves as the primary inhibitory neurotransmitter in the brain, its numerous biological activities in the periphery, including anti-inflammatory and anti-diabetic functions, have been documented. Additionally, GABA may be a mediator underlying effects of ketone bodies/ketogenic diets on muscle regeneration. Here, we investigated effects of GABA on muscle regeneration in Type 1 Diabetes mouse models. Akita and wild-type (WT) mice were treated with GABA in drinking water for 6 weeks, followed by cardiotoxin (CTX)-induced muscle injury. At 5 days post-injury, GABA treatment exhibited no effects on regenerating myofiber size in both WT and Akita mice. Unexpectedly, regenerating GABA-treated Akita muscles exhibited significantly increased embryonic myosin heavy chain (eMHC) expression and higher intramuscular-macrophage content, suggesting delays in muscle regeneration and in elevated macrophage infiltration in diabetic muscles. Next, we determined if GABA treatment delayed the inflammatory process during muscle regeneration. Providing GABA in the drinking water during the peak inflammatory period (days 0 to 5 post-injury) resulted in a significantly greater amount of small regenerating myofibers and higher expressions of TNFα and eMHC in regenerating streptozotocin (STZ)-diabetic muscles, indicating delays in inflammation process and muscle regeneration in diabetes. Plasma GABA levels were found higher in GABA-treated STZ mice than WT mice and negatively correlated with regenerating myofiber size. This delay in muscle regeneration in STZ-diabetic mice was abolished by a lower dose of GABA water that did not raise plasma GABA levels. Together, high doses of GABA intake during the early phases of muscle repair may delay regeneration.

Inflammation is a significant risk factor for preterm birth. Inflammation enhances glycolytic processes in various cell types and contributes to the development of myometrial contractions. However, the potential of inflammation to activate glycolysis in pregnant murine uterine smooth muscle cells (mUSMCs) and its role in promoting inflammatory preterm birth remain unexplored. In this study, lipopolysaccharide was employed to establish both cell and animal inflammation models. We found that inflammation of mUSMCs during late pregnancy could initiate glycolysis and promoted cell contraction. Subsequently, the inhibition of glycolysis using the glycolysis inhibitor 2-deoxyglucose can reverse inflammation-induced cell contraction. The expression of 6-phosphofructokinase 2 kinase (PFKFB3) was significantly upregulated in mUSMCs following lipopolysaccharide stimulation. Additionally, lactate accumulation and enhanced contraction were observed. Inhibition of PFKFB3 reversed the lactate accumulation and enhanced contraction induced by inflammation. We also found that inflammation activated the phosphatidylinositol 3-kinase (PI3K) - protein kinase B (Akt) - mammalian target of rapamycin (mTOR) pathway, leading to the upregulation of PFKFB3 expression. The PI3K-Akt pathway inhibitor LY294002 and the mTOR pathway inhibitor Rapamycin effectively inhibited the upregulation of PFKFB3 protein expression, lactate production, and the enhancement of cell contraction induced by lipopolysaccharide. This study indicates that inflammation regulates PFKFB3 through the PI3K-Akt-mTOR pathway, which enhances the glycolytic process in pregnant mUSMCs, ultimately leading to myometrial contraction.

Overreaching (OR) can be defined as a decline in physical performance resulting from excessive exercise training, necessitating days to weeks recovery. Impairments in the contractile function of skeletal muscle are believed to be a primary factor contributing to OR. However, the cellular mechanism triggering OR remains unclear. The purpose of this study was to elu idate the mechanisms underlying OR. Rats' plantar flexor muscles were subjected to repeated electrical stimulations mimicking excessive high-intensity interval training (HIIT) daily for 13 consecutive days, and isometric torques were monitored. The torque was measured one day after HIIT, and subsequently, the physiological function of type II fibers was analyzed by using mechanically-skinned-fiber technique. Eleven out of 17 rats exhibited torque decline, while others did not. Thus, the rats were divided into OR and non-overreaching (NOR) groups. Skinned fibers from the gastrocnemius (GAS) muscles of both groups showed decreased depolarization-induced force and increased myofibrillar Ca²⁺ sensitivity.However, the fibers from the OR group, but not the NOR group, exhibited a decrease in myofibrillar maximal force. Biochemical analyses of a superficial region of GAS muscle revealed that α-actinin 2 content was increased in the NOR group, but not the OR group, whereas calpain-3 autolysis was increased in the OR group, but not the NOR group. These findings shed light on the cellular mechanism underlying OR: OR following excessive HIIT was induced by a decreased myofibrillar maximal force, while Ca²⁺ sensitivity was increased.

Arterial stiffening is a hallmark of chronic kidney disease (CKD)-related cardiovascular events and is primarily attributed to the elevated matrix stiffness. Stiffened arteries are accompanied by low-grade inflammation, but the causal effects of matrix stiffness on inflammation remain unknown. For analysis of the relationship between arterial stiffness and vascular inflammation, pulse-wave velocity (PWV) and aortic inflammatory markers were analyzed in an adenine-induced mouse model of CKD in chronological order. Compared with their control littermates, mice with CKD showed elevated arterial stiffness at the early stage of disease progression, which preceded the onset of vascular inflammation. Correspondingly, the increase of matrix stiffness induced vascular smooth muscle cells (VSMCs) to transdifferentiate into an inflammatory phenotype, as indicated by the increased expression and secretion of MCP-1, IL-6, IL-1β, and IL-18. RNA-sequencing analysis of stiff matrix-cultured VSMCs and bioinformatics analysis with the ChIP-Atlas database revealed the potential involvement of the transcription factor Runx2. The expression and the nuclear localization of Runx2 were significantly increased in stiff matrix-cultured VSMCs. High-throughput ChIP-sequencing and promoter luciferase assays further revealed that NLRP3 was directly transcriptionally regulated by Runx2. The inhibition of Runx2 or NLRP3 inflammasome abrogated the proinflammatory effect of matrix stiffening on VSMCs. Together, these data revealed that arterial stiffness precedes vascular inflammatory responses in CKD mice and that the Runx2-NLRP3 axis orchestrates matrix stiffness and the VSMC inflammatory phenotype, which may contribute to the pathogenic role in arterial stiffness-related vascular inflammation and CKD-related cardiovascular complications.NEW & NOTEWORTHY As a hallmark of chronic kidney disease (CKD), arterial stiffening is related to increased vascular inflammation and cardiovascular morbidity, whereas the underlying mechanism is unclear. The study demonstrates that increased arterial stiffness precedes the onset of vascular inflammation, and matrix stiffness stimulates the transdifferentiation of vascular smooth muscle cells (VSMCs) to an inflammatory phenotype via activating Runx2-NLRP3 signaling, which provides novel insights into CKD-related cardiovascular disorder treatment.

Histone lactylation is crucial in a variety of physiopathological processes; however, the function and mechanism of histone lactylation in endometriosis remain poorly understood. Therefore, the objective of this investigation was to illuminate the function and mechanism of histone lactylation in endometriosis. Immunohistochemistry was used to investigate the expression of histone lactylation. Cell Counting Kit-8 assay (CCK8), Transwell assay, and endometriosis mouse models were used to investigate the effects of histone lactylation in vitro and in vivo. Transcriptomics and immunoprecipitation-mass spectrometry (IP-MS), Western blot, co-immunoprecipitation (Co-IP), quantitative reverse transcription polymerase chain reaction (qRT-PCR), and chromatin immunoprecipitation-qPCR (ChIP-qPCR) were used to explore the intrinsic mechanisms. In this study, we found that histone lactylation was upregulated in endometriosis and could promote endometriosis progression both in vivo and in vitro. Mechanistically, histone lactylation H3K18la promoted the transcription of Ras homolog enriched in striatum (RASD2), and RASD2, in turn, increased the stability of CTP synthase 1 (CTPS1) by promoting the SUMOylation and inhibiting the ubiquitination of CTPS1, thereby promoting endometriosis progression. Overall, our findings indicated that histone lactylation could promote the progression of endometriosis through the RASD2/CTPS1 axis. This investigation uncovered a novel mechanism and identified prospective targets for endometriosis diagnosis and therapy.NEW & NOTEWORTHY Our finding reveals a novel mechanism that promotes the progression of endometriosis, namely the histone lactylation/RASD2/CTPS1 axis. This finding suggests that inhibiting histone lactylation or inhibiting RASD2 and CTPS1 might be a potential therapeutic strategy to inhibit endometriosis lesion growth.

The epidermal growth factor receptor (EGFR) signaling pathway is an evolutionary conserved mechanism to control cell behavior during tissue development and homeostasis. Deregulation of this pathway has been associated with abnormal cell behavior, including hyperproliferation, senescence, and an inflammatory cell phenotype, thereby contributing to pathologies across a variety of organs, including the kidneys, skin, and lungs. To date, there are seven distinct EGFR ligands described. Although binding of these ligands to the receptor is cell type-specific and spatio-temporally controlled with distinct affinities and kinetics, epiregulin (EREG) stands out as a long-acting EGFR ligand that emerges under pathological conditions, particularly in tissue fibrosis. Although EREG has been extensively studied in cancer, its contribution to the maladaptive remodeling of tissue is elusive. The aim of this review is to highlight the role of EREG in skin, kidney, and lung fibrosis and to discuss opportunities for therapeutic intervention.

Thoracic aortic aneurysm (TAA) is a vascular disease associated with high mortality rates. Ferroptosis has been shown to mediate the transformation of vascular smooth muscle cells (VSMCs). However, the regulatory mechanisms by which ferroptosis influences TAA remain unclear. In this study, we induced TAA mouse models using angiotensin II (Ang II) and evaluated the impact of ferroptosis on the pathological changes observed in TAA mice, employing liproxstatin-1 as a treatment. In addition, we assessed the regulatory effect of METTL14 on the ferroptosis of VSMCs after treating them with a ferroptosis activator (imidazole ketone erastin, IKE). RNA binding protein immunoprecipitation (RIP) and RNA pull-down assays were conducted to investigate the interaction between acyl-CoA synthase long-chain family member 4 (ACSL4) mRNA and the proteins METTL14 or IGF2BP2. The results indicated that the level of ferroptosis was elevated in the thoracic aorta of TAA mice, and METTL14 was upregulated in TAA models and IKE-induced VSMCs. Knockdown of METTL14 was found to inhibit the progression of TAA by reducing the ferroptosis of VSMCs. Furthermore, IGF2BP2 recognized METTL14-modified ACSL4 mRNA and regulated its stability, thereby mediating the ferroptosis of VSMCs. Collectively, the effects of METTL14 on VSMC ferroptosis present therapeutic potential for the treatment of TAA.NEW & NOTEWORTHY Our study confirmed that METTL14 can induce ferroptosis in vascular smooth muscle cells during the progression of thoracic aortic aneurysm by mediating the m⁶A modification of ACSL4 mRNA.

Intestinal microbiota are pathophysiologically involved in diabetic nephropathy (DN). Dapagliflozin, recognized for its blood glucose-lowering effect, has demonstrated efficacy in improving DN. However, the mechanisms beyond glycemic control that mediate the impact of dapagliflozin on DN remain unclear. Here, we investigated the effects of dapagliflozin on DN and gut microbiota, elucidating how it mitigates DN via the gut-kidney axis. Low-dose dapagliflozin markedly ameliorated renal inflammation and fibrosis and improved gut barrier function in high-fat diet (HFD)/streptozotocin (STZ)-induced DN mice and db/db mice without affecting blood glucose levels. These effects were associated with altered gut microbial composition and function. Eradication of the resident microbiota abolished the protective effects of dapagliflozin against kidney injury in DN mice. Moreover, dapagliflozin significantly altered microbial metabolites in DN mice, decreasing argininosuccinic acid (ASA) and palmitic acid (PA), while increasing S-allylcysteine (SAC) levels. ASA and PA increased the expression of renal inflammation- and fibrosis-related markers in HK-2 cells, whereas SAC ameliorated renal damage and altered the microbial composition in a manner similar to dapagliflozin in DN mice. Notably, Muribaculaceae and Desulfovibrionaceae were correlated with the alleviation of DN-associated renal dysfunction by low- and high-dose dapagliflozin treatments in DN mice. These findings demonstrate a potential application of dapagliflozin in managing DN by targeting the gut microbiota.NEW & NOTEWORTHY We demonstrated that dapagliflozin administration alleviated renal inflammation and fibrosis in vivo and in vitro, along with reshaping the gut microbiota composition and altering levels of key microbial metabolites, including argininosuccinic acid (ASA) and palmitic acid (PA), while increasing S-allylcysteine (SAC). Importantly, the genera Muribaculaceae and Desulfovibrionaceae emerged as pivotal microbial genera mediating the protective effects of dapagliflozin against diabetic nephropathy.

Mitochondria are metabolic hubs that govern skeletal muscle health. Although exercise has been established as a powerful inducer of quality control processes that ultimately enhance mitochondrial function, there are currently limited pharmaceutical interventions available that emulate exercise-induced mitochondrial adaptations. To investigate a novel candidate for this role, we examined sulforaphane (SFN), a naturally occurring compound found in cruciferous vegetables. SFN has been documented as a potent antioxidant inducer through its activation of the nuclear factor erythroid 2-related factor 2 (Nrf-2) antioxidant response pathway. However, its effects on muscle health have been underexplored. To investigate the interplay between chronic exercise and SFN, C2C12 myotubes were electrically stimulated to model chronic contractile activity (CCA) in the presence or absence of SFN. SFN promoted Nrf-2 nuclear translocation, enhanced mitochondrial respiration, and upregulated key antioxidant proteins including catalase and glutathione reductase. These adaptations were accompanied by reductions in cellular and mitochondrial reactive oxygen species (ROS) emission. Signaling toward biogenesis was enhanced, demonstrated by increases in mitochondrial transcription factor A (TFAM), peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α nuclear translocation, PGC-1α promoter activity, mitochondrial content, and organelle branching, suggestive of a larger, more interconnected mitochondrial pool. These mitochondrial adaptations were accompanied by an increase in lysosomal proteins, suggesting coordinated regulation. There was no difference in mitochondrial and antioxidant-related proteins between CCA and non-CCA SFN-treated cells. Our data suggest that SFN activates signaling cascades that are common to those produced by contractile activity, indicating that SFN-centered therapeutic strategies may improve the mitochondrial phenotype in skeletal muscle.NEW & NOTEWORTHY Nrf-2 is a transcription factor that has been implicated in mitigating oxidative stress and regulating mitochondrial homeostasis. However, limited research has demonstrated how Nrf-2-mediated adaptations compare with those produced by exercise. To investigate this, we treated myotubes with Sulforaphane, a well-established Nrf-2 activator, and combined this with stimulation-induced chronic contractile activity to model exercise training. Our work is the first to establish that sulforaphane mimics training-induced mitochondrial adaptations, including enhancements in respiration, biogenesis, and dynamics.