Wet age-related macular degeneration is a leading cause of irreversible vision loss, primarily due to choroidal neovascularization (CNV) and subsequent fibrosis. Although current anti-vascular endothelial growth factor A (anti-VEGF) therapies offer significant benefits, many patients exhibit limited or no response and develop drug resistance over time, necessitating the exploration of complementary or alternative therapeutics. This study aimed to identify and characterize a platelet-derived growth factor-C (PDGF-C)-targeting DNA aptamer and to evaluate its therapeutic potential for suppressing CNV and fibrosis, including in an anti-VEGF-refractory setting. A DNA aptamer against PDGF-C (α-PC aptamer) was identified using systematic evolution of ligands by exponential enrichment. Its binding to PDGF-C and inhibition of PDGF-C/platelet-derived growth factor receptor alpha (PDGFRα) interaction were assessed using surface plasmon resonance. The effects of the α-PC aptamer on PDGF-C-induced proliferation, migration, and PDGFRα, Akt, and extracellular-regulated kinase (ERK) signaling were examined in fibroblasts and human umbilical vein smooth muscle cells (HUVSMCs). In vivo efficacy was evaluated in a laser-induced CNV mouse model, including anti-VEGF refractory aged mice. The α-PC aptamer specifically bound to PDGF-C and effectively blocked its binding to PDGFRα. The α-PC aptamer significantly inhibited PDGFRα, Akt, and ERK activation and suppressed PDGF-C-induced proliferation and migration of both fibroblasts and HUVSMCs. Importantly, in a laser-induced CNV mouse model, the α-PC aptamer markedly reduced neovascularization and fibrosis; it particularly retained efficacy in suppressing CNV in anti-VEGF refractory aged mice, where anti-VEGF treatment failed to do so. These findings suggest that the α-PC aptamer represents a promising therapeutic agent for treating neovascular diseases, especially in patients refractory to anti-VEGF treatment.

TRPC1 channel modulates mechanical stretch-induced bone marrow mesenchymal stem cell proliferation through Ca2+-dependent ERK1/2 activation.

Plasma accumulation of the gut microbial metabolite 4-ethylphenylsulfate (4EPS), derived from dietary amino acid, tyrosine, has been associated with cardiovascular, renal, metabolic, and neurological disorders. AngII (angiotensin II) infusion increases circulating 4EPS in mice, suggesting a potential mechanistic role. We hypothesized that 4EPS modulates AngII-regulated pathophysiology and disease progression by directly inhibiting AT1R (angiotensin II type 1 receptor). This hypothesis was tested by combining AT1R pharmacology, cell signaling assays, ex vivo vascular studies, an AngII-induced aortic aneurysm growth model, and plasma proteomics analysis. in vitro, 4EPS reduced the binding of both AngII and the antagonist candesartan to AT1R and suppressed AngII-induced calcium signaling. Ex vivo, 4EPS attenuated AngII-mediated vasoconstriction. In vivo, high-fat diet-fed ApoE-null mice coinfused with AngII and 4EPS showed significant blunting of blood pressure elevation and a marked reduction in aortic aneurysm-related mortality compared with mice infused with AngII alone. Analysis of aortic remodeling revealed increased elastin preservation and decreased thickening of the intimal and medial layers in 4EPS-treated animals. Plasma proteomics indicated alterations in actin-cytoskeletal signaling pathways consistent with reduced activation of ERK (extracellular-regulated kinase) 1/2, filamin-A, and proteins involved in vascular smooth muscle cell motility. These findings identify 4EPS as a benign, endogenous AT1R antagonist that diminishes AngII-mediated hemodynamic and vascular pathology. By suppressing cytoskeletal signaling associated with vascular remodeling, 4EPS provides significant protection against hypertension and aortic aneurysm progression in mice, revealing a previously unrecognized protective role for a gut microbial metabolite in modulating renin-angiotensin system activity.

Mathematical models are indispensable for studying the architecture and behavior of intracellular signaling networks. It is common to develop models using phenomenological approximations due to the difficulty of fully observing the intermediate steps in intracellular signaling pathways. Thus, multiple models can be built to represent the same pathway. This opens up challenges for model selection and decreases certainty in predictions. Here, we investigate Bayesian multimodel inference (MMI) as an approach to increase certainty in systems biology predictions, which becomes relevant when one wants to leverage a set of potentially incomplete models. Using existing models of the extracellular-regulated kinase (ERK) pathway, we show that MMI successfully combines models and yields predictors robust to model set changes and data uncertainties. We then use MMI to identify possible mechanisms of experimentally measured subcellular location-specific ERK activity. This work highlights MMI as a disciplined approach to increasing the certainty of intracellular signaling activity predictions.

BackgroundThe epithelial sodium channel (ENaC) situated in the apical membrane of alveolar epithelial type 2 (AT2) cells is beneficial to edematous fluid reabsorption in acute lung injury (ALI). Recently, mesenchymal stem cells (MSCs), particularly their secretome, has emerged as a novel approach for treating pulmonary diseases. Among these secreted factors, keratinocyte growth factor (KGF) plays a critical role in mediating alveolar epithelial repair during ALI by enhancing epithelial cell proliferation, restoring epithelial integrity, and alleviating pulmonary edema, making it a promising candidate for therapeutic strategies. This study primarily focused on investigating the impact of KGF secreted from MSC on ALI, and clarifying its specific mechanism in regulating the expression of ENaC.MethodsLipopolysaccharide (LPS)-stimulated primary mouse AT2 cells were treated with KGF in vitro, and western blots along with immunofluorescence assays were performed to investigate the regulatory mechanism of KGF on ENaC protein expression. To further confirm the role of mouse bone marrow MSC-derived KGF, co-culture experiments with AT2 cells and either MSC or MSC with KGF knockdown (MSC-siKGF) were conducted. In vivo, an ALI model was established in mice by LPS-induced lung injury. The therapeutic effects of tail vein-injected MSC or MSC-siKGF were assessed using hematoxylin–eosin staining, lung wet/dry weight ratio, and alveolar fluid clearance.ResultsIn primary mouse AT2 cells, KGF stimulation effectively restored the reduction of growth factor receptor-bound protein 2-associated binding protein 1 (Gab1) and α/γ-ENaC protein levels induced by LPS. KGF inhibited the activation of the LPS-induced extracellular regulated protein kinases (ERK) and nuclear factor-kappaB (NF-κB) signaling pathway. Treatment with the ERK pathway inhibitor PD98059 reversed the LPS-induced reduction in ENaC protein levels but had no effect on Gab1 levels. In addition, PD98059 suppressed LPS-induced activation of the NF-κB signaling pathway. Further analysis revealed that LPS stimulation weakened the interaction between the NF-κB p65 subunit and inhibitor kappaB (IκB), while KGF enhanced this interaction and inhibited the nuclear translocation of p65. Both KGF and the NF-κB inhibitor QNZ reversed the LPS-induced downregulation of ENaC protein levels and gene expression. Furthermore, both agents effectively restored the functional activity of ENaC channels. Co-culture with MSCs increased Gab1 protein levels, inhibited ERK/NF-κB signaling activation, and suppressed p65 nuclear translocation in LPS-treated AT2 cells, whereas these effects were attenuated in cells co-cultured with MSC-siKGF. In an ALI mouse model, tail-vein injection of MSCs alleviated lung injury and pulmonary edema, while the therapeutic effects of MSC-siKGF were weaker they were partly restored by the combination of QNZ.ConclusionsOur study validated that the efficacy of MSCs in the treatment of edematous ALI was significantly associated with KGF, which potentially enhanced the upregulation of ENaC through the Gab1/ERK/NF-κB signaling pathway.

Although every cell biologist knows the importance of selecting the right growth conditions and it is well known that the composition of growth medium may vary depending on a product brand or lot affecting many cellular processes, still those effects are poorly systematized. We addressed this issue by comparing the effect of 12 fetal bovine sera (FBS) and eight growth media from different brands on the morphological and functional parameters of five cell types: lung adenocarcinoma, neuroblastoma, glioblastoma, embryonic kidney, and colorectal cancer cells. Using high-throughput imaging, we compared cell proliferation; performed morphological profiling based on the imaging of 561,519 cells; measured extracellular regulated kinases (ERK1/2) activity, mitochondria potential, and lysosome accumulation; and compared cell sensitivity to drugs, response to EGF stimulation, and ability to differentiate. We found that changes in cell proliferation and morphology were independent, and morphological changes were associated with differences in mitochondria potential or the cell's ability to differentiate. Surprisingly, the most drastic differences were detected in serum-free conditions, where medium choice affected cell survival and response to EGF. Overall, our data may be used to improve the reproducibility of experiments involving cell cultures, and the effects of 28 growth conditions on proliferation and 44 morphological parameters can be explored through a Shinyapp.

Cannabinoid type 1 receptors (CB 1 Rs) play important roles in regulating neurotransmitter release, synaptic plasticity, cell differentiation, and survival. CB 1 R is coupled via pertussis toxin (PTX)-sensitive Gαi/o proteins to the activation of extracellular regulated kinase (ERK) signaling. However, there are multiple Gαi/o isoforms, and it is unknown which of these isoforms is responsible for CB 1 R-induced phosphorylation of ERK. The purpose of this study was to determine which Gαi/o isoform(s) couple CB 1 R to ERK phosphorylation. HEK293 cells stably expressing the mouse CB 1 R (CB 1 R-HEK cells) were transfected with either pcDNA3.1 or pcDNA3.1 encoding PTX-insensitive mutants of Gαo, Gαi1, Gαi2, or Gαi3. PTX was used to inactivate endogenous Gαi/o isoforms before cells were treated with vehicle, delta-9-tetrahydrocannabinol (∆ 9 -THC), or CP55940 and ERK phosphorylation was measured by western blotting. CP55940 induced robust phosphorylation of ERK in cells transfected with vector alone. This effect was completely abolished by PTX treatment. CP55940-induced ERK phosphorylation was rescued by expression of PTX-insensitive forms of Gαo, Gαi1, Gαi2, or Gαi3, indicating that the CB1 receptor can couple to ERK phosphorylation through each of these Gαi/o isoforms. Consistent with its actions as a partial agonist, ∆ 9 -THC induced nominal (two to four-fold) increases in ERK phosphorylation that did not reach statistical significance except in cells transfected with PTX-insensitive Gαi3. These data demonstrate that CB 1 R can couple to ERK phosphorylation through Gαo, Gαi1, Gαi2, or Gαi3 when stimulated with CP55940 (full agonist). However, ∆ 9 -THC (partial agonist)-induced ERK activation might require high levels of Gαi3 expression.

Oxidative stress is a pivotal factor in the pathogenesis of various cardiovascular diseases. Rhodiola, a traditional Chinese medicine, is recognized for its potent antioxidant properties. Salidroside, a phenylpropanoid glycoside derived from Rhodiola rosea, has shown remarkable antioxidant capabilities. This study aimed to elucidate the potential protective mechanisms of Rhodiola and salidroside against H2O2-induced cardiac apoptosis in H9c2 cardiomyoblast cells. H9c2 cells were exposed to H2O2 for 4 h, and subsequently treated with Rhodiola or salidroside for 24 h. Cell viability and apoptotic pathways were assessed. The involvement of insulin-like growth factor 1 receptor (IGF1R) and the activation of extracellular regulated protein kinases 1/2 (ERK1/2) were investigated. H2O2 (100 μM) exposure significantly induced cardiac apoptosis in H9c2 cells. However, treatment with Rhodiola (12.5, 25, and 50 μg/mL) and salidroside (0.1, 1, and 10 nM) effectively attenuated H2O2-induced cytotoxicity and apoptosis. This protective effect was associated with IGF1R-activated phosphorylation of ERK1/2, leading to the inhibition of Fas-dependent proteins, HIF-1α, Bax, and Bak expression in H9c2 cells. The images from hematoxylin and eosin staining and immunofluorescence assays also revealed the protective effects of Rhodiola and salidroside in H9c2 cells against oxidative damage. Our findings suggest that Rhodiola and salidroside possess antioxidative properties that mitigate H2O2-induced apoptosis in H9c2 cells. The protective mechanisms involve the activation of IGF1R and subsequent phosphorylation of ERK1/2. These results propose Rhodiola and salidroside as potential therapeutic agents for cardiomyocyte cytotoxicity and apoptosis induced by oxidative stress in heart diseases. Future studies may explore their clinical applications in cardiac health.

Acrolein is a ubiquitous gaseous air pollutant and endogenous toxicant, which poses strong risk for oxidative stress-related diseases such as cardiovascular disease. Adenosine has been identified as potential therapeutic agent for age-related cardiovascular disease, while the molecular mechanisms underlying its cardioprotection remain elusive. In the present study, we investigated the myocardial protective effects and the mechanism of adenosine on acrolein-induced toxicity in H9c2 cells and primary neonatal rat cardiomyocytes. We found that acrolein caused apoptosis of cardiomyocytes resulting from oxidative damage, autophagy defect, and mitochondrial dysfunction, as evidenced by loss of mitochondrial membrane potential, impairment of mitochondrial biogenesis, dynamics, and oxidative phosphorylation, decrease of mitochondrial deoxyribonucleic acid (mtDNA) copy number and adenosine 5’-triphosphate (ATP) production. Adenosine pretreatment protected against acrolein-induced cardiotoxicity by maintaining mitochondrial homeostasis, activating the phase II detoxifying enzyme system, promoting autophagic flux, and alleviating mitochondrial-dependent apoptosis. We further demonstrated that the up-regulation of forkhead box protein O1 (FoxO1) mediated by extracellular regulated protein kinases (ERK) activation contributes to the cardioprotection of adenosine. These results expand the application of adenosine in cardioprotection to preventing myocardial damages induced by environmental pollutant acrolein exposure, and uncover the adenosine-ERK-FoxO1 axis as the underlying mechanism mediating the protection of mitochondrial homeostasis, Nrf2-mediated antioxidant defense and autophagic flux, shedding light on the better understanding about the pathological mechanism of cardiovascular disease caused by environmental pollutants and applications of adenosine in cardioprotection.

This study aimed to produce single-chain recombinant Anguillid eel follicle-stimulating hormone (rec-eel FSH) analogs with high activity in Cricetulus griseus ovary DG44 (CHO DG44) cells. We recently reported that an O-linked glycosylated carboxyl-terminal peptide (CTP) of the equine chorionic gonadotropin (eCG) β-subunit contributes to high activity and time-dependent secretion in mammalian cells. We constructed a mutant (FSH-M), in which a linker including the eCG β-subunit CTP region (amino acids 115-149) was inserted between the β-subunit and α-subunit of wild-type single-chain eel FSH (FSH-wt). Plasmids containing eel FSH-wt and eel FSH-M were transfected into CHO DG44 cells, and single cells expressing each protein were isolated from 10 and 7 clones. Secretion increased gradually during the cultivation period and peaked at 4000-5000 ng/mL on day 9. The molecular weight of eel FSH-wt was 34-40 kDa, whereas that of eel FSH-M increased substantially, with two bands at 39-46 kDa. Treatment with PNGase F to remove the N glycosylation sites decreased the molecular weight remarkably to approximately 8 kDa. The EC50 value and maximal responsiveness of eel FSH-M were approximately 1.23- and 1.06-fold higher than those of eel FSH-wt, indicating that the mutant showed slightly higher biological activity. Phosphorylated extracellular-regulated kinase (pERK1/2) activation exhibited a sharp peak at 5 min, followed by a rapid decline. These findings indicate that the new rec-eel FSH molecule with the eCG β-subunit CTP linker shows potent activity and could be produced in massive quantities using the stable CHO DG44 cell system.

We produced a recombinant eel luteinizing hormone (rec-eel LH) analog with high potency in Chinese hamster ovary DG44 (CHO DG44) cells. The tethered eel LH mutant (LH-M), which had a linker comprising the equine chorionic gonadotropin (eLH/CG) β-subunit carboxyl-terminal peptide (CTP) region (amino acids 115 to 149), was inserted between the β-subunit and α-subunit of wild-type tethered eel LH (LH-wt). Monoclonal cells transfected with the tethered eel LH-wt and eel LH-M plasmids were isolated from five to nine clones of CHO DG44 cells, respectively. The secreted quantities abruptly increased on day 3, with peak levels of 5000-7500 ng/mL on day 9. The molecular weight of tethered rec-eel LH-wt was 32-36 kDa, while that of tethered rec-eel LH-M increased to approximately 38-44 kDa, indicating the detection of two bands. Treatment with the peptide N-glycanase F decreased the molecular weight by approximately 8 kDa. The oligosaccharides at the eCG β-subunit O-linked glycosylation sites were appropriately modified post-translation. The EC50 value and maximal responsiveness of eel LH-M increased by approximately 2.90- and 1.29-fold, respectively, indicating that the mutant exhibited more potent biological activity than eel LH-wt. Phosphorylated extracellular regulated kinase (pERK1/2) activation resulted in a sharp peak 5 min after agonist treatment, with a rapid decrease thereafter. These results indicate that the new tethered rec-eel LH analog had more potent activity in cAMP response than the tethered eel LH-wt in vitro. Taken together, this new eel LH analog can be produced in large quantities using a stable CHO DG44 cell system.

Ca2+ permeation through TRPV4 in fibroblasts is associated with pathological matrix degradation. In human gingival fibroblasts, IL-1β binding to its signaling receptor (IL-1R1) induces activation of extracellular regulated kinase (ERK) and MMP1 expression, processes that require Ca2+ flux across the plasma membrane. It is not known how IL-1R1, which does not conduct Ca2+, generates Ca2+ signals in response to IL-1. We examined whether TRPV4 mediates the Ca2+ fluxes required for ERK signaling in IL-1 stimulated gingival fibroblasts. TRPV4 was immunostained in fibroblasts of human gingival connective tissue and in focal adhesions of cultured mouse gingival fibroblasts. Human gingival fibroblasts treated with IL-1β showed no change of TRPV4 expression but there was increased MMP1 expression. In mouse, gingival fibroblasts expressing TRPV4, IL-1 strongly increased [Ca2+]i. Pre-incubation of cells with IL-1 Receptor Antagonist blocked Ca2+ entry induced by IL-1 or the TRPV4 agonist GSK101. Knockout of TRPV4 or expression of a non-Ca2+-conducting TRPV4 pore-mutant or pre-incubation with the TRPV4 inhibitor RN1734, blocked IL-1-induced Ca2+ transients and expression of the mouse interstitial collagenase, MMP13. Treatment of mouse gingival fibroblasts with GSK101 phenocopied Ca2+ and ERK responses induced by IL-1; these responses were absent in TRPV4-null cells or cells expressing a non-conducting TRPV4 pore-mutant. Immunostained IL-1R1 localized with TRPV4 in adhesions within cell extensions. While TRPV4 immunoprecipitates analyzed by mass spectrometry showed no association with IL-1R1, TRPV4 associated with Src-related proteins and Src co-immunoprecipitated with TRPV4. Src inhibition reduced IL-1-induced Ca2+ responses. The functional linkage of TRPV4 with IL-1R1 expands its repertoire of innate immune signaling processes by mediating IL-1-driven Ca2+ responses that drive matrix remodeling in fibroblasts. Thus, inhibiting TRPV4 activity may provide a new pharmacological approach for blunting matrix degradation in inflammatory diseases.

Chronically elevated neurohumoral drive, and particularly elevated adrenergic tone leading to β-adrenergic receptor (β-AR) overstimulation in cardiac myocytes, is a key mechanism involved in the progression of heart failure. β1-AR (β1-adrenergic receptor) and β2-ARs (β2-adrenergic receptor) are the 2 major subtypes of β-ARs present in the human heart; however, they elicit different or even opposite effects on cardiac function and hypertrophy. For example, chronic activation of β1-ARs drives detrimental cardiac remodeling while β2-AR signaling is protective. The underlying molecular mechanisms for cardiac protection through β2-ARs remain unclear. β2-AR signaling mechanisms were studied in isolated neonatal rat ventricular myocytes and adult mouse ventricular myocytes using live cell imaging and Western blotting methods. Isolated myocytes and mice were used to examine the roles of β2-AR signaling mechanisms in the regulation of cardiac hypertrophy. Here, we show that β2-AR activation protects against hypertrophy through inhibition of phospholipaseCε signaling at the Golgi apparatus. The mechanism for β2-AR-mediated phospholipase C inhibition requires internalization of β2-AR, activation of Gi and Gβγ subunit signaling at endosome and ERK (extracellular regulated kinase) activation. This pathway inhibits both angiotensin II and Golgi-β1-AR-mediated stimulation of phosphoinositide hydrolysis at the Golgi apparatus ultimately resulting in decreased PKD (protein kinase D) and histone deacetylase 5 phosphorylation and protection against cardiac hypertrophy. This reveals a mechanism for β2-AR antagonism of the phospholipase Cε pathway that may contribute to the known protective effects of β2-AR signaling on the development of heart failure.

This study investigated the protective effects of magnolol on the kidneys of diabetic nephropathy (DN) rats via the mitogenactivated protein kinase/nuclear factor-kappa-B (MAPK/NF-κB) signaling pathway. Rats were divided into control, diabetic control, low-dose magnolol, and high-dose magnolol groups. The DN model was induced by a high-glucose/high-fat diet and streptozocin injection. The results showed that in the diabetic control group, various parameters indicative of DN worsened compared to the control group. However, in the magnolol-treated groups, there were improvements in glucose levels, urine volume, proteinuria, kidney function markers, inflammatory factors, and renal tissue morphology. Magnolol treatment also correlated with the decreased activation of extracellular regulated protein kinases, c-jun N-terminal kinase, p38 MAPK, and increased levels of the inhibitor of NF-κB, suggesting inhibition of the MAPK/NF-κB signaling pathway. These findings suggest that magnolol exerts a protective effect on DN rats by inhibiting the MAPK/NF-κB signaling pathway and reducing inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, and interleukin-1β.

Traumatic brain injury (TBI) is a major cause of mortality and disability around the world, for which no treatment has been found. Nociceptin/Orphanin FQ (N/OFQ) and the nociceptin opioid peptide (NOP) receptor are rapidly increased in response to fluid percussion, stab injury, and controlled cortical impact (CCI) TBI. TBI-induced upregulation of N/OFQ contributes to cerebrovascular impairment, increased excitotoxicity, and neurobehavioral deficits. Our objective was to identify changes in N/OFQ and NOP receptor peptide, protein, and mRNA relative to the expression of injury markers and extracellular regulated kinase (ERK) 24 h following mild (mTBI) and moderate TBI (ModTBI) in wildtype (WT) and NOP receptor-knockout (KO) rats. N/OFQ was quantified by radioimmunoassay, mRNA expression was assessed using real-time PCR and protein levels were determined by immunoblot analysis. This study revealed increased N/OFQ mRNA and peptide levels in the CSF and ipsilateral tissue of WT, but not KO, rats 24 h post-TBI; NOP receptor mRNA increased after ModTBI. Cofilin-1 activation increased in the brain tissue of WT but not KO rats, ERK activation increased in all rats following ModTBI; no changes in injury marker levels were noted in brain tissue at this time. In conclusion, this study elucidates transcriptional and translational changes in the N/OFQ-NOP receptor system relative to TBI-induced neurological deficits and initiation of signaling cascades that support the investigation of the NOP receptor as a therapeutic target for TBI.

Smooth muscle cell (SMC) contraction and vascular tone are modulated by phosphorylation and multiple modifications of the thick filament, and thin filament regulation of SMC contraction has been reported to involve extracellular regulated kinase (ERK). Previous studies in ferrets suggest that the actin-binding protein, calponin 1 (CNN1), acts as a scaffold linking protein kinase C (PKC), Raf, MEK and ERK, promoting PKC-dependent ERK activation. To gain further insight into this function of CNN1 in ERK activation and the regulation of SMC contractility in mice, we generated a novel Calponin 1 knockout mouse (Cnn1 KO) by a single base substitution in an intronic CArG box that preferentially abolishes expression of CNN1 in vascular SMCs. Using this new Cnn1 KO mouse, we show that ablation of CNN1 has two effects, depending on the cytosolic free calcium level: (1) in the presence of elevated intracellular calcium caused by agonist stimulation, Cnn1 KO mice display a reduced amplitude of stress and stiffness but an increase in agonist-induced ERK activation; and (2) during intracellular calcium depletion, in the presence of an agonist, Cnn1 KO mice exhibit increased duration of SM tone maintenance. Together, these results suggest that CNN1 plays an important and complex modulatory role in SMC contractile tone amplitude and maintenance.

Inflammatory cytokine mediated responses are important in the development of many diseases that are associated with angiogenesis. Targeting angiogenesis as a prominent strategy has shown limited effects in many contexts such as cardiovascular diseases and cancer. One potential reason for the unsuccessful outcome is the mutual dependent role between inflammation and angiogenesis. Inflammation-based therapies primarily target inflammatory cytokines such as interleukin-6 (IL-6) in T cells, macrophages, cancer cells, and muscle cells, and there is a limited understanding of how these cytokines act on endothelial cells. Thus, we focus on one of the major inflammatory cytokines, IL-6, mediated intracellular signaling in endothelial cells by developing a detailed computational model. Our model quantitatively characterized the effects of IL-6 classic and trans-signaling in activating the signal transducer and activator of transcription 3 (STAT3), phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), and mitogen-activated protein kinase (MAPK) signaling to phosphorylate STAT3, extracellular regulated kinase (ERK) and Akt, respectively. We applied the trained and validated experiment-based computational model to characterize the dynamics of phosphorylated STAT3 (pSTAT3), Akt (pAkt), and ERK (pERK) in response to IL-6 classic and/or trans-signaling. The model predicts that IL-6 classic and trans-signaling induced responses are IL-6 and soluble IL-6 receptor (sIL-6R) dose-dependent. Also, IL-6 classic and trans-signaling showed similar potency in inducing downstream signaling; however, trans-signaling induces stronger downstream responses and plays a dominant role in the overall effects from IL-6 due to the in vitro experimental setting of abundant sIL-6R. In addition, both IL-6 and sIL-6R levels regulate signaling strength. Moreover, our model identifies the influential species and kinetic parameters that specifically modulate the downstream inflammatory and/or angiogenic signals, pSTAT3, pAkt, and pERK responses. Overall, the model predicts the effects of IL-6 classic and/or trans-signaling stimulation quantitatively and provides a framework for analyzing and integrating experimental data. More broadly, this model can be utilized to identify potential targets that influence IL-6 mediated signaling in endothelial cells and to study their effects quantitatively in modulating STAT3, Akt, and ERK activation.

Renal fibrosis is characterized by the excessive deposition of extracellular matrix that destroys and replaces the functional renal parenchyma, ultimately leading to organ failure. It is a common pathway by which chronic kidney disease can develop into end-stage renal disease, which has high global morbidity and mortality, and there are currently no good therapeutic agents available. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been indicated to be closely related to the occurrence of renal fibrosis, and its specific inhibitory peptide, autocamtide-2-related inhibitory peptide (AIP), was shown to directly bind the active site of CaMKII. In this study, we examined the effect of AIP on the progression of renal fibrosis and its possible mechanism. The results showed that AIP could inhibit the expression of the fibrosis markers fibronectin, collagen I, matrix metalloproteinase 2, and α-smooth muscle actin in vivo and in vitro. Further analysis revealed that AIP could inhibit the expression of various epithelial-to-mesenchymal transformation-related markers, such as vimentin and Snail 1, in vivo and in vitro. Mechanistically, AIP could significantly inhibit the activation of CaMKII, Smad 2, Raf, and extracellular regulated protein kinases (ERK) in vitro and in vivo and reduce the expression of transforming growth factor-β (TGF-β) in vivo. These results suggested that AIP could alleviate renal fibrosis by inhibiting CaMKII and blocking activation of the TGF-β/Smad2 and RAF/ERK pathways. Our study provides a possible drug candidate and demonstrates that CaMKII is a potential pharmacological target for the treatment of renal fibrosis. SIGNIFICANCE STATEMENT: We have demonstrated that AIP significantly attenuated transforming growth factor-β-1-induced fibrogenesis and ameliorated unilateral ureteral obstruction-induced renal fibrosis through the CaMKII/TGF-β/Smad and CaMKII/RAF/ERK signaling pathways in vitro and in vivo. Our study provides a possible drug candidate and demonstrates that CaMKII can be a potential pharmacological target for the treatment of renal fibrosis.

Dual-specificity phosphatase 2 (DUSP2) regulates the activation of members of the mitogen-activated protein kinase (MAPK) family, which is involved in a variety of cellular processes including cell proliferation, differentiation, apoptosis, and migration. DUSP2 also regulates the expression of inflammatory mediators in macrophages; however, it remains unknown whether DUSP2 participates in macrophage migration. Here, using the tail fin injury model in zebrafish larvae, we found that the deletion of DUSP2 inhibited the expression of pro-inflammatory cytokines and macrophage chemokines. Moreover, live imaging results showed that the migration of macrophages to the injury site was inhibited after DUSP2 deletion. This inhibitory effect was mediated through the reduced activation of extracellular regulated protein kinases (ERK) in DUSP2 knockout zebrafish.

Polystyrene nanoplastics induce glycolipid metabolism disorder via NF-κB and MAPK signaling pathway in mice