Epinephrine modulates Na+/K+ ATPase activity in Caco-2 cells via Src, p38MAPK, ERK and PGE2

Synergistic and attenuated effects and molecular biological mechanisms of Shouhui Tongbian capsule in the treatment of slow transit constipation based on UPLC-MS/MS, network pharmacology and animal experimental validation

BACKGROUND

Shouhui Tongbian capsule (SHTB) has been widely used for the treatment of constipation. There are few studies on SHTB at present. The current study aimed to explore the effects of multi-components compatibility of SHTB for efficacy enhancement and toxicity reduction and evaluate its molecular biological mechanisms in the treatment of slow transit constipation (STC).

METHODS

Ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to quantify 17 anthraquinone components in different compatible systems of SHTB. Network pharmacological analysis was used to probe the potential mechanisms of SHTB in treating STC. In addition, an animal experiment combined with western blot analysis was performed to further validate the predicted results.

RESULTS

After compatibility, the dissolution of 13 components with good effects in treating constipation increased, while the dissolution of 3 components with hepatotoxicity decreased. Overall, 145 common targets of 13 synergistic components and constipation were identified. A synergistic component-target-disease network showed that chrysoobtusin, obtusifolin, emodin, obtusin and 2-hydroxyl emodin-1-methyl ether were the potential key synergistic components. A protein-protein interaction network analysis identified 91 targets, and an analysis of topological characteristics was conducted to confirm the core targets. Gene Ontology function revealed that the 13 synergistic components for the treatment of STC mainly played roles via protein phosphorylation, positive regulation of phosphorylation, phosphotransferase activity, kinase activity and protein kinase activity, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that these components were enriched in pathways in cancer, MAPK signaling pathway, IL-17 signaling pathway, NF-κB signaling pathway, etc. The results of animal experimental validation showed that SHTB significantly reduced the expression levels of p-p38 and p-ERK proteins in the colon tissue of the STC rats.

CONCLUSION

This study preliminarily demonstrated that efficacy enhancement and toxicity reduction of SHTB could be achieved after compatibility, which expounded the connotation of compatibility theory of traditional Chinese medicine from the perspective of chemical composition, reflecting the rationality and scientificity of compatibility theory. Meanwhile, the study also revealed the core targets and potential molecular biological mechanisms of SHTB in the treatment of STC, which may serve as a reference for subsequent studies and clinical applications of SHTB.

Na+/K+-ATPase Revisited: On Its Mechanism of Action, Role in Cancer, and Activity Modulation

Maintenance of Na⁺ and K⁺ gradients across the cell plasma membrane is an essential process for mammalian cell survival. An enzyme responsible for this process, sodium-potassium ATPase (NKA), has been currently extensively studied as a potential anticancer target, especially in lung cancer and glioblastoma. To date, many NKA inhibitors, mainly of natural origin from the family of cardiac steroids (CSs), have been reported and extensively studied. Interestingly, upon CS binding to NKA at nontoxic doses, the role of NKA as a receptor is activated and intracellular signaling is triggered, upon which cancer cell death occurs, which lies in the expression of different NKA isoforms than in healthy cells. Two major CSs, digoxin and digitoxin, originally used for the treatment of cardiac arrhythmias, are also being tested for another indication—cancer. Such drug repositioning has a big advantage in smoother approval processes. Besides this, novel CS derivatives with improved performance are being developed and evaluated in combination therapy. This article deals with the NKA structure, mechanism of action, activity modulation, and its most important inhibitors, some of which could serve not only as a powerful tool to combat cancer, but also help to decipher the so-far poorly understood NKA regulation.

Increased Renal Dysfunction, Apoptosis, and Fibrogenesis Through Sympathetic Hyperactivity After Focal Cerebral Infarction

Sympathetic nervous system plays an important role in secondary injury of diseases. Accumulating evidence has observed association between ischemic stroke and renal dysfunction, but the mechanisms are incompletely clear. In this study, we investigated whether sympathetic hyperactivity can cause the development of renal dysfunction, apoptosis, and fibrogenesis after focal cerebral infarction. To determine the renal consequences of focal cerebral ischemia, we subjected a mice model of transient middle cerebral artery occlusion (tMCAO) and examined systolic blood pressure, heart rate, renal structure and function, serum catecholamine, and cortisol levels, and the expression of active caspase-3 bcl-2, bax, and phosphorylated p38 MAPK after 8 weeks. We also analyzed the relationship between insular cortex infarction and acute kidney injury (AKI) in 172 acute anterior circulation ischemic stroke (ACIS) patients. Transient right middle cerebral artery occlusion induced sympathetic hyperactivity, renal dysfunction, upregulation of apoptosis, and fibrogenesis in kidneys of mice. Metoprolol treatment relieves the development of renal injury. Study in stroke patients demonstrated that insular cortex infarction, especially the right insular cortex infarction, is an independent risk factor of AKI. Focal cerebral ischemia in mice leads to the development of renal injury driven by sympathetic hyperactivity. Right insular cortex infarction is an independent risk factor of AKI in older patients. Understanding the brain-kidney interaction after stroke would have clinical implications for the treatment and overall patient outcome.

The epinephrine-induced PGE2 reduces Na+/K+ ATPase activity in Caco-2 cells via PKC, NF-κB and NO

We showed previously an epinephrine-induced inhibition of the Na⁺/K⁺ ATPase in Caco-2 cells mediated via PGE2. This work is an attempt to further elucidate mediators downstream of PGE2 and involved in the observed inhibitory effect. The activity of the Na⁺/K⁺ ATPase was assayed by measuring the amount of inorganic phosphate liberated in presence and absence of ouabain, a specific inhibitor of the enzyme. Changes in the protein expression of the Na⁺/K⁺ ATPase were investigated by western blot analysis which revealed a significant decrease in the abundance of the ATPase in plasma membranes. Treating the cells with epinephrine or PGE2 in presence of SC19220, a blocker of EP1 receptors abolished completely the effect of the hormone and the prostaglandin while the effect was maintained unaltered in presence of antagonists to all other receptors. Treatment with calphostin C, PTIO, ODQ or KT5823, respective inhibitors of PKC, NO, soluble guanylate cyclase and PKG, abrogated completely the effect of epinephrine and PGE2, suggesting an involvement of these mediators. A significant inhibition of the ATPase was observed when cells were treated with PMA, an activator of PKC or with 8-Br-cGMP, a cell permeable cGMP analogue. PMA did reduce the protein expression of IκB, as shown by western blot analysis, and its effect on the ATPase was not manifested in presence of an inhibitor of NF-κB while that of SNAP, a nitric oxide donor, was not affected. The results infer that NF-κB is downstream PKC and upstream NO. The data support a pathway in which epinephrine induces the production of PGE2 which binds to EP1 receptors and activates PKC and NF-κB leading to NO synthesis. The latter activates soluble guanylate cyclase resulting in cGMP production and activation of PKG which through direct or indirect phosphorylation inhibits the Na⁺/K⁺ ATPase by inducing its internalization.

Anti-Breast Cancer Activity of Latroeggtoxin-V Mined from the Transcriptome of Spider Latrodectus tredecimguttatus Eggs

As a black widow spider, Latrodectus tredecimguttatus has poisonous components not only in venomous glands but also in eggs. Our previous work had carried out a transcriptome analysis of the spider eggs in an attempt to probe into the molecular basis of the egg toxicity. A proteinaceous toxin, named Latroeggtoxin-V, was mined from the identified transcriptome. In this study, the gene of Latroeggtoxin-V was cloned and heterologously expressed, and the anticancer activity of the recombinant Latroeggtoxin-V (rLatroeggtoxin-V) was characterized. Activity assay found that rLatroeggtoxin-V could selectively act on breast cancer line MDA-MB-231 cells, not only arresting their cell cycle, inhibiting their proliferation and migration, but also inducing their apoptosis. Bioinformatics analysis suggested that Latroeggtoxin-V belongs to the ATPase inhibitor protein family and the further activity assay showed that the rLatroeggtoxin-V inhibited the activity of the Na⁺/K⁺-ATPase in MDA-MB-231 cells in a concentration-dependent manner, suggesting that the anticancer activity of Latroeggtoxin-V is based on its affecting the ion transport and receptor functions of Na⁺/K⁺-ATPase. The present work not only laid the foundation for the utilization of Latroeggtoxin-V in the anticancer drug development and the related fields, but also provided a new paradigm for exploration of the proteinaceous toxins under the direction of transcriptomics and bioinformatics.