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

Nanoplastics-induced developmental and reproductive toxicity, neurotoxicity and immunotoxicity are a focus of widespread attention. However, the effects of nanoplastics (NPs) on glycolipid metabolism and the precise underlying mechanisms are unclear at present. Here, we showed that oral administration of polystyrene nanoparticles (PS-NPs) disrupts glycolipid metabolism, with reactive oxygen species (ROS) identified as a potential key signaling molecule. After PS-NPs treatment, excessive production of ROS induced the inflammatory response and activated the antioxidant pathway through nuclear factor-erythroid factor 2-related factor 2. The activation of nuclear factor-κB (NFκB) signaling pathway induced the phosphorylation of the mitogen-activated protein kinases (MAPK) signaling pathway, which induced the activation of extracellular regulated kinases (ERK) and p38. Constitutive activation of the MAPK signaling proteins induced high continued phosphorylation of insulin receptor substrate-1, in turn, leading to decreased protein kinase B (Akt) activity, which weakened the sensitivity of liver cells to insulin signals and induced insulin resistance. In parallel, phosphorylation of Akt led to loss of control of FoXO1, a key gene of gluconeogenesis, activating transcription of glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase (PEPCK) in a manner dependent on PGC1α. Moreover, the activated ERK promoted lipid accumulation through ERK-PPARγ cascades. Therefore, sterol regulatory element-binding protein-1 and levels of its downstream lipogenic enzymes, ACC-1, were up-regulated. Upon treatment with the antioxidant resveratrol, PS-NPs-induced glucose and lipid metabolic disorders were improved by inhibiting ROS-induced activation of NFκB and MAPK signaling pathway in mice. Based on above, PS-NPs exposure disrupts glycolipid metabolism in mice, with ROS identified as a potential key signaling molecule.

Role of MAPK and PI3K-Akt signaling pathways in cuprizone-induced demyelination and cognitive impairment in mice

This study aimed to find the genes and signaling pathways underlying cuprizone-induced demyelination and cognitive impairments in mice. We used the cuprizone-exposed mice as an animal model of schizophrenia and assessed cognitive function in mice. Total RNA was extracted from mouse brain tissues for RNA sequencing. The DESeq2 R package was utilized to analyze the differentially expressed genes (DEGs). Functional and pathway enrichment analyses were performed simultaneously. We also constructed a protein-protein interaction (PPI) network to screen potential hub genes, and quantitative real-time polymerase chain reaction (qRT-PCR) was employed to validate the screened genes. After 6 weeks of cuprizone treatment, the cognitive function of mice was impaired. Compared to the controls, the cuprizone-exposed mice contained 351 DEGs, including 167 upregulated and 184 downregulated genes. Enrichment analysis showed that the DEGs were enriched in some biological processes involved in demyelination, including the MAPK pathway. Functional pathway analysis revealed that the DEGs were significantly enriched in the PI3K-Akt signaling pathway, which may be associated with cognitive impairments. MBP, IGF1, GFAP, PTPRC, CD14, CD68, ITGB2, LYN, TLR2, TLR4, VAV1, and PLEK were considered as potential hub genes. Except for MBP, all genes were upregulated in the cuprizone models, as verified by qRT-PCR. We suggest that the MAPK and PI3K-Akt signaling pathways may be associated with demyelination and cognitive impairments, respectively. GFAP and IGF-1 expression levels increased in cuprizone-exposed mice, suggesting that astrocytes may play a role in protecting the myelin sheath following treatment with cuprizone.

Megakaryocytes possess a STING pathway that is transferred to platelets to potentiate activation

Platelets display unexpected roles in immune and coagulation responses. Emerging evidence suggests that STING is implicated in hypercoagulation. STING is an adaptor protein downstream of the DNA sensor cyclic GMP-AMP synthase (cGAS) that is activated by cytosolic microbial and self-DNA during infections, and in the context of loss of cellular integrity, to instigate the production of type-I IFN and pro-inflammatory cytokines. To date, whether the cGAS-STING pathway is present in platelets and contributes to platelet functions is not defined. Using a combination of pharmacological and genetic approaches, we demonstrate here that megakaryocytes and platelets possess a functional cGAS-STING pathway. Our results suggest that in megakaryocytes, STING stimulation activates a type-I IFN response, and during thrombopoiesis, cGAS and STING are transferred to proplatelets. Finally, we show that both murine and human platelets contain cGAS and STING proteins, and the cGAS-STING pathway contributes to potentiation of platelet activation and aggregation. Taken together, these observations establish for the first time a novel role of the cGAS-STING DNA sensing axis in the megakaryocyte and platelet lineage.

Black mulberry extract inhibits hepatic adipogenesis through AMPK/mTOR signaling pathway in T2DM mice

ETHNOPHARMACOLOGICAL RELEVANCE

Black mulberry (Morus nigra L.) is an ancient dual-use plant resource for medicine and food. It is widely used in Uyghur folklore for hypoglycemic treatment and is a folkloric plant medicine with regional characteristics. However, the mechanism of Morus nigra L. treatment in diabetes mellitus has not been fully understood, especially from the perspective of hepatic lipid accumulation is less reported.

OBJECTIVE OF THIS STUDY

This study was to explore the potential of Morus nigra L. fruit ethyl acetate extract (MNF-EA) to reduce blood sugar levels by preventing the production of hepatic lipogenesis and to provide more evidence for the use of MNF-EA as an adjuvant therapy for type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

In this study, the chemical composition of MNF-EA was first analyzed and characterized using UPLC-Q-TOF-MS technique. A series of in vitro studies were performed with HepG2-IR cells and oleic acid (OA)-induced HepG2 cells, including MTT assay, glucose uptake assay, oil red O staining and Western blot analysis. The STZ-HFD co-induced T2DM mice were employed for in vivo research, including physical indices, biochemical analysis, histopathological examination, and Western blot analysis.

RESULTS

The 19 compounds in MNF-EA were identified by UPLC-Q-TOF-MS technique. Insulin resistance (IR) and lipid droplet accumulation in HepG2 cells were greatly improved by MNF-EA treatment, which had no appreciable side effects at the dosage used. In T2DM mice, MNF-EA decreased fasting blood glucose (FBG), saved body weight, and significantly improved oral glucose tolerance (OGTT) and IR status. In addition, MNF-EA treatment also improved lipid metabolism disorders and liver function in T2DM mice. Histopathological sections showed that MNF-EA treatment reduced hepatic steatosis. Mechanistic studies suggest that MNF-EA acted through the AMPK/mTOR pathway.

CONCLUSIONS

These results suggest that MNF-EA has great potential to reverse the metabolic abnormalities associated with T2DM by regulating the AMPK/mTOR signaling pathway. Therefore, we believe that MNF is a promising medicinal and food-homologous agent to improve T2DM.