Activation of activator protein-1-fibroblast growth factor 21 signaling attenuates Cisplatin hepatotoxicity

Fibroblast growth factor-21 potentiates the stimulatory effects of 1,25-dihydroxyvitamin D3 on transepithelial calcium transport and TRPV6 Ca2+ channel expression

Fibroblast growth factor (FGF)-21 is a salient liver-derived endocrine regulator for metabolism of glucose and triglyceride as well as bone remodeling. Previously, certain peptides in the FGF family have been shown to modulate calcium absorption across the intestinal epithelia. Since FGF21 receptor, i.e., FGF receptor-1, is abundantly expressed in the enterocytes, there was a possibility that FGF21 might exert direct actions on the intestine. Herein, a large-scale production of recombinant FGF21 at the multi-gram level was developed in order to minimize variations among various batches. In the oral glucose tolerance test, recombinant FGF21 was found to reduce plasma glucose levels in mice fed high-fat diet. A series of experiments applying radioactive tracer 45Ca in Ussing chamber showed that FGF21 potentiated the stimulatory effect of low-dose 1,25-dihydroxyvitamin D3 [10 nM 1,25(OH)2D3] on the transepithelial calcium transport across intestinal epithelium-like Caco-2 monolayer. FGF21 + 1,25(OH)2D3 also decreased transepithelial resistance, but had no effect on epithelial potential difference or short-circuit current. Furthermore, 1,25(OH)2D3 alone upregulated the Caco-2 mRNA expression of the major apical calcium channels, i.e., transient receptor potential vanilloid subfamily member 6 (TRPV6), which was further elevated by a combination of FGF21 and 1,25(OH)2D3, consistent with the upregulated TRPV6 protein expression in enterocytes of FGF21-treated mice. However, FGF21 was without effects on the mRNA expression of voltage-gated calcium channel 1.3, calbindin-D9k, plasma membrane Ca2+-ATPase 1b, claudin-12 or claudin-15. In conclusion, FGF21 did exert a direct action on the intestinal epithelial cells by potentiating the 1,25(OH)2D3-enhanced calcium transport, presumably through the upregulation of TRPV6 expression.

Network Pharmacology Prediction and Experimental Validation of Ferulic Acid’s Protective Effects against Diclofenac‐Induced Liver Injury

Despite being one of the most consumed analgesics worldwide, liver injury is an adverse effect of diclofenac (DF). In pursuit of reliable hepatoprotective natural remedies, this study aimed to investigate the potential protective effect of ferulic acid (FA) and its mechanism against DF‐induced liver injury. Various network databases and datasets were used to collect targets corresponding to FA and DF‐induced liver injury. Enrichment analyses of common targets were performed, a protein‐protein interaction (PPI) network was constructed, the hub genes were identified, and the upstream miRNA interacting with the top hub gene was later predicted. A DF‐induced liver injury rat model was established to verify FA’s protective effects, and the selected hub gene expression level with its upstream regulatory miRNA and a downstream set of targets was examined to elucidate the underlying mechanism. A total of 18 genes were identified as potential targets of FA to protect against DF‐induced liver injury. Data from the enrichment and PPI analyses and the prediction of the upstream miRNAs indicated that the most worthwhile pair to study was miR‐296‐5p/Jun. In vivo findings showed that coadministration of FA significantly reduced the DF‐induced alterations in the liver function indices, oxidative stress, and liver histology. Mechanistically, FA downregulated the expression of Jun, Bim, Bax, Casp3, IL‐1β, IL‐6, and TNF‐α, whereas it upregulated the expression of rno‐miR‐296‐5p and Bcl2. In conclusion, combining network pharmacology and an in vivo study revealed that miR‐296‐5p/Jun axis could mediate the mitigative effect of FA against DF‐induced liver injury.