Introduction

Pancreatic fibrosis is the main pathological feature of chronic pancreatitis and stroma of pancreatic cancer, which is the result of excessive deposition of extracellular matrix of collagen fibers. Activated pancreatic stellate cells (PSCs) are the main effector cells of pancreatic fibrosis. The characteristics of heterogeneity and subgroup of PSCs may help to determine the therapeutic target of pancreatic fibrosis. The purpose of this study was to investigate the function of JUND in the activation of PSCs, evaluate the role of JUND in glutamine metabolism during pancreatic fibrosis, and explore the molecular regulated mechanism between JUND and PIWIL1/mTOR signaling pathway.

Aims & Methods

When inducing pancreatic fibrosis in C57BL/6 mice, 20% L-arginine (250 mg/100g) was injected intraperitoneally twice a week, with an interval of 1 hour, lasting for 8 weeks, and then PSCs were isolated. Use RNA interference (RNAi) constructed by lentivirus and vectors constructed based on over-expression vectors to knock out and over-express JUDN and PIWIL1 Protein. In order to explore the effects of JUND on PSC activation, EMC secretion, actin cytoskeleton, invasion and migration ability, as well as glutamine metabolism, ELISA, western blotting, wound healing test, transwell and phalloidin staining were used respectively. To explore transcriptional molecular mechanism between JUND and PIWIL1, luciferase reporter assay, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) were applied. Hematoxylin-eosin, Masson and Sirius red staining were used to analyze the effect of JUND on histological changes and collagen deposition.

Results

In LV-JUND group, the level of α-SMA, Col I and Col III were significantly increased compared with si-JUND group. However, the expression of PIWIL1, desmin and p-mTOR were reduced in LV-JUND group. Meanwhile, the synthesis and metabolism of glutamine decreased significantly under the LV-JUND treatment. Wound healing test, transwell indicated that JUND promoted the migration and invasion ability of PSCs. Furthermore, JUND directly binded to the PIWIL1 promoter and then activated its transcription. In addition, as fibrosis aggravated over time, the levels of JUND significantly increased.

Conclusion

Our findings suggest that JUND-regulated glutamine metabolism in PSCs promotes pancreatic fibrosis via PIWIL1/mTOR signaling pathway. JUND could become a potential target for the treatment of pancreatic fibrosis.

Disclosure

This work was supported by grants from the Fund for Fostering Young Scholars of Peking University Health Science Center (BMU2021PY010), National Natural Science Foundation of China (No. 82002461), Beijing Municipal Hospital Management Center "Youth" Talent Plan (QML20231104) and Medjaden Academy and Research Foundation for Young Scientists (MJR20211110).