Multiple roles for TGFβ receptor type II in regulating the pancreatic response in acute pancreatitis

TGFβ and Hippo Signaling Pathways Coordinate to Promote Acinar to Ductal Metaplasia in Human Pancreas

BACKGROUND & AIMS

Acinar-to-ductal metaplasia (ADM) serves as a precursor event in the development of pancreatic ductal adenocarcinoma (PDAC) upon constitutive environmental and genetical stress. While the role of ADM in PDAC progression has been established, the molecular mechanisms underlying human ADM remain elusive. We previously demonstrated the induction of ADM in human acinar cells through the transforming growth factor beta (TGFβ) signaling pathway. We aim to investigate the interaction between TGFβ and Hippo pathways in mediating ADM.

METHODS

RNA-sequencing was conducted on sorted normal primary human acinar, ductal, and AD (acinar cells that have undergone ADM) cells. ATAC-seq analysis was utilized to reveal the chromatin accessibility in these three cell types. ChIP-Seq of YAP1, SMAD4, and H3K27ac was performed to identify the gene targets of YAP1 and SMAD4. The role of YAP1/TAZ in ADM-driven cell proliferation, as well as in oncogenic KRAS driven proliferation, was assessed using sphere formation assay.

RESULTS

AD cells have a unique transcription profile, with upregulated genes in open chromatin states in acinar cells. YAP1 and SMAD4 co-occupy the loci of ADM-related genes, including PROM1, HES1, and MMP7, co-regulating biological functions such as cell adhesion, cell migration, and inflammation. Overexpression of YAP1/TAZ promoted acinar cell proliferation but still required the TGFβ pathway. YAP1/TAZ were also crucial for TGFβ-induced sphere formation and were necessary for KRAS-induced proliferation.

CONCLUSIONS

Our study reveals the intricate transition between acinar and AD states in human pancreatic tissues. It unveils the complex interaction between the Hippo and TGF-β pathways during ADM, highlighting the pivotal role of YAP1/TAZ and SMAD4 in PDAC initiation.

CircRNA Expression Profiles and the Potential Role of CircZFP644 in Mice With Severe Acute Pancreatitis via Sponging miR-21-3p

Severe acute pancreatitis (SAP) is the most serious type of pancreatitis with high morbidity and mortality. The underlying mechanism behind SAP pathogenesis is complex and remains elusive. Circular RNAs (circRNAs) are emerging as vital regulators of gene expression in various diseases by sponging microRNAs (miRNAs). However, the roles of circRNAs in the pathophysiology of SAP remain unknown. In the present study, next-generation RNA sequencing was utilized to identify circRNA transcripts in the pancreatic tissues from three SAP mice and three matched normal tissues. The differentially expressed circRNAs were confirmed by real-time PCR, and the biological functions of their interaction with miRNAs and mRNAs were analyzed. Our results demonstrate that 56 circRNAs were differentially expressed in SAP mice compared with normal controls. Six differentially expressed circRNAs were confirmed with the sequencing data. Importantly, we characterized a significantly downregulated circRNA derived from the ZFP664 gene in SAP. CircZFP644 was found to be negatively correlated with miR-21-3p, with a perfectly matched binding sequence to miR-21-3p. In conclusion, CircZFP644 may play an important role in the pathogenesis of SAP through sponging miR-21-3p. Our findings may provide novel insights regarding the workings of the pathophysiological mechanism of SAP and offer novel targets for SAP.

Transforming growth factor-β in pancreatic diseases: Mechanisms and therapeutic potential

Pancreatic diseases, such as acute pancreatitis, chronic pancreatitis, and pancreatic cancer, are common gastrointestinal diseases resulting in the development of local and systemic complications with a high risk of death. Numerous studies have examined pancreatic diseases over the past few decades; however, the pathogenesis remains unclear, and there is a lack of effective treatment options. Recently, emerging evidence has suggested that transforming growth factor beta (TGF-β) exerts controversial functions in apoptosis, inflammatory responses, and carcinogenesis, indicating its complex role in the pathogenesis of pancreas-associated disease. Therefore, a further understanding of relevant TGF-β signalling will provide new ideas and potential therapeutic targets for preventing disease progression. This is the first systematic review of recent data from animal and human clinical studies focusing on TGF-β signalling in pancreas damage and diseases. This information may aid in the development of therapeutic agents for regulating TGF-β in this pathology to prevent or treat pancreatic diseases.

Small molecule inhibitor RepSox prevented ovariectomy-induced osteoporosis by suppressing osteoclast differentiation and bone resorption

Osteoporosis (OP) is a serious metabolic disease that, due to the increased number or function of osteoclasts, results in increased bone brittleness and, therefore, fragile fracture. Some recent studies report the importance of the transforming growth factor β (TGFβ) pathway in bone homeostasis. RepSox is a small molecule inhibitor of TGFβRI that has a wide range of potential application in clinical medicine, except OP. The aim of our study is to evaluate the effects of RepSox on the differentiation and bone resorption of osteoclasts in vitro and in vivo in an ovariectomy (OVX)-induced OP model. An initial analysis showed TGFβRI messenger RNA expression in both bone samples and bone cells. In the in vitro study, RepSox inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation and bone resorption activity. Real-time polymerase chain reaction (PCR) analysis showed that RepSox suppressed osteoclastic marker gene expression in both dose-dependent and time-dependent manners. In addition, RepSox did not affect osteoblast differentiation, migration or osteoblastic-specific gene expression in vitro. Furthermore, western blot analysis indicated the underlying mechanisms of the RepSox suppression of osteoclastogenesis via the Smad3 and c-Jun N-terminal kinase/activator protein-1 (JNK/AP-1) signaling pathways. Finally, our animal experiments revealed that RepSox prevented OVX-induced bone loss in vivo. Together, our data suggest that RepSox regulates osteoclast differentiation, bone resorption, and OVX-induced OP via the suppression of the Smad3 and JNK/AP-1 pathways.