ECM Substrates Impact RNAi Localization at Adherens Junctions of Colon Epithelial Cells

The epithelial adherens junction component PLEKHA7 regulates ECM remodeling and cell behavior through miRNA-mediated regulation of MMP1 and LOX

Epithelial adherens junctions (AJs) are cell-cell adhesion complexes that are influenced by tissue mechanics, such as those emanating from the extracellular matrix (ECM). Here, we introduce a mechanism whereby epithelial AJs can also regulate the ECM. We show that the AJ component PLEKHA7 regulates levels and activity of the key ECM remodeling components MMP1 and LOX in well-differentiated colon epithelial cells, through the miR-24 and miR-30c miRNAs. PLEKHA7 depletion in epithelial cells results in LOX-dependent ECM remodeling in culture and in the colonic mucosal lamina propria in mice. Furthermore, PLEKHA7-depleted cells exhibit increased migration and invasion rates that are MMP1- and LOX- dependent, and form colonies in 3D cultures that are larger in size and acquire aberrant morphologies in stiffer matrices. These results reveal an AJ-mediated mechanism, through which epithelial cells drive ECM remodeling to modulate their behavior, including acquisition of phenotypes that are hallmarks of conditions such as fibrosis and tumorigenesis.

Novel Preoperative Type IV Collagen to Predict the Risk of Hepatocellular Carcinoma in Patients with Hepatitis B Virus-Related Cirrhotic Portal Hypertension After Laparoscopic Splenectomy and Azygoportal Disconnection

Purpose

Although laparoscopic splenectomy and azygoportal disconnection (LSD) can significantly decrease portal vein pressure and even the incidence of hepatocellular carcinoma (HCC) in patients with cirrhotic portal hypertension (CPH), postoperative HCC inevitably occurs in certain patients. The purpose of this study was to seek a novel preoperative non-invasive predictive indicator to predict the occurrence of postoperative HCC.

Patients and Methods

From April 2012 to April 2022, we collected clinical data of 178 hepatitis B virus (HBV)-related CPH patients. Based on inverse treatment probability weighting, candidate variables for predicting postoperative HCC were determined by means analysis. Then, a novel preoperative non-invasive prediction indicator (ie, type IV collagen-alpha fetoprotein-fibrosis-4 score [IVAF-FIB-4]) was established based on candidate variables, and its predictive ability was explored.

Results

Postoperative HCC occurred in 9 (5.1%) patients. Correlation analyses showed that the IVAF-FIB-4 had a significant positive correlation with HCC (r = 0.835, P < 0.001). IVAF-FIB-4 showed a high accuracy (the area under the receiver operating characteristic curve: 0.939, 95% confidence interval [CI]: 0.818-1.000; sensitivity: 88.9%; specificity: 93.5%). At the end of follow-up, the incidence density of HCC in patients with IVAF-FIB-4 (1) was significant higher than that in patients with IVAF-FIB-4 (0) (138.1/1000 vs 1.1/1000 person-years; rate ratio: 130.475, 95% CI: 16.318-1043.227). In logistic regression, IVAF-FIB-4 was an independent risk factor for HCC (odds ratio: 668.000, 95% CI: 53.895-8279.541; P < 0.001).

Conclusion

IVAF-FIB-4 is a novel preoperative noninvasive predictive indicator for predicting postoperative HCC in HBV-related CPH patients after LSD, with satisfactory predictive ability.

Actin-dependent recruitment of AGO2 to the zonula adherens

Adherens junctions are cadherin-based structures critical for cellular architecture. E-cadherin junctions in mature epithelial cell monolayers tether to an apical actomyosin ring to form the zonula adherens (ZA). We have previously shown that the adherens junction protein PLEKHA7 associates with and regulates the function of the core RNA interference (RNAi) component AGO2 specifically at the ZA. However, the mechanism mediating AGO2 recruitment to the ZA remained unexplored. Here, we reveal that this ZA-specific recruitment of AGO2 depends on both the structural and tensile integrity of the actomyosin cytoskeleton. We found that depletion of not only PLEKHA7, but also either of the three PLEKHA7-interacting, LIM-domain family proteins, namely LMO7, LIMCH1, and PDLIM1, results in disruption of actomyosin organization and tension, as well as disruption of AGO2 junctional localization and of its miRNA-binding ability. We also show that AGO2 binds Myosin IIB and that PLEKHA7, LMO7, LIMCH1, and PDLIM1 all disrupt interaction of AGO2 with Myosin IIB at the ZA. These results demonstrate that recruitment of AGO2 to the ZA is sensitive to actomyosin perturbations, introducing the concept of mechanosensitive RNAi machinery, with potential implications in tissue remodeling and in disease.

Natural compound fraxinellone ameliorates intestinal fibrosis in mice via direct intervention of HSP47-collagen interaction in the epithelium

Intestinal fibrosis is a common complication of inflammatory bowel disease. There is still a lack of effective drugs for the prevention or treatment of intestinal fibrosis. Heat shock protein 47 (HSP47) plays a key role in the development of intestinal fibrosis. In this study we investigated the therapeutic potential and underlying mechanisms of fraxinellone, a degraded limonoid isolated from the root bark of Dictamnus dasycarpus, in the treatment of intestinal fibrosis. Intestinal fibrosis was induced in mice by dextran sodium sulfate (DSS) treatment. DDS-treated mice were administered fraxinellone (7.5, 15, 30 mg·kg-1·d-1, i.g.) for 45 days. We showed that fraxinellone administration dose-dependently alleviated DSS-induced intestinal impairments, and reduced the production of intestinal fibrosis biomarkers such as α-smooth muscle actin (SMA), collagen I, hydroxyproline, fibronectin and laminin, and cytokines such as TGF-β, TNF-α and IL-β. We then established in vitro intestinal fibrosis cell models in SW480 and HT-29 cells, and demonstrated that treatment with fraxinellone (3, 10, 30 μM) significantly relieved TGF-β-induced fibrosis responses by inhibiting the TGF-β/Smad2/3 signaling pathway. Molecular docking suggested that the fraxinellone might disrupt the interaction between HSP47 and collagen, which was confirmed by coimmunoprecipitation experiments. SPR analysis showed that fraxinellone had a high affinity for HSP47 with a Kd value of 3.542 × 10-5 M. This study provides a new example of HSP47-collagen intervention by a natural compound and has important implications for the clinical treatment of inflammation-induced issue fibrosis.