MiR-199a-5p regulates rat liver regeneration and hepatocyte proliferation by targeting TNF-α TNFR1/TRADD/CASPASE8/CASPASE3 signalling pathway

Epigenetic regulation in liver regeneration

The liver is considered unique in its enormous capacity for regeneration and self-repair. In contrast to other regenerative organs (i.e., skin, skeletal muscle, and intestine), whether the adult liver contains a defined department of stem cells is still controversial. In order to compensate for the massive loss of hepatocytes following liver injury, the liver processes a precisely controlled transcriptional reprogram that can trigger cell proliferation and cell-fate switch. Epigenetic events are thought to regulate the organization of chromatin architecture and gene transcription during the liver regenerative process. In this review, we will summarize how changes to the chromatin by epigenetic modifiers are translated into cell fate transitions to restore liver homeostasis during liver regeneration.

Exploring the roles of non-coding RNAs in liver regeneration

Liver regeneration (LR) is a complex process encompassing three distinct phases: priming, proliferation phase and restoration, all influenced by various regulatory factors. After liver damage or partial resection, the liver tissue demonstrates remarkable restorative capacity, driven by cellular proliferation and repair mechanisms. The essential roles of non-coding RNAs (ncRNAs), predominantly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNA (circRNA), in regulating LR have been vastly studied. Additionally, the impact of ncRNAs on LR and their abnormal expression profiles during this process have been extensively documented. Mechanistic investigations have revealed that ncRNAs interact with genes involved in proliferation to regulate hepatocyte proliferation, apoptosis and differentiation, along with liver progenitor cell proliferation and migration. Given the significant role of ncRNAs in LR, an in-depth exploration of their involvement in the liver's self-repair capacity can reveal promising therapeutic strategies for LR and liver-related diseases. Moreover, understanding the unique regenerative potential of the adult liver and the mechanisms and regulatory factors of ncRNAs in LR are crucial for improving current treatment strategies and exploring new therapeutic approaches for various liver-related diseases. This review provides a brief overview of the LR process and the ncRNA expression profiles during this process. Furthermore, we also elaborate on the specific molecular mechanisms through which multiple key ncRNAs regulate the LR process. Finally, based on the expression characteristics of ncRNAs and their interactions with proliferation-associated genes, we explore their potential clinical application, such as developing predictive indicators reflecting liver regenerative activity and manipulating LR processes for therapeutic purposes.

Hydrogen sulfide plays an important role by regulating microRNA in different ischemia-reperfusion injury

MicroRNAs (miRNAs) are the short endogenous non-coding RNAs that regulate the expression of the target gene at posttranscriptional level through degrading or inhibiting the specific target messenger RNAs (mRNAs). MiRNAs regulate the expression of approximately one-third of protein coding genes, and in most cases inhibit gene expression. MiRNAs have been reported to regulate various biological processes, such as cell proliferation, apoptosis and differentiation. Therefore, miRNAs participate in multiple diseases, including ischemia-reperfusion (I/R) injury. Hydrogen sulfide (H2S) was once considered as a colorless, toxic and harmful gas with foul smelling. However, in recent years, it has been discovered that it is the third gas signaling molecule after carbon monoxide (CO) and nitric oxide (NO), with multiple important biological functions. Increasing evidence indicates that H2S plays a vital role in I/R injury through regulating miRNA, however, the mechanism has not been fully understood. In this review, we summarized the current knowledge about the role of H2S in I/R injury by regulating miRNAs, and analyzed its mechanism in detail.

Signaling pathways of liver regeneration: Biological mechanisms and implications

The liver possesses a unique regenerative ability to restore its original mass, in this regard, partial hepatectomy (PHx) and partial liver transplantation (PLTx) can be executed smoothly and safely, which has important implications for the treatment of liver disease. Liver regeneration (LR) can be the very complicated procedure that involves multiple cytokines and transcription factors that interact with each other to activate different signaling pathways. Activation of these pathways can drive the LR process, which can be divided into three stages, namely, the initiation, progression, and termination stages. Therefore, it is important to investigate the pathways involved in LR to elucidate the mechanism of LR. This study reviews the latest research on the key signaling pathways in the different stages of LR.

The role of microRNAs in the different phases of liver regeneration

INTRODUCTION

Since the first discovery of microRNAs (miRs) extensive evidence reveals their indispensable role in different patho-physiological processes. They are recognized as critical regulators of hepatic regeneration, as they modulate multiple complex signaling pathways affecting liver regeneration. MiR-related translational suppression and degradation of target mRNAs and proteins are not limited to one specific gene, but act on multiple targets.

AREAS COVERED

In this review, we are going to explore the role of miRs in the context of liver regeneration and discuss the regulatory effects attributed to specific miRs. Moreover, specific pathways crucial for liver regeneration will be discussed, with a particular emphasis on the involvement of miRs within the respective signaling cascades.

EXPERT OPINION

The considerable amount of studies exploring miR functions in a variety of diseases paved the way for the development of miR-directed therapeutics. Clinical implementation has already shown promising results, but additional research is warranted to assure safe and efficient delivery. Nevertheless, given the broad functional properties of miRs and their critical involvement during hepatic regeneration, they represent an attractive treatment target to promote liver recovery after hepatic resection.

CINC-2 and miR-199a-5p in EVs secreted by transplanted Thy1+ cells activate hepatocytic progenitor cell growth in rat liver regeneration

BACKGROUND

Small hepatocyte-like progenitor cells (SHPCs) are hepatocytic progenitor cells that transiently form clusters in rat livers treated with retrorsine (Ret) that underwent 70% partial hepatectomy (PH). We previously reported that transplantation of Thy1⁺ cells obtained from D-galactosamine-treated livers promotes SHPC expansion, thereby accelerating liver regeneration. Extracellular vesicles (EVs) secreted by Thy1⁺ cells induce sinusoidal endothelial cells (SECs) and Kupffer cells (KCs) to secrete IL17B and IL25, respectively, thereby activating SHPCs through IL17 receptor B (RB) signaling. This study aimed to identify the inducers of IL17RB signaling and growth factors for SHPC proliferation in EVs secreted by Thy1⁺ cells (Thy1-EVs).

METHODS

Thy1⁺ cells isolated from the livers of rats treated with D-galactosamine were cultured. Although some liver stem/progenitor cells (LSPCs) proliferated to form colonies, others remained as mesenchymal cells (MCs). Thy1-MCs or Thy1-LSPCs were transplanted into Ret/PH-treated livers to examine their effects on SHPCs. EVs were isolated from the conditioned medium (CM) of Thy1-MCs and Thy1-LSPCs. Small hepatocytes (SHs) isolated from adult rat livers were used to identify factors regulating cell growth in Thy1-EVs.

RESULTS

The size of SHPC clusters transplanted with Thy1-MCs was significantly larger than that of SHPC clusters transplanted with Thy1-LSPCs (p = 0.02). A comprehensive analysis of Thy1-MC-EVs revealed that miR-199a-5p, cytokine-induced neutrophil chemoattractant-2 (CINC-2), and monocyte chemotactic protein 1 (MCP-1) were candidates for promoting SHPC growth. Additionally, miR-199a-5p mimics promoted the growth of SHs (p = 0.02), whereas CINC-2 and MCP-1 did not. SECs treated with CINC-2 induced Il17b expression. KCs treated with Thy1-EVs induced the expression of CINC-2, Il25, and miR-199a-5p. CM derived from SECs treated with CINC-2 accelerated the growth of SHs (p = 0.03). Similarly, CM derived from KCs treated with Thy1-EVs and miR-199a-5p mimics accelerated the growth of SHs (p = 0.007). In addition, although miR-199a-overexpressing EVs could not enhance SHPC proliferation, transplantation of miR-199a-overexpressing Thy1-MCs could promote the expansion of SHPC clusters.

CONCLUSION

Thy1-MC transplantation may accelerate liver regeneration owing to SHPC expansion, which is induced by CINC-2/IL17RB signaling and miR-199a-5p via SEC and KC activation.

Complex molecular mechanism of ammonia-induced apoptosis in chicken peripheral blood lymphocytes: miR-27b-3p, heat shock proteins, immunosuppression, death receptor pathway, and mitochondrial pathway

Ammonia gas, a toxic environmental pollutant, is a vital component of PM2.5 aerosols, and can decrease human and animal immunity. Peripheral blood lymphocytes (PBLs) are main immune cells. Nevertheless, poisoning mechanism of PBLs under ammonia exposure remains unclear. Here, we established an ammonia poisoning model of chicken PBLs to explore poisoning mechanism of ammonia-caused apoptosis in chicken PBLs. Cell viability and apoptosis rate were detected using CCK8 assay and flow cytometry, respectively. Mitochondrial membrane potential (MMP) was observed using fluorescent staining. In addition, qRT-PCR was performed to measure mRNA levels of apoptosis-related genes (tumor necrosis factor-α (TNF-α), tumor necrosis factor receptor 1 (TNFR1), TNF receptor-associated death domain (TRADD), Fas-associated death domain (FADD), Caspase-8, BH3-interacting domain death agonist (Bid), Bcl-2-associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), B-cell lymphoma-2 (Bcl-2), Cytochrome-c (Cytc), apoptotic protease activating factor-1 (APAF1), Caspase-9, and Caspase-3), immune-related genes (interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-4, IL-6, IL-1β, IL-10, transforming growth factor-β1 (TGF-β1), IL-17, IL-21, and IL-22), heat shock protein (HSP) genes (HSP25, HSP40, HSP60, HSP70, HSP90, and HSP110), as well as miR-27b-3p. Western blot was used to determine protein levels of apoptosis-related factors (TNF-α, Caspase-8, Bcl-2, Caspase-9, and Caspase-3), as well as HSPs (HSP40, HSP60, HSP70, and HSP90). The results indicated that TRADD, FADD, and APAF1 were target genes of miR-27b-3p, as well as miR-27b-3p participated in molecular mechanism of apoptosis through targeting TNF-α/TNFR1/Caspase-8 death receptor pathway-triggered Bid/Cytc/Caspase-9 mitochondrial pathway in ammonia-treated chicken PBLs. In addition, our findings demonstrated that excess ammonia led to immunosuppression via Th1/Th2 imbalance and Treg/Th17 imbalance. Simultaneously, ammonia stress activated HSPs. In summary, for the first time, our data demonstrated that HSPs-triggered immunosuppression led to apoptosis under ammonia exposure. Our findings provided a new insight into molecular mechanism of ammonia poisoning and an important reference for environmental risk assessment related to ammonia.

HOTAIR/Sp1/miR-199a critically regulates cancer stemness and malignant progression of cutaneous squamous cell carcinoma

The long non-coding RNA (lncRNA), HOX antisense intergenic RNA (HOTAIR) is a well-characterized oncogene in multiple human cancers, but not in cutaneous squamous cell carcinoma (CSCC). In this study, we focused on investigating the potential role of HOTAIR in stemness of CSCC. By measuring its expression using RT-qPCR in CSCC vs. normal tissues, as well as in CSCC cell lines A431 or SCC13, A431- or SCC13-derived CSCC stem cells (CSCSCs), and normal skin fibroblasts (HSFs), we detected higher expression of HOTAIR in CSCC than in normal tissues, in recurrent than in non-recurrent CSCC tissues, in CSCCs and CSCSCs than in HSFs, and particularly, in CSCSCs than in CSCCs. Kaplan-Meier analysis suggested that higher expression of HOTAIR was positively correlated with worse overall survival of CSCC patients. Functional assays on colony formation, EdU incorporation, sphere formation, western blot on stem-cell biomarkers, and in vivo models showed that HOTAIR was essential in maintaining multiple stem cell phenotypes of CSCSCs in vitro and in vivo xenograft growth as well as metastasis. Mechanistically, HOTAIR directly interacted with and up-regulated Sp1. Sp1 then induced DNMT1-mediated promoter methylation and direct transcriptional repression of miR-199a-5p. Targeting Sp1 or DNMT1 further boosted the in vivo anti-tumor and anti-metastasis activities of targeting HOTAIR. In conclusion, HOTAIR, by up-regulating Sp1 and targeting miR-199a, promotes stemness and progression of CSCC. Targeting HOTAIR, Sp1 or the underlying mechanisms may thus benefit CSCC treatment.

Preparation of MED1(transcription mediator subunit) gene nanocarrier and its mechanism of action on liver cell regeneration in chronic acute liver failure

Liver failure has attracted attention in clinical work due to its high mortality, and the development of liver transplantation is restricted by various factors. Therefore, it is very important to carry out research on the mechanism of liver cell regeneration. This article has studied in depth the preparation of MED1 gene nanocarriers, collected human plasmids and cells through experimental materials and experimental instruments, and conducted comparative research on conventional culture. This question conducts a regeneration experiment on liver cells in chronic-onset acute liver failure, divides patients into an experimental group and a control group, and understands the recovery of liver function according to the screening of their plasma samples and separation of plasma. This article selects the commonly used clinical biological markers, such as Na+, AFP, Alb, CHE (serum cholinesterase) and other indicators to reflect the regeneration ability of liver function. The incidence of surgical complications in the control group, such as ascites, infection, bleeding, HE, hepatorenal syndrome, and hyponatremia were 71.3%, 87.4%, 16.1%, 41.4%, 19.5%, and 33.3%, respectively. Significantly higher than the experimental group, the difference was statistically significant (P < 0.05); while gender, age, PLT level and whether to use hormones, artificial liver or not there was no significant difference between the two groups (P > 0.05).

miR-199a-5p inhibits the Expression of ABCB11 in Obstructive Cholestasis

ATP-binding cassette, subfamily B member 11 (ABCB11) is an efflux transporter for bile acids on the liver canalicular membrane. The expression of this transporter is reduced in cholestasis; however, the mechanisms contributing to this reduction are unclear. In this study, we sought to determine whether miR-199a-5p contributes to the depletion of ABCB11/Abcb11 in cholestasis in mice. In a microRNA (miRNA) screen of mouse liver after common bile duct ligation (CBDL), we found that miR-199a-5p was significantly upregulated by approximately fourfold. In silico analysis predicted that miR-199a-5p would target the 3′-untranslated region (3′-UTR) of ABCB11/Abcb11 mRNA. The expression of ABCB11-3′-UTR luciferase construct in Huh-7 cells was markedly inhibited by cotransfection of a miRNA-199a-5p mimic, which was reversed by an miRNA-199a-5p mimic inhibitor. We also show treatment of mice after CBDL with the potent nuclear receptor FXR agonist obeticholic acid (OCA) significantly increased Abcb11 mRNA and protein and decreased miR-199a-5p expression. Computational mapping revealed a well-conserved FXR-binding site (FXRE) in the promoter of the gene encoding miR-199a-5, termed miR199a-2. Electromobility shift, chromatin immunoprecipitation, and miR199a-2 promoter-luciferase assays confirmed that this binding site was functional. Finally, CBDL in mice led to depletion of nuclear repressor NcoR1 binding at the miR199a-2 promoter, which facilitates transcription of miR199a-2. In CBDL mice treated with OCA, NcoR1 recruitment to the miR199a-2 FXRE was maintained at levels found in sham-operated mice. In conclusion, we demonstrate that miR-199a-5p is involved in regulating ABCB11/Abcb11 expression, is aberrantly upregulated in obstructive cholestasis, and is downregulated by the FXR agonist OCA.

miR-199a-5p suppresses epithelial- mesenchymal-transition in anaplastic thyroid carcinoma cells via targeting Snail signals

MicroRNAs (miRNAs) have been validated to play prominent roles in the occurrence and development of anaplastic thyroid carcinoma (ATC). miR-199a-5p was previously reported to act as a tumor suppressor or oncomiRNA in various types of cancer. However, its accurate expression, function, and mechanism in ATC remain unclear. Here, we find that miR-199a-5p is significantly downregulated in ATC tissues compared with adjacent non-cancerous tissues. Overexpression of miR-199a-5p significantly inhibits migration and invasion of ATC cells in vitro, and lung metastasis in vivo. Importantly, miR-199a-5p suppresses epithelial-mesenchymal transition (EMT) both in vitro and in vivo by targeting Snail. Taken together, this study reveals that miR-199a-5p is critical to the EMT progression in ATC cells. Targeting the pathway described here may be a novel approach for inhibiting metastasis of ATC.

Caspase-3-related apoptosis prevents pathological regeneration in a living liver donor rat model

PURPOSE

The main goal of this study was to determine the relationship of cleaved-caspase-3 (C3)-related apoptosis and hepatic proliferation, during the liver repopulation in a living liver donor rat model.

MATERIAL/METHODS

Thirty-three animals were randomized into eleven groups and evaluated on postoperative from 3 ​h until 384 ​h after 30%-partial hepatectomy (30%-PHx). Liver sections (5 ​μm) were processed by hematoxylin-eosin, and immunostaining for C3, accompanied by hepatic function test. C3 content and the hepatic lobule enlargement were analyzed by optical density, followed by cell counting.

RESULTS

Transient variations of alanine transferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were found. Significant increase in the C3 levels, and cell nuclei number, were detected at 12 ​h and 48 ​h after 30%-PHx, evidencing a correlation of p ​= ​-0.3679.

CONCLUSION

In the 30%-PHx rat model, C3-related apoptosis prevents proliferative pathological conditions during the hepatic lobule re-modeling.