Role of microRNA in liver regeneration

Nanoparticles for Creating a Strategy to Stimulate Liver Regeneration

Presently, there is a need in the developing new approaches to stimulate liver regeneration, which would make its recovery more effective after resection. Application of nanoparticles, loaded with small bioactive molecules, with their targeted delivery into the liver is a promising approach. The aim of the investigation is to study the interaction of nanoparticles with various types of hepatic cells on the models of liver slices and primary hepatic cell cultures using the methods of multiphoton microscopy with fluorescence lifetime imaging.

Materials and Methods

Nanoparticles have been synthetized from polylactide (PLA), gold (Au), and silicon (SiO2), and characterized using scanning and transmission electron microscopy. These types of particles were labeled with a fluorescent Cy5 dye for their visualization. Liver slices and a primary hepatocyte culture were used as models for biological testing of nanoparticles. Biodistribution of the nanoparticles in the tissue and cells, their cytotoxicity, and the effect on the cell metabolism were assessed using optical bioimaging methods.

Results

The silicon nanoparticles are accumulated mainly by macrophages, which generate reactive oxygen species in a large amount and impair the native metabolic state of hepatocytes. The gold nanoparticles accumulate in all types of the liver cells but possess a marked toxic effect, which is indicated by the appearance of necrotic and apoptotic cells and a sharp change in the hepatocyte metabolic state. The polylactide nanoparticles accumulate most effectively in the liver cells, preferably in hepatocytes, do not change their native metabolic state, making this type of nanoparticles most promising for creating the bioactive molecule delivery systems to stimulate liver regeneration.

Distinct hepatocyte identities in liver homeostasis and regeneration

The process of metabolic liver zonation is spontaneously established by assigning distributed tasks to hepatocytes along the porto-central blood flow. Hepatocytes fulfil critical metabolic functions, while also maintaining hepatocyte mass by replication when needed. Recent technological advances have enabled us to fine-tune our understanding of hepatocyte identity during homeostasis and regeneration. Subsets of hepatocytes have been identified to be more regenerative and some have even been proposed to function like stem cells, challenging the long-standing view that all hepatocytes are similarly capable of regeneration. The latest data show that hepatocyte renewal during homeostasis and regeneration after liver injury is not limited to rare hepatocytes; however, hepatocytes are not exactly the same. Herein, we review the known differences that give individual hepatocytes distinct identities, recent findings demonstrating how these distinct identities correspond to differences in hepatocyte regenerative capacity, and how the plasticity of hepatocyte identity allows for division of labour among hepatocytes. We further discuss how these distinct hepatocyte identities may play a role during liver disease.

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.

Effect of Hepatic Pathology on Liver Regeneration: The Main Metabolic Mechanisms Causing Impaired Hepatic Regeneration

Liver regeneration has been studied for many decades, and the mechanisms underlying regeneration of normal liver following resection are well described. However, no less relevant is the study of mechanisms that disrupt the process of liver regeneration. First of all, a violation of liver regeneration can occur in the presence of concomitant hepatic pathology, which is a key factor reducing the liver's regenerative potential. Understanding these mechanisms could enable the rational targeting of specific therapies to either reduce the factors inhibiting regeneration or to directly stimulate liver regeneration. This review describes the known mechanisms of normal liver regeneration and factors that reduce its regenerative potential, primarily at the level of hepatocyte metabolism, in the presence of concomitant hepatic pathology. We also briefly discuss promising strategies for stimulating liver regeneration and those concerning methods for assessing the regenerative potential of the liver, especially intraoperatively.

MicroRNA-183 accelerates the proliferation of hepatocyte during liver regeneration through targeting programmed cell death protein 6

BACKGROUND

Liver regeneration is a highly orchestrated process concerning the modulation of various microRNAs (miRs). miR-183 was recently found to be involved in the process of liver regeneration, that miR-183 was remarkably up-regulated at 2-6 h after partial hepatectomy.

OBJECTIVE

This study was aimed to explore the mechanism of miR-183 in on liver regeneration.

METHODS

After partial hepatectomy (PH) or transfection, we measured the changes of miR-183 and programmed cell death protein 6 (PDCD6) levels in rats and the hepatocytes. The histopathology was observed with hematoxylin-eosin staining. The miR-183 mimic and inhibitor plasmids were intravenously injected into rats, and the liver weight/body weight ratio was calculated. The prediction of TargetScan and the validation of luciferase activity assay were employed to confirm the targeting relationship between miR-183 and PDCD6. The viability, apoptosis and cell cycle of transfected rat hepatocyte BRL-3A were determined via MTT and flow cytometry assays.

RESULTS

MiR-183 expression showed a contrary tendency with that of PDCD6 during liver regeneration. Enhanced miR-183 in rats could notably increase liver/body weight ratio, while its inhibition did conversely. Overexpressed PDCD6, a target of miR-183, repressed the viability and cell cycle in hepatocytes, whereas its silence led to contrary results. Overexpressed miR-183 in BRL-3A cells enhanced cell viability and promoted the cell cycle yet suppressed apoptosis, whereas its inhibition showed contrary results, which were offset by PDCD6.

CONCLUSIONS

Collectively, miR-183 promoted liver regeneration via targeting PDCD6.

Diverse MicroRNAs-mRNA networks regulate the priming phase of mouse liver regeneration and of direct hyperplasia

Objectives

Adult hepatocytes are quiescent cells that can be induced to proliferate in response to a reduction in liver mass (liver regeneration) or by agents endowed with mitogenic potency (primary hyperplasia). The latter condition is characterized by a more rapid entry of hepatocytes into the cell cycle, but the mechanisms responsible for the accelerated entry into the S phase are unknown.

Materials and methods

Next generation sequencing and Illumina microarray were used to profile microRNA and mRNA expression in CD‐1 mice livers 1, 3 and 6 h after 2/3 partial hepatectomy (PH) or a single dose of TCPOBOP, a ligand of the constitutive androstane receptor (CAR). Ingenuity pathway and DAVID analyses were performed to identify deregulated pathways. MultiMiR analysis was used to construct microRNA‐mRNA networks.

Results

Following PH or TCPOBOP we identified 810 and 527 genes, and 102 and 10 miRNAs, respectively, differentially expressed. Only 20 genes and 8 microRNAs were shared by the two conditions. Many miRNAs targeting negative regulators of cell cycle were downregulated early after PH, concomitantly with increased expression of their target genes. On the contrary, negative regulators were not modified after TCPOBOP, but Ccnd1 targeting miRNAs, such as miR‐106b‐5p, were downregulated.

Conclusions

While miRNAs targeting negative regulators of the cell cycle are downregulated after PH, TCPOBOP caused downregulation of miRNAs targeting genes required for cell cycle entry. The enhanced Ccnd1 expression may explain the more rapid entry into the S phase of mouse hepatocytes following TCPOBOP.

Characterization of the microRNA Expression Profiles in the Goat Kid Liver

The liver is the largest digestive gland in goats with an important role in early metabolic function development. MicroRNAs (miRNA) are crucial for regulating the development and metabolism in the goat liver. In the study, we sequenced the miRNAs in the liver tissues of the goat kid to further research their regulation roles in early liver development. The liver tissues were procured at 5-time points from the Laiwu black goats of 1 day (D1), 2 weeks (W2), 4 weeks (W4), 8 weeks (W8), and 12 weeks (W12) after birth, respectively with five goats per time point, for a total of 25 goats. Our study identified 214 differential expression miRNAs, and the expression patterns of 15 randomly selected miRNAs were examined among all five age groups. The Gene ontology annotation results showed that differential expression miRNA (DE miRNA) target genes were significantly enriched in the fatty acid synthase activity, toxin metabolic process, cell surface, and antibiotic metabolic process. The KEGG analysis result was significantly enriched in steroid hormone synthesis and retinol metabolism pathways. Further miRNA-mRNA regulation network analysis reveals 9 differently expressed miRNA with important regulation roles. Overall, the DE miRNAs were mainly involved in liver development, lipid metabolism, toxin related metabolism-related biological process, and pathways. Our results provide new information about the molecular mechanisms and pathways in the goat kid liver development.

Hypoxia promotes the proliferation of mouse liver sinusoidal endothelial cells: miRNA-mRNA expression analysis

During the initial stage of liver regeneration (LR), hepatocytes and liver sinusoidal endothelial cells (LSECs) initiate regeneration in a hypoxic environment. However, the role of LSECs in liver regeneration in hypoxic environments and their specific molecular mechanism is unknown. Therefore, this study aimed to explore the miRNA-mRNA network that regulates the proliferation of LSECs during hypoxia. In this study, first, we found that the proliferation ability of primary LSECs treated with hypoxia was enhanced compared with the control group, and then whole transcriptome sequencing was performed to screen 1837 differentially expressed (DE) genes and 17 DE miRNAs. Subsequently, the bioinformatics method was used to predict the target genes of miRNAs, and 309 pairs of interacting miRNA-mRNA pairs were obtained. Furthermore, the miRNA-gene action network was established using the negative interacting miRNA-mRNA pairs. The selected mRNAs were analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and biological processes (BP) and signal pathways related to LSEC proliferation that were significantly enriched in GO-BP and KEGG were selected. Finally, 22 DE genes and 17 DE miRNAs were screened and the network was created. We also successfully verified the significant changes in the top six genes and miRNAs using qRT-PCR, and the results were consistent with the sequencing results. This study proposed that a specific miRNA-mRNA network is associated with hypoxia-induced proliferation of LSECs, which will assist in elucidating the potential mechanisms involved in hypoxia-promoting liver regeneration during LR.

Regeneration linked miRNA modify tumor phenotype and can enforce multi-lineage growth arrest in vivo

Regulated cell proliferation is an effector mechanism of regeneration, whilst dysregulated cell proliferation is a feature of cancer. We have previously identified microRNA (miRNA) that regulate successful and failed human liver regeneration. We hypothesized that these regulators may directly modify tumor behavior. Here we show that inhibition of miRNAs -503 and -23a, alone or in combination, enhances tumor proliferation in hepatocyte and non-hepatocyte derived cancers in vitro, driving more aggressive tumor behavior in vivo. Inhibition of miRNA-152 caused induction of DNMT1, site-specific methylation with associated changes in gene expression and in vitro and in vivo growth inhibition. Enforced changes in expression of two miRNA recapitulating changes observed in failed regeneration led to complete growth inhibition of multi-lineage cancers in vivo. Our results indicate that regulation of regeneration and tumor aggressiveness are concordant and that miRNA-based inhibitors of regeneration may constitute a novel treatment strategy for human cancers.

Molecular pathways of liver regeneration: A comprehensive review

The liver is a unique parenchymal organ with a regenerative capacity allowing it to restore up to 70% of its volume. Although knowledge of this phenomenon dates back to Greek mythology (the story of Prometheus), many aspects of liver regeneration are still not understood. A variety of different factors, including inflammatory cytokines, growth factors, and bile acids, promote liver regeneration and control the final size of the organ during typical regeneration, which is performed by mature hepatocytes, and during alternative regeneration, which is performed by recently identified resident stem cells called "hepatic progenitor cells". Hepatic progenitor cells drive liver regeneration when hepatocytes are unable to restore the liver mass, such as in cases of chronic injury or excessive acute injury. In liver maintenance, the body mass ratio is essential for homeostasis because the liver has numerous functions; therefore, a greater understanding of this process will lead to better control of liver injuries, improved transplantation of small grafts and the discovery of new methods for the treatment of liver diseases. The current review sheds light on the key molecular pathways and cells involved in typical and progenitor-dependent liver mass regeneration after various acute or chronic injuries. Subsequent studies and a better understanding of liver regeneration will lead to the development of new therapeutic methods for liver diseases.

Research Trends in the Efficacy of Stem Cell Therapy for Hepatic Diseases Based on MicroRNA Profiling

Liver diseases, despite the organ’s high regenerative capacity, are caused by several environmental factors and persistent injuries. Their optimal treatment is a liver transplantation. However, this option is limited by donor shortages and immune response issues. Therefore, many researchers have been interested in identifying the therapeutic potential in treating irreversible liver damage based on stem cells and developing suitable therapeutic agents. Mesenchymal stem cells (MSCs), which are representative multipotent stem cells, are known to be highly potential stem cell therapy compared to other stem cells in the clinical trial worldwide. MSCs have therapeutic potentials for several hepatic diseases such as anti-fibrosis, proliferation of hepatocytes injured, anti-inflammation, autophagic mechanism, and inactivation of hepatic stellate cells. There are much data regarding clinical treatments, however, the data for examining the efficacy of stem cell treatment and the correlation between the stem cell engraftment and the efficacy in liver diseases is limited due to the lack of monitoring system for treatment effectiveness. Therefore, this paper introduces the characteristics of microRNAs (miRNAs) and liver disease-specific miRNA profiles, and the possibility of a biomarker that miRNA can monitor stem cell treatment efficacy by comparing miRNAs changed in liver diseases following stem cell treatment. Additionally, we also discuss the miRNA profiling in liver diseases when treated with stem cell therapy and suggest the candidate miRNAs that can be used as a biomarker that can monitor treatment efficacy in liver diseases based on MSCs therapy.

[Liver regeneration: solved and problem issues]

It is known that liver is able to restore own dimensions and functional properties in response to various injuries. Despite extensive injuries, liver can preserve functional activity. Analysis of liver regeneration mechanisms allowed us to obtain significant results in the treatment of hepatitis, cirrhosis and liver failure. Liver regeneration processes substantiate the development of hepatocellular cancer following cirrhosis. Modern experimental and clinical data on liver regeneration, as well as current methods of stimulating this process are summarized in the manuscript. Despite significant advances in this issue, there are still many questions in scientific understanding of liver regeneration.

Platelet microparticles-derived miR-25-3p promotes the hepatocyte proliferation and cell autophagy via reducing B-cell translocation gene 2

Platelets are critical regulators of liver regeneration, but the mechanisms are still not fully understood. Platelets have been shown to contain a wide variety of microRNAs (miRNAs) and play an important role in many diseases. However, the mechanism that how the platelet microparticles (PMPs)-derived miRNA regulate the hepatocyte proliferation is not very clear. In this study, we have successfully isolated and identified PMPs. We also found that PMPs, which could be well integrated into the HHL-5 cells, could upregulate the level of miR-25-3p in HHL-5 cells. Meanwhile, we found that PMPs-derived miR-25-3p promoted HHL-5 cells proliferation by accelerating cells into the S phase, and enhanced the autophagy by increasing the LC3II expression and reducing the P62 expression. Then, we proved that the miR-25-3p could target the B-cell translocation gene 2 (BTG2) and downregulate the expression levels of the BTG2 gene in HHL-5 cells. In addition, the overexpression of BTG2 significantly inhibited the proliferation and autophagy abilities of HHL-5 cells, while cotransfected miR-25-3p mimics or PMPs could partially rescue HHL-5 cells proliferation and autophagy. Furthermore, we proved that PMPs accelerated hepatocyte proliferation by regulating autophagy pathways. Therefore, PMPs-derived miR-25-3p promoted HHL-5 cell proliferation and autophagy by targeting BTG2, which may be a new therapeutic method for liver regeneration.

Bovine hepatic miRNAome profiling and differential miRNA expression analyses between beef steers with divergent feed efficiency phenotypes

MicroRNAs (miRNAs) are small RNA molecules involved in regulation of multiple biological processes through modulating expression of their target genes. Here we employed RNAseq to profile liver tissue miRNAome of 60 steers from Angus, Charolais, and Kinsella Composite (KC) populations. Of these animals, 36 animals (n = 12 for each breed) were utilized to identify differentially expressed (DE) miRNAs between animals with high (n = 6) or low (n = 6) phenotypic values of residual feed intake (RFI), a common measurement of feed efficiency. At a threshold of fold-change > 1.5 and P-value < 0.05, we detected 12 (7 up- and 5 downregulated in low-RFI animals), 18 (12 up- and 6 downregulated), and 13 (8 up- and 5 downregulated) DE miRNAs for Angus, Charolais, and KC steers, respectively. Most of the DE miRNAs were breed specific, with bta-miR-449a and bta-miR-AB-2 being differentially expressed in all three breeds. The predicted target genes of the identified DE miRNA are mainly involved in cell cycle, cell death and survival, cell signaling, cellular growth and proliferation, protein trafficking, cell morphology, cell-to-cell signaling and interaction, cellular development, molecular transport, post-translational modification, as well as nutrient metabolism (lipids, carbohydrates, protein and amino acid). Our results provide insights into the bovine hepatic miRNAome and their potential roles in molecular regulation of RFI in beef cattle.

Molecular and Functional Roles of MicroRNAs in the Progression of Hepatocellular Carcinoma-A Review

Liver cancer is the fourth leading cause of cancer deaths globally, of which hepatocellular carcinoma (HCC) is the major subtype. Viral hepatitis B and C infections, alcohol abuse, and metabolic disorders are multiple risk factors for liver cirrhosis and HCC development. Although great therapeutic advances have been made in recent decades, the prognosis for HCC patients remains poor due to late diagnosis, chemotherapy failure, and frequent recurrence. MicroRNAs (miRNAs) are endogenous, non-coding RNAs that regulate various molecular biological phenomena by suppressing the translation of target messenger RNAs (mRNAs). miRNAs, which often become dysregulated in malignancy, control cell proliferation, migration, invasion, and development in HCC by promoting or suppressing tumors. Exploring the detailed mechanisms underlying miRNA-mediated HCC development and progression can likely improve the outcomes of patients with HCC. This review summarizes the molecular and functional roles of miRNAs in the pathogenesis of HCC. Further, it elucidates the utility of miRNAs as novel biomarkers and therapeutic targets.

Brg1 regulates murine liver regeneration by targeting miR-187-5p dependent on Hippo signalling pathway

Brg1 and Hippo signalling pathway are abnormally expressed in many malignant tumours, especially in Hepatocellular carcinoma, but their role in liver regeneration (LR) is unknown. In our research, we investigated the role of Brg1 and Hippo signalling pathway in hepatocyte proliferation and LR. Following 2/3 partial hepatectomy (PH) in liver-specific Brg1 deleted mice (Brg1-/-) (KO) mice and sex-matched wild-type (WT), depletion of Brg1 in mouse embryos caused liver cell growth disorders and significantly decreased expression of miR-187-5p. We identified LATS1 as a target gene of miR-187-5p and the introduction of miR-187-5p decrease the expression of LATS1 and inactivated the Hippo signalling pathway, which facilitated the expression of cell cycle-related proteins, and rescues the inhibitory effect of Brg1 in LR. Taken together, our findings suggested that deletion of Brg1 inhibits hepatocyte proliferation and LR by targeting miR-187-5p dependent on Hippo signalling pathway.

RNA-seq Used to Explore circRNA Expression and Identify Key circRNAs During the DNA Synthesis Phase of Mice Liver Regeneration

The liver has an excellent capacity for regeneration when faced with external injury and the damage differs from that of other organs in the body. Our aim was to identify the role of circular RNA (circRNA) during the DNA synthesis phase (36 h) of mice liver regeneration. High-throughput RNA sequencing was conducted to explore circRNA and messenger RNA (mRNA) expression in three pairs of mice liver tissue at 0 and 36 h after 2/3 partial hepatectomy. One hundred differentially expressed circRNAs were detected, including 66 upregulated and 34 downregulated circRNAs. We also explored 2483 differentially expressed mRNAs, including 1422 upregulated and 1061 downregulated mRNAs. Gene ontology and Kyoto Encyclopedia of Genes and Genomes indicated that cell cycle regulation, material metabolism, and multiple classical pathways were involved in the DNA synthesis process. A competing endogenous RNA (ceRNA) network containing 5 circRNAs, 28 target genes, and 533 microRNAs (miRNAs) was constructed, and we selected the top 5 miRNAs to map it. Potential key circRNAs were validated with the quantitative real-time PCR technique and their regeneration curves, including consecutive time points, were produced. Finally, a cell counting kit-8 assay on key circRNAs of ceRNA network was performed to further confirm their roles in the DNA synthesis phase of liver regeneration. This study provides a circRNA expression profile for liver regeneration and contributes valuable information for future research.

Evolution and current status of the subclassification of intermediate hepatocellular carcinoma

The staging and treatment of intermediate hepatocellular carcinoma (HCC) remains controversial. According to the recommendations of Barcelona Clinic Liver Cancer staging system, patients with intermediate HCC are candidates for transcatheter arterial chemoembolization. However, not all patients with intermediate HCC benefit from transcatheter arterial chemoembolization. Therefore, it is meaningful to propose a novel staging system of intermediate HCC in order to allocate different treatments for different subgroups. Bolondi et al proposed the first subclassification system of intermediate HCC. Subsequently, investigators performed studies to validate the feasibility of Bolondi^’ s criteria and proposed several novel staging systems. The present study reviewed the literatures and provided a general overview of the evolution and current status of the subclassification of intermediate HCC. We propose to expand the indication of liver resection and add radical treatments as the first option of the treatment for patients with intermediate HCC.

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

Abnormally expressed miR-199a-5p (miR-199a) has been frequently reported in multiple types of malignancies. Nevertheless, its effect in liver regeneration (LR) is largely still unclear. Herein, we investigated the function of miR-199a in hepatocyte proliferation during LR. As a result, miR-199a expression was significantly increased 12-30 h, in rat hepatic tissue, after partial hepatectomy (PH). The down-regulated expression of miR-199a inhibited proliferation as well as promoted cell apoptosis of BRL-3A. Additionally, TNF-α was found as a target of miR-199a. The administration of TNF-α siRNA regulated the effects of miR-199a on hepatocyte proliferation as well as miR-199a-modulated TNF-α/TNFR1/TRADD/CASPASE8/CASPASE3 signalling pathways. Taken together, these present findings suggested that miR-199a promoted hepatocyte proliferation as well as LR via targeting TNF-α/TNFR1/TRADD/CASPASE8/CASPASE3.

Exploration of the Transcriptional Landscape of ALPPS Reveals the Pathways of Accelerated Liver Regeneration

Background and Aims: ALPPS (associating liver partition and portal vein ligation for staged hepatectomy), a novel 2-staged hepatectomy, dramatically accelerates liver regeneration and thus enables extensive liver tumor resection. The signaling networks underlying the ALPPS-induced accelerated regeneration process are largely unknown.

Methods: We performed transcriptome profiling (TP) of liver tissue obtained from a mouse model of ALPPS, standard hepatectomy (68% model), and additional control surgeries (sham, PVL and Tx). We also performed TP using human liver biopsies (n = 5) taken from the occluded lobe and the future liver remnant (FLR) during the first step of ALPPS surgery (4–5 h apart). We used Oncofinder computational tools, which covers 378 ISPs, for unsupervised, unbiased quantification of ISP activity.

Results: Gene expression cluster analysis revealed an ALPPS specific signature: the IGF1R Signaling Pathway (Cell survival), the ILK Pathway (Induced cell proliferation), and the IL-10 Pathway (Stability determination) were significantly enriched, whereas the activity of the Interferon Pathway (Transcription) was reduced (p < 0.05). Further, the PAK- and ILK-associated ISPs were activated at an earlier time point, reflecting significant acceleration of liver regeneration (p < 0.001). These pathways, which were also recovered in human liver biopsies, control cell growth and proliferation, inflammatory response, and hypoxia-related processes.

Conclusions: ALPPS is not a straightforward addition of portal vein ligation (PVL) plus transection—it is more. The early stages of normal and accelerated liver regeneration are clearly discernible by a significantly increased and earlier activation of a small number of signaling pathways. Compounds mimicking these responses may help to improve the ALPPS method and further reduce the hospitalization time of the patient.

Regulation of Long Non-Coding RNA-Dreh Involved in Proliferation and Migration of Hepatic Progenitor Cells during Liver Regeneration in Rats

Liver regeneration plays a significant role in protecting liver function after liver injury or chronic liver disease. Long non-coding RNAs (lncRNAs) are considered to be involved in the proliferation of hepatocytes and liver regeneration. Therefore, this study aimed to explore the effects of LncRNA-Dreh on the regulation of hepatic progenitor cells (HPCs) during liver regeneration in rats. Initially, the rat model of liver injury was established to investigate the effect of LncRNA-Dreh down-regulation on liver tissues of rats with liver injury. Subsequently, HPCs line WB-F344 cells were transfected with interference plasmid of LncRNA-Dreh and the expression of LncRNA-Dreh and Vimentin was detected. The proliferation and migration ability of WB-F344 cells, as well as the content of albumin (ALB) and alpha fetoprotein (AFP) in cell differentiation were then determined. Disorderly arranged structure of liver tissue, a large number of HPCs set portal area as center extended to hepatic lobule and ductular reaction were observed in liver tissues of rats with liver injury. The expression of LncRNA-Dreh decreased while Vimentin increased in liver tissues of rats with liver injury. Moreover, the proliferation and migration ability, expression of Vimentin and AFP in WB-F344 cells were increased after silencing of LncRNA-Dreh and ALB was decreased. Collectively, our findings demonstrate that inhibition of LncRNA-Dreh can enhance the proliferation and migration abilities of HPCs in liver regeneration but cause abnormal differentiation of HPCs.

MiR-429 regulates rat liver regeneration and hepatocyte proliferation by targeting JUN/MYC/BCL2/CCND1 signaling pathway

Increasing evidence indicates that miR-429 is involved in tumor suppression in various human cancers. However, its role in liver regeneration remains unexplored. Liver regeneration is a highly orchestrated process that can be regulated by microRNAs (miRNAs), although the mechanisms are largely unclear. In this study, we aimed to identify the role of miR-429 in hepatocyte proliferation during liver regeneration. First, we performed microarray analysis and qRT-PCR. Results indicated that miR-429 level in rat liver markedly decreased 30 h after partial hepatectomy, and miR-429 overexpression disrupted BRL-3A proliferation and the transition of G1 to S phase in rat hepatocyte and promoted hepatocyte apoptosis. By contrast, miR-429 down-regulation had inverse effects. MiR-429 negatively regulated JUN expression in vitro and in vivo. After using JUN siRNA, we found that JUN inhibition mediates the effect of miR-429 in hepatocyte proliferation and growth and miR-429 negatively regulates JUN/MYC/BCL2/CCND1 signaling pathways. Our results also indicated that miR-429 inhibits hepatocyte proliferation and liver regeneration by targeting JUN/MYC/BCL2/CCND1.

microRNA-183 is Essential for Hair Cell Regeneration after Neomycin Injury in Zebrafish

PURPOSE

microRNAs (miRNAs) are non-coding RNAs composed of 20 to 22 nucleotides that regulate development and differentiation in various organs by silencing specific RNAs and regulating gene expression. In the present study, we show that the microRNA (miR)-183 cluster is upregulated during hair cell regeneration and that its inhibition reduces hair cell regeneration following neomycin-induced ototoxicity in zebrafish.

MATERIALS AND METHODS

miRNA expression patterns after neomycin exposure were analyzed using microarray chips. Quantitative polymerase chain reaction was performed to validate miR-183 cluster expression patterns following neomycin exposure (500 μM for 2 h). After injection of an antisense morpholino (MO) to miR-183 (MO-183) immediately after fertilization, hair cell regeneration after neomycin exposure in neuromast cells was evaluated by fluorescent staining (YO-PRO1). The MO-183 effect also was assessed in transgenic zebrafish larvae expressing green fluorescent protein (GFP) in inner ear hair cells.

RESULTS

Microarray analysis clearly showed that the miR-183 cluster (miR-96, miR-182, and miR-183) was upregulated after neomycin treatment. We also confirmed upregulated expression of the miR-183 cluster during hair cell regeneration after neomycin-induced ototoxicity. miR-183 inhibition using MO-183 reduced hair cell regeneration in both wild-type and GFP transgenic zebrafish larvae.

CONCLUSION

Our work demonstrates that the miR-183 cluster is essential for the regeneration of hair cells following ototoxic injury in zebrafish larvae. Therefore, regulation of the miR-183 cluster can be a novel target for stimulation of hair cell regeneration.

Progress and prospects of circular RNAs in Hepatocellular carcinoma: Novel insights into their function

Hepatocellular carcinoma (HCC) is one of the most predominant subjects of liver malignancies, which arouses global concern in the recent years. Advanced studies have found that Circular RNAs (circRNAs) are differentially expressed in HCC, with its regulatory capacity in HCC pathogenesis and metastasis. However, the underlying mechanism remains largely unknown. In this review, we summarized the functions and mechanisms of those aberrantly expressed circRNAs in HCC tissues. We hope to enlighten more comprehensive studies on the detailed mechanisms of circRNAs and explore their potential values in clinic applications. It revealed that hsa_circ_0004018 can be used as a potential biomarker in HCC diagnosis, with its superior sensitivity to alpha-fetoprotein (AFP). Notably, the correlation of circRNA abundance in the proliferation of liver regeneration (LR) has recently been clarified and different circRNA profiles served as candidates for nonalcoholic steatohepatitis (NASH) diagnosis also be discussed. Therefore, the improved understanding of circRNAs in HCC pathogenesis and metastasis proposed a novel basis for the early diagnosis in HCC patients, which provides a useful resource to explore the pathogenesis of HCC.

MicroRNA-203 promotes liver regeneration after partial hepatectomy in cirrhotic rats

BACKGROUND

Liver resection or partial hepatectomy (PH) is still the most commonly used therapeutic option for hepatocellular carcinoma (HCC) at present. However, the impaired regenerative ability induced by the accompanied liver cirrhosis is an important risk factor of posthepatectomy liver failure, and posthepatectomy liver failure is a feared complication that accounts for up to 75% of mortality after extensive liver resection. MicroRNA(miR)-203 is a tumor suppressor of HCC and may act as a positive intermediary in A20-enhanced interleukin (IL-6)/signal transducer and activator of transcription 3 (STAT3) pro-proliferative signals, which may promote liver regeneration after PH. However, its direct pro-proliferative effect on cirrhotic liver after hepatectomy is unknown.

MATERIALS AND METHODS

Liver cirrhosis was induced by intraperitoneal injection of 50% CCl4-olive oil solution in adult male Wistar rat. Rats with liver cirrhosis received portal vein injection of physiological saline, miR-203 lentivirus, or control empty lentivirus, and then 70% PH was performed under ether anesthesia 7 d later. Liver samples were harvested at 0, 24, 36, and 72 h after 70% PH. Hepatic expressions of cyclin D1 and Ki67 were checked to evaluate the liver regenerative ability. Hepatic expressions of IL-6, suppressor of cytokine signaling 3 (SOCS3), and phospho-STAT3 were also tested to clarify the mechanisms of miR-203 in liver regeneration.

RESULTS

The regeneration of miR-203 overexpression cirrhotic liver after 70% PH was enhanced and peaked at 24 and 36 h after 70% PH. The cyclin D1-positive liver cells/high-power field (HPF) in miR-203 overexpression liver markedly increased at 24 and 36 h after 70% PH compared with 0-h samples. When comparing with the control groups, cyclin D1-positive liver cells/HPF in miR-203 overexpression liver were also significantly increased at 24 and 36 h after 70% PH. A similar result of the Ki67-positive liver cells/HPF was achieved at 36 h after 70% PH. The hepatic expression of IL-6 showed a rising tendency after 70% PH, and the levels of IL-6 are significantly higher in miR-203 overexpression livers. Hepatic expression of SOCS3 was negatively expressed with hepatic miR-203 expression level, and the reduced expression of SOCS3 facilitated the phosphorylation of STAT3.

CONCLUSIONS

By targeting SOCS3 and then enhancing proliferating IL-6/STAT3 signaling pathway, hepatic overexpression of miR-203 can facilitate the initiation of liver regeneration and enhance the potency of liver regeneration after 70% PH in cirrhotic rat. Together with the tumor suppressive effect on HCC, miR-203 would be an ideal candidate for promoting liver regeneration in HCC patients undergoing liver resection without the risk of tumorigenesis or cancer recurrence.