Loss of histone acetyltransferase cofactor transformation/transcription domain-associated protein impairs liver regeneration after toxic injury

Targeting Myc Interacting Proteins as a Winding Path in Cancer Therapy

MYC, as a well-known oncogene, plays essential roles in promoting tumor occurrence, development, invasion and metastasis in many kinds of solid tumors and hematologic neoplasms. In tumors, the low expression and the short half-life of Myc are reversed, cause tumorigenesis. And proteins that directly interact with different Myc domains have exerted a significant impact in the process of Myc-driven carcinogenesis. Apart from affecting the transcription of Myc target genes, Myc interaction proteins also regulate the stability of Myc through acetylation, methylation, phosphorylation and other post-translational modifications, as well as competitive combination with Myc. In this review, we summarize a series of Myc interacting proteins and recent advances in the related inhibitors, hoping that can provide new opportunities for Myc-driven cancer treatment.

Identification of functional candidate variants and genes for feed efficiency in Holstein and Jersey cattle breeds using RNA-sequencing

The identification of functional genetic variants and associated candidate genes linked to feed efficiency may help improve selection for feed efficiency in dairy cattle, providing economic and environmental benefits for the dairy industry. This study used RNA-sequencing data obtained from liver tissue from 9 Holstein cows [n = 5 low residual feed intake (RFI), n = 4 high RFI] and 10 Jersey cows (n = 5 low RFI, n = 5 high RFI), which were selected from a single population of 200 animals. Using RNA-sequencing, 3 analyses were performed to identify: (1) variants within low or high RFI Holstein cattle; (2) variants within low or high RFI Jersey cattle; and (3) variants within low or high RFI groups, which are common across both Holstein and Jersey cattle breeds. From each analysis, all variants were filtered for moderate, modifier, or high functional effect, and co-localized quantitative trait loci (QTL) classes, enriched biological processes, and co-localized genes related to these variants, were identified. The overlapping of the resulting genes co-localized with functional SNP from each analysis in both breeds for low or high RFI groups were compared. For the first two analyses, the total number of candidate genes associated with moderate, modifier, or high functional effect variants fixed within low or high RFI groups were 2,810 and 3,390 for Holstein and Jersey breeds, respectively. The major QTL classes co-localized with these variants included milk and reproduction QTL for the Holstein breed, and milk, production, and reproduction QTL for the Jersey breed. For the third analysis, the common variants across both Holstein and Jersey breeds, uniquely fixed within low or high RFI groups were identified, revealing a total of 86,209 and 111,126 functional variants in low and high RFI groups, respectively. Across all 3 analyses for low and high RFI cattle, 12 and 31 co-localized genes were overlapping, respectively. Among the overlapping genes across breeds, 9 were commonly detected in both the low and high RFI groups (INSRR, CSK, DYNC1H1, GAB1, KAT2B, RXRA, SHC1, TRRAP, PIK3CB), which are known to play a key role in the regulation of biological processes that have high metabolic demand and are related to cell growth and regeneration, metabolism, and immune function. The genes identified and their associated functional variants may serve as candidate genetic markers and can be implemented into breeding programs to help improve the selection for feed efficiency in dairy cattle.

Depletion of TRRAP Induces p53-Independent Senescence in Liver Cancer by Down-Regulating Mitotic Genes

Hepatocellular carcinoma (HCC) is an aggressive subtype of liver cancer with few effective treatments, and the underlying mechanisms that drive HCC pathogenesis remain poorly characterized. Identifying genes and pathways essential for HCC cell growth will aid the development of new targeted therapies for HCC. Using a kinome CRISPR screen in three human HCC cell lines, we identified transformation/transcription domain-associated protein (TRRAP) as an essential gene for HCC cell proliferation. TRRAP has been implicated in oncogenic transformation, but how it functions in cancer cell proliferation is not established. Here, we show that depletion of TRRAP or its co-factor, histone acetyltransferase KAT5, inhibits HCC cell growth through induction of p53-independent and p21-independent senescence. Integrated cancer genomics analyses using patient data and RNA sequencing identified mitotic genes as key TRRAP/KAT5 targets in HCC, and subsequent cell cycle analyses revealed that TRRAP-depleted and KAT5-depleted cells are arrested at the G2/M phase. Depletion of topoisomerase II alpha (TOP2A), a mitotic gene and TRRAP/KAT5 target, was sufficient to recapitulate the senescent phenotype of TRRAP/KAT5 knockdown. Conclusion: Our results uncover a role for TRRAP/KAT5 in promoting HCC cell proliferation by activating mitotic genes. Targeting the TRRAP/KAT5 complex is a potential therapeutic strategy for HCC.

Metabolic Comorbidities and Risk of Development and Severity of Drug-Induced Liver Injury

The incidence and rates of diagnosis of drug-induced liver injury (DILI) have been increasing in recent years as findings from basic research and the examination of clinical databases reveal information about the clinical course, etiology, and prognosis of this complex disease. The prevalence of metabolic comorbidities (e.g., diabetes mellitus, fatty liver, obesity, and metabolic syndrome (MetS)) has been increasing during the same period. The results of preclinical and clinical research studies indicate that characteristics of metabolic comorbidities are also factors that affect DILI phenotype and progression. The objective of this review is to present the evidence for DILI and hepatotoxicity mechanisms, incidence, and outcomes in patients with MetS and nonalcoholic fatty liver disease. Moreover, we also summarize the relationships between drugs used to treat metabolic comorbidities and DILI.

Quantitative proteomics of Bombyx mori after BmNPV challenge

The domesticated silkworm is an ideal and economic insect model that plays crucial roles in sericulture and bioreactor. Bombyx mori nucleopolyhedrovirus (BmNPV) is not only an infectious pathogen to B. mori, but also an efficient vector expressing recombinant proteins. Although, the proteomics of silkworm and BmN cell membrane lipid raft towards BmNPV infection had been investigated, proteome results of BmN cells upon BmNPV challenge currently remain ambiguous. In order to explore the interaction between silkworm and BmNPV, we analyzed several pivotal processes of BmNPV infected BmN cell by quantitative mass spectrometry. Our study indicated that a total of 4205 identified proteins, among which 4194 were with quantitative level. Concretely, during BmNPV infection, several transcription factors and epigenetically modified proteins showed substantially different abundance levels. Especially, proteins with binding activity, displayed significant changes in their molecular functions. Disabled non-homologous end joining by BmNPV reflects irreversible breakage of DNA. Nevertheless, highly abundant superoxide dismutase suggests that the cellular defense system is persistently functional in maintaining biochemical homeostasis. Our comparative and quantitative proteomics will be helpful to unravel the dynamics of B.mori after BmNPV infection and could provide new insights to decipher the mechanism of interaction between BmN cell and BmNPV.

MiR-17~92 ablation impairs liver regeneration in an estrogen-dependent manner

As one of the most important post‐transcriptional regulators, microRNAs (miRNAs) participate in diverse biological processes, including the regulation of cell proliferation. MiR‐17~92 has been found to act as an oncogene, and it is closely associated with cell proliferation. However, its role in liver regeneration is still unclear. We generated a hepatocyte‐specific miR‐17~92‐deficient mouse and used a mouse model with 70% partial hepatectomy (PH) or intraperitoneal injection of carbon tetrachloride to demonstrate the role of MiR‐17~92 in liver regeneration. In quiescent livers, the expression of the miR‐17~92 cluster showed a gender disparity, with much higher expression in female mice. The expression of four members of this cluster was found to be markedly reduced after 70% PH. The ablation of miR‐17~92 led to obvious regeneration impairment during the early‐stage regeneration in the female mice. Ovariectomy greatly reduced miR‐17~92 expression but significantly promoted liver regeneration in wild‐type mice. In addition, early regeneration impairment in miR‐17~92‐deficient livers could be largely restored following ovariectomy. The proliferation suppressors p21 and Pten were found to be the target effectors of miR‐17~92. MiR‐17~92 disruption resulted in elevated protein levels of p21 and Pten in regenerating livers. MiR‐17~92 functions as a proliferation stimulator and acts in an oestrogen‐dependent manner. The loss of this miRNA results in increases in p21 and Pten expression and therefore impairs liver regeneration in female mice.

Drug-induced liver injury: Interactions between drug properties and host factors

Idiosyncratic drug-induced liver injury (DILI) is a common cause for drug withdrawal from the market and although infrequent, DILI can result in serious clinical outcomes including acute liver failure and the need for liver transplantation. Eliminating the iatrogenic "harm" caused by a therapeutic intent is a priority in patient care. However, identifying culprit drugs and individuals at risk for DILI remains challenging. Apart from genetic factors predisposing individuals at risk, the role of the drugs' physicochemical and toxicological properties and their interactions with host and environmental factors need to be considered. The influence of these factors on mechanisms involved in DILI is multi-layered. In this review, we summarize current knowledge on 1) drug properties associated with hepatotoxicity, 2) host factors considered to modify an individuals' risk for DILI and clinical phenotypes, and 3) drug-host interactions. We aim at clarifying knowledge gaps needed to be filled in as to improve risk stratification in patient care. We therefore broadly discuss relevant areas of future research. Emerging insight will stimulate new investigational approaches to facilitate the discovery of clinical DILI risk modifiers in the context of disease complexity and associated interactions with drug properties, and hence will be able to move towards safety personalized medicine.

The role dietary of bioactive compounds on the regulation of histone acetylases and deacetylases: a review

Nutrigenomics is an area of epigenomics that explores and defines the rapidly evolving field of diet-genome interactions. Lifestyle and diet can significantly influence epigenetic mechanisms, which cause heritable changes in gene expression without changes in DNA sequence. Nutrient-dependent epigenetic variations can significantly affect genome stability, mRNA and protein expression, and metabolic changes, which in turn influence food absorption and the activity of its constituents. Dietary bioactive compounds can affect epigenetic alterations, which are accumulated over time and are shown to be involved in the pathogenesis of age-related diseases such as diabetes, cancer, and cardiovascular disease. Histone acetylation is an epigenetic modification mediated by histone acetyl transferases (HATs) and histone deacetylases (HDACs) critically involved in regulating affinity binding between the histones and DNA backbone. The HDAC-mediated increase in histone affinity to DNA causes DNA condensation, preventing transcription, whereas HAT-acetylated chromatin is transcriptionally active. HDAC and HAT activities are reported to be associated with signal transduction, cell growth and death, as well as with the pathogenesis of various diseases. The aim of this review was to evaluate the role of diet and dietary bioactive compounds on the regulation of HATs and HDACs in epigenetic diseases. Dietary bioactive compounds such as genistein, phenylisothiocyanate, curcumin, resveratrol, indole-3-carbinol, and epigallocatechin-3-gallate can regulate HDAC and HAT activities and acetylation of histones and non-histone chromatin proteins, and their health benefits are thought to be attributed to these epigenetic mechanisms. The intake of dietary compounds that regulate epigenetic modifications can provide significant health effects and may prevent various pathological processes involved in the development of cancer and other life-threatening diseases.

Circulating histones exacerbate inflammation in mice with acute liver failure

Circulating histones are a newly recognized mediator implicated in various inflammatory diseases. It is likely that the release of histones, from dying hepatocytes or inflammatory leukocytes, into the circulation initiates and amplifies inflammation during the course of acute liver failure (ALF). In this study, we investigated a putative pathogenic role of circulating histones in a murine model of ALF induced by D-galactosamine (GalN) plus lipopolysaccharide (LPS). Hepatic function and histological indexes, myeloperoxidase (MPO) activity, hepatocyte apoptosis and the levels of circulating histone were measured in GalN/LPS-treated mice. GalN/LPS caused severe liver damage and a notable increase in plasma concentration of circulating histones. To further assess the role of circulating histones in our model, we administered exogenous histones and anti-histone H4 antibody. Notably, exogenous histones aggravated GalN/LPS-induced hepatotoxicity, whereas anti-histone antibody significantly protected mice. Circulating histones may serve as both a functional marker of ALF activity and as an inflammatory mediator contributing to the progression of ALF. Blockade of circulating histones shows potent protective effects, suggesting a potential therapeutic strategy for ALF.

Loss of histone deacetylases 1 and 2 in hepatocytes impairs murine liver regeneration through Ki67 depletion

Histone deacetylases 1 and 2 (HDAC1 and HDAC2) are ubiquitously expressed in tissues, including the liver, and play critical roles in numerous physiopathological processes. Little is known regarding the role of HDAC1 and HDAC2 in liver regeneration. In this study we generated mice in which Hdac1, Hdac2 or both genes were selectively knocked out in hepatocytes to investigate the role of these genes in liver regeneration following hepatic injury induced by partial hepatectomy or carbon tetrachloride administration. The loss of HDAC1 and/or HDAC2 (HDAC1/2) protein resulted in impaired liver regeneration. HDAC1/2 inactivation did not decrease hepatocytic 5-bromo-2-deoxyuridine uptake or the expression of proliferating cell nuclear antigen, cyclins, or cyclin-dependent kinases. However, the levels of Ki67, a mitotic marker that is expressed from the mid-G1 phase to the end of mitosis and is closely involved in the regulation of mitotic progression, were greatly decreased, and abnormal mitosis lacking Ki67 expression was frequently observed in HDAC1/2-deficient livers. The down-regulation of either HDAC1/2 or Ki67 in the mouse liver cancer cell line Hepa1-6 resulted in similar mitotic defects. Finally, both HDAC1 and HDAC2 proteins were associated with the Ki67 gene mediated by CCAAT/enhancer-binding protein β.

CONCLUSION

Both HDAC1 and HDAC2 play crucial roles in the regulation of liver regeneration. The loss of HDAC1/2 inhibits Ki67 expression and results in defective hepatocyte mitosis and impaired liver regeneration.

Dietary regulation of histone acetylases and deacetylases for the prevention of metabolic diseases

Age-related diseases such as type 2 diabetes, cardiovascular disease, and cancer involve epigenetic modifications, where accumulation of minute changes in the epigenome over time leads to disease manifestation. Epigenetic changes are influenced by life style and diets. This represents an avenue whereby dietary components could accelerate or prevent age-related diseases through their effects on epigenetic modifications. Histone acetylation is an epigenetic modification that is regulated through the opposing action of histone acetylases (HATs) and deacetylases (HDACs). These two families of enzymes play critical roles in metabolic processes and their dysregulation is associated with pathogenesis of several diseases. Dietary components, such as butyrate, sulforaphane, and curcumin, have been shown to affect HAT and HDAC activity, and their health benefits are attributed, at least in part, to epigenetic modifications. Given the decades that it takes to accumulate epigenetic changes, it is unlikely that pharmaceuticals could undo epigenetic changes without side effects. Therefore, long term consumption of dietary components that can alter the epigenome could be an attractive means of disease prevention. The goal of this review is to highlight the roles of diets and food components in epigenetic modifications through the regulation of HATs and HDACs for disease prevention.

Expression and function of fibroblast growth factor (FGF) 7 during liver regeneration

BACKGROUND/AIM

Previous studies have shown that fibroblast growth factors (FGFs) are involved in the process of liver injury repair. Liver regeneration after partial hepatectomy (PH) is impaired in transgenic mice expressing dominant-negative FGFR2b in hepatocytes. Although FGF7, a ligand specifically bound to FGFR2b, is expressed by activated hepatic stellate cells (HSCs) in fibrotic livers, the expressions and functions of FGF7 and FGFR2b after PH remain unexplored. Therefore, this study sought to examine the potential role of FGF7 signaling during liver regeneration.

METHODS

We examined the expression of FGF7 and FGFR2b in normal and regenerating livers. Effects of FGF7 on hepatocytes were examined in vitro using primary hepatocyte culture with FGF7 recombinant protein and in vivo by hydrodynamic-based gene transfer method.

RESULTS

We found that FGF7 expression was increased according to the activation status of HSCs after PH. The receptor, FGFR2b, was also increased in hepatocytes during liver regeneration. In vitro treatment with FGF7 protein activated ERK1/2 and promoted proliferation of hepatocytes isolated from regenerating livers. In vivo overexpression of exogenous FGF7 could notably promote hepatic proliferation and activate MAPKs after PH.

CONCLUSION

This study suggests a role for activated HSC-expressed FGF7 in stimulating FGF signaling pathways in hepatocytes and regulating liver regeneration.