Betaine prevents Mallory-Denk body formation in drug-primed mice by epigenetic mechanisms

The glycine betaine role in neurodegenerative, cardiovascular, hepatic, and renal diseases: Insights into disease and dysfunction networks

Glycine betaine (N, N, N-trimethyl amine) is an osmolyte accumulated in cells that is key for cell volume and turgor regulation, is the principal methyl donor in the methionine cycle and is a DNA and proteins stabilizer. In humans, glycine betaine is synthesized from choline and can be obtained from some foods. Glycine betaine (GB) roles are illustrated in chemical, metabolic, agriculture, and clinical medical studies due to its chemical and physiological properties. Several studies have extensively described GB role and accumulation related to specific pathologies, focusing mainly on analyzing its positive and negative role in these pathologies. However, it is necessary to explain the relationship between glycine betaine and different pathologies concerning its role as an antioxidant, ability to methylate DNA, interact with transcription factors and cell receptors, and participate in the control of homocysteine concentration in liver, kidney and brain. This review summarizes the most important findings and integrates GB role in neurodegenerative, cardiovascular, hepatic, and renal diseases. Furthermore, we discuss GB impact on other dysfunctions as inflammation, oxidative stress, and glucose metabolism, to understand their cross-talks and provide reliable data to establish a base for further investigations.

Beneficial Effects of Betaine: A Comprehensive Review

Medicinal herbs and many food ingredients possess favorable biological properties that contribute to their therapeutic activities. One such natural product is betaine, a stable, nontoxic natural substance that is present in animals, plants, and microorganisms. Betaine is also endogenously synthesized through the metabolism of choline or exogenously consumed through dietary intake. Betaine mainly functions as (i) an osmolyte and (ii) a methyl-group donor. This review describes the major physiological effects of betaine in whole-body health and its ability to protect against both liver- as well as non-liver-related diseases and conditions. Betaine's role in preventing/attenuating both alcohol-induced and metabolic-associated liver diseases has been well studied and is extensively reviewed here. Several studies show that betaine protects against the development of alcohol-induced hepatic steatosis, apoptosis, and accumulation of damaged proteins. Additionally, it can significantly prevent/attenuate progressive liver injury by preserving gut integrity and adipose function. The protective effects are primarily associated with the regulation of methionine metabolism through removing homocysteine and maintaining cellular SAM:SAH ratios. Similarly, betaine prevents metabolic-associated fatty liver disease and its progression. In addition, betaine has a neuroprotective role, preserves myocardial function, and prevents pancreatic steatosis. Betaine also attenuates oxidant stress, endoplasmic reticulum stress, inflammation, and cancer development. To conclude, betaine exerts significant therapeutic and biological effects that are potentially beneficial for alleviating a diverse number of human diseases and conditions.

The Role of FAT10 in Alcoholic Hepatitis Pathogenesis

FAT10 expression is highly up-regulated by pro-inflammatory cytokines IFNγ and TNFα in all cell types and tissues. Increased FAT10 expression may induce increasing mitotic non-disjunction and chromosome instability, leading to tumorigenesis. In this review, we summarized others’ and our work on FAT10 expression in liver biopsy samples from patients with alcoholic hepatitis (AH). FAT10 is essential to maintain the function of liver cell protein quality control and Mallory–Denk body (MDB) formation. FAT10 overexpression in AH leads to balloon degeneration and MDB aggregation formation, all of which is prevented in fat10-/- mice. FAT10 causes the proteins’ accumulation, overexpression, and forming MDBs through modulating 26s proteasome’s proteases. The pathway that increases FAT10 expression includes TNFα/IFNγ and the interferon sequence response element (ISRE), followed by NFκB and STAT3, which were all up-regulated in AH. FAT10 was only reported in human and mouse specimens but plays critical role for the development of alcoholic hepatitis. Flavanone derivatives of milk thistle inhibit TNFα/IFNγ, NFκB, and STAT3, then inhibit the expression of FAT10. NFκB is the key nodal hub of the IFNα/TNFα-response genes. Studies on Silibinin and other milk thistle derivatives to treat AH confirms that overexpressed FAT10 is the major key molecule in these networks.

UBA6 and Its Bispecific Pathways for Ubiquitin and FAT10

Questions have been raised since the discovery of UBA6 and its significant coexistence with UBE1 in the ubiquitin–proteasome system (UPS). The facts that UBA6 has the dedicated E2 enzyme USE1 and the E1–E2 cascade can activate and transfer both ubiquitin and ubiquitin-like protein FAT10 have attracted a great deal of attention to the regulational mechanisms of the UBA6–USE1 cascade and to how FAT10 and ubiquitin differentiate with each other. This review recapitulates the latest advances in UBA6 and its bispecific UBA6–USE1 pathways for both ubiquitin and FAT10. The intricate networks of UBA6 and its interplays with ubiquitin and FAT10 are briefly reviewed, as are their individual and collective functions in diverse physiological conditions.

Maternal Factors that Induce Epigenetic Changes Contribute to Neurological Disorders in Offspring

It is well established that the regulation of epigenetic factors, including chromatic reorganization, histone modifications, DNA methylation, and miRNA regulation, is critical for the normal development and functioning of the human brain. There are a number of maternal factors influencing epigenetic pathways such as lifestyle, including diet, alcohol consumption, and smoking, as well as age and infections (viral or bacterial). Genetic and metabolic alterations such as obesity, gestational diabetes mellitus (GDM), and thyroidism alter epigenetic mechanisms, thereby contributing to neurodevelopmental disorders (NDs) such as embryonic neural tube defects (NTDs), autism, Down's syndrome, Rett syndrome, and later onset of neuropsychological deficits. This review comprehensively describes the recent findings in the epigenetic landscape contributing to altered molecular profiles resulting in NDs. Furthermore, we will discuss potential avenues for future research to identify diagnostic markers and therapeutic epi-drugs to reverse these abnormalities in the brain as epigenetic marks are plastic and reversible in nature.

Role of Protein Quality Control Failure in Alcoholic Hepatitis Pathogenesis

The mechanisms of protein quality control in hepatocytes in cases of alcoholic hepatitis (AH) including ufmylation, FAT10ylation, metacaspase 1 (Mca1), ERAD (endoplasmic reticulum-associated degradation), JUNQ (juxta nuclear quality control), IPOD (insoluble protein deposit) autophagocytosis, and ER stress are reviewed. The Mallory–Denk body (MDB) formation develops in the hepatocytes in alcoholic hepatitis as a consequence of the failure of these protein quality control mechanisms to remove misfolded and damaged proteins and to prevent MDB aggresome formation within the cytoplasm of hepatocytes. The proteins involved in the quality control pathways are identified, quantitated, and visualized by immunofluorescent antibody staining of liver biopsies from patients with AH. Quantification of the proteins are achieved by measuring the fluorescent intensity using a morphometric system. Ufmylation and FAT10ylation pathways were downregulated, Mca1 pathways were upregulated, autophagocytosis was upregulated, and ER stress PERK (protein kinase RNA-like endoplasmic reticulum kinase) and CHOP (CCAAT/enhancer-binding protein homologous protein) mechanisms were upregulated. In conclusion: Despite the upregulation of several pathways of protein quality control, aggresomes (MDBs) still formed in the hepatocytes in AH. The pathogenesis of AH is due to the failure of protein quality control, which causes balloon-cell change with MDB formation and ER stress.

Aberrant modulation of the BRCA1 and G1/S cell cycle pathways in alcoholic hepatitis patients with Mallory Denk Bodies revealed by RNA sequencing

Mallory-Denk Bodies (MDBs) are prevalent in various liver diseases including alcoholic hepatitis (AH) and are formed in mice livers by feeding DDC. Liver injury from alcohol administration causes balloon hepatocytes and MDB formation impeding liver regeneration. By comparing AH livers where MDBs had formed with normal liver transcriptomes obtained by RNA sequencing (RNA-Seq), there was significant upregulation of BRCA1-mediated signaling and G1/S cell cycle checkpoint pathways. The transcriptional architecture of differentially expressed genes from AH livers reflected step-wise transcriptional changes progressing to AH. Key molecules such as BRCA1, p15 and p21 were significantly upregulated both in AH livers and in the livers of the DDC re-fed mice model where MDBs had formed. The increase of G1/S cell cycle checkpoint inhibitors p15 and p21 results in cell cycle arrest and inhibition of liver regeneration, implying that p15 and p21 could be exploited for the identification of specific targets for the treatment of liver disease. Provided here for the first time is the RNA-Seq data that represents the fully annotated catalogue of the expression of mRNAs. The most prominent alterations observed were the changes in BRCA1-mediated signaling and G1/S cell cycle checkpoint pathways. These new findings expand previous and related knowledge in the search for gene changes that might be critical in the understanding of the underlying progression to the development of AH.

The mechanisms of Mallory-Denk body formation are similar to the formation of aggresomes in Alzheimer's disease and other neurodegenerative disorders

There is a possibility that the aggresomes that form in the brain in neurodegenerative diseases like Alzheimer's disease (AD) and in the liver where aggresomes like Mallory-Denk Bodies (MDB) form, share mechanisms. MDBs can be prevented by feeding mice sadenosylmethionine (SAMe) or betaine. Possibly these proteins could prevent AD. We compared the literature on MDBs and AD pathogenesis, which include roles played by p62, ubiquitin UBB +1, HSPs70, 90, 104, FAT10, NEDD8, VCP/97, and the protein quality control mechanisms including the 26s proteasome, the IPOD and JUNQ and autophagosome pathways.

Acetaldehyde accelerates HCV-induced impairment of innate immunity by suppressing methylation reactions in liver cells

Alcohol exposure worsens the course and outcomes of hepatitis C virus (HCV) infection. Activation of protective antiviral genes is induced by IFN-α signaling, which is altered in liver cells by either HCV or ethanol exposure. However, the mechanisms of the combined effects of HCV and ethanol metabolism in IFN-α signaling modulation are not well elucidated. Here, we explored a possibility that ethanol metabolism potentiates HCV-mediated dysregulation of IFN-α signaling in liver cells via impairment of methylation reactions. HCV-infected Huh7.5 CYP2E1(+) cells and human hepatocytes were exposed to acetaldehyde (Ach)-generating system (AGS) and stimulated with IFN-α to activate IFN-sensitive genes (ISG) via the Jak-STAT-1 pathway. We observed significant suppression of signaling events by Ach. Ach exposure decreased STAT-1 methylation via activation of protein phosphatase 2A and increased the protein inhibitor of activated STAT-1 (PIAS-1)-STAT-1 complex formation in both HCV(+) and HCV(-) cells, preventing ISG activation. Treatment with a promethylating agent, betaine, attenuated all examined Ach-induced defects. Ethanol metabolism-induced changes in ISGs are methylation related and confirmed by in vivo studies on HCV(+) transgenic mice. HCV- and Ach-induced impairment of IFN signaling temporarily increased HCV RNA levels followed by apoptosis of heavily infected cells. We concluded that Ach potentiates the suppressive effects of HCV on activation of ISGs attributable to methylation-dependent dysregulation of IFN-α signaling. A temporary increase in HCV RNA sensitizes the liver cells to Ach-induced apoptosis. Betaine reverses the inhibitory effects of Ach on IFN signaling and thus can be used for treatment of HCV(+) alcohol-abusing patients.

Altered regulation of miR-34a and miR-483-3p in alcoholic hepatitis and DDC fed mice

MicroRNAs are small noncoding RNAs that negatively regulate gene expression by binding to the untranslated regions of their target mRNAs. Deregulation of miRNAs is shown to play pivotal roles in tumorigenesis and progression. Mallory-Denk Bodies (MDBs) are prevalent in various liver diseases including alcoholic hepatitis (AH) and are formed in mice livers by feeding DDC. By comparing AH livers where MDBs had formed with normal livers, there were significant changes of miR-34a and miR-483-3p by RNA sequencing (RNA-Seq) analyses. Real-time PCR further shows a 3- and 6-fold upregulation (respectively) of miR-34a in the AH livers and in the livers of DDC re-fed mice, while miR-483-3p was significantly downregulated in AH and DDC re-fed mice livers. This indicates that miR-34a and miR-483-3p may be crucial for liver MDB formation. P53 mRNA was found to be significantly downregulated both in the AH livers and in the livers of DDC re-fed mice, indicating that the upregulation of miR-34a is permitted by the decrease of p53 in AH since miR-34a is a main target of p53. Overexpression of miR-34a leads to an increase of p53 targets such as p27, which inhibits the cell cycle leading to cell cycle arrest. Importantly, BRCA1 is a target gene of miR-483-3p by RNA-Seq analyses and the downregulation of miR-483-3p may be the mechanism for liver MDB formation since the BRCA1 signal was markedly upregulated in AH livers. These results constitute a demonstration of the altered regulation of miR-34a and miR-483-3p in the livers of AH and mice fed DDC where MDBs formed, providing further insight into the mechanism of MDB formation mediated by miR-34a and miR-483-3p in AH.

IL-8 signaling is up-regulated in alcoholic hepatitis and DDC fed mice with Mallory Denk Bodies (MDBs) present

Chemokines and their receptors are involved in oncogenesis and in tumor progression, invasion, and metastasis. Various chemokines also promote cell proliferation and resistance to apoptosis of stressed cells. The chemokine CXCL8, also known as interleukin-8 (IL-8), is a proinflammatory molecule that has functions within the tumor microenvironment. Deregulation of IL-8 signaling is shown to play pivotal roles in tumorigenesis and progression. Mallory-Denk Bodies (MDBs) are prevalent in various liver diseases including alcoholic hepatitis (AH) and are formed in mice livers by feeding DDC. By comparing AH livers where MDBs had formed with normal livers, there were significant changes of IL-8 signaling by RNA sequencing (RNA-Seq) analyses. Real-time PCR analysis of CXCR2 further shows a 6-fold up-regulation in AH livers and a 26-fold up-regulation in the livers of DDC re-fed mice. IL-8 mRNA was also significantly up-regulated in AH livers and DDC re-fed mice livers. This indicates that CXCR2 and IL-8 may be crucial for liver MDB formation. MDB containing balloon hepatocytes in AH livers had increased intensity of staining of the cytoplasm for both CXCR2 and IL-8. Overexpression of IL-8 leads to an increase of the mitogen activated protein kinase (MAPK) cascade and exacerbates the inflammatory cycle. These observations constitute a demonstration of the altered regulation of IL-8 signaling in the livers of AH and mice fed DDC where MDBs formed, providing further insight into the mechanism of MDB formation mediated by IL-8 signaling in AH.

Proteomic analysis of the European flounder Platichthys flesus response to experimental PAH-PCB contamination

Platichthys flesus is often used as a sentinel species to monitor the estuarine water quality. In this study, we carried out an experimental contamination of fish using a PAHs/PCBs mixture, which was designed to mimic the concentrations found in the Seine estuary (C1) and 10 times these concentrations (C2). We used a proteomic approach to understand the molecular mechanisms implied in the response of P. flesus to these xenobiotics. We showed that 54 proteins were differentially accumulated in one or several conditions, which 34 displayed accumulation factors higher than two. 18 of these proteins were identified by MALDI TOF-TOF mass spectrometry. The results indicated the deregulation of oxidative stress- and glutathione metabolism-(GST, GPx) proteins as well as of several proteins belonging to the betaine demethylation pathway and the methionine cycle (BHMT, SHMT, SAHH), suggesting a role for these different pathways in the P. flesus response to chemical contamination.

Considering maternal dietary modulators for epigenetic regulation and programming of the fetal epigenome

Fetal life is characterized by a tremendous plasticity and ability to respond to various environmental and lifestyle factors, including maternal nutrition. Identification of the role of dietary factors that can modulate and reshape the cellular epigenome during development, including methyl group donors (e.g., folate, choline) and bioactive compounds (e.g., polyphenols) is of great importance; however, there is insufficient knowledge of a particular effect of each type of modulator and/or their combination on fetal life. To enhance the quality and safety of food products for proper fetal health and disease prevention in later life, a better understanding of the underlying mechanisms of dietary epigenetic modulators during the critical prenatal period is necessary. This review focuses on the influence of maternal dietary components on DNA methylation, histone modification, and microRNAs, and summarizes current knowledge of the effect and importance of dietary components on epigenetic mechanisms that control the proper expression of genetic information. Evidence reveals that some components in the maternal diet can directly or indirectly affect epigenetic mechanisms. Understanding the underlying mechanisms of how early-life nutritional environment affects the epigenome during development is of great importance for the successful prevention of adult chronic diseases through optimal maternal nutrition.

Mallory-Denk Body (MDB) formation modulates Ufmylation expression epigenetically in alcoholic hepatitis (AH) and non-alcoholic steatohepatitis (NASH)

Promoter CpG island hypermethylation is an important mechanism for inactivating key cellular enzymes that mediate epigenetic processes in hepatitis-related hepatocellular carcinoma (HCC). The ubiquitin-fold modifier 1 (Ufm1) conjugation pathway (Ufmylation) plays an essential role in protein degradation, protein quality control and signal transduction. Previous studies showed that the Ufmylation pathway was downregulated in alcoholic hepatitis (AH), non-alcoholic steatohepatitis (NASH) and in mice fed DDC, resulting in the formation of Mallory-Denk Bodies (MDBs). In this study, we further discovered that betaine, a methyl donor, fed together with DDC significantly prevents the increased expression of Ufmylation in drug-primed mice fed DDC. Betaine significantly prevented transcript silencing of Ufm1, Uba5 and UfSP1 where MDBs developed and also prevented the increased expression of FAT10 and LMP7 caused by DDC re-fed mice. Similar downregulation of Ufmylation was observed in multiple AH and NASH biopsies which had formed MDBs. The DNA methylation levels of Ufm1, Ufc1 and UfSP1 in the promoter CpG region were significantly increased both in AH and NASH patients compared to normal subjects. DNA (cytosine-5-)-methyltransferase 1 (DNMT1) and DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) mRNA levels were markedly upregulated in AH and NASH patients, implying that the maintenance of Ufmylation methylation might be mediated by DNMT1 and DNMT3B together. These data show that MDB formation results from Ufmylation expression epigenetically in AH and NASH patients. Promoter CpG methylation may be a major mechanism silencing Ufmylation expression.

Ufmylation and FATylation pathways are downregulated in human alcoholic and nonalcoholic steatohepatitis, and mice fed DDC, where Mallory-Denk bodies (MDBs) form

We previously reported the mechanisms involved in the formation of Mallory-Denk bodies (MDBs) in mice fed DDC. To further provide clinical evidence as to how ubiquitin-like protein (Ubls) modification, gene transcript expression in Ufmylation and FATylation were investigated in human archived formalin-fixed, paraffin-embedded (FFPE) liver biopsies and frozen liver sections from DDC re-fed mice were used. Real-time PCR analysis showed that all Ufmylation molecules (Ufm1, Uba5, Ufc1, Ufl1 and UfSPs) were significantly downregulated, both in DDC re-fed mice livers and patients' livers where MDBs had formed, indicating that gene transcript changes were limited to MDB-forming livers where the protein quality control system was downregulated. FAT10 and subunits of the immunoproteasome (LMP2 and LMP7) were both upregulated as previously shown. An approximate 176- and 5-fold upregulation (respectively) of FAT10 was observed in the DDC re-fed mice liver and in the livers of human alcoholic hepatitis with MDBs present, implying that there was an important role played by this gene. The FAT10-specific E1 and E2 enzymes Uba6 and USE1, however, were found to be downregulated both in patients' livers and in the liver of DDC re-fed mice. Interestedly, the downregulation of mRNA levels was proportionate to MDB abundance in the liver tissues. Our results show the first systematic demonstration of transcript regulation of Ufmylation and FATylation in the liver of patients who form MDBs, where protein quality control is downregulated. This was also shown in the livers of DDC re-fed mice where MDBs had formed.

Impact of altered methylation in cytokine signaling and proteasome function in alcohol and viral-mediated diseases

Data from several laboratories have shown that ethanol (EtOH) feeding impairs many essential methylation reactions that contribute to alcoholic liver disease (ALD). EtOH is also a comorbid factor in the severity of hepatitis C virus-induced liver injury. The presence of viral proteins further exacerbates the methylation defects to disrupt multiple pathways that promote the pathogenesis of liver disease. This review is a compilation of presentations that linked the methylation reaction defects with proteasome inhibition, decreased antigen presentation, and impaired interferon (IFN) signaling in the hepatocytes and dysregulated TNFα expression in macrophages. Two therapeutic modalities, betaine and S-adenosylmethionine, can correct methylation defects to attenuate many EtOH-induced liver changes, as well as improve IFN signaling pathways, thereby overcoming viral treatment resistance.

Mallory-Denk bodies form when EZH2/H3K27me3 fails to methylate DNA in the nuclei of human and mice liver cells

EZH2/H3K27me3 and polycomb group complex (PcG) play a major role in regulating global gene expression including tumor suppressor genes. EZH2 is linked to cell cycle regulated EZH2 phosphorylation by CDK1, a mitotic kinase which increases in arrested mitosis compared to S phase. CDK1 phosphorylation of EZH2 accelerates the degradation of pEZH2. Phospho-EZH2 is subjected to ubiquitination. The half-like of pEZH2 is shorter when compared to total EZH2. In the present study, pEZH2 was found concentrated together with ubiquitin in the Mallory-Denk bodies (MDB) that were formed in hepatocytes in the livers of drug primed mice refed DDC and humans with alcoholic hepatitis or hepatocellular carcinoma. The cells that formed MDBs in the mice livers studied were associated with a growth advantage and a high proliferative index. However, the livers from patients with alcoholic hepatitis showed evidence of cell cycle arrest where PCNA, cyclin D1 and p27 positive nuclei were numerous but Ki-67 positive nuclei were scarce. It is concluded that MDB formation is linked to the cell cycle and global gene expression (i.e. loss of gene silencing) through its association with the regulation of the polycomb group PRC2/EZH2/H3K27me3 complex.

Changes in IL12A methylation pattern in livers from mice fed DDC

Mallory-Denk body (MDB) formation is a component of alcoholic and non alcoholic hepatitis. Proteins of the TLR pathway were shown to be involved in the formation of MDBs, in mice fed DDC. TLR genes are upregulated and SAMe supplementation prevents this up regulation and prevented the formation of MDBs. DNA of livers from control mice, from mice fed DDC 10weeks, refed 1week with DDC and with DDC+SAMe were extracted and used to study the methylation pattern of genes involves in the TLR pathway. A PCR array was used to analyze it. Using PCR arrays for the mouse TLR pathway,24 genes were found whose expression of IL12A was regulated by the methylation of its gene. DDC fed for 10weeks reduced the methylation of the IL12A gene expression. This expression was also reduced when DDC was refed. However, when SAMe was fed, the intermediate level methylation of IL12A was up regulated to the intermediate level and the methylation of the promoter decreased compared to DDC refeeding or DDC 10weeks. IL12A is known to induce the production of IFNg by NK and L(T). We showed in a previous publication that IFNg is one of the major cytokines involved in the induction of MDB formation. The low expression of IL12A associated with the intermediate methylation of its promoter could explain one step in the mechanism which leads to the formation of MDBs.

The role of innate immunity in the pathogenesis of preneoplasia in drug-induced chronic hepatitis based on a mouse model

Innate immunity factors such as conversion of the 26S proteasome to form the immunoproteasome and the Toll-like receptor signaling pathways are activated in chronic hepatitis induced by the carcinogenic drug DDC. Over time, preneoplastic hepatocyte phenotypes appear in the liver parenchyma. These changed hepatocytes expand in number because they have a growth advantage over normal hepatocytes when responding to chronic liver injury. The changed hepatocytes can be identified using immunofluorescent antibodies to preneoplastic cells e.g. FAT10/UbD, A2 macroglobulin, glutathione transpeptidase, alpha fetoprotein, glycipan 3, FAS, and gamma glutamyl transpeptidase. The formation of the preneoplastic cells occurs concomitant with activation of the Toll-like receptor signaling pathways and the transformation of the 26S proteasome to form the immunoproteasome. This transformation is in response to interferon stimulating response element on the promoter of the FAT10/UbD gene. NFκB, Erk, p38 and Jnk are also up regulated. Specific inhibitors block these responses in vitro in a mouse tumor cell line exposed to interferon gamma. Mallory-Denk bodies form in these preneoplastic cells, because of the depletion of the 26S proteasome due to formation of the immunoproteasome. Thus, MDB forming cells are also markers of the preneoplastic hepatocytes. The UbD positive preneoplastic cells regress when the liver injury induced chronic hepatitis subsides. When the drug DDC is refed to mice and chronic hepatitis is activated, the preneoplastic cell population expands and Mallory-Denk bodies rapidly reform. This response is remembered by the preneoplastic cells for at least four months indicating that an epigenetic cellular memory has formed in the preneoplastic cells. This proliferative response is prevented by feeding methyl donors such as S-adenosylmethionine or betaine. Drug feeding reduces the methylation of H(3) K4, 9, and 27 and this response is prevented by feeding the methyl donors. After 8 to 15months of drug withdrawal in mice the preneoplastic liver cells persist as single or small clusters of cells in the liver lobules. Multiple liver tumors form, some of which are hepatocellular carcinomas. The tumors immunostain positively for the same preneoplastic markers as the preneoplastic cells. Similar cells are identified in human cirrhosis and hepatocellular carcinoma indicating the relevance of the drug model described here to the preneoplastic changes associated with human chronic hepatitis and hepatocellular carcinoma.

Hepatocellular ballooning in nonalcoholic steatohepatitis: the pathologist's perspective

Nonalcoholic fatty liver disease (NAFLD) is an important complication of the metabolic syndrome. The increasing prevalence of the metabolic syndrome is paralleled by an increasing prevalence of NAFLD, which has become one of the most common chronic liver diseases. NAFLD comprises a morphological spectrum ranging from nonalcoholic fatty liver (NAFL), characterized by accumulation of fat in hepatocytes, to nonalcoholic steatohepatitis (NASH). The key histological features of NASH accepted by most pathologists include steatosis, hepatocellular ballooning and lobular inflammation, whereas, like in other chronic liver diseases, the presence of fibrosis is not considered a requirement for the diagnosis. The diagnosis of NASH and the distinction from NAFL carries important prognostic and therapeutic implications because NASH, in contrast to NAFL, is associated with an increased risk of progression to cirrhosis and hepatocellular carcinoma. Hepatocellular ballooning is a key feature required for the diagnosis of NASH and a component of currently used histological grading and staging systems of NAFLD. However, it represents an ill-defined form of liver cell injury associated with cell swelling and rounding of the cytoplasm, the detection of which is prone to intra- as well as inter-observer variation. Some of the factors that may contribute to ballooning are the rearrangement of the intermediate filament cytoskeleton, accumulation of small-droplet fat in the cytoplasm and dilation of the endoplasmic reticulum. The rearrangement of the intermediate filament cytoskeleton can be demonstrated by the loss of keratin 8/18 immunostaining of the cytoplasm, and may thus be evaluated in the future as a marker for the more objective detection of hepatocellular ballooning in NASH.

Nutritional influence on epigenetics and effects on longevity

PURPOSE OF REVIEW

This review synthesizes recently published information regarding nutrition and its impact upon epigenetically mediated mechanisms involved in longevity and aging.

RECENT FINDINGS

Recent studies enriched considerably our understanding of the relationship between aging and gene-nutrient interactions that continuously shape our phenotype. Epigenetic mechanisms play an important role in mediating between the nutrient inputs and the ensuing phenotypic changes throughout our entire life and seem to be responsible, in part, for the biological changes that occur during aging. Less is known about the epigenetic role that nutrients have in directly influencing longevity and aging. However, recent studies clearly indicated that because nutrition modulates epigenetic events associated with various diseases (e.g., cancer, obesity, and diabetes), there is at least an indirect epigenetic link between nutrition and longevity and, therefore, biologic plausibility to hypothesize the epigenetic role of nutrition in altering longevity. Apart from limited human studies, promising animal studies brought us much closer to understanding how nutrition could have such an impact upon longevity and aging.

SUMMARY

Complex epigenetic mechanisms are involved in aging and longevity, directly or indirectly via disease mechanisms. Nutrition has a strong impact upon epigenetic processes and, therefore, holds promise in having important roles in regulating longevity and aging.

Early increases in transglutaminase activity and polyamine levels in a Mallory-Denk body mouse model

Rodents treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) are a model of two hepatic toxic manifestations: porphyria and the appearance of hepatic cytoplasmic protein aggregates (Mallory-Denk Bodies, MDBs). MDBs are induced after long-term DDC feeding, consist primarily of keratins 8 and 18, and contain glutamine-lysine cross-links generated by transglutaminases (TGs). TGs are Ca(2+)-dependent enzymes which catalyze the formation of covalent bonds between proteins and between proteins and polyamines. The aim of the current study was to investigate the time-course of TG hepatic activity in CF1 male mice either acutely or chronically treated with DDC and to correlate this activity with polyamine and porphyrin levels. On day 3 of the treatment, statistically significant increases in TG activity (75%), porphyrin content (6740%) and spermidine levels (73%) were observed. Although not statistically significant, at this time point putrescine levels showed an increase of 52%. The highest TG activity was observed on day 30 (522%), while porphyrin levels were still gradually increasing by day 45 (37,000%). From day 7 of the treatment and until the end of the experiment, putrescine levels remained increased (781%). Spermine levels were not affected by the treatment. The DDC-induced increases in putrescine and spermidine levels herein reported seem to be an early event contributing to the stimulation of liver TG activity, and thus to the promotion of cross-linking reactions between keratin proteins. This in turn would contribute to the formation of protein aggregates, which would lead to the appearance of MDBs. Due to the pro-oxidant and antioxidant properties of polyamines, it is possible to speculate that putrescine and spermidine may also participate at several levels in the oxidative stress processes associated with MDB formation.

Ubiquitin D is correlated with colon cancer progression and predicts recurrence for stage II-III disease after curative surgery

BACKGROUND

Our recent study observed that the expression of ubiquitin D (UBD), a member of ubiquitin-like modifier family, was upregulated in colon cancer parenchymal cells. The present study further investigated the clinical signicance of UBD in colon cancer.

METHODS

Using quantitative PCR, tissue microarray (TMA), western blot analysis and immunohistochemical stain, we evaluated UBD mRNA and protein levels in tumour tissues from patients with colon cancer at different stages and in paired adjacent normal epithelium.

RESULTS

Immunohistochemical detection of UBD on a TMA containing 203 paired specimens showed that increased cytoplasmic UBD was signicantly associated with depth of cancer invasion, lymph node metastasis, distant metastasis, tumour histologic grade, advanced clinical stage and Ki-67 proliferative index. Patients with UBD-positive tumours had a significantly higher disease recurrence rate and poorer survival than patients with UBD-negative tumours after the radical surgery. Stratification analysis according to tumour stage revealed UBD as an independent predictor for tumour recurrence in patients with stage II and III tumours.

CONCLUSION

UBD may contribute to the progression of colon carcinogenesis and function as a novel prognostic indicator of forecasting recurrence of stage II and III patients after curative operations.

Mallory-Denk body pathogenesis revisited

This editorial reviews the recent evidence showing that Mallory-Denk bodies (MDBs) form in hepatocytes as the result of a drug-induced shift from the 26s proteasome formation to the immunoproteasome formation. The shift is the result of changes in gene expression induced in promoter activation, which is induced by the IFNγ and TNFα signaling pathway. This activates TLR 2 and 4 receptors. The TLR signaling pathway stimulates both the induction of a cytokine proinflammatory response and an up regulation of growth factors. The MDB- forming hepatocytes proliferate as a result of the increase in growth factor expression by the MDB- forming cells, which selectively proliferate in response to drug toxicity. All of these mechanisms are induced by drug toxicity, and are prevented by feeding the methyl donors SAMe and betaine, supporting the epigenetic response of MDB formation.

SAMe prevents the induction of the immunoproteasome and preserves the 26S proteasome in the DDC-induced MDB mouse model

Mallory-Denk bodies (MDBs) form in the liver of alcoholic patients. This occurs because of the accumulation and aggregation of ubiquitinated cytokeratins, which hypothetically is due to the ubiquitin-proteasome pathway's (UPP) failure to degrade the cytokeratins. The experimental model of MDB formation was used in which MDBs were induced by refeeding DDC to drug-primed mice. The gene expression and protein levels of LMP2, LMP7 and MECL-1, the catalytic subunits in the immunoproteasome, as well as FAT10, were increased in the liver cells forming MDBs but not in the intervening normal hepatocytes. Chymotrypsin-like activity of the UPP was decreased by DDC refeeding, indicating that a switch from the UPP to the immunoproteasome had occurred at the expense of the 26S proteasome. The failure of the UPP to digest cytokeratins would explain MDB aggregate formation. SAMe prevented the decrease in UPP activity, the increase in LMP2, LMP7, and MECL-1 protein levels and MDB formation induced by DDC. DDC refeeding also induced the TNFalpha and IFNgamma receptors. SAMe prevented the increase in the TNFalpha and IFNgamma receptors, supporting the idea that TNFalpha and IFNgamma were responsible for the up regulation of LMP2, LPM7, and FAT10. These results support the conclusion that MDBs form in FAT10 over-expressing hepatocytes where the up regulation of the immunoproteasome occurs at the expense of the 26S proteasome.

SAMe prevents the up regulation of toll-like receptor signaling in Mallory-Denk body forming hepatocytes

Mallory-Denk body (MDB) formation is a component of alcoholic and non alcoholic hepatitis. In the present study, the role of the toll-like receptor (TLR) signaling pathway was investigated in the mechanism of MDB formation in the DDC-fed mouse model. Microarray analysis data mining, performed on the livers of drug-primed mice refed DDC, showed that TLR2/4 gene expression was significantly up regulated by DDC refeeding. SAMe supplementation prevented this up regulation and prevented the formation of MDBs. qRT-PCR analysis confirmed these results. TLR2/4 activates the adapter protein MyD88. The levels of MyD88 were increased by DDC refeeding. The increase of MyD88 was also prevented by SAMe supplementation. Results showed that MyD88-independent TLR3/4-TRIF-IRF3 pathway was not up regulated in the liver of DDC refed mice. Tumor necrosis factor receptor-associated factor 6 (TRAF6) is the downstream protein recruited by the MyD88/IRAK protein complex, and is involved in the regulation of innate immune responses. Results showed a significant increase in the levels of TRAF-6. TRAF-6 activation leads to activation of NFkB and the mitogen-activated protein kinase (MAPK) cascade. The TRAF-6 increase was ameliorated by SAMe supplementation. These results suggest that DDC induces MDB formation through the TLR2/4 and MyD88-dependent signaling pathway. In conclusion, SAMe blocked the over-expression of TLR2/4, and their downstream signaling components MyD88 and TRAF-6. SAMe prevented the DDC-induced up regulation of the TLR signaling pathways, probably by preventing the up regulation of INF-gamma receptors by DDC feeding. INFgamma stimulates the up regulation of TLR2. The ability of SAMe feeding to prevent TLR signaling up regulation has not been previously described.

Alcohol, nutrition and liver cancer: Role of Toll-like receptor signaling

This article reviews the evidence that ties the development of hepatocellular carcinoma (HCC) to the natural immune pro-inflammatory response to chronic liver disease, with a focus on the role of Toll-like receptor (TLR) signaling as the mechanism of liver stem cell/progenitor transformation to HCC. Two exemplary models of this phenomenon are reviewed in detail. One model applies chronic ethanol/lipopolysaccharide feeding to the activated TLR4 signaling pathway. The other applies chronic feeding of a carcinogenic drug, in which TLR2 and 4 signaling pathways are activated. In the drug-induced model, two major methyl donors, S-adenosylmethionine and betaine, prevent the upregulation of the TLR signaling pathways and abrogate the stem cell/progenitor proliferation response when fed with the carcinogenic drug. This observation supports a nutritional approach to liver cancer prevention and treatment. The observation that upregulation of the TLR signaling pathways leads to liver tumor formation gives evidence to the popular concept that the chronic pro-inflammatory response is an important mechanism of liver oncogenesis. It provides a nutritional approach, which could prevent HCC from developing in many chronic liver diseases.

The effects of betaine treatment on rats fed an acute bolus of ethanol at 3 and 12 h post bolus: a microarray analysis

Betaine, a methyl donor active in methionine metabolism, is effective in preventing and reversing experimental alcohol liver disease. The metabolic and molecular biologic mechanisms involved in this prevention are only partially known. To further investigate how betaine modifies the effects of ethanol on the liver, rats were given an acute ethanol bolus with or without betaine and the results were compared to isocaloric dextrose-fed controls. Livers were subjected to microarray analysis, and functional pathways and individual gene expression changes were analyzed. Experimental groups were compared by Venn diagrams showing that both ethanol and betaine caused a change in the expression of a large number of genes indicating that the changes were global. The bio-informatic analysis showed that all the KEGG functional pathways were affected and mainly down regulated at 3 h post bolus when ethanol plus betaine were compared with ethanol-fed rats. The most profound effect of betaine was on the metabolic pathways both at 3 and 12 h post bolus. At 3 h, the changes in gene expression were mostly down regulated, but at 12 h, the changes were regulated equally up and down. This hypothesis-driven analysis showed that the effects of betaine on the effects of ethanol were partly transient.

The cyclic pattern of blood alcohol levels during continuous ethanol feeding in rats: the effect of feeding S-adenosylmethionine

S-adenosylmethionine (SAMe), the major methyl donor for DNA and histone methylation was fed with ethanol for 1month in order to modify the effects of ethanol on rat liver. The following parameters were studied to determine the effects of SAMe; liver histology, the blood alcohol cycle (BAL), changes in gene expression mined from microarray analysis, changes in histone methylation, changes in liver SAMe levels and its metabolites and ADH. SAMe changed the type of fatty liver, reduced liver ALT levels and prevented the BAL cycle caused by intragastric ethanol feeding. Microarray analysis showed that SAMe feeding prevented most of the changes in gene expression induced by ethanol feeding, presumably by inducing H3K27me3 and gene silencing. H3K27me3 was significantly increased by SAMe with or without ethanol feeding. It is concluded that SAMe feeding stabilized global gene expression so that the changes in gene expression involved in the blood alcohol cycle were prevented.

The role of stem cells/progenitor cells in liver carcinogenesis in glycine N-methyltransferase deficient mice

Regeneration of the liver is inhibited as a result of a sustained increase in S-adenosylmethionine levels in glycine N-methyltransferase (GNMT)-/- mice. This sets the stage for normally dormant stem cells/progenitor cells to replicate and differentiate to replenish the liver parenchyma with liver cells. With time the stem cells/progenitor cells may aggregate and ultimately form liver tumors. This transformation of stem cells persists within the tumors that form in order to maintain the growth of the tumors that have formed. To test this hypothesis, GNMT-/- mice were maintained for 18 months and their livers were studied at intervals, in order to document the process of tumors formation and the identification of stem cells/progenitor cells involved in the process. Progenitor cell (OV-6 positive cells) hyperplasia was already established at 8 months in the livers of the GNMT-/- mice. This process was expanded at 18 months when liver tumors had formed. Stem cells which stained positive in the livers at 8 months and within tumors at 18 months (Oct 4 and CK 19 positive cells) were found. Fat 10, a marker for progenitor liver cells, was uniformly expressed by all tumors that developed at 8 and 18 months in GNMT-/- mice.

The regulation of non-coding RNA expression in the liver of mice fed DDC

Mallory-Denk bodies (MDBs) are found in the liver of patients with alcoholic and chronic nonalcoholic liver disease, and hepatocellular carcinoma (HCC). Diethyl 1,4-dihydro-2,4,6,-trimethyl-3,5-pyridinedicarboxylate (DDC) is used as a model to induce the formation of MDBs in mouse liver. Previous studies in this laboratory showed that DDC induced epigenetic modifications in DNA and histones. The combination of these modifications changes the phenotype of the MDB forming hepatocytes, as indicated by the marker FAT10. These epigenetic modifications are partially prevented by adding to the diet S-adenosylmethionine (SAMe) or betaine, both methyl donors. The expression of three imprinted ncRNA genes was found to change in MDB forming hepatocytes, which is the subject of this report. NcRNA expression was quantitated by real-time PCR and RNA FISH in liver sections. Microarray analysis showed that the expression of three ncRNAs was regulated by DDC: up regulation of H19, antisense Igf2r (AIR), and down regulation of GTL2 (also called MEG3). S-adenosylmethionine (SAMe) feeding prevented these changes. Betaine, another methyl group donor, prevented only H19 and AIR up regulation induced by DDC, on microarrays. The results of the SAMe and betaine groups were confirmed by real-time PCR, except for AIR expression. After 1 month of drug withdrawal, the expression of the three ncRNAs tended toward control levels of expression. Liver tumors that developed also showed up regulation of H19 and AIR. The RNA FISH approach showed that the MDB forming cells' phenotype changed the level of expression of AIR, H19 and GTL2, compared to the surrounding cells. Furthermore, over expression of H19 and AIR was demonstrated in tumors formed in mice withdrawn for 9 months. The dysregulation of ncRNA in MDB forming liver cells has been observed for the first time in drug-primed mice associated with liver preneoplastic foci and tumors.