Signal transduction of gap junctional genes, connexin32, connexin43 in human hepatocarcinogenesis

Transcriptional responses of liver and spleen in Lota lota to polyriboinosinic polyribocytidylic acid

Introduction

The cultured Lota lota can meet the market demand in the context of the decline of wild resources, but the disease in the high-density culture process also deserves attention. Therefore, understanding the immune regulation mechanisms of L. lota will be the basis for obtaining high benefits in artificial culture.

Methods

To explore the viral response mechanism of L. lota, RNA-seq was applied to identify the transcriptomic changes of the liver and spleen in L. lota by poly (I:C) stress.

Results

The DEGs (liver: 2186 to 3123; spleen 1542 to 2622) and up-regulated genes (liver: 1231 to 1776; spleen 769 to 1502) in the liver and spleen increased with the prolongation (12h to 48h) of poly (I:C)-stimulation time. This means L. lota needs to mobilize more functional genes in response to longer periods of poly (I:C)-stimulation. Despite the responses of L. lota to poly (I:C) showed tissue-specificity, we hypothesized that both liver and spleen of L. lota can respond to poly (I:C) challenge may be through promoting apoptosis of DNA-damaged cells, increasing the activity of immune-enhancing enzymes, and increasing energy supply based on DEGs annotation information.

Conclusions

Our results demonstrate the transcriptional responses of L. lota to poly (I:C)-stimulation, and these data provide the first resource on the genetic regulation mechanisms of L. lota against viruses. Furthermore, the present study can provide basic information for the prevention of viral diseases in L. lota artificial culture process.

Efficacy of continuous positive airway pressure on TNF-α in obstructive sleep apnea patients: A meta-analysis

BACKGROUND

Tumor necrosis factor-α (TNF-α) is an important mediator of the immune response. At present, the improvement of TNF-α after continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS) is still controversial.

METHODS

We conducted a systematic review of the present evidence based on a meta-analysis to elucidate the effects of TNF-α on OSAHS after CPAP treatment.

RESULTS

To measure TNF-α, ten studies used enzyme-linked immunosorbent assay (ELISA), and one used radioimmunoassay. The forest plot outcome indicated that CPAP therapy would lower the TNF-α levels in OSAHS patients, with a weighted mean difference (WMD) of 1.08 (95% CI: 0.62-1.55; P < 0.001) based on the REM since there is highly significant heterogeneity (I2 = 90%) among the studies. Therefore, we used the subgroup and sensitivity analyses to investigate the source of heterogeneity. The findings of the sensitivity analysis revealed that the pooled WMD ranged from 0.91 (95% CI: 0.52-1.31; P < 0.001) to 1.18 (95% CI: 0.74-1.63; P < 0.001). The findings were not influenced by any single study. Notably, there was homogeneity in the Asia subgroup and publication year: 2019, implying that these subgroups could be the source of heterogeneity.

CONCLUSION

Our meta-analysis recommends that CPAP therapy will decrease the TNF-α level in OSAHS patients, but more related research should be conducted.

Quantitative and integrative analysis of paracrine hepatocyte activation by nonparenchymal cells upon lipopolysaccharide induction

Gut-derived bacterial lipopolysaccharides (LPS) stimulate the secretion of tumour necrosis factor (TNF) from liver macrophages (MCs), liver sinusoidal endothelial cells (LSECs) and hepatic stellate cells (HSCs), which control the acute phase response in hepatocytes through activation of the NF-κB pathway. The individual and cooperative impact of nonparenchymal cells on this clinically relevant response has not been analysed in detail due to technical limitations. To gain an integrative view on this complex inter- and intracellular communication, we combined a multiscale mathematical model with quantitative, time-resolved experimental data of different primary murine liver cell types. We established a computational model for TNF-induced NF-κB signalling in hepatocytes, accurately describing dose-responsiveness for physiologically relevant cytokine concentrations. TNF secretion profiles were quantitatively measured for all nonparenchymal cell types upon LPS stimulation. This novel approach allowed the analysis of individual and collective paracrine TNF-mediated NF-κB induction in hepatocytes, revealing strongest effects of MCs and LSECs on hepatocellular NF-κB signalling. Simulations suggest that both cell types act together to maximize the NF-κB pathway response induced by low LPS concentrations (0.1 and 1 ng/mL). Higher LPS concentrations (≥ 5 ng/mL) induced sufficient TNF levels from MCs or LSECs to induce a strong and nonadjustable pathway response. Importantly, these simulations also revealed that the initial cytokine secretion (1-2 h after stimulation) rather than final TNF level (10 h after stimulation) defines the hepatocellular NF-κB response. This raises the question whether the current experimental standard of single high-dose cytokine administration is suitable to mimic in vivo cytokine exposure.

DATABASE

The computational models described in this manuscript are available in the JWS database via the following link: https://jjj.bio.vu.nl/database/beuke.

A quantitative inverse relationship between connexin32 expression and cell proliferation in a rat hepatoma cell line

Gap junctions comprised of connexin proteins are involved in direct intercellular communication and the regulation of cell behaviour and homeostasis. Reduced connexin expression and loss of gap junction function is a characteristic of many cancer cells and of the effect of many non-genotoxic carcinogens that induce cell proliferation. Moreover, when certain cancer cell lines are transfected with specific connexin genes, cells can regain control over proliferation. We have employed RNA interference and dexamethasone to modulate connexin32 expression in MH(1)C(1) cells to a range of concentrations. This allowed the determination of the quantitative relationship between connexin32 protein expression and cell proliferation. The magnitude of cell proliferation, measured by bromodeoxyuridine incorporation, was inversely proportional to the level of connexin32 expression. Q-PCR indicated a lack of change of expression of a range of cell cycle-related genes at 24h. The inverse relationship between Cx32 expression and proliferation was continuous, and a threshold level of reduction of connexin32 was not observable for an influence on proliferation.

Alpha-synuclein overexpression reduces gap junctional intercellular communication in dopaminergic neuroblastoma cells

Alpha-synuclein has been implicated in the pathology of certain neurodegenerative diseases, including Parkinson disease (PD) and dementia with Lewy bodies (LBs). Overexpression of human alpha-synuclein in neuronal cells reduces cell viability, but the precise cellular and molecular mechanisms remain poorly understood. Gap junctional intercellular communication (GJIC) is thought to be essential for maintaining cellular homeostasis and growth control. In the present study, the effect of alpha-synuclein overexpression on GJIC in human dopaminergic neuroblastoma SH-SY5Y cells was investigated. Cells overexpressing wild-type alpha-synuclein were more vulnerable to hydrogen peroxide and 6-hydroxydopamine. GJIC was decreased in cells overexpressing alpha-synuclein. In addition, alpha-synuclein binds directly to connexin-32 (Cx32). As such, the post-translational modification of Cx32 was enhanced in cells overexpressing alpha-synuclein. These findings suggest that alpha-synuclein can modulate GJIC in a dopaminergic neuronal cell line through specific binding to Cx32.

Liver cell lines for the study of hepatocyte functions and immunological response

BACKGROUND

Liver cell lines closely resembling primary hepatocyte are essential for research on hepatitis viruses and hepatocyte function. Currently used cell lines are derived from hepatic tumours and have altered gene expression.

AIMS

The generation and characterisation of novel human hepatocyte lines (HHLs) derived from healthy human liver, retaining the primary hepatocyte phenotype.

RESULTS

Primary hepatocytes were immortalised with Moloney's mouse leukaemia virus expressing E6 and E7 proteins of human papillomavirus, and cultures propagated long-term. All HHLs contained markers of hepatocyte and biliary phenotype (cytokeratins 7, 8, 18 and 19), Cytochrome P450 and albumin. The HHLs did not express high levels of p53 or alpha-fetoprotein. When grown in a collagen sandwich culture, or at the air-liquid interface, HHLs were maintained as monolayer whereas Huh-7 and HepG2 formed thick layers. All HHLs showed increased capacity to bind recombinant hepatitis C virus-like particles in comparison with Huh-7 and HepG2. We also demonstrate that HHLs contained active gap junctions, and that the cells respond to stimulation with IFN-alpha by upregulation of major histocompatibility complex (MHC)-I and -II.

CONCLUSIONS

These HHLs retain primary hepatocyte phenotype and should be useful for investigating mechanisms of entry and replication of hepatotropic viruses, and should also be valuable in the study of hepatocyte biology and pathology.