Depolarized Hepatocytes Express the Stem/Progenitor Cell Marker Neighbor of Punc E11 After Bile Duct Ligation in Mice

Connexin-Based Channels in the Liver

Connexin proteins oligomerize in hexameric structures called connexin hemichannels, which then dock to form gap junctions. Gap junctions direct cell-cell communication by allowing the exchange of small molecules and ions between neighboring cells. In this way, hepatic gap junctions support liver homeostasis. Besides serving as building blocks for gap junctions, connexin hemichannels provide a pathway between the intracellular and the extracellular environment. The activation of connexin hemichannels is associated with acute and chronic liver pathologies. This article discusses the role of gap junctions and connexin hemichannels in the liver. © 2022 American Physiological Society. Compr Physiol 12:1-17, 2022.

Repolarization Precedes Oval Cell-mediated Hepatocytic Regeneration in the CDE Diet Mouse Model

The liver has a unique ability to recover from injury unlike any other organ. A poorly understood aspect of liver regeneration is the role of hepatocellular polarization. Neighbor of Punc E11 (Nope) is an oncofetal stem/progenitor cell marker, which is expressed by depolarized adult hepatocytes after cholestatic liver injury and in hepatocellular carcinoma. Liver injury induced by a choline-deficient and ethionine-supplemented diet is reversible if followed by an additional dietary stop interval and enabled us to study the expression of Nope during the induction of chronic liver injury and during subsequent liver regeneration. We could show by quantitative RT-PCR, Western blotting, and immunohistochemistry that the expression of Nope is induced in depolarized adult hepatocytes during injury. However, after another 2 weeks of a normal diet, the polarization of hepatocytes was almost completely restored and the expression of Nope remained limited to bile ducts and oval cells. Using an inducible CK19-lineage tracing model, we could demonstrate that oval cell-mediated hepatocyte regeneration is rare and was preceded by repolarization of hepatocytes. In conclusion, polarization of hepatocytes is an important part of liver regeneration and precedes oval cell-mediated regeneration of the liver. This process can be visualized by a characteristic expression pattern of Nope.

Expression of Neighbor of Punc E11 (NOPE) in early stage esophageal adenocarcinoma is associated with reduced survival

Current recommendations suggest neoadjuvant treatment in node-positive esophageal cancer or tumors staged T3 and upwards but some T2 N0 patients might benefit from neoadjuvant therapy. It is of clinical relevance to identify this subgroup. Loss of epithelial apicobasal polarity is a key factor in the development of invasive capabilities of carcinoma. The oncofetal stem/progenitor cell marker NOPE is expressed in adult depolarized murine hepatocytes and in murine/human hepatocellular carcinoma. We analyzed NOPE expression in 363 patients with esophageal adenocarcinoma using an RNA Scope Assay on a tissue microarray and correlated results with clinical data. Median follow-up was 57.7 months with a 5-year survival rate of 26.6%. NOPE was detectable in 32 patients (8.8%). In pT1/2 stages, NOPE expression was associated with a significantly reduced median OS of 6.3 months (95% CI 1.2-19.4 months), the median OS is not reached in the NOPE-negative group (calculated mean OS 117.1 months) (P = 0.012). In advanced tumor stages, a NOPE dependent survival difference was not detected. This is the first report of NOPE expression demonstrating a prognostic value in esophageal cancer. Early stage, NOPE positive patients are at a high risk of tumor progression and may benefit from neoadjuvant treatment analogous to advanced stage cancer.

A role of connexin 43 on the drug-induced liver, kidney, and gastrointestinal tract toxicity with associated signaling pathways

Drug-induced organ toxicity/injury, especially in the liver, kidney, and gastrointestinal tract, is a systematic disorder that causes oxidative stress formation and inflammation resulting in cell death and organ failure. Current therapies target reactive oxygen species (ROS) scavenging and inhibit inflammatory factors in organ injury to restore the functions and temporary relief. Organ cell function and tissue homeostasis are maintained through gap junction intercellular communication, regulating connexin hemichannels. Mis-regulation of such connexin, especially connexin (Cx) 43, affects a comprehensive process, including cell differentiation, inflammation, and cell death. Aim to describe knowledge about the importance of connexin role and insights therapeutic targeting. Cx43 misregulation has been implicated in recent decades in various diseases. Moreover, in recent years there is increasing evidence that Cx43 is involved in the toxicity process, including hepatic, renal, and gastrointestinal disorders. Cx43 has the potential to initiate the immune system to cause cell death, which has been activated in the acceleration of apoptosis, necroptosis, and autophagy signaling pathway. So far, therapies targeting Cx43 have been under inspection and are subjected to clinical trial phases. This review elucidates the role of Cx43 in drug-induced vital organ injury, and recent reports compromise its function in the major signaling pathways.

The Consumption of Cholesterol-Enriched Diets Conditions the Development of a Subtype of HCC with High Aggressiveness and Poor Prognosis

Simple Summary

It is well known that non-alcoholic fatty liver disease is an important risk factor in the development of hepatocellular carcinoma, but the implication of cholesterol in this subject remains unclear, especially in western countries where its consumption is particularly elevated. This work provides evidence of a cholesterol-related transcriptional fingerprint and its implications in the progression and aggressiveness of hepatocellular carcinoma with remarkable interest in clinical practice.

Abstract

Non-alcoholic fatty liver disease (NAFLD) and progression to non-alcoholic steatohepatitis (NASH) result as a consequence of diverse conditions, mainly unbalanced diets. Particularly, high-fat and cholesterol content, as well as carbohydrates, such as those commonly ingested in Western countries, frequently drive adverse metabolic alterations in the liver and promote NAFLD development. Lipid liver overload is also one of the main risk factors for initiation and progression of hepatocellular carcinoma (HCC), but detailed knowledge on the relevance of high nutritional cholesterol remains elusive. We were aimed to characterize HCC development in mice fed with a Western diet (high in lipids and cholesterol) and to identify molecular alterations that define a subtype of liver cancer induced by lipid overload. Mice under western or high cholesterol diets more frequently developed tumors with a more aggressive phenotype than animals fed with a chow diet. Associated changes involved macrophage infiltration, angiogenesis, and stemness features. RNA-seq revealed a specific gene expression signature (Slc41a; Fabp5; Igdcc4 and Mthfd1l) resembling the adverse phenotypic features and poor clinical outcomes seen in patients with HCC. In conclusion; consumption of lipid enriched diets; particularly cholesterol; could accelerate HCC development with an aggressive phenotype and poor prognosis