Hypoxia-inducible factor affects hepatitis B virus transcripts and genome levels as well as the expression and subcellular location of the hepatitis B virus core protein

Unraveling the role of HIF-1α in sepsis: from pathophysiology to potential therapeutics-a narrative review

Sepsis is characterized by organ dysfunction resulting from a dysregulated inflammatory response triggered by infection, involving multifactorial and intricate molecular mechanisms. Hypoxia-inducible factor-1α (HIF-1α), a notable transcription factor, assumes a pivotal role in the onset and progression of sepsis. This review aims to furnish a comprehensive overview of HIF-1α's mechanism of action in sepsis, scrutinizing its involvement in inflammatory regulation, hypoxia adaptation, immune response, and organ dysfunction. The review encompasses an analysis of the structural features, regulatory activation, and downstream signaling pathways of HIF-1α, alongside its mechanism of action in the pathophysiological processes of sepsis. Furthermore, it will delve into the roles of HIF-1α in modulating the inflammatory response, including its association with inflammatory mediators, immune cell activation, and vasodilation. Additionally, attention will be directed toward the regulatory function of HIF-1α in hypoxic environments and its linkage with intracellular signaling, oxidative stress, and mitochondrial damage. Finally, the potential therapeutic value of HIF-1α as a targeted therapy and its significance in the clinical management of sepsis will be discussed, aiming to serve as a significant reference for an in-depth understanding of sepsis pathogenesis and potential therapeutic targets, as well as to establish a theoretical foundation for clinical applications.

Oxygen-dependent histone lysine demethylase 4 restricts hepatitis B virus replication

Mammalian cells have evolved strategies to regulate gene expression when oxygen is limited. Hypoxia-inducible factors (HIF) are the major transcriptional regulators of host gene expression. We previously reported that HIFs bind and activate hepatitis B virus (HBV) DNA transcription under low oxygen conditions; however, the global cellular response to low oxygen is mediated by a family of oxygenases that work in concert with HIFs. Recent studies have identified a role for chromatin modifiers in sensing cellular oxygen and orchestrating transcriptional responses, but their role in the HBV life cycle is as yet undefined. We demonstrated that histone lysine demethylase 4 (KDM4) can restrict HBV, and pharmacological or oxygen-mediated inhibition of the demethylase increases viral RNAs derived from both episomal and integrated copies of the viral genome. Sequencing studies demonstrated that KDM4 is a major regulator of the hepatic transcriptome, which defines hepatocellular permissivity to HBV infection. We propose a model where HBV exploits cellular oxygen sensors to replicate and persist in the liver. Understanding oxygen-dependent pathways that regulate HBV infection will facilitate the development of physiologically relevant cell-based models that support efficient HBV replication.

Association of hypoxia-inducible factor 1α expression with susceptibility to hepatitis B virus-related hepatocellular carcinoma: A meta-analysis

Hypoxia-inducible factor 1α (HIF-1α) triggers tumorigenesis and progression in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Inconsistent findings have been reported on the influence of HIF-1α over-expression on the clinical outcomes of HBV-related HCC. This study aims to clarify the role of HIF-1α overexpression in the tumorigenesis and prognosis of HBV-induced HCC. Systematic and comprehensive search of online papers was carried out to elucidate the contribution of HIF-1α expression to susceptibility of HBV-induced HCC. STATA 12.0 software was utilized to analyze available data extracted from all eligible literature. Publication bias and sensitivity were comprehensively analyzed. A total of 23 published studies involving 2244 subjects were finally screened. The HIF-1α expression was remarkably upregulated in HBV-induced HCC tissues than in normal liver tissues, non-tumorous tissues, paraneoplastic tissues, and non-HBV HCC tissues. The high HIF-1α expression tended to be positively related to capsular infiltration (odds ratio (OR) 1.767; 95% confidence interval (CI) 1.058, 2.950). The HIF-1α expression was relevant to lymph node metastasis (OR 3.778; 95% CI 1.666, 8.568). High levels of HIF-1α expression tended to be closely implicated in portal vein invasion (OR 6.728, 95% CI 2.191, 20.656) but were irrelevant to alpha-fetoprotein, cirrhosis, Edmondson grading, tumor size, age, gender, and histological grade. Analysis of pooled data showed that HIF-1α was not statistically relevant to poor overall survival in HBV-related HCC. Our data provides compelling evidence that HIF-1α overexpression may imply a greater probability of invasion and metastasis in patients with HBV-induced HCC.