Characterization of apolipoprotein C1 in hepatitis C virus infection and morphogenesis

Cellular factors involved in the hepatitis C virus life cycle

The hepatitis C virus (HCV), an obligatory intracellular pathogen, highly depends on its host cells to propagate successfully. The HCV life cycle can be simply divided into several stages including viral entry, protein translation, RNA replication, viral assembly and release. Hundreds of cellular factors involved in the HCV life cycle have been identified over more than thirty years of research. Characterization of these cellular factors has provided extensive insight into HCV replication strategies. Some of these cellular factors are targets for anti-HCV therapies. In this review, we summarize the well-characterized and recently identified cellular factors functioning at each stage of the HCV life cycle.

Expression of apolipoprotein C1 in clear cell renal cell carcinoma: An oncogenic gene and a prognostic marker

This study aimed to explore whether APOC1 expression has a function in the biological behavior of clear cell renal cell carcinoma (ccRCC) cells and its possible mechanism. Bioinformatics analysis of data TCGA and OnComine was conducted to explore the expression pattern and prognostic value of APOC1, as well as the relationship between APOC1 expression and clinical indicators. Loss- and gain- of APOC1 function assays were carried out to assess the biological functions of APOC1. Western blotting was applied to detect protein expression. We revealed that APOC1 was upregulated in ccRCC tissues. APOC1 expression was related to gender, grade, pathologic-T, pathologic-stage, and pathologic-M in patients with ccRCC. Meanwhile, Kaplan-Meier analysis evidenced that the high APOC1 expression indicated unfavorable outcomes of ccRCC. Functional experiments in vitro revealed that upregulation of APOC1 in UT33A cells promoted cell proliferation, invasion, and migration, while downregulation of APOC1 in 786-O cells had the opposite effect. Furthermore, epithelial mesenchymal transition (EMT) was activated in cells with upregulated APOC1 but inhibited in cells with down-regulated APOC1. Collectively, our data suggested that APOC1 was overexpressed in ccRCC cells and promoted the malignant biological behaviors and EMT of ccRCC cells.

Proline-Rich Hypervariable Region of Hepatitis E Virus: Arranging the Disorder

The hepatitis E virus (HEV) hypervariable region (HVR) presents the highest divergence of the entire HEV genome. It is characteristically rich in proline, and so is also known as the “polyproline region” (PPR). HEV genotype 3 (HEV-3) exhibits different PPR lengths due to insertions, PPR and/or RNA-dependent RNA polymerase (RdRp) duplications and deletions. A total of 723 PPR-HEV sequences were analyzed, of which 137 HEV-3 sequences were obtained from clinical specimens (from acute and chronic infection) by Sanger sequencing. Eight swine stool/liver samples were also analyzed. N- and C-terminal fragments were confirmed as being conserved, but they harbored differences between genotypes and were not proline-plentiful regions. The genuine PPR is the intermediate region between them. HEV-3 PPR contains a higher percentage (30.4%) of prolines than other genotypes. We describe for the first time: (1) the specific placement of HEV-3 PPR rearrangements in sites 1 to 14 of the PPR, noting that duplications are more frequently attached to sites 11 and 12 (AAs 74–79 and 113–118, respectively); (2) the cadence of repetitions follows a circular-like pattern of blocks A to J, with F, G, H, and I being the most frequent; (3) a previously unreported insertion homologous to apolipoprotein C1; and (4) the increase in frequency of potential N-glycosylation sites and differences in AAs composition related to duplications.

Hepatitis C virus infection and tight junction proteins: The ties that bind

The hepatitis C virus (HCV) is a major cause of liver diseases ranging from liver inflammation to advanced liver diseases like cirrhosis and hepatocellular carcinoma (HCC). HCV infection is restricted to the liver, and more specifically to hepatocytes, which represent around 80% of liver cells. The mechanism of HCV entry in human hepatocytes has been extensively investigated since the discovery of the virus 30 years ago. The entry mechanism is a multi-step process relying on several host factors including heparan sulfate proteoglycan (HSPG), low density lipoprotein receptor (LDLR), tetraspanin CD81, Scavenger Receptor class B type I (SR-BI), Epidermal Growth Factor Receptor (EGFR) and Niemann-Pick C1-like 1 (NPC1L1). Moreover, in order to establish a persistent infection, HCV entry is dependent on the presence of tight junction (TJ) proteins Claudin-1 (CLDN1) and Occludin (OCLN). In the liver, tight junction proteins play a role in architecture and homeostasis including sealing the apical pole of adjacent cells to form bile canaliculi and separating the basolateral domain drained by sinusoidal blood flow. In this review, we will highlight the role of liver tight junction proteins in HCV infection, and we will discuss the potential targeted therapeutic approaches to improve virus eradication.