Zika virus: An emerging challenge for obstetrics and gynecology

MicroRNA-34c-5p Reduces Malignant Properties of Lung Cancer Cells through Regulation of TBL1XR1/Wnt/β-catenin Signaling

INTRODUCTION

Lung cancer is common cancer with high mortality. A growing number of studies have focused on investigating the regulatory effects of microRNAs (miRs/miRNAs) during cancer progression. Nevertheless, the biological function of miR- 34c-5p in lung cancer and the underlying mechanism have not been determined. This study explored the effect of miR-34c-5p on the malignant behaviors of lung cancer cells.

METHODS

In this study, we utilized diverse public databases to obtain differentially expressed miRNAs. Then, qRT-PCR and western blot were conducted to determine miR-34c-5p and transducin β-like 1 X-linked receptor 1 (TBL1XR1) expression. Next, H1299 and H460 cells were transfected with miR-34c-5p-mimic and pcDNA3.1- TBL1XR1. To examine the anticancer effects of miR-34c-5p, CCK-8, scratch, and Matrigel-Transwell assays were conducted to test cell viability, migration, and invasion, respectively. The StarBase database and dual-luciferase reporter gene assay were used to predict and verify the relationship between miR-34c-5p and TBL1XR1.

RESULTS

Finally, Wnt/β-catenin signaling- and epithelial-mesenchymal transition (EMT)- related protein levels were detected using western blot. The results demonstrated that miR-34c-5p was poorly expressed in lung cancer cells, while TBL1XR1 was highly expressed. The findings also confirmed the direct interaction between miR-34c-5p and TBL1XR1. In H1299 and H460 cells, miR-34c-5p overexpression inhibited cell proliferation, migration, and invasion, Wnt/β-catenin signaling activity, and EMT, while TBL1XR1 upregulation reversed these effects of miR-34c-5p overexpression.

CONCLUSION

These findings illustrated that miR-34c-5p might repress the malignant behaviors of lung cancer cells via TBL1XR1, providing evidence for miR-34c-5p-based lung cancer therapy.

Molecular and Cellular Mechanisms Underlying Neurologic Manifestations of Mosquito-Borne Flavivirus Infections

Flaviviruses are a family of enveloped viruses with a positive-sense RNA genome, transmitted by arthropod vectors. These viruses are known for their broad cellular tropism leading to infection of multiple body systems, which can include the central nervous system. Neurologic effects of flavivirus infection can arise during both acute and post-acute infectious periods; however, the molecular and cellular mechanisms underlying post-acute sequelae are not fully understood. Here, we review recent studies that have examined molecular and cellular mechanisms that may contribute to neurologic sequelae following infection with the West Nile virus, Japanese encephalitis virus, Zika virus, dengue virus, and St. Louis encephalitis virus. Neuronal death, either from direct infection or due to the resultant inflammatory response, is a common mechanism by which flavivirus infection can lead to neurologic impairment. Other types of cellular damage, such as oxidative stress and DNA damage, appear to be more specific to certain viruses. This article aims to highlight mechanisms of cellular damage that are common across several flavivirus members and mechanisms that are more unique to specific members. Our goal is to inspire further research to improve understanding of this area in the hope of identifying treatment options for flavivirus-associated neurologic changes.

Noncoding RNA of Zika Virus Affects Interplay between Wnt-Signaling and Pro-Apoptotic Pathways in the Developing Brain Tissue

Zika virus (ZIKV) has a unique ability among flaviviruses to cross the placental barrier and infect the fetal brain causing severe abnormalities of neurodevelopment known collectively as congenital Zika syndrome. In our recent study, we demonstrated that the viral noncoding RNA (subgenomic flaviviral RNA, sfRNA) of the Zika virus induces apoptosis of neural progenitors and is required for ZIKV pathogenesis in the developing brain. Herein, we expanded on our initial findings and identified biological processes and signaling pathways affected by the production of ZIKV sfRNA in the developing brain tissue. We employed 3D brain organoids generated from induced human pluripotent stem cells (ihPSC) as an ex vivo model of viral infection in the developing brain and utilized wild type (WT) ZIKV (producing sfRNA) and mutant ZIKV (deficient in the production of sfRNA). Global transcriptome profiling by RNA-Seq revealed that the production of sfRNA affects the expression of >1000 genes. We uncovered that in addition to the activation of pro-apoptotic pathways, organoids infected with sfRNA-producing WT, but not sfRNA-deficient mutant ZIKV, which exhibited a strong down-regulation of genes involved in signaling pathways that control neuron differentiation and brain development, indicating the requirement of sfRNA for the suppression of neurodevelopment associated with the ZIKV infection. Using gene set enrichment analysis and gene network reconstruction, we demonstrated that the effect of sfRNA on pathways that control brain development occurs via crosstalk between Wnt-signaling and proapoptotic pathways.

Involvement of host microRNAs in flavivirus-induced neuropathology: An update

Flaviviruses are a spectrum of vector-borne RNA viruses that cause potentially severe diseases in humans including encephalitis, acute-flaccid paralysis, cognitive disorders and foetal abnormalities. Japanese encephalitis virus (JEV), Zika virus (ZIKV), West Nile virus (WNV) and Dengue virus (DENV) are globally emerging pathogens that lead to epidemics and outbreaks with continued transmission to newer geographical areas over time. In the past decade, studies have focussed on understanding the pathogenic mechanisms of these viruses in a bid to alleviate their disease burden. MicroRNAs (miRNAs) are short single-stranded RNAs that have emerged as master-regulators of cellular gene expression. The dynamics of miRNAs within a cell have the capacity to modulate hundreds of genes and, consequently, their physiological manifestation. Increasing evidence suggests their role in host response to disease and infection including cell survival, intracellular viral replication and immune activation. In this review, we aim to comprehensively update published evidence on the role of miRNAs in host cells infected with the common neurotropic flaviviruses, with an increased focus on neuropathogenic mechanisms. In addition, we briefly cover therapeutic advancements made in the context of miRNA-based antiviral strategies.

Zika Virus Neuropathogenesis: The Different Brain Cells, Host Factors and Mechanisms Involved

Zika virus (ZIKV), despite being discovered six decades earlier, became a major health concern only after an epidemic in French Polynesia and an increase in the number of microcephaly cases in Brazil. Substantial evidence has been found to support the link between ZIKV and neurological complications in infants. The virus targets various cells in the brain, including radial glial cells, neural progenitor cells (NPCs), astrocytes, microglial and glioblastoma stem cells. It affects the brain cells by exploiting different mechanisms, mainly through apoptosis and cell cycle dysregulation. The modulation of host immune response and the inflammatory process has also been demonstrated to play a critical role in ZIKV induced neurological complications. In addition to that, different ZIKV strains have exhibited specific neurotropism and unique molecular mechanisms. This review provides a comprehensive and up-to-date overview of ZIKV-induced neuroimmunopathogenesis by dissecting its main target cells in the brain, and the underlying cellular and molecular mechanisms. We highlighted the roles of the different ZIKV host factors and how they exploit specific host factors through various mechanisms. Overall, it covers key components for understanding the crosstalk between ZIKV and the brain.

Evasion strategies of Zika virus antagonizing host innate immunity

Zika virus is a small enveloped positive-strand RNA virus, which belongs to the Flaviviridae family. The RNA genome of all flaviviruses encodes three structural and seven nonstructural genes, together with 5′- and 3′-untranslated region genes flanking. Accompanying the explosive nature of the Zika outbreak in 2014, there was a devastating congenital neurodevelopmental disease in fetuses. Apart from viral RNA replication, polyprotein cleavage, Zika virus nonstructural proteins also play vital roles in the host's innate immune evasion. In this brief report, we summarize the evasion mechanisms of the viral nonstructural proteins antagonizing host antiviral innate immunity.