Human cytomegalovirus infection perturbs neural progenitor cell fate via the expression of viral microRNAs

Human cytomegalovirus infection impairs neural differentiation via repressing sterol regulatory element binding protein 2-mediated cholesterol biosynthesis

Congenital human cytomegalovirus (HCMV) infection is a major cause of abnormalities and disorders in the central nervous system (CNS) and/or the peripheral nervous system (PNS). However, the complete pathogenesis of neural differentiation disorders caused by HCMV infection remains to be fully elucidated. Stem cells from human exfoliated deciduous teeth (SHEDs) are mesenchymal stem cells (MSCs) with a high proliferation and neurogenic differentiation capacity. Since SHEDs originate from the neural crest of the early embryonic ectoderm, SHEDs were hypothesized to serve as a promising cell line for investigating the pathogenesis of neural differentiation disorders in the PNS caused by congenital HCMV infection. In this work, SHEDs were demonstrated to be fully permissive to HCMV infection and the virus was able to complete its life cycle in SHEDs. Under neurogenic inductive conditions, HCMV infection of SHEDs caused an abnormal neural morphology. The expression of stem/neural cell markers was also disturbed by HCMV infection. The impairment of neural differentiation was mainly due to a reduction of intracellular cholesterol levels caused by HCMV infection. Sterol regulatory element binding protein-2 (SREBP2) is a critical transcription regulator that guides cholesterol synthesis. HCMV infection was shown to hinder the migration of SREBP2 into nucleus and resulted in perinuclear aggregations of SREBP2 during neural differentiation. Our findings provide new insights into the prevention and treatment of nervous system diseases caused by congenital HCMV infection.

MicroRNA expression profiling of urine exosomes in children with congenital cytomegalovirus infection

Congenital cytomegalovirus (cCMV) infection can damage the central nervous system in infants; however, its prognosis cannot be predicted from clinical evaluations at the time of birth. Urinary exosomes can be used to analyze neuronal damage in neuronal diseases. To investigate the extent of neuronal damage in patients with cCMV, exosomal miRNA expression in the urine was investigated in cCMV-infected infants and controls. Microarray analysis of miRNA was performed in a cohort of 30 infants, including 11 symptomatic cCMV (ScCMV), 7 asymptomatic cCMV (AScCMV), and one late-onset ScCMV cases, and 11 healthy controls (HC). Hierarchical clustering analysis revealed the distinct expression profile of ScCMV. The patient with late-onset ScCMV was grouped into the ScCMV cluster. Pathway enrichment analysis of the target mRNAs differed significantly between the ScCMV and HC groups; this analysis also revealed that pathways related to brain development were linked to upregulated pathways. Six miRNAs that significantly different between groups (ScCMV vs. HC and ScCMV vs. AScCMV) were selected for digital PCR in another cohort for further validation. Although these six miRNAs seemed insufficient for predicting ScCMV, expression profiles of urine exosomal miRNAs can reveal neurological damage in patients with ScCMV compared to those with AcCMV or healthy infants.

Regulation of Onecut2 by miR-9-5p in Japanese encephalitis virus infected neural stem/progenitor cells

Japanese encephalitis virus (JEV) is one of the major neurotropic viral infections that is known to dysregulate the homeostasis of neural stem/progenitor cells (NSPCs) and depletes the stem cell pool. NSPCs are multipotent stem cell population of the central nervous system (CNS) which are known to play an important role in the repair of the CNS during insults/injury caused by several factors such as ischemia, neurological disorders, CNS infections, and so on. Viruses have evolved to utilize host factors for their own benefit and during JEV infection, host factors, including the non-coding RNAs such as miRNAs, are reported to be affected, thereby cellular processes regulated by the miRNAs exhibit perturbed functionality. Previous studies from our laboratory have demonstrated the role of JEV infection in dysregulating the function of neural stem cells (NSCs) by altering the cell fate and depleting the stem cell pool leading to a decline in stem cell function in CNS repair mechanism post-infection. JEV-induced alteration in miRNA expression in the NSCs is one of the major interest to us. In prior studies, we have observed an altered expression pattern of certain miRNAs following JEV infection. In this study, we have validated the role of JEV infection in NSCs in altering the expression of miR-9-5p, which is a known regulator of neurogenesis in NSCs. Furthermore, we have validated the interaction of this miRNA with its target, Onecut2 (OC2), in primary NSCs utilizing miRNA mimic and inhibitor transfection experiments. Our findings indicate a possible role of JEV mediated dysregulated interaction between miR-9-5p and its putative target OC2 in NSPCs.

IMPORTANCE

MicroRNAs have emerged as key disease pathogenic markers and potential therapeutic targets. In this study, we solidify this concept by studying a key miRNA, miR-9-5p, in Japanese encephalitis virus infection of neural stem/progenitor cells. miRNA target Onecut2 has a possible role in stem cell pool biology. Here, we show a possible mechanistic axis worth investing in neurotropic viral biology.

MiR-199a-5P promotes osteogenic differentiation of human stem cells from apical papilla via targeting IFIT2 in apical periodontitis

Introduction

Periapical alveolar bone loss is the common consequence of apical periodontitis (AP) caused by persistent local inflammation around the apical area. Human stem cells from apical papilla (hSCAPs) play a crucial role in the restoration of bone lesions during AP. Studies have recently identified the critical role of microRNAs (miRNAs) involved in AP pathogenesis, but little is known about their function and potential molecular mechanism, especially in the osteogenesis of hSCAPs during AP. Here, we investigated the role of clinical sample-based specific miRNAs in the osteogenesis of hSCAPs.

Methods

Differential expression of miRNAs were detected in the periapical tissues of normal and patients with AP via transcriptomic analysis, and the expression of miR-199a-5p was confirmed by qRT-PCR. Treatment of hSCAPs with miR-199a-5p mimics while loaded onto beta-tricalcium phosphate (β-TCP) ceramic particle scaffold to explore its effect on osteogenesis in vivo. RNA binding protein immunoprecipitation (RIP) and Luciferase reporter assay were conducted to identify the target gene of miR-199a-5p.

Results

The expression of miR-199a-5p was decreased in the periapical tissues of AP patients, and miR-199a-5p mimics markedly enhanced cell proliferation and osteogenic differentiation of hSCAPs, while miR-199a-5p antagomir dramatically attenuated hSCAPs osteogenesis. Moreover, we identified and confirmed Interferon Induced Protein with Tetratricopeptide Repeats 2 (IFIT2) as a specific target of miR-199a-5p, and silencing endogenous IFIT2 expression alleviated the inhibitory effect of miR-199a-5p antagomir on the osteogenic differentiation of hSCAPs. Furthermore, miR-199a-5p mimics transfected hSCAPs loaded onto beta-tricalcium phosphate (β-TCP) scaffolds induced robust subcutaneous ectopic bone formation in vivo.

Discussion

These results strengthen our understanding of predictors and facilitators of the key AP miRNAs (miR-199a-5p) in bone lesion repair under periapical inflammatory conditions. And the regulatory networks will be instrumental in exploring the underlying mechanisms of AP and lay the foundation for future regenerative medicine based on dental mesenchymal stem cells.