Linc-GALMD1 Regulates Viral Gene Expression in the Chicken.

Yanghua He,Shuang Chang,Yi Ding,Jiuzhou Song,Ning Yang,Huanmin Zhang,Chunfang Zhao,Li Zhang,Bo Han

doi:10.3389/fgene.2019.01122

Abstract

A rapidly increasing number of reports on dysregulated long intergenic non-coding RNA (lincRNA) expression across numerous types of cancers indicates that aberrant lincRNA expression may be a major contributor to tumorigenesis. Marek’s disease (MD) is a T cell lymphoma of chickens induced by Marek’s disease virus (MDV). Although we have investigated the roles of lincRNAs in bursa tissue of MDV-infected chickens in previous studies, the molecular mechanisms of lincRNA functions in T cells remain poorly understood. In the present study, Linc-GALMD1 was identified from CD4+ T cells and MSB1 cells, and its expression was significantly downregulated in MD-resistant line of birds in response to MDV challenge. Furthermore, loss-of-function experiments indicated that linc-GALMD1 significantly affected the expression of 290 genes in trans. Through integrated analysis of differentially expressed genes (DEGs) induced by MDV and linc-GALMD1, we found that IGLL1 gene expression levels had a positive correlation with the degree of MD infection and could potentially serve as an indicator for clinical diagnosis of MD. Moreover, an interaction between MDV and linc-GALMD1 was also observed. Accordingly, chicken embryonic fibroblast cells were inoculated with MDV with and without the linc-GALMD1 knockdown, and the data showed that linc-GALMD1 could repress MDV gene expression during the course of MDV infection. These findings uncovered a role of linc-GALMD1 as a viral gene regulator and suggested a function of linc-GALMD1 contributing to tumor suppression by coordinating expression of MDV genes and tumor-related genes and regulating immune responses to MDV infection.

Highlights

Marek’s disease (MD) is a naturally occurring rapid-onset aggressive T-cell lymphoma of poultry, and it is caused by Marek’s disease virus type 1 (MDV-1)
To explore changes of protein-coding genes and non-coding transcripts, as well as their interactions upon MDV infection in chickens, transcriptomic sequencing was conducted in eight RNA samples extracted from chicken CD4+ T cells isolated from individuals of F0 generation before and after Marek’s disease viral infection
Red dots represent genes with increased expression after the linc-GALMD1 knockdown and blue dots mean genes with decreased expression, gray dots indicate genes with non-significant expression change after the long intergenic non-coding RNA knockdown. **The structure of linc-GALMD1 was detected in CD4+ T cells and MSB1 cells since we identified the lincRNA from CD4+ T cells and used MSB1 cells for loss-of-function assays of the lincRNA, which confirmed that our functional validation system works and linc-GALMD1 does relate to Marek's Disease Virus infection

Summary

Introduction

Marek’s disease (MD) is a naturally occurring rapid-onset aggressive T-cell lymphoma of poultry, and it is caused by Marek’s disease virus type 1 (MDV-1). Virulent MDV undergoes four overlapping infection stages, having critical consequences that contribute to viral persistence and pathogenesis in the host: early cytolytic, latent, late cytolytic, and transformation (Biggs, 1968). In the early cytolytic stage, the virus replicates in macrophages, B and T lymphocytes, and the MDV genome can be detected in B and T lymphocytes as early as 2 days post-infection (dpi). Long Non-Coding RNAs in Chicken the lytic phase of infection, latent (non-replicating) infection occurs primarily in CD4+ T cells (T-helper cells) that are capable of being transformed around 7 dpi. In the late cytolytic stage from 14 to 21 dpi, latently infected cells carry the virus to the thymus, bursa, and some epithelial tissues. Necrosis of lymphocytes and epithelial cells is accompanied by pronounced inflammation, infiltration of mononuclear cells and heterophils, and (for the bursa and thymus) severe atrophy (Baigent and Davison, 2004)

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Conclusion