Viral Ubiquitin Ligase Stimulates Selective Host MicroRNA Expression by Targeting ZEB Transcriptional Repressors

Abstract

Infection with herpes simplex virus-1 (HSV-1) brings numerous changes in cellular gene expression. Levels of most host mRNAs are reduced, limiting synthesis of host proteins, especially those involved in antiviral defenses. The impact of HSV-1 on host microRNAs (miRNAs), an extensive network of short non-coding RNAs that regulate mRNA stability/translation, remains largely unexplored. Here we show that transcription of the miR-183 cluster (miR-183, miR-96, and miR-182) is selectively induced by HSV-1 during productive infection of primary fibroblasts and neurons. ICP0, a viral E3 ubiquitin ligase expressed as an immediate-early protein, is both necessary and sufficient for this induction. Nuclear exclusion of ICP0 or removal of the RING (really interesting new gene) finger domain that is required for E3 ligase activity prevents induction. ICP0 promotes the degradation of numerous host proteins and for the most part, the downstream consequences are unknown. Induction of the miR-183 cluster can be mimicked by depletion of host transcriptional repressors zinc finger E-box binding homeobox 1 (ZEB1)/δ-crystallin enhancer binding factor 1 (δEF1) and zinc finger E-box binding homeobox 2 (ZEB2)/Smad-interacting protein 1 (SIP1), which we establish as new substrates for ICP0-mediated degradation. Thus, HSV-1 selectively stimulates expression of the miR-183 cluster by ICP0-mediated degradation of ZEB transcriptional repressors.

Herpes Simplex Virus 1 Deregulation of Host MicroRNAs

“…As described above, many studies have shown that HSV-1 triggers massive changes in host miRNAs, but most of these studies were limited to only one cell type or specific experimental conditions. Recently, Lutz et al, while analyzing the miRNA expression pattern in two different HSV-1 in vitro latency models, have observed that the relative abundance of overall miRNAs does not dramatically change, suggesting that HSV-1 does not cause global changes in host miRNA abundance [86,108]. In addition, they have observed that miR-183, miR-96, and miR-182, which are miRNAs expressed from a single cluster, were significantly upregulated during early times of latency establishment in vitro and during the productive infection in primary cells (human foreskin fibroblasts or rat neurons) but not in transformed cell lines (HeLa, U2OS) [86].…”

“…Recently, Lutz et al, while analyzing the miRNA expression pattern in two different HSV-1 in vitro latency models, have observed that the relative abundance of overall miRNAs does not dramatically change, suggesting that HSV-1 does not cause global changes in host miRNA abundance [86,108]. In addition, they have observed that miR-183, miR-96, and miR-182, which are miRNAs expressed from a single cluster, were significantly upregulated during early times of latency establishment in vitro and during the productive infection in primary cells (human foreskin fibroblasts or rat neurons) but not in transformed cell lines (HeLa, U2OS) [86]. More recently, Majer et al have found that this cluster is upregulated in brain tissue of mice with acute HSVE, indicating roles for these miRNAs in host defense mechanisms [85].…”

“…miRNAs of the miR-183/96/182 cluster are co-expressed and have important roles in stemness, embryogenesis, and development [109,110,111], and are frequently found to be deregulated in cancer and other diseases (reviewed in [112]). Using a battery of virus mutants deficient for the expression of different IE proteins, Lutz et al have demonstrated that the expression of ICP0 and ICP4 is required for the maximal induction of the miR-183/96/182 cluster during HSV-1 infection [86]. Furthermore, they have shown that the expression of ICP0 in the absence of any other HSV-1 gene product is sufficient to induce the cluster and that is mediated by the E3 ligase function of ICP0.…”

“…HSV-1 expresses its genes in a controlled cascade of gene expression, first immediate early (IE), early (E), and then late (L) genes. IE protein ICP0 directs host protein Zinc Finger E-Box Binding Homeobox (ZEB) for ubiquitin-dependent proteasomal degradation and de-represses the miR-183/96/182 cluster [86]. The targets of the co-expressed miR-183, miR-96, and miR-182 are unknown.…”

The impact of miR‐183/182/96 gene regulation on the maturation, survival, and function of photoreceptor cells in the retina

“…The miR‐183 cluster is an intergenic miRNA cluster located between Nrf1 (the gene encoding nuclear respiratory factor‐1) and Ube2h (ubiquitin‐conjugating enzyme E2H) at a distance of approximately 60 kb. Obviously, each has its own unique precursor for miRNA processing (Lutz et al, ; Z. Zhang et al, ). Although the exact start site of transcription is unknown, the promoter prediction analysis using PROSCAN has determined that there exists a hypothetical conserved promoter located at the 5′ end of miR‐183 with a size of 7 and 6 kb in the genome of human and mouse (129X1/SvJ, RRID:MGI:5658926), respectively (Figure ).…”