Transplant-induced reactivation of murine cytomegalovirus immediate early gene expression is associated with recruitment of NF-κB and AP-1 to the major immediate early promoter

Abstract

Reactivation of latent human cytomegalovirus is a significant infectious complication of organ transplantation and current therapies target viral replication once reactivation of latent virus has already occurred. The specific molecular pathways that activate viral gene expression in response to transplantation are not well understood. Our studies aim to identify these factors, with the goal of developing novel therapies that prevent transcriptional reactivation in transplant recipients. Murine cytomegalovirus (MCMV) is a valuable model for studying latency and reactivation of CMV in vivo. We previously demonstrated that transplantation of MCMV-latently infected kidneys into allogeneic recipients induces reactivation of immediate early (IE) gene expression and epigenetic reprogramming of the major immediate early promoter (MIEP) within 48 h. We hypothesize that these events are mediated by activation of signalling pathways that lead to binding of transcription factors to the MIEP, including AP-1 and NF-k B. Here we show that transplantation induces rapid activation of several members of the AP-1 and NF-k B transcription factor family and we demonstrate that canonical NF-k B (p65/p50), the junD component of AP-1, and nucleosome remodelling complexes are recruited to the MIEP following transplantation. Proteomic analysis of recipient plasma and transcriptome analysis of kidney RNA identified five extracellular ligands, including TNF, IL-1b, IL-18, CD40L and IL-6, and three intracellular signalling pathways associated with reactivation of IE gene expression. Identification of the factors that mediate activation of these signalling pathways may eventually lead to new therapies to prevent reactivation of CMV and its sequelae.

Activator protein-1 transactivation of the major immediate early locus is a determinant of cytomegalovirus reactivation from latency

“…Consistent with this, several groups have shown AP-1 binds to and activates the MIE enhancer/promoter in in vitro expression assays (26, 34, 35). In agreement with our results herein, AP-1 is recruited to the MIE enhancer in a murine model of allograft-induced murine CMV (MCMV) reactivation (36). Furthermore, work from Isern, et al, revealed disruption of both AP-1 binding sites within the MIE enhancer region had no effect on HCMV lytic replication in fibroblast and epithelial cells (26), consistent with our current findings.…”

A clinically relevant murine model unmasks a “two-hit” mechanism for reactivation and dissemination of cytomegalovirus after kidney transplant

“…Plasma (70 μL) from treated and untreated or untreated transplant recipients was frozen in liquid nitrogen and analyzed for inflammatory proteins at Ampersand Biosciences (Saranac Like, NY) by using Luminex system and the Rodent MAP 4.0 Multiplex assay as previously described. 27…”

Native kidney cytomegalovirus nephritis and cytomegalovirus prostatitis in a kidney transplant recipient

“…TNF‐α binds to TNF receptors on latently infected cells and leads to downstream nuclear factor‐kB (NF‐kB) activation, which translocates into the nucleus, binds to the immediate‐early enhancer region of CMV, and initiates viral replication. Reactivation of CMV is associated with elevated serum TNF‐α levels in patients with sepsis, atopic dermatitis, transplant organ rejection in solid organ transplant recipients, and graft‐versus‐host‐disease in hematopoietic cell transplant recipients . Other proinflammatory mediators such as prostaglandins and stress catecholamines that act via TNF‐α independent pathways have also been found to trigger viral reactivation .…”