Human cytomegalovirus induces neuronal enolase to support virally mediated metabolic remodeling

Abstract

Viruses depend on cellular metabolic resources to supply the energy and biomolecular building blocks necessary for their replication. Human cytomegalovirus (HCMV), a leading cause of birth defects and morbidity in immunosuppressed individuals, induces numerous metabolic activities that are important for productive infection. However, many of the mechanisms through which these metabolic activities are induced and how they contribute to infection are unclear. We find that HCMV infection of fibroblasts induces a neuronal gene signature as well as the expression of several metabolic enzyme isoforms that are typically expressed in other tissue types. Of these, the most substantially induced glycolytic gene was the neuron-specific isoform of enolase 2 (ENO2). Induction of ENO2 expression is important for HCMV-mediated glycolytic activation as well as for the virally induced remodeling of pyrimidine-sugar metabolism, which provides the glycosyl subunits necessary for protein glycosylation. Inhibition of ENO2 expression or activity reduced uridine diphosphate (UDP)-sugar pools, attenuated the accumulation of viral glycoproteins, and induced the accumulation of noninfectious viral particles. In addition, our data indicate that the induction of ENO2 expression depends on the HCMV U L 38 protein. Collectively, our data indicate that HCMV infection induces a tissue atypical neuronal glycolytic enzyme to activate glycolysis and UDP-sugar metabolism, increase the accumulation of glycosyl building blocks, and enable the expression of an essential viral glycoprotein and the production of infectious virions.

Intercellular communication within the virus microenvironment affects the susceptibility of cells to secondary viral infections

“…This observation is consistent with the reported HCMV-induced strategy to enhance eIF4F activity and translation initiation during productive replication ( 26 ). The nuclear import factor karyopherin subunit alpha-2 (KPNA2) and neuron-specific enolase ENO2 were also elevated, which were reported to be important for efficient viral genome synthesis ( 27 ) and tissue atypical metabolism through glycolysis and pyrimidine sugar production ( 28 ), respectively. Concurrently, we identified expected decreases in proteins including proteasome-degraded factors, such as the protein tyrosine phosphatase PTPN14, antiviral constituents of promyelocytic leukemia (PML) nuclear bodies, SP100, and death domain associated protein (DAXX) ( 25 , 29 ), and the gap junction protein alpha 1 (GJA1) ( 25 , 30 ).…”

A virally encoded GPCR drives glioblastoma through feed-forward activation of the SK1-S1P 1 signaling axis

“…Abrogation of HCMV-induced CIP2A levels upon expression of the US28-targeting intrabody VUN103 indicates US28 to be responsible for the elevation of this oncogene in HCMV-infected glioblastoma cells. The simultaneous increase in SK1 and CIP2A expression upon HCMV infection is not limited to U251 cells, because analysis of RNAseq datasets revealed that HCMV also elevated transcript levels of these proteins in fibroblasts, epithelial cells, and proneural glioblastoma stem-like cells ( 61 , 63 , 64 ).…”

“…For GSE210989 and SRA458685, RNAseq datasets processed and statistically analyzed by the original authors were used to identify differential expression of SK1 (SPHK1 gene) and CIP2A (KIAA1524 gene) for HCMV-infected versus reference mock samples ( 61 , 62 ). For the other datasets, with accession numbers E-MTAB-7613 and GSE210989 ( 63 , 64 ), SRA tool-kits were used to download fastq files.…”

“…This HCMVinduced response was reduced by the expression of VUN103 but not by a nontargeting control intrabody, indicating the involvement of US28. Next, we analyzed publicly available RNAseq datasets of HCMV infection in other cellular models, like fibroblasts, epithelial cells, and proneural glioblastoma stem-like cells (61)(62)(63)(64). In most of these cellular models of HCMV infection, at time points after infection (48 to 120 hours after infection) that should coincide with substantial levels of US28 expression (27), elevation of SK1 and CIP2A transcript levels was observed (table S6).…”

Metabolites that feed upper glycolytic branches support glucose independent human cytomegalovirus replication

“…Glucose carbons are also shuttled to citrate and then to malonyl-CoA for fatty acid synthesis and elongation and lipid synthesis (9, 10, 17, 18, 25, 26). Chemical inhibition of glucose uptake, glycolysis, or the PPP (21, 23, 24, 27) as well as suppression of glycolytic activating proteins (22, 24, 28) result in loss of infectious virus production.…”