title: Viral mitochondria-localized inhibitor of apoptosis (UL37 exon 1 protein) does not protect human neural precursor cells from human cytomegalovirus-induced cell death.
abstract: Congenital human cytomegalovirus (HCMV) infection can cause severe brain abnormalities. Apoptotic HCMV-infected brain cells have been detected in a congenitally infected infant. In biologically relevant human neural precursor cells (hNPCs), cultured in physiological oxygen tensions, HCMV infection (m.o.i. of 1 or 3) induced cell death within 3 days post-infection (p.i.) and increased thereafter. Surprisingly, its known anti-apoptotic genes, including the potent UL37 exon 1 protein (pUL37x1) or viral mitochondria-localized inhibitor of apoptosis (vMIA), which protects infected human fibroblasts (HFFs) from apoptosis and from caspase-independent, mitochondrial serine protease-mediated cell death, were expressed by 2 days p.i. Consistent with this finding, an HCMV UL37x1 mutant, BADsubstitutionUL37x1 (BADsubUL37x1) induced cell death in hNPCs (m.o.i. = 1) to level which were indistinguishable from parental virus (BADwild-type)-infected hNPCs. Surprisingly, although BADsubUL37x1 is growth defective in permissive HFFs, it produced infectious progeny in hNPCs with similar kinetics and to levels comparable to BADwild-type-infected hNPCs (m.o.i. = 1). While delayed at a lower multiplicity (m.o.i. = 0.3), the BADsubUL37x1 mutant reached similar levels to revertant within 12 days, in contrast to its phenotype in HFFs. The inability of pUL37x1/vMIA to protect hNPCs from HCMV-induced cell death did not result from impaired trafficking as pUL37x1/vMIA trafficked efficiently to mitochondria in transfected hNPCs and in HCMV-infected hNPCs. These results establish that pUL37x1/vMIA, although protective in permissive HFFs, does not protect HCMV-infected hNPCs from cell death under physiologically relevant oxygen tensions. They further suggest that pUL37x1/vMIA is not essential for HCMV growth in hNPCs and has different cell type-specific roles.
authors.affiliation: Molecular Medicine Program, George Washington University, Washington, DC 20052, USA.|Research Center for Genetic Medicine, Children's Research Institute, Washington, DC 20010, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hildreth
authors.affiliation: Research Center for Genetic Medicine, Children's Research Institute, Washington, DC 20010, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Bullough
authors.affiliation: Research Center for Genetic Medicine, Children's Research Institute, Washington, DC 20010, USA.
authors.forename: Aiping
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Center for Neuroscience Research, Children's Research Institute; Research Center for Genetic Medicine, Room M5110, Children's National Medical Center, 111 Michigan Ave, NW, Washington, DC 20010, USA.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Chen
authors.affiliation: National Human Neural Stem Cell Resource, Children's Hospital of Orange County Research Institute, Orange, CA, USA.
authors.forename: Philip H
authors.initials: PH
authors.lastname: Schwartz
authors.affiliation: Division of Neuroscience and Basic Behavioral Science, National Institutes of Mental Health, National Institutes of Health, Bethesda, MD, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Panchision
authors.affiliation: Molecular Medicine Program, George Washington University, Washington, DC 20052, USA.|Department of Biochemistry and Molecular Biology, George Washington University, USA.|Department of Integrative Systems Biology, George Washington University, USA.|Research Center for Genetic Medicine, Children's Research Institute, Washington, DC 20010, USA.
authors.forename: Anamaris M
authors.initials: AM
authors.lastname: Colberg-Poley
mesh_terms: D016923:Cell Death; D002460:Cell Line; D003587:Cytomegalovirus / Q000502:physiology*; D003588:Cytopathogenic Effect, Viral; D005091:Exons; D005434:Flow Cytometry; D015967:Gene Expression Regulation, Viral; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D009154:Mutation; D058953:Neural Stem Cells / Q000378:metabolism* / Q000821:virology*; D010100:Oxygen; D021381:Protein Transport; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism
chemical_list: D017874:Immediate-Early Proteins; D012367:RNA, Viral; C420323:UL37 protein, Human herpesvirus 5; D010100:Oxygen