Apolipoprotein E4 Suppresses Neuronal-Specific Gene Expression in Maturing Neuronal Progenitor Cells Exposed to HIV.
The apolipoprotein ε4 gene allele and the apolipoprotein E4 protein (ApoE4) are important host susceptibility factors linked to neurocognitive disorders associated with HIV infection or Alzheimer's disease. Our previous studies showed differential effects of the two most common human ApoE genotypes, APOE3/3 and APOE3/4, on gene expression by differentiating human neuroepithelial progenitor cells continuously exposed to HIV. To investigate the effects of ApoE3 versus ApoE4 isoforms specifically on maturing neurons, we adapted a human neuronal progenitor cell line, hNP1, with ApoE genotype APOE3/3. Differentiating hNP1 cells were exposed for 16 days to HIV- or mock-infected supernatants and to added recombinant ApoE isoforms rApoE3 or rApoE4 to modulate the ApoE phenotype of the cells. Gene expression was investigated using microarray and functional genomics analyses. Added rApoE3 differentially affected 36 genes. Added rApoE4 differentially affected 85 genes; 41 of which were differentially expressed only in HIV or mock-supernatant treated cells, and 80% of which were downregulated. Genes differentially downregulated only by rApoE4 represented multiple neuronal functions related to neurogenesis. Approximately five times more genes were differentially enriched by rApoE4 versus rApoE3 in the Gene Ontology (GO) cellular process analysis, with 4 orders of magnitude greater significance. Half of the top 10 GO processes affected by rApoE4 treatment were neurogenesis-related. The largest differences in gene expression between the two isoforms were observed within the HIV-exposed cultures, suggesting that HIV exposure magnifies ApoE4's suppressive effect on neuronal gene expression. This study provides evidence for neuronal-specific responses to ApoE4 that could affect neurogenesis and neuronal survival.
Bruce W. Carter Veterans Affairs Medical Center, 1201 NW 16th Street, Miami, FL, 33125, USA.|Department of Neurology, Miller School of Medicine, University of Miami, 1120 NW 14th St, Miami, FL, 33136, USA.
Rebeca
R
Geffin
Bruce W. Carter Veterans Affairs Medical Center, 1201 NW 16th Street, Miami, FL, 33125, USA.
Ricardo
R
Martinez
Bruce W. Carter Veterans Affairs Medical Center, 1201 NW 16th Street, Miami, FL, 33125, USA.
Alicia
A
de Las Pozas
Biostatistics and Bioinformatics Core/Division of Bioinformatics, Clinical Research Building, University of Miami/Sylvester Comprehensive Cancer Center, 1120 NW 14th Street, 6th Floor, Room 610L, Miami, FL, 33136, USA.
Biju
B
Issac
Bruce W. Carter Veterans Affairs Medical Center, 1201 NW 16th Street, Miami, FL, 33125, USA. mmccarth@med.miami.edu.|Department of Neurology, Miller School of Medicine, University of Miami, 1120 NW 14th St, Miami, FL, 33136, USA. mmccarth@med.miami.edu.
Micheline
M
McCarthy
D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D015658:HIV Infections; D006801:Humans; D058953:Neural Stem Cells / Q000378:metabolism / Q000821:virology*; D055495:Neurogenesis / Q000235:genetics*; D059467:Transcriptome
D053318:Apolipoprotein E3; D053327:Apolipoprotein E4
Apolipoprotein E; Gene expression microarray; Human Immunodeficiency Virus; Neurogenesis; Neuron