tretinoin and Cytomegalovirus-Infections

Triggers and regulatory pathways that effectively link human cytomegalovirus (HCMV) major immediate early (MIE) latent-lytic switch activation with progeny production are incompletely understood. In the quiescently infected human NTera2 cell model of primitive neural stem cells, we found that costimulation with vasoactive intestinal peptide (V) and phorbol ester (P) synergistically activated viral infection, but this effect waned over time. Coupling retinoic acid (R), an inducer of neuronal differentiation, to VP pulse stimulation attenuated the decline in viral activity and promoted the spread of the active infection through concentric layers of neighboring cells as cellular differentiation progressed. R stimulation alone was unable to activate the infection. The MIE enhancer cis-regulatory mechanisms responsible for this result were characterized by a strategy of combinatorial mutagenesis of five cis-acting element types (retinoic acid receptor binding elements [RARE], cyclic AMP [cAMP] response elements [CRE], NF-κB binding sites [kB], serum response element, and ETS/ELK-1 binding site) and multiple methods of assessment. We found that the CRE and kB combination sets the preinduction enhancer tone, is the major initiator and amplifier of RVP-induced MIE gene expression, and cooperates with RARE during cellular differentiation to enhance viral spread. In predifferentiated NTera2, we also found that the CRE-kB combination functions as initiator and amplifier of unstimulated HCMV MIE gene expression and cooperatively interacts with RARE to enhance viral spread. We conclude that RVP-stimulated signaling cascades and cellular differentiation operate through the enhancer CRE-kB-RARE core in strengthening induction of HCMV MIE gene expression in linkage with viral propagation.. Cytomegalovirus-seropositive persons commonly lack detectable levels of cytomegalovirus replication, even when profoundly immunocompromised. In a human NTera2 cell model of primitive neural stem cells carrying resting cytomegalovirus genomes, we show that costimulation of protein kinase A and C-delta signaling cascades in conjunction with retinoic acid-induced neuronal differentiation brings about progeny virus propagation. Iterated DNA binding sites for retinoic acid receptor, CREB, and NF-κB family members in the cytomegalovirus major enhancer are at the crux in the pathway to HCMV activation. The stimulated CREB and NF-κB binding site combination vigorously initiates and amplifies the active cytomegalovirus infection and cooperates with activated retinoic acid receptor binding sites to further promote viral proliferation and spread between differentiated cells. These results support a paradigm in which a specific combination of stimuli coupled with cellular differentiation satisfies a core cis-activating code that unlocks enhancer silence to repower the cycle of cytomegalovirus propagation.

Topics: Cyclic AMP; Cytomegalovirus; Cytomegalovirus Infections; Humans; NF-kappa B; Response Elements; Signal Transduction; Tretinoin; Virus Replication

We investigated the role of homeobox B4 (HOXB4) mRNA/protein expression induced by human cytomegalovirus (HCMV) and/or all-trans retinoic acid (ATRA) in proliferation and committed differentiation of human cord blood hematopoietic stem cells (HSCs) into colony-forming-units of T-lymphocyte (CFU-TL) and erythroid (CFU-E) progenitors in vitro. Twelve cord blood samples were collected from the fetal placenta umbilical vein and cultured in vitro. The proliferation and differentiation of cord blood HSCs into CFU-TL and CFU-E were continuously disrupted with HCMV-AD169 and/or 6 × 10(-8) mol/l of ATRA. HOXB4 mRNA/protein expression in CFU-TL and CFU-E was detected in control, ATRA, HCMV and ATRA + HCMV groups on days 3, 7, and 12 of culture by fluorescent qRT-PCR/western blot. We found that HOXB4 mRNA/protein expression was detectable on day 3, increased on day 7 and was highest on day 12. HOXB4 mRNA/protein expression in HCMV group was downregulated compared with control group (P < 0.05). However, the levels were significantly upregulated in HCMV + ATRA group compared with HCMV group (P < 0.05). We concluded that the abnormal HOXB4 mRNA/protein expression induced by HCMV could play a role in hematopoietic damage. ATRA, at the concentration used, significantly up-regulated HOXB4 mRNA/protein expression in normal lymphocyte and erythrocyte progenitor cells as well as in HCMV-infected cells.

Topics: Cell Differentiation; Cell Proliferation; Cytomegalovirus; Cytomegalovirus Infections; Erythrocytes; Fetal Blood; Gene Expression Regulation; Hematopoietic Stem Cells; Homeodomain Proteins; Humans; Lymphocytes; RNA, Messenger; Transcription Factors; Transcription, Genetic; Tretinoin

The objective of this study was to observe the expression of hoxc4 and hoxc6 genes in the process of differentiation of hematopoietic stem cell (HSC) to colony forming unit-T Lymphocyte (CFU-TL) in vitro. and to explore the possible mechanism of HCMV-induced maldevelopment of human cord blood CFU-TL on genetic level through effecting the differentiation progress by human cytomegalovirus (HCMV) with and/or all-trans retinoic acid (ATRA), Normal CFU-TL culture was used as blank control. After detection with MTT, mRNA expression levels in the human cord blood CFU-TL hoxc4 and hoxc6 genes following HCMV infection and ATRA treatment were detected by fluorogenic quantitative reserve transcription polymerize chain reaction (FQ-RT-PCR) method. HCMV of 10(6) plaque formation unit (PFU)/ml was diluted to 0.1 ml 10(5) PFU/ml and added into the infected group. The results showed that the expression of hoxc4 and hoxc6 genes in the differentiation process increased slightly on day 3, and were up to the most on day 7 (p < 0.05), while became lower on day 12 respectively in normal group, HCMV group and ATRA group. Compared with the expression of hoxc6, the expression of hoxc4 was obviously higher in each group (p < 0.05). Compared with the expression of hoxc4 and hoxc6 genes in normal group, the expressions of hoxc4 and hoxc6 in ATRA group were up-regulated remarkably (p < 0.05), while the expressions of hoxc4 and hoxc6 in group HCMV were down-regulated (p < 0.05). It is concluded that the regular expression of hoxc4 and hoxc6 genes mRNA appeared in each group. A positive co-relationship exits between hoxc4/hoxc6 genes and lymphocytic progenitor hematopoiesis. Compared with the expression of hoxc6 gene, the expression of hoxc4 gene is obviously higher in each group. HCMV can down-regulate the expression of hoxc4 and hoxc6 genes and lead to suppression effect on cell morphology, which confirms that the normal hematopoietic lineage determination and maturation rely on the stable and consistent expression of homeobox gene. At the same condition, ATRA (6 x 10(-8) mol/L at 60 nmol/ml) can up-regulate hoxc4 and hoxc6 genes expression. ATRA can up-regulate the expression of hoxc4 and hoxc6 genes.

Topics: Cell Line; Cell Proliferation; Cytomegalovirus; Cytomegalovirus Infections; Homeodomain Proteins; Humans; Lymphoid Progenitor Cells; Tretinoin

Retinoic acid (RA)-induced differentiation of human teratocarcinoma (T2) cells results in a change from a normally non-permissive phenotype for human cytomegalovirus (HCMV) infection to cells which are fully permissive. We have used this system to analyse factors associated with differentiation which may regulate HCMV gene expression. Differentiation of T2 cells results in an increase of c-ras expression. Consequently, we have introduced ras expression vectors into T2 cells. We find that, as with RA induction, transfection of T2 cells with oncogenic human Ha-ras results in cells which are permissive for HCMV infection and gene expression. However, unlike RA which induces a cessation of cell proliferation and terminal differentiation, ras transfection only appears to result in changes associated with early events in RA-induced differentiation of T2 cells.

Topics: Cell Transformation, Neoplastic; Cytomegalovirus; Cytomegalovirus Infections; Gene Expression Regulation; Genes, ras; Humans; Phenotype; Teratoma; Transfection; Tretinoin; Tumor Cells, Cultured

Retinoic acid increases the incorporation of radioactivity from a mixture of [3H]-galactose and [3H]-glucosamine into glycosphingolipids of serum-starved quiescent human foreskin fibroblasts with a preferential labelling of ceramide mono- and dihexoside as compared to ceramide tri- and tetrahexoside. Under the conditions used, no similar change in the specific labelling of glycoprotein is observed. Alteration in [3H]-precursor uptake into glycolipids comparable to that seen under the influence of retinoic acid does not occur in the presence of phorbolester, colchicine, butyrate or after infection with cytomegalovirus.

Topics: Butyrates; Cell Differentiation; Cells, Cultured; Cholera Toxin; Colchicine; Cytomegalovirus Infections; Glycoproteins; Glycosphingolipids; Humans; Membrane Lipids; Tetradecanoylphorbol Acetate; Tretinoin

Whereas human cytomegalovirus (HCMV) did not replicate in human embryonal carcinoma (EC) cells, it did replicate in some of the differentiated cells arising following the exposure of TERA-2-derived human EC cells to retinoic acid. On the other hand, retinoic acid did not induce a permissive state in several other diverse human cell lines, including an EC line, 2102Ep, which did not differentiate in response to this agent. Also, both TERA-2 and 2102Ep EC cells differentiated to a limited extent when grown at low cell density and a few of these cells became permissive for HCMV. Thus, susceptibility is the result of differentiation and not due to a direct effect of retinoic acid on viral replication. The nature of the block to HCMV replication in human EC cells is unknown, but viral DNA could be detected in the nucleus within an hour of infection and there was an increased anchorage-independent growth of undifferentiated and differentiated cells following HCMV infection. Viral replication is not subject to a general block in these cells, since another herpesvirus, herpes simplex virus type 1, replicated well.

Topics: Cell Adhesion; Cell Differentiation; Cells, Cultured; Cytomegalovirus; Cytomegalovirus Infections; Humans; Teratoma; Tretinoin; Virus Replication