Expression from the human parvovirus B 19p6 promoter fused to the firefly luciferase (' Luc') reporter gene was evaluated in a non-erythroid human nasopharyngeal carcinoma cell line, KB, and a human megakaryocytic leukaemia cell line, MB-02, known to become permissive for B19 replication following erythroid-differentiation. The B19p6-Luc construct was introduced into KB and MB-02 cells, both in undifferentiated and differentiated states, either via DNA-mediated transfection, or via infection with recombinant adeno-associated virus 2 (AAV), a non-pathogenic human parvovirus known to possess a broad host-range. Although Luc activity was readily detected in KB cells following transfection of the B 19p6-Luc plasmid DNA, no expression from the B 19p6 promoter was observed following infection with recombinant virus. In addition, transfection of the reporter plasmid resulted in high-level expression of Luc in differentiated but not in undifferentiated MB-02 cells. However, no Luc activity was detected, even in differentiated MB-02 cells, following infection with recombinant virus. Further studies with an additional recombinant as well as wild-type (wt) AAV revealed that MB-02 cells were non-permissive for AAV infection. A second human megakaryocytic leukaemia cell line, M07e, was likewise resistant to infection by recombinant as well as wt AAV. Taken together, these studies identify the first human cell type that cannot be infected by AAV.They indicate that expression from the B 19p6 promoter, in the context of an AAV genome, is restricted to primary human haematopoietic cells, perhaps because parvoviral DNA replication and transcription are intrinsically coupled.
StlmmlryRecombinant adeno-assodated virus 2 (AAV) virions were constructed containing a gene for resistance to neomycin (neoa), under the control of either the herpesvirus thymidine kinase (TK) gene promoter (vTK-Neo), or the human parvovirus B19 p6 promoter (vB19-Neo), as well as those containing an upstream erythroid cell-specific enhancer (HS-2) from the locus control region of the human fl-globin gene cluster (vHS2-TK-Neo; vHS2-B19-Neo). These recombinant virions were used to infect either low density or highly enriched populations of CD34 + cells isolated from human umbilical cord blood. In donogenic assays initiated with cells infected with the different recombinant AAV-Neo virions, equivalent high frequency transduction of the neo p" gene into slow-cycling multipotential, erythroid, and granulocyte/macrophage (GM) progenitor cells, including those with high proliferative potential, was obtained without prestimulation with growth factors, indicating that these immature and mature hematopoietic progenitor cells were susceptible to infection by the recombinant AAV virions. Successful transduction did not require and was not enhanced by prestimulation of these cell populations with cytokines. The functional activity of the transduced neo gene was evident by the development of resistance to the drug G418, a neomycin analogue. Individual high and low proliferative colony-forming unit (CFU)-GM, burst-forming unit--erythroid, and CFU-granulocyte erythroid macrophage megakaryocyte colonies from mock-infected, or the recombinant virus-infected cultures were subjected to polymerase chain reaction analysis using a neo-specific synthetic oligonucleotide primer pair. A 276-bp DNA fragment that hybridized with a neo-spedfic DNA probe on Southern blots was only detected in those colonies cloned from the recombinant virus-infected calls, indicating stable integration of the transduced neo gene. These studies suggest that parvovirus-based vectors may prove to be a useful alternative to the more commonly used retroviral vectors for high efficiency gene transfer into slow or noncycling primitive hematopoietic progenitor cells, without the need for growth factor stimulation, which could potentially lead to differentiation of these calls before transplantation.
The genetic elements and regulatory mechanisms responsible for human interleukin 9 (IL-9) gene expression in a human T cell leukemia virus type I-transformed human T cell line, C5MJ2, were investigated. We demonstrated that IL-9 gene expression is controlled, at least in part, by transcriptional activation. Transient expression of the luciferase reporter gene linked to serially deleted sequences of the 5'-flanking region of the IL-9 gene has revealed several positive and negative regulatory elements involved in the basal and inducible expression of the IL-9 gene in C5MJ2 cells. An AP-1 site at -146 to -140 was shown to be involved in the expression of the IL-9 gene. A proximal region between -46 and -80 was identified as the minimum sequence for the basal and inducible expression of the IL-9 gene in C5MJ2 cells. Within this region, an NF-kappaB site at -59 to -50 and its adjacent 20-base pair upstream sequence were demonstrated to play a critical role for the IL-9 promoter activity. DNA-protein binding studies indicated that NF-kappaB, c-Jun, and potentially novel proteins (around 35 kDa) can bind to this important sequence. Mutations at different sites within this proximal promoter region abolished the promoter activity as well as the DNA binding. Taken together, these results suggest that the cooperation of different transcription factors is essential for IL-9 gene expression in T cells.
Interleukin 9 (IL-9) stimulates the proliferation of various hematopoietic cell types. To elucidate the molecular mechanisms underlying the cell proliferation action, immediate-early gene expression elicited by IL-9 in a human factor-dependent cell line, MO7e, was studied. IL-9 stimulation resulted in a rapid and transient elevation of primary response genes including junB and c-myc. The differential effects of protein kinase inhibitors, herbimycin A, genistein, and H-7 on the steady-state mRNA level and the transcription rate of junB and c-myc genes triggered by IL-9 were also investigated. Herbimycin A, but not genistein, specifically inhibited the expression of junB steady-state mRNA and the in vitro transcription of the junB gene. IL-9-enhanced c-myc gene expression was completely inhibited by both herbimycin A and genistein at the level of transcriptional initiation. H-7 failed to inhibit c-myc, but partially abolished junB mRNA induction. The role of protein kinase C in IL-9-mediated junB induction was also examined. The different responses of junB and c-myc messages to protein kinase inhibitors suggested that more than one pathway may be involved in IL-9-mediated signal transduction which leads to the expression of junB and c-myc genes.
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