Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Virus Integration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed1996

Proviral burden and infection kinetics of feline immunodeficiency virus in lymphocyte subsets of blood and lymph node.

Feline immunodeficiency virus (FIV) is similar to human immunodeficiency virus type 1 virologically and induces a clinical syndrome in cats comparable to human immunodeficiency virus type 1 syndrome in humans. To determine the lymphoid target cells of FIV, populations of CD4+ lymphocytes, CD8+ lymphocytes, and CD21+ lymphocytes (B cells) were enriched to more than 96.5% purity and then analyzed for FIV provirus by semiquantitative DNA amplification. We found FIV provirus in CD4+, CD8+, and B lymphocytes. In cats infected for <4 months, proviral burden was greatest in CD4+ cells, followed by B cells and then by CD8+ cells. In cats infected for more than 5 years, proviral burden was greatest in B cells, followed by CD4+ cells and then by CD8+ cells. The total proviral burden was > 1 log10 higher in acutely infected cats than in chronically infected cats, primarily because of a higher level of CD4+ infection in the acutely infected cats. A comparison of proviral loads in mesenteric lymph node and peripheral blood mononuclear cells in acutely or chronically infected cats revealed no significant difference. A kinetics study of FIV infection demonstrated that all lymphocyte subpopulations were infected by 4 weeks postinoculation. Virus was isolated from CD4+, CD8+, and B cells in vitro, and reverse transcriptase PCR demonstrated that all subsets contained viral RNA in vivo and therefore are productive reservoirs for FIV.

Animals↗
PubMed1999

Persistent Hz-1 virus infection in insect cells: evidence for insertion of viral DNA into host chromosomes and viral infection in a latent status.

Persistent/latent viral infections of insect cells are a prominent though poorly understood phenomenon. In this study, the long-term association between the Hz-1 virus and insect host cells, conventionally referred to as persistent viral infection, is described. With the aid of a newly developed fluorescent cell-labeling system, we found that productive viral replication occurs by spontaneous viral reactivation in fewer than 0.2% of persistently infected cell lines over a 5-day period. Once viral reactivation takes place, the host cell dies. The persistently infected cells contain various amounts of viral DNA, and, in an extreme case, up to 16% of the total DNA isolated from infected cells could be of viral origin. Both pulsed-field gel electrophoresis and in situ hybridization experiments showed that some of these viral DNA molecules are inserted into the host chromosomes but that the rest of viral DNA copies are free from host chromosomes. Thus, Hz-1 virus is the first nonretroviral insect virus known to insert its genome into the host chromosome during the infection process. These data also suggest that the previously described persistent infection of Hz-1 virus in insect cells should be more accurately referred to as latent viral infection.

Animals↗
PubMed1999

Visualization of alternative Epstein-Barr virus expression programs by fluorescent in situ hybridization at the cell level.

Epstein-Barr virus (EBV) transforms human B lymphocytes into immortalized lymphoblastoid cell lines (LCLs). They regularly express six virally encoded nuclear proteins (EBNA1 to EBNA6) and three membrane proteins (LMP1, LMP2A, and LMP2B). In contrast, EBV-carrying Burkitt lymphoma (BL) cells in vivo and derived type I cell lines that maintain the BL phenotype express only EBNA1. During prolonged in vitro culturing, most EBV-carrying BL lines drift toward a more immunoblastic (type II or III) phenotype. Their viral antigen expression is upregulated in parallel. We have used fluorescent in situ hybridization to visualize viral transcripts in type I and III BL lines and LCLs. In type I cells, EBNA1 is encoded by a monocistronic message that originates from the Qp promoter. In type III cells, the EBNA1 transcript is spliced from a giant polycistronic message that originates from one of several alternative Wp or Cp promoters and encodes all six EBNAs. We have obtained a "track" signal with a BamHI W DNA probe that could hybridize with the polycistronic but not with the monocistronic message in two type III BL lines (Namalwa-Cl8 and MUTU III) and three LCLs (LCL IB4-D, LCL-970402, and IARC-171). A BamHI K probe that can hybridize to both the monocistronic and the polycistronic message visualized the same pattern in the type III BLs and the LCLs as the BamHI W probe. A positive signal was obtained with the BamHI K but not the BamHI W probe in the type I BL lines MUTU I and Rael. The RNA track method can thus distinguish between cells that use a type III and those that use a type I program. The former cells hybridize with both the W and the K probes, but the latter cells hybridize with only the K probe. Our findings may open the way for studies of the important but still unanswered question of whether cells with type I latency arise from immunoblasts with a full type III program or are generated by a separate pathway during primary infection.

Amino Acid Sequence↗
PubMed2000

The synthetic immunomodulator murabutide controls human immunodeficiency virus type 1 replication at multiple levels in macrophages and dendritic cells.

Macrophages and dendritic cells are known to play an important role in the establishment and persistence of human immunodeficiency virus (HIV) infection. Besides antiretroviral therapy, several immune-based interventions are being evaluated with the aim of achieving better control of virus replication in reservoir cells. Murabutide is a safe synthetic immunomodulator presenting a capacity to enhance nonspecific resistance against viral infections and to target cells of the reticuloendothelial system. In this study, we have examined the ability of Murabutide to control HIV type 1 (HIV-1) replication in acutely infected monocyte-derived macrophages (MDMs) and dendritic cells (MDDCs). Highly significant suppression of viral replication was consistently observed in Murabutide-treated cultures of both cell types. Murabutide did not affect virus entry, reverse transcriptase activity, or early proviral DNA formation in the cytoplasm of infected cells. However, treated MDMs and MDDCs showed a dramatic reduction in nuclear viral two-long terminal repeat circular form and viral mRNA transcripts. This HIV-1-suppressive activity was not mediated by inhibiting cellular DNA synthesis or by activating p38 mitogen-activated protein kinase. Furthermore, Murabutide-stimulated cells expressed reduced CD4 and CCR5 receptors and secreted high levels of beta-chemokines, although neutralization of the released chemokines did not alter the HIV-1-suppressive activity of Murabutide. These results provide evidence that a clinically acceptable immunomodulator can activate multiple effector pathways in macrophages and in dendritic cells, rendering them nonpermissive for HIV-1 replication.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2000

Inhibition of CD3/CD28-mediated activation of the MEK/ERK signaling pathway represses replication of X4 but not R5 human immunodeficiency virus type 1 in peripheral blood CD4(+) T lymphocytes.

Binding of human immunodeficiency virus type 1 (HIV-1) to CD4 receptors induces multiple cellular signaling pathways, including the MEK/ERK cascade. While the interaction of X4 HIV-1 with CXCR4 does not seem to activate this pathway, viruses using CCR5 for entry efficiently activate MEK/ERK kinases (W. Popik, J. E. Hesselgesser, and P. M. Pitha, J. Virol. 72:6406-6413, 1998; W. Popik and P. M. Pitha, Virology 252:210-217, 1998). Since the importance of MEK/ERK in the initial steps of viral replication is poorly understood, we have examined the role of MEK/ERK signaling in the CD3- and CD28 (CD3/CD28)-mediated activation of HIV-1 replication in resting peripheral blood CD4(+) T lymphocytes infected with X4 or R5 HIV-1. We have found that the MEK/ERK inhibitor U0126 selectively inhibited CD3/CD28-stimulated replication of X4 HIV-1, while it did not affect the replication of R5 HIV-1. Inhibition of the CD3/CD28-stimulated MEK/ERK pathway did not affect the formation of the early proviral transcripts in cells infected with either X4 or R5 HIV-1, indicating that virus reverse transcription is not affected in the absence of MEK/ERK signaling. In contrast, the levels of nuclear provirus in cells infected with X4 HIV-1, detected by the formation of circular proviral DNA, was significantly lower in cells stimulated in the presence of MEK/ERK inhibitor than in the absence of the inhibitor. However, in cells infected with R5 HIV-1, the inhibition of the MEK/ERK pathway did not affect nuclear localization of the proviral DNA. These data suggest that the nuclear import of X4, but not R5, HIV-1 is dependent on a CD3/CD28-stimulated MEK/ERK pathway.

Biological Transport↗
PubMed2002

Characterization of producer cell-dependent restriction of murine leukemia virus replication.

We previously reported that the human bronchocarcinoma cell line A549 produces poorly infectious gibbon ape leukemia virus-pseudotyped Moloney murine leukemia virus (MLV). In contrast, similar amounts of virions recovered from human fibrosarcoma HT1080 cells result in 10-fold-higher transduction rates (G. Duisit, A. Salvetti, P. Moullier, and F. Cosset, Hum. Gene Ther. 10:189-200, 1999). We have now extended this initial observation to other type-C envelope (Env) pseudotypes and analyzed the mechanism involved. Structural and morphological analysis showed that viral particles recovered from A549 (A549-MLV) and HT1080 (HT1080-MLV) cells were normal and indistinguishable from each other. They expressed equivalent levels of mature Env proteins and bound similarly to the target cells. Furthermore, incoming particles reached the cytosol and directed the synthesis of linear viral DNA equally efficiently. However, almost no detectable circular DNAs could be detected in A549-MLV-infected cells, indicating that the block of infection resulted from defective nuclear translocation of the preintegration complex. Interestingly, pseudotyping of A549-MLV with vesicular stomatitis virus glycoprotein G restored the amount of circular DNA forms as well as the transduction rates to HT1080-MLV levels, suggesting that the postentry blockage could be overcome by endocytic delivery of the core particles downstream of the restriction point. Thus, in contrast to the previously described target cell-dependent Fv-1 (or Fv1-like) restriction in mammalian cells (P. Pryciak and H. E. Varmus, J. Virol. 66:5959-5966, 1992; G. Towers, M. Bock, S. Martin, Y. Takeuchi, J. P. Stoye, and O. Danos, Proc. Natl. Acad. Sci. USA 97:12295-12299, 2000), we report here a new restriction of MLV replication that relies only on the producer cell type.

3T3 Cells↗
PubMed2002

Inserting a nuclear targeting signal into a replication-competent Moloney murine leukemia virus affects viral export and is not sufficient for cell cycle-independent infection.

The effects of inserting reported nuclear localization signals (NLSs) into the Moloney murine leukemia virus (Mo-MuLV) integrase (IN) protein, within a replication-competent viral construct, were studied. In contrast to the virus harboring IN fused to the simian virus 40 (SV40) large T antigen NLS (SV40 NLS) (J. A. Seamon, M. Adams, S. Sengupta, and M. J. Roth, Virology 274:412-419, 2000), a codon-modified SV40 NLS was stably expressed during viral propagation. Incorporation of the codon-modified SV40 NLS into IN, however, altered the packaging of the Gag-Pol precursor in the virus; viral particles contained decreased levels of reverse transcriptase (RT) and IN. In addition, the virus showed delayed kinetics of viral DNA synthesis upon infection. A panel of infectious MuLVs containing alternative IN-NLS fusions was generated and assayed for cell cycle-independent infection. Viral infection with the NLS-tagged proteins, however, remained dependent on passage of the cells through mitosis. This finding has direct implications for engineering murine-based retroviral vectors for gene therapy.

Amino Acid Sequence↗
PubMed2002

Wild-type levels of nuclear localization and human immunodeficiency virus type 1 replication in the absence of the central DNA flap.

Numerous factors have been implicated in the nuclear localization of retroviral preintegration complexes. Whereas sequences in human immunodeficiency virus type 1 (HIV-1) matrix, Vpr, and integrase proteins were initially reported to function specifically in nondividing cells, other recently identified sequences apparently function in dividing cells as well. One of these, the central DNA flap formed during reverse transcription, is specific to lentiviruses. It was previously reported that flap-negative (F(-)) HIV-1(LAI) was completely defective for viral spread in the MT-4 T-cell line, yet F(-) HIV-1 vectors were only 2- to 10-fold defective in various single-round transduction assays. To address these different findings, we analyzed the infectivity and nuclear localization phenotypes of two highly related T-cell-tropic strains, HIV-1(NL4-3) and a derivative of HIV-1(HXBc2) deficient for both Vpr and Nef. In stark contrast to the previous report, F(-) derivatives of both strains replicated efficiently in MT-4 cells. F(-) HIV-1(NL4-3) also spread like wild-type HIV-1(NL4-3) in infected Jurkat and primary T-cell cultures. In contrast, F(-) HIV-1(HXBc2) was replication defective in primary T cells. Results of real-time quantitative PCR assays, however, indicated that F(-) HIV-1(HXBc2) entered primary T-cell nuclei as efficiently as its wild-type counterpart. Thus, the F(-) HIV-1(HXBc2) growth defect did not appear to correlate with defective nuclear import. Consistent with this observation, wild-type nef restored replication to F(-) HIV-1(HXBc2) in primary T cells. Our results indicate that the central DNA flap does not play a major role in either preintegration complex nuclear import or HIV-1 replication in a variety of cell types.

Active Transport, Cell Nucleus↗
PubMed2002

Reassessment of the roles of integrase and the central DNA flap in human immunodeficiency virus type 1 nuclear import.

Human immunodeficiency virus type 1 (HIV-1) can infect nondividing cells productively because the nuclear import of viral nucleic acids occurs in the absence of cell division. A number of viral factors that are present in HIV-1 preintegration complexes (PICs) have been assigned functions in nuclear import, including an essential valine at position 165 in integrase (IN-V165) and the central polypurine tract (cPPT). In this article, we report a comparison of the replication and infection characteristics of viruses with disruptions in the cPPT and IN-V165. We found that viruses with cPPT mutations still replicated productively in both dividing and nondividing cells, while viruses with a mutation at IN-V165 did not. Direct observation of the subcellular localization of HIV-1 cDNAs by fluorescence in situ hybridization revealed that cDNAs synthesized by both mutant viruses were readily detected in the nucleus. Thus, neither the cPPT nor the valine residue at position 165 of integrase is essential for the nuclear import of HIV-1 PICs.

Active Transport, Cell Nucleus↗
PubMed2002

A cis-acting element that directs circular adeno-associated virus replication and packaging.

A novel pathway of adeno-associated virus (AAV) replication marked by the assembly of circular monomer duplex intermediates (cAAV) has been recently discovered. In the present report we identify a single AD domain of the inverted terminal repeat as a minimal origin of cAAV replication. A small internal palindrome (BB'), necessary for optimal Rep-inverted terminal repeat interaction, does not contribute to the efficiency of cAAV replication, while the terminal resolution site is an essential cis-acting element. Furthermore, recombinant cAAV vectors that encompass only the AD domain replicate exclusively in a circular form and no detectable linear duplex replicative intermediates are generated, suggesting that both pathways of AAV replication are independent and can be separated. In addition, we show that cAAVs are efficient templates for encapsidation of single-stranded DNA genomes, an observation that assigns a biological role for these novel replication species. Together, these findings shed new light on the current model of AAV replication and packaging.

Base Sequence↗
PubMed2002

Characterization of chromosomally assigned replication-competent gamma porcine endogenous retroviruses derived from a large white pig and expression in human cells.

Vertically transmitted endogenous retroviruses pose an infectious risk in the course of pig-to-human transplantation of cells, tissues, and organs. Two classes of polytropic type C porcine endogenous retroviruses (PERV) productively infect human cells in vitro. The cloning and characterization of replication-competent PERV-B sequences from infected human cells (F. Czauderna, N. Fischer, K. Boller, R. Kurth, and R. R. Tönjes, J. Virol. 74:4028-4038, 2000) as well as the cloning of functional PERV-A and -B sequences from porcine cell line PK15 (U. Krach, N. Fischer, F. Czauderna, and R. R. Tönjes, J. Virol. 75:5465-5472, 2001) have been previously described. Here we report the isolation of four full-length proviral sequences from a porcine bacterial artificial chromosome (BAC) library that comprises chromosomally assigned PERV. Clones Bac-PERV-A(130A12) and Bac-PERV-A(151B10) map to pig chromosome 1 and demonstrate close homology to PK15-PERV-A(58) in env and to PERV-MSL in long terminal repeat (LTR), gag, and pro/pol sequences. Clone Bac-PERV-A(463H12) is located on pig chromosome 3 and demonstrates close homology to PK15-PERV-A(58) in env and to 293-PERV-B(43) in LTR, gag, and pro/pol (Czauderna et al.; R. R. Tönjes, F. Czauderna, N. Fischer, U. Krach, K. Boller, P. Chardon, C. Rogel-Gailard, M. Niebert, G. Scheef, A. Werner, and R. Kurth, Transplant Proc. 32:1158-1161, 2000). Clone Bac-PERV-B(192B9) is located on pig chromosome 7 in the swine leukocyte antigen region and is highly homologous with but distinct from the previously described functional clone 293-PERV-B(43) and bears the number of repeats initially observed in the LTRs of clone 293-PERV-A(42) (Czauderna et al.; Krach et al.). Clones Bac-PERV-A(130A12), Bac-PERV-A(151B10), and Bac-PERV-A(463H12) were replication competent upon transfection into susceptible 293 and HeLa cells. Bac-PERV-B(192B9), however, bears two stop codons in pro/pol preventing this clone from being replication competent in some individual pigs, but initial screenings indicate that this provirus might be intact in others. The data suggest that the porcine genome harbors a limited number of infectious PERV sequences, allowing for specific screening in different pig breeds.

Animals↗
PubMed2004

Assessment of the role of the central DNA flap in human immunodeficiency virus type 1 replication by using a single-cycle replication system.

In this study, reverse transcriptase (RT)- and integrase (IN)-defective human immunodeficiency virus type 1 (HIV-1) was transcomplemented with Vpr-RT-IN fusion proteins to delineate pol sequences important for HIV-1 replication. Our results reveal that a 194-bp sequence encompassing the 3'end of the IN gene and containing the central DNA flap is necessary and sufficient for efficient HIV-1 single-cycle replication in dividing and nondividing cells. Furthermore, we show that the central DNA flap enhances HIV-1 single-round replication by five- to sevenfold, primarily by facilitating nuclear import of proviral DNA. In agreement with previous reports, our data support a functional role of the central DNA flap during the early stages of HIV-1 infection.

Cell Nucleus↗
PubMed2005

Potential autoregulation of transcription factor PU.1 by an upstream regulatory element.

Regulation of the hematopoietic transcription factor PU.1 (Spi-1) plays a critical role in the development of white cells, and abnormal expression of PU.1 can lead to leukemia. We previously reported that the PU.1 promoter cannot induce expression of a reporter gene in vivo, and cell-type-specific expression of PU.1 in stable lines was conferred by a 3.4-kb DNA fragment including a DNase I hypersensitive site located 14 kb upstream of the transcription start site. Here we demonstrate that this kb -14 site confers lineage-specific reporter gene expression in vivo. This kb -14 upstream regulatory element contains two 300-bp regions which are highly conserved in five mammalian species. In Friend virus-induced erythroleukemia, the spleen focus-forming virus integrates into the PU.1 locus between these two conserved regions. DNA binding experiments demonstrated that PU.1 itself and Elf-1 bind to a highly conserved site within the proximal homologous region in vivo. A mutation of this site abolishing binding of PU.1 and Elf-1 led to a marked decrease in the ability of this upstream element to direct activity of reporter gene in myelomonocytic cell lines. These data suggest that a potential positive autoregulatory loop mediated through an upstream regulatory element is essential for proper PU.1 gene expression.

Animals↗
PubMed1987

Unusual sequence element found at the end of an amplicon.

In a polyomavirus-transformed rat cell line, designated LPT, the polyomavirus DNA is integrated into a single chromosomal site. Treatment of LPT cells with carcinogens induces amplification of the integrated virus DNA and flanking cellular sequences. We show that the amplification is arrested within a specific cell DNA segment that maps 1.3 to 1.85 kilobases beyond one virus-cell DNA junction, defined as the left junction. We also present the sequence of an 897-base-pair fragment spanning the arrest site. This fragment contains an unusual sequence element, which consists of two contiguous components, a potential cruciform with stems of 6 base pairs and a d(G-A)27 X d(T-C)27 tract, and maps 1,497 to 1,564 nucleotides beyond the left junction. The possibility that this unusual sequence plays a role in the arrest of the amplification process is discussed.

Animals↗
PubMed1993

Mechanisms of genome propagation and helper exploitation by satellite phage P4.

Temperate coliphage P2 and satellite phage P4 have icosahedral capsids and contractile tails with side tail fibers. Because P4 requires all the capsid, tail, and lysis genes (late genes) of P2, the genomes of these phages are in constant communication during P4 development. The P4 genome (11,624 bp) and the P2 genome (33.8 kb) share homologous cos sites of 55 bp which are essential for generating 19-bp cohesive ends but are otherwise dissimilar. P4 turns on the expression of helper phage late genes by two mechanisms: derepression of P2 prophage and transactivation of P2 late-gene promoters. P4 also exploits the morphopoietic pathway of P2 by controlling the capsid size to fit its smaller genome. The P4 sid gene product is responsible for capsid size determination, and the P2 capsid gene product, gpN, is used to build both sizes. The P2 capsid contains 420 capsid protein subunits, and P4 contains 240 subunits. The size reduction appears to involve a major change of the whole hexamer complex. The P4 particles are less stable to heat inactivation, unless their capsids are coated with a P4-encoded decoration protein (the psu gene product). P4 uses a small RNA molecule as its immunity factor. Expression of P4 replication functions is prevented by premature transcription termination effected by this small RNA molecule, which contains a sequence that is complementary to a sequence in the transcript that it terminates.

Amino Acid Sequence↗
PubMed1999

Delayed expression of adeno-associated virus vector DNA.

Two previous reports indicated that recombinant adeno-associated virus (rAAV) vectors were dependent on helper adenovirus (Ad) for efficient conversion of single-stranded (ss) rAAV DNA to the double-stranded (ds) form. This finding is somewhat paradoxical, however, since during a latent infection wild-type (wt)-AAV is rapidly converted to a ds form in the absence of Ad. Our hypothesis was that the effect observed in the previous studies was due to kinetic factors, i.e. to a relative delay in conversion to ds-DNA rather than to an absolute requirement for Ad. To test this, Hela cells were infected with a rAAV-CMV-green fluorescent protein (GFP) vector either in the presence or absence of Ad. Within the first 2 days, Ad infection resulted in a 4-fold increase in AAV vector expression and an augmentation of conversion to a ds-AAV DNA. By 6 days, however, the total number of GFP-expressing cells in the Ad-free culture had exceeded the original number in the Ad co-infected cells, and the conversion to ds-DNA episomes was substantial and ongoing.

Adenoviridae↗
PubMed1992

Rescue of the adeno-associated virus 2 genome correlates with alterations in DNA-modifying enzymes in human cells.

The adeno-associated virus 2 (AAV) genome can be rescued either from a recombinant plasmid upon transfection into human cells or from cells latently infected with AAV, following subsequent infection with adenovirus. Using human diploid fibroblasts as a model for a natural AAV infection, we observed increased efficiency of rescue of the AAV genome in these cells as they traversed their limited proliferative life span in vitro. The efficiency of rescue correlated well with the augmented nuclease activity in these cells. Furthermore, rescue of the AAV genome, either from a recombinant plasmid or from the chromosomal DNA, was more efficient in cells from a patient with Bloom's syndrome, a rare autosomal recessive disease associated with increased chromosomal breakage due to DNA ligase I deficiency, as compared with normal human diploid fibroblasts. These studies suggest that alterations in DNA-modifying enzymes may play a role in rescue of the AAV genome in human cells.

Blotting, Southern↗
PubMed2002

The peripheral cannabinoid receptor Cb2, a novel oncoprotein, induces a reversible block in neutrophilic differentiation.

We previously identified a novel common virus integration site, Evi11, by means of retroviral insertional mutagenesis. We demonstrated that the gene encoding the peripheral cannabinoid receptor (Cb2) is the potential target, suggesting that Cb2 is a proto-oncogene. To elucidate a role for this G protein-coupled receptor (GPCR) in leukemic transformation we generated a Cb2-EGFP cDNA construct that was introduced into 32D/G-CSF-R cells. These cells require interleukin 3 (IL-3) to proliferate in vitro, whereas in the presence of granulocyte-colony-stimulating factor (G-CSF) they differentiate toward mature neutrophils. We demonstrate that 32D/G-CSF-R/Cb2-EGFP cells migrate in a transwell assay in reponse to the Cb2 ligand 2-arachidonoylglycerol (2-AG), indicating that the fusion protein was functional. When cultured in the presence of G-CSF neutrophilic differentiation of Cb2-EGFP-expressing 32D/G-CSF-R cells was completely blocked. Moreover, a Cb2-specific antagonist fully recovered the G-CSF-induced neutrophilic differentiation of 32D/G-CSF-R/Cb2-EGFP cells. To investigate which signal transduction pathway(s) may be involved in the block of neutrophilic maturation, differentiation experiments were carried out using specific inhibitors of signaling routes. Interestingly, full rescue of G-CSF-induced neutrophilic differentiation was observed when cells were cultured with the mitogen-induced extracellular kinase (MEK) inhibitors, PD98059 or U0126, and partial recovery was detected with the phosphoinositide 3-kinase (PI3-K) inhibitor LY-294002. These studies demonstrate that the Cb2 receptor is an oncoprotein that blocks neutrophilic differentiation when overexpressed in myeloid precursor cells. Cb2 appears to mediate its activity through MEK/extracellular signal-related kinase (ERK) and PI3-K pathways.

Arachidonic Acids↗