Interdomain but not intermolecular interactions observed in CFTR channels

Gating of the cystic fibrosis transmembrane conductance regulator (CFTR) channels requires interdomain and/or intermolecular interactions involving different parts of the protein, yet the exact nature of those interactions remains unclear. In this study we report that treating wild type CFTR-expressing cells with oxidizing agents results in a significant reduction in the gel mobility of the protein indicative of the formation of disulfide bonds. In contrast, mutant CFTR channels in which cysteine residues in both nucleotide binding domains (NBDs) were mutated to serine, showed little change in gel mobility in oxidizing conditions. Mutation of the two cysteine residues in either the first or the second NBD alone also eliminates the change in gel mobility in oxidizing conditions. Wild type channels treated with oxidizing agents did not appear to form disulfide bonds with other proteins, suggesting that the close association that allows the formation of disulfide bonds occurs only within single proteins and not between separate channels interacting in a multimer.

Expression and subcellular localization of the cyclin-dependent kinase inhibitor p27(Kip1) in epithelial ovarian cancer

OBJECTIVE

To determine if p27(Kip1) expression was altered in epithelial ovarian cancers as compared to normal ovarian surface epithelial (NOSE) cells and to determine if subcellular localization of p27(Kip1) was an important feature.

METHODS

Thirteen tumor samples (1 Stage IC [early] and 12 Stage III/IV [advanced]) from patients with epithelial ovarian cancer and five NOSE samples were evaluated. Samples were surgically dissected to obtain an enriched population (90%) of cancer cells. The level of p27(Kip1) protein expression was determined by Western blot analysis. Actin was used as a loading control, and results were quantified by scanning densitometry using the ratio of the p27(Kip1) signal to the actin signal for comparison. To evaluate the subcellular localization of p27(Kip1), immunocytochemical staining was performed. Clinical pathological parameters were correlated to nuclear p27(Kip1) staining to establish if any association existed.

RESULTS

When comparing the expression of p27(Kip1) between NOSE and ovarian cancer samples, only 2 of 13 ovarian cancer samples had altered p27(Kip1) expression. No correlation was found between the expression level of p27(Kip1) on Western blot and clinical pathological correlates. While no correlation between expression level of p27(Kip1) and subcellular localization was found, decreased nuclear staining (1+) was associated with shorter survivals using the log-rank test (P < 0.001). More importantly, in all tumor samples examined under the microscope, no nuclear p27(Kip1) staining was noted in cells that were undergoing mitosis.

CONCLUSIONS

p27(Kip1) protein degradation may not be modified in ovarian cancer cells undergoing mitosis. Altered expression of p27(Kip1) is not an overwhelming feature in certain epithelial ovarian cancers. Decreased nuclear staining of p27(Kip1) is associated with poor survival in some epithelial ovarian cancers.

SIMPL is a tumor necrosis factor-specific regulator of nuclear factor-kappaB activity

The IL-1 receptor-associated kinase (IRAK/mPLK) is linked to the regulation of nuclear factor-kappaB (NF-kappaB)-dependent gene expression. Here we describe a novel binding partner of IRAK/mPLK that we term SIMPL (signaling molecule that associates with the mouse pelle-like kinase). Overexpression of SIMPL leads to the activation of NF-kappaB-dependent promoters, and inactivation of SIMPL inhibits IRAK/mPLK as well as tumor necrosis factor receptor type I-induced NF-kappaB activity. Dominant inhibitory alleles of IkappaB kinase (IKKalpha or IKKbeta) block the activation of NF-kappaB by IRAK/mPLK and SIMPL. Furthermore, SIMPL binds IRAK/mPLK and the IKKs in vitro and in vivo. In the presence of antisense mRNA to SIMPL, the physical association between IRAK/mPLK and IKKbeta but not IRAK/mPLK and IKKalpha is greatly diminished. Moreover, dominant-negative SIMPL blocks IKKalpha- or IKKbeta-induced NF-kappaB activity. These results lead us to propose a model in which SIMPL functions to regulate NF-kappaB activity by linking IRAK/mPLK to IKKbeta/alpha-containing complexes.

Molecular Characterization of Vegetative Compatibility Group 4A and 4B Isolates of Verticillium dahliae Associated with Potato Early Dying

Forty isolates of Verticillium dahliae, collected from potato seed tubers and potato plants from various regions in North America and previously assigned to vegetative compatibility groups (VCGs) 4A or 4B, were characterized using molecular markers. The VCG 4A isolates were previously shown to be a highly virulent pathotype of potato and to interact synergistically with the root-lesion nematode Pratylenchus penetrans to cause potato early dying. All but one of the VCG 4A isolates characterized in this study lacked the subspecies-specific repetitive DNA sequence E18 and could be differentiated from the remaining isolates by restriction fragment length polymorphisms (RFLPs) in the nuclear rDNA and Trp1 loci. The E18 RFLP patterns of several VCG 4B isolates from Maine and New York were highly similar to those of VCG 4B isolates previously collected from potato and tomato fields in Ontario. The data presented here suggest that the molecular markers will be useful for the detection and classification of isolates of V. dahliae associated with potato early dying.

Hypoxia activates jun-N-terminal kinase, extracellular signal-regulated protein kinase, and p38 kinase in pulmonary arteries

Chronic alveolar hypoxia is the major cause of pulmonary hypertension. The cellular mechanisms involved in hypoxia- induced pulmonary arterial remodeling are still poorly understood. Mitogen-activated protein kinase (MAPK) is a key enzyme in the signaling pathway leading to cellular growth and proliferation. The purpose of this investigation was to determine the roles that MAPKs, specifically Jun-N-terminal kinase (JNK), extracellular signal-regulated protein kinase (ERK), and p38 kinase, play in the hypoxia-induced pulmonary arterial remodeling. Rats were exposed to normobaric hypoxia (10% O(2)) for 1, 3, 7, or 14 d. Hypoxia caused significant remodeling in the pulmonary artery characterized by thickening of pulmonary arterial wall and increases in tissue mass and total RNA. JNK, ERK, and p38 kinase tyrosine phosphorylations and their activities were significantly increased by hypoxia. JNK activation peaked at Day 1 and ERK/p38 kinase activation peaked after 7 d of hypoxia. The results from immunohistochemistry show that hypoxia increased phospho-MAPK staining in both large and small intrapulmonary arteries. Hypoxia also upregulated vascular endothelial growth factor messenger RNA (mRNA) and platelet-derived growth factor receptor mRNA levels in pulmonary artery with a time course correlated to the activation of ERK and p38 kinase. The gene expressions of c-jun, c-fos, and egr-1, known as downstream effectors of MAPK, were also investigated. Hypoxia upregulated egr-1 mRNA but downregulated c-jun and c-fos mRNAs. These data suggest that hypoxia-induced activation of JNK is an early response to hypoxic stress and that activation of ERK and p38 kinase appears to be associated with hypoxia-induced pulmonary arterial remodeling.

H(2)O(2)-induced egr-1, fra-1, and c-jun gene expression is mediated by tyrosine kinase in aortic smooth muscle cells

Hydrogen peroxide (H(2)O(2)) has recently been shown to have a dual effect on cell growth by stimulating proliferation and triggering apoptosis. Apoptosis induced by H(2)O(2) is a direct consequence of oxidant injury, while the proliferative response to H(2)O(2) is thought to be a protective mechanism against oxidant injury. Signaling of the H(2)O(2)-induced proliferative effect has been proposed to occur via the activation of mitogen-activated protein kinase (MAPK) and increase in expression of transcription factors. In the present study, H(2)O(2)-induced mitogenic signaling in aortic smooth muscle cells (ASMC) was investigated with a specific focus on the roles of tyrosine kinase and tyrosine phosphatase in the regulation of the H(2)O(2)-stimulated egr-1, fra-1, and c-jun transcription. The results show that H(2)O(2)-induced increases in egr-1, fra-1, and c-jun mRNA levels, as measured by Northern blot analysis, are time and dose dependent with the peak of the response within 2 h. Tyrosine kinase inhibitors (genistein, amino-genistein, and tyrphostin 51) significantly attenuated H(2)O(2)-induced expression of these genes and a tyrosine phosphatase inhibitor (perox-vanadate) stimulated their expression. H(2)O(2) stimulated tyrosine kinase activities and caused protein tyrosine phosphorylation, which was blocked by tyrphostin 51. H(2)O(2) also caused tyrosine phosphorylation of platelet derived growth factor (PDGF) receptor. These data show that H(2)O(2) increases egr-1, fra-1, and c-jun mRNA levels in vascular smooth muscle cells, and the increase in expression of these genes is mediated by activation of tyrosine kinase. Our data also provide evidence that the H(2)O(2)-induced mitogenic response is, in part, mediated through the receptor tyrosine kinase, PDGF receptor.

Influences of Cropping Practices on Verticillium dahliae Populations in Commercial Processing Tomato Fields in Ontario

ABSTRACT The abundance of Verticillium dahliae in the soil and the incidence of V. dahliae-infected plants were determined for 12 commercial processing tomato fields in Kent County, Ontario. Comparison of the data with those from a previous survey of fields in adjacent Essex County showed that soil inoculum levels and incidence of infection were generally lower in Kent County fields and that race 2 V. dahliae was not common in Kent County. From the two counties, 128 isolates were characterized by restriction fragment length polymorphism (RFLP) analysis, using the subspecies-specific repetitive DNA sequence E18. A subset of these isolates was also characterized by vegetative compatibility and DNA hybridization analysis with a second subspecies-specific DNA sequence. Isolates with E18 RFLP profiles highly similar to those of isolates previously collected from potato fields in North America were prevalent in Essex County tomato fields but not common in Kent County fields. The data are consistent with the hypothesis that the group I isolates were introduced into southwestern Ontario with potato and that the different cultural practices in Essex County and Kent County have contributed to the differences in the accumulation of these isolates in the two regions.

Repression of transforming-growth-factor-beta-mediated transcription by nuclear factor kappaB

Activation of transforming growth factor-beta (TGF-beta) and activin receptors leads to phosphorylation of Sma- and Mad-related protein 2 (Smad2) and Smad3, which function as transcription factors to regulate gene expression. Smad7 is a regulatory protein which is able to inhibit TGF-beta and activin signalling in a negative-feedback loop, mediated by a direct regulation by Smad3 and Smad4 via a Smad-binding element (SBE) in the Smad7 promoter. Interestingly, we found that the Smad7 promoter was also regulated by nuclear factor kappaB (NF-kappaB), a transcription factor which plays an important role in inflammation and the immune response. Expression of NF-kappaB p65 subunit was able to inhibit the Smad7 promoter activity, and this inhibition could be reversed by co-expression of IkappaB, an inhibitor of NF-kappaB. In addition, the inhibitory activity of p65 was observed in a minimal promoter that contained only the Smad7 SBE and a TATA box, without any consensus NF-kappaB binding site. This inhibitory effect appeared to be common to other TGF-beta- and activin-responsive promoters, since p65 also inhibited the forkhead-activin-signal-transducer-2-mediated activation of a Xenopus Mix.2 promoter, as well as the Smad3-mediated activation of 3TP-lux which contains PMA-responsive elements and a plasminogen-activator-inhibitor-1 promoter. Activation of endogenous NF-kappaB by tumour necrosis factor-alpha (TNF-alpha) was also able to inhibit the Smad7 promoter in human embryonic kidney 293 cells. In human hepatoma HepG2 cells, TNF-alpha was able to inhibit TGF-beta- and activin-mediated transcriptional activation. Furthermore, overexpression of the transcription co-activator p300 could abrogate the inhibitory effect of NF-kappaB on the Smad7 promoter. Taken together, these data have indicated a novel mode of crosstalk between the Smad and the NF-kappaB signalling cascades at the transcriptional level by competing for a limiting pool of transcription co-activators.

A comparison of macrophage colony-stimulating factor (M-CSF) gene expression in primary and immortalized endothelial cells

M-CSF is produced by a wide variety of cell types, including EC, fibroblasts, and monocyte/macrophages, where it functions as a survival factor and a chemotactic agent for monocytes. An early event in the development of atherosclerosis is the infiltration of monocytes into the artery wall. Local expression of M-CSF by EC lining the blood vessels is thought to promote the growth and survival of lesional monocytes and macrophages, thus enhancing lesion development and disease progression. Primary cultures of EC are difficult to maintain for long periods of time, which complicates their use for biochemical and molecular analysis. As a step toward identifying a representative endothelial-like cell line, serum-dependent and IL-1-dependent changes in M-CSF gene expression in two endothelial-like cell lines were compared to that detected in primary EC cultures. The data presented here demonstrate that the two endothelial-like cell lines, like primary cultures of EC, express the M-CSF gene under basal conditions. In both types of cell cultures, IL-1alpha stimulation increased M-CSF mRNA levels 2-7-fold, whereas serum stimulation elicited a more modest effect (2-3-fold increase). The IL-1alpha-induced change in M-CSF gene expression is mediated at the transcriptional level, and M-CSF promoter activity is, in part, dependent on the activity of the NF-kappaB-inducing kinase. Collectively, our results demonstrate that either endothelial-like cell line would be a representative model in which endothelial-specific changes in M-CSF gene expression could be identified.

Mouse receptor interacting protein 3 does not contain a caspase-recruiting or a death domain but induces apoptosis and activates NF-kappaB

The death domain-containing receptor superfamily and their respective downstream mediators control whether or not cells initiate apoptosis or activate NF-kappaB, events critical for proper immune system function. A screen for upstream activators of NF-kappaB identified a novel serine-threonine kinase capable of activating NF-kappaB and inducing apoptosis. Based upon domain organization and sequence similarity, this novel kinase, named mRIP3 (mouse receptor interacting protein 3), appears to be a new RIP family member. RIP, RIP2, and mRIP3 contain an N-terminal kinase domain that share 30 to 40% homology. In contrast to the C-terminal death domain found in RIP or the C-terminal caspase-recruiting domain found in RIP2, the C-terminal tail of mRIP3 contains neither motif and is unique. Despite this feature, overexpression of the mRIP3 C terminus is sufficient to induce apoptosis, suggesting that mRIP3 uses a novel mechanism to induce death. mRIP3 also induced NF-kappaB activity which was inhibited by overexpression of either dominant-negative NIK or dominant-negative TRAF2. In vitro kinase assays demonstrate that mRIP3 is catalytically active and has autophosphorylation site(s) in the C-terminal domain, but the mRIP3 catalytic activity is not required for mRIP3 induced apoptosis and NF-kappaB activation. Unlike RIP and RIP2, mRIP3 mRNA is expressed in a subset of adult tissues and is thus likely to be a tissue-specific regulator of apoptosis and NF-kappaB activity. While the lack of a dominant-negative mutant precludes linking mRIP3 to a known upstream regulator, characterizing the expression pattern and the in vitro functions of mRIP3 provides insight into the mechanism(s) by which cells modulate the balance between survival and death in a cell-type-specific manner.

Redox reagents and divalent cations alter the kinetics of cystic fibrosis transmembrane conductance regulator channel gating

Gating of the cystic fibrosis Cl(-) channel requires hydrolysis of ATP by its nucleotide binding folds, but how this process controls the kinetics of channel gating is poorly understood. In the present work we show that the kinetics of channel gating and presumably the rate of ATP hydrolysis depends on the species of divalent cation present and the oxidation state of the protein. With Ca(2+) as the dominant divalent cation instead of Mg(2+), the open burst duration of the channel is increased approximately 20-fold, and this change is reversible upon washout of Ca(2+). In contrast, "soft" divalent cations such as Cd(2+) interact covalently with cystic fibrosis transmembrane conductance regulator (CFTR). These metals decrease both opening and closing rates of the channel, and the effects are not reversed by washout. Oxidation of CFTR channels with a variety of oxidants resulted in a similar slowing of channel gating. In contrast, reducing agents had the opposite effect, increasing both opening and closing rates of the channel. In cell-attached patches, CFTR channels exhibit both oxidized and reduced types of gating, raising the possibility that regulation of the redox state of the channel may be a physiological mode of control of CFTR channel activity.

Modulation of tumor necrosis factor and interleukin-1-dependent NF-kappaB activity by mPLK/IRAK

The innate immune response is an important defense against pathogenic agents. A component of this response is the NF-kappaB-dependent activation of genes encoding inflammatory cytokines such as interleukin-8 (IL-8) and cell adhesion molecules like E-selectin. Members of the serine/threonine innate immune kinase family of proteins have been proposed to mediate the innate immune response. One serine/threonine innate immune kinase family member, the mouse Pelle-like kinase/human interleukin-1 receptor-associated kinase (mPLK/IRAK), has been proposed to play an obligate role in promoting IL-1-mediated inflammation. However, it is currently unknown whether mPLK/IRAK catalytic activity is required for IL-1-dependent NF-kappaB activation. The present study demonstrates that mPLK/IRAK catalytic activity is not required for IL-1-mediated activation of an NF-kappaB-dependent signal. Intriguingly, catalytically inactive mPLK/IRAK inhibits type 1 tumor necrosis factor (TNF) receptor-dependent NF-kappaB activation. The pathway through which mPLK/IRAK mediates this TNF response is TRADD- and TRAF2-independent. Our data suggest that in addition to its role in IL-1 signaling, mPLK/IRAK is a component of a novel signal transduction pathway through which TNF R1 activates NF-kappaB-dependent gene expression.

Regulation of interleukin-1-stimulated GMCSF mRNA levels in human endothelium

The regulation of interleukin-1 (IL-1)-mediated increases in GMCSF mRNA levels in human endothelium was examined and determined to occur in a time- and protein kinase C (PKC)-dependent manner. IL-1beta induced the early activation and translocation of PKC isotypes alpha and beta2 to the nucleus and PKC inhibition attenuated the IL-1-mediated increase in GMCSF mRNA levels. PKC activation by PMA alone, in the absence of IL-1beta activation, however, was insufficient to allow GMCSF mRNA detection. Increasing cyclic adenosine nucleotide (cAMP) levels suppressed IL-1beta-induced increases in GMCSF mRNA levels. In contrast, botulinum toxin C, which mediates the ADP ribosylation of a 21 kD ras-related G protein, augmented IL-1beta-induced GMCSF mRNA expression. Inhibition of protein synthesis (with cycloheximide) raised basal GMCSF mRNA transcripts to detectable levels, augmented IL-1-induced increases in GMCSF mRNA levels, and exhibited negative regulation by cAMP. Finally, disruption of either microtubules (with colchicine) or microfilaments (with cytochalasin B) resulted in reduced GMCSF mRNA expression in response to IL-1beta. These results are compatible with a model wherein IL-1-mediated increases in human endothelial cell GMCSF mRNA may be linked to both nuclear protein kinase C activation and activation of a low molecular weight G-protein, although neither activity alone is sufficient to increase the levels of GMCSF mRNA.

Regulation of mouse colony-stimulating factor-1 gene promoter activity by AP1 and cellular nucleic acid-binding protein

Macrophage colony-stimulating factor (M-CSF; CSF-1) is a member of a complex network of cytokines that regulate monocytic cell development and activity. It is produced in nearly all organs by cell types commonly found in connective tissue, including fibroblasts and monocytes. Whether different cell types share common or have divergent mechanisms for regulating CSF-1 gene expression is not known. To address this question, the identity of cis-acting elements and cognate trans-acting factors was characterized in a region of the CSF-1 promoter known to be more active in monocytes than in fibroblasts. The results of DNase I protection assays performed with fibroblast- or monocyte-derived nuclear extracts revealed a difference in the pattern of DNA-binding proteins. One protected region, common to both fibroblasts and monocytes, spans a putative phorbol ester-responsive element (TRE), and binding to the TRE by AP1 was verified with antibodies directed against c-fos and c-jun family members. Mutational analysis revealed that the TRE is required for CSF-1 gene expression in proliferating fibroblasts and monocytes. Binding of a second putative trans-acting factor, preferentially expressed in fibroblasts, to the region immediately upstream of the TRE was also detected. Screening a mouse expression library with oligonucleotides spanning the putative cis-acting element identified cellular nucleic acid-binding protein (CNBP) as the cognate binding activity, and antiserum to CNBP disrupted the electromobility shift assay complex. Mutational analysis revealed that loss of CNBP binding leads to a decrease in CSF-1 promoter activity in fibroblasts but has no effect on CSF-1 promoter activity in monocytes. Our results demonstrate that control of CSF-1 gene expression in monocytes and fibroblasts is mediated by common and cell type-specific trans-acting factors.

Phosphorylation of nuclear MyoD is required for its rapid degradation

MyoD is a basic helix-loop-helix transcription factor involved in the activation of genes encoding skeletal muscle-specific proteins. Independent of its ability to transactivate muscle-specific genes, MyoD can also act as a cell cycle inhibitor. MyoD activity is regulated by transcriptional and posttranscriptional mechanisms. While MyoD can be found phosphorylated, the functional significance of this posttranslation modification has not been established. MyoD contains several consensus cyclin-dependent kinase (CDK) phosphorylation sites. In these studies, we examined whether a link could be established between MyoD activity and phosphorylation at putative CDK sites. Site-directed mutagenesis of potential CDK phosphorylation sites in MyoD revealed that S200 is required for MyoD hyperphosphorylation as well as the normally short half-life of the MyoD protein. Additionally, we determined that turnover of the MyoD protein requires the proteasome and Cdc34 ubiquitin-conjugating enzyme activity. Results of these studies demonstrate that hyperphosphorylated MyoD is targeted for rapid degradation by the ubiquitin pathway. The targeted degradation of MyoD following CDK phosphorylation identifies a mechanism through which MyoD activity can be regulated coordinately with the cell cycle machinery (CDK2 and CDK4) and/or coordinately with the cellular transcriptional machinery (CDK7, CDK8, and CDK9).

Imported malaria: prospective analysis of problems in diagnosis and management

Imported malaria is an increasing problem in many countries. The objective of this study was to prospectively evaluate the diagnosis and treatment of imported malaria cases identified by active surveillance. Microscopic diagnosis at the community level was also compared to reference microscopic and blinded molecular diagnostic methods. Most travelers who acquire malaria had sought pretravel advice from a physician; however, only 11% used recommended chemoprophylaxis and only 17% used insect protection measures. The diagnosis of malaria was initially missed in 59% of cases. Community-based microscopic diagnosis provided incorrect species identification in 64% of cases. After presentation, the average delay before treatment was 7.6 days for falciparum malaria and 5.1 days for vivax malaria. Overall, 7.5% of Plasmodium falciparum-infected patients developed severe malaria, and in 11% of all cases therapy failed. Patients who present to a center without expertise in tropical medicine receive suboptimal treatment. Improvements in recognition, diagnosis, and treatment of malaria are essential to prevent morbidity and death among travelers.

PLA2-independent induction of CSF-1 gene expression in growth-arrested fibroblasts

At the site of a wound or an infection, localized production of colony-stimulating factor-1 (CSF-1) by resident macrophages is chemotactic for circulating monocytes. Several intracellular signaling pathways, including those initiated in response to activation of phospholipase A2 (PLA2) have been proposed to play a role in the regulation of CSF-1 gene expression. The goal of these studies was to determine whether PLA2 is required for the initial increase in CSF-1 gene expression in serum- or IL-1 alpha-stimulated growth-arrested fibroblasts. IL-1 alpha- or serum-stimulation of growth-arrested fibroblasts had no effect on PLA2 enzyme activity and inhibitors of cytosolic or Ca(2+)-independent PLA2 activity had no effect on IL-1 alpha- or serum-mediated increases in CSF-1 mRNA levels. High concentrations of the PLA2 inhibitors, 4-bromophenacyl lactone and quinacrine, resulted in a generalized decrease in cellular mRNA levels. Our results, obtained in fibroblasts, suggest treatment with 4-bromophenacyl lactone or quinacrine, instead of inhibiting PLA2 activity specifically, results in a generalized depression of cellular mRNA levels. These data demonstrate that the initial increase in CSF-1 gene expression in growth-arrested fibroblasts treated with serum or IL-1 alpha occurs through a PLA2-independent mechanism.

Comparison of the ParaSight-F test and the ICT Malaria Pf test with the polymerase chain reaction for the diagnosis of Plasmodium falciparum malaria in travellers

Rapid and accurate methods are needed for the diagnosis of imported malaria. The ParaSight-F test and the ICT Malaria Pf test are commercially available kits marketed for the diagnosis of Plasmodium falciparum malaria. Both tests are antigen-capture assays based on the detection of P. falciparum histidine-rich protein 2 in peripheral blood. Using microscopy and a polymerase chain reaction (PCR)-based method as reference standards, we performed a 'blinded' comparison of these assays for the detection of P. falciparum infection in 200 febrile travellers returning from malaria-endemic areas. As determined by PCR and microscopy, 148 travellers had malaria and, of these patients, 54.7% (81/148) were infected with P. vivax only, 31.1% (46/148) with P. falciparum only, 9.5% (14/148) with P. ovale, 0.7% (1/148) with P. malariae, and 4.1% (6/148) had mixed infections. Compared to PCR, the ParaSight-F and ICT Malaria Pf tests had initial sensitivities of 94% and 90% and specificities of 95% and 97%, respectively, for the detection of P. falciparum malaria. When discrepant samples were retested with day 0 and day 1 bloods, the sensitivities improved to 96% and 94%, respectively. The 2 remaining false negative results with the Para-Sight-F test and 2 of the 3 false negative results with the ICT Malaria Pf test occurred in samples with < 100 parasites/microL. The performance of these kits was not significantly different (P = 0.75) and both are simple, rapid, and accurate tests for the detection of P. falciparum infection in the returned traveller.

Evaluation of a non-isotopic polymerase chain reaction-based assay to detect and predict treatment failure of Plasmodium vivax malaria in travellers

With the emergence of chloroquine-resistant Plasmodium vivax (CRPV), new tests to detect P. vivax and predict response to therapy would be useful for clinical and research applications. We performed a 'blinded' evaluation of a non-isotopic (colourimetric) polymerase chain reaction (PCR) based assay (Digene SHARP Signal System) compared with microscopy and PCR/radiometric probe hybridization of ribosomal ribonucleic acid genes (RPH) for the detection of P. vivax malaria in 182 febrile travellers. Compared with PCR/RPH as the reference standard, the colourimetric assay had a sensitivity of 100% and specificity of 98%. Using microscopy as the reference standard, 84 of 87 patients with P. vivax infection had a positive colourimetric assay. The 3 patients with a negative assay were subsequently shown to be infected with P. ovale as determined by PCR/RPH. In a subset of patients followed longitudinally, the colourimetric assay was positive in 5 of 13 patients 6 or more days after initiation of therapy. Of these 5 patients, 4 were subsequently demonstrated to be infected with CRPV as determined by treatment failure in vivo and/or chloroquine blood levels. A positive assay result 6 or more days after initiation of therapy was associated with subsequent treatment failure (P < 0.01). This non-isotopic assay is a sensitive, specific, and rapid method for the detection of P. vivax PCR products and may prove useful in predicting treatment failure.

Parasight F test compared with the polymerase chain reaction and microscopy for the diagnosis of Plasmodium falciparum malaria in travelers

Imported malaria is an increasing problem worldwide. A rapid and accurate test for Plasmodium falciparum infection would facilitate the diagnosis of malaria in the returned traveler. The ParaSight F antigen capture assay (dipstick test) is a new diagnostic test for P. falciparum based on detection of circulating histidine-rich protein-2 antigen. We performed a blinded evaluation of this assay compared with microscopy and the polymerase chain reaction (PCR) for the detection of P. falciparum infection in 151 febrile travelers. Compared with the PCR, the dipstick test had a sensitivity of 88% and a specificity of 97%. The ability of the dipstick test to detect P. falciparum was similar with that of microscopy (88% versus 83%) since the species of Plasmodium in 14 of 133 malaria-infected patients could not be determined by microscopy due to low parasite numbers. The dipstick test was 40% sensitive for infections with < 50 parasites/microliter, 89% with 50-100 parasites/microliter, and > or = 93% with > 100 parasites/microliter. Circulating antigen was detectable in 68% of the patients seven days after initiation of treatment and in 27% at day 28. The dipstick test represents a simple and accurate test for the diagnosis of P. falciparum infection in the returned traveler.

Developmental and tissue-specific expression of mouse pelle-like protein kinase

The NF-kappaB/c-Rel proteins are a family of evolutionarily conserved transcription factors activated during development that in the adult, mediate many processes including the immune response. A high degree of sequence similarity is shared between the NF-kappaB/c-Rel family of transcription factors and the Drosophila Dorsal protein as well as between its cytoplasmic inhibitor, IkappaBalpha, and the Drosophila Cactus protein. Genetic analyses of Dorsal have defined components of a signaling pathway for Dorsal activation, including a serine/threonine kinase, Pelle, placed upstream of Dorsal and Cactus. We demonstrate that this pathway is likely to be conserved in mammals by the isolation of a cDNA that encodes a novel mouse protein highly related to Pelle, mPLK (mouse Pelle-like protein kinase). Expression of mPLK mRNA is developmentally regulated in the mouse and in adult tissue mPLK expression is greatest in the liver, a tissue that expresses a high level of NF-kappaB. Recombinant mPLK produced in bacteria is a protein kinase capable of autophosphorylating and phosphorylating IkappaBalpha.

Activation of the nitric oxide/cGMP pathway is required for refilling intracellular Ca2+ stores in a sympathetic neuron cell line

Fura-2 fluorescence imaging was used to measure changes in intracellular Ca2+ concentration in individual N1E-115 neuroblastoma cells during repeated activation of M1 muscarinic receptors with carbachol. Ca2+ transients could be elicited repeatedly at 4 min intervals with little decrement as long as external Ca2+ was present. When the cells were bathed in Ca(2+)-free saline, however, the response amplitude decreased rapidly in a use-dependent fashion, indicating that external Ca2+, and presumably Ca2+ influx, is required for refilling Ca2+ stores during the interval between trials. The response amplitude also decreased during repeated stimulation in cells treated with the NO-synthase inhibitor L-NMMA or with the guanylyl cyclase inhibitor LY-83583 even when Ca2+ was present. Application of the membrane permeable cGMP analog 8-Br-cGMP reversed the effect of L-NMMA and promoted refilling in the continued presence of NO-synthase inhibitor. These results indicate that activation of the NO/cGMP pathway is necessary for refilling Ca2+ stores during muscarinic signaling. Evidence is also presented suggesting that the NO/cGMP pathway is involved in long term modulation of the content of Ca2+ stores.

Binding of a CTF/NF1-like protein to the mouse colony-stimulating factor-1 gene promoter

Circulating and tissue-specific monocytes/macrophages, through production of hydrolytic enzymes and growth factors, can dramatically affect the local tissue environment. Colony-stimulating factor-1 (CSF-1) is a key regulator of monocyte/macrophage cell activity. CSF-1 is produced by stromal elements, including fibroblasts, which are found in all tissues. To understand at the molecular level how changes in CSF-1 gene transcription are initiated in fibroblasts, we set out to identify the cis-acting elements and cognate trans-acting factor(s) that bind regulatory regions of the mouse CSF-1 gene. Analysis of heterologous reporter constructs containing the mouse CSF-1 promoter linked to the bacterial chloramphenicol acetyltransferase (CAT) gene in transiently transfected fibroblasts identified a cis-acting element located between base pairs -88 and -43 of the CSF-1 gene. Electrophoretic mobility-shift assays (EMSAs) and DNase I protection assays with nuclear extracts isolated from proliferating fibroblasts revealed distinct protein binding to the region spanning base pairs -90 to -68. Results from methylation interference assays suggest CTF/NF1 or a CTF/NF1-like factor is the cognate trans-acting factor. Mutation of the putative CTF/NF1 binding site in the CSF-1 promoter lead to a modest decrease in promoter activity in transiently transfected fibroblasts and monocytes. Therefore, we have demonstrated that CTF/NF1 or a CTF/NF1-like protein binds to the CSF-1 gene promoter; however, binding of the CTF/NF1-like protein alone does not significantly effect changes in CSF-1 gene promoter activity.

Agonist-induced desensitization and loss of high-affinity binding sites of stably expressed human 5-HT1A receptors

Exposure of HeLa cells stably expressing cloned human 5-hydroxytryptamine (5-HT)1A receptors (HA7 cells) to the agonist 8-hydroxy-2-(di-N-propylamino)-tetralin (8-OH-DPAT) results in a loss of high-affinity binding sites and a desensitization of receptor-adenylate cyclase coupling, as measured by 5-HT1A-mediated inhibition of forskolin-stimulated adenylate cyclase activity. These responses can also be observed after exposure to forskolin, which activates cyclic AMP-dependent protein kinase A or after treatment with known activators of protein kinase C (PKC) such as phorbol-12-myristate 13-acetate (PMA). The responses elicited by exposure to 8-OH-DPAT or PMA can be blocked completely by inhibitors of PKC and also by 24-hr exposure to PMA. Preincubation of HA7 cells with 8-OH-DPAT also stimulates hydrolysis of inositol phospholipids and the production of arachidonic acid. Inhibition of phospholipase A2 with quinacrine or by removal of extracellular Ca++ blocks the agonist-mediated loss of 5-HT1A receptor binding sites. These data demonstrate that agonist-induced down regulation of the 5-HT1A receptor occurs after stimulation of both the PKC and phospholipase A2 signaling pathways, both of which may activate PKC. The subsequent response is a loss of high-affinity ligand binding sites and functional receptor coupling to adenylate cyclase.

Inhibition of colony-stimulating factor-1 promoter activity by the product of the Wilms' tumor locus

Colony-stimulating factor-1 (CSF-1) is a member of the immediate early gene family, which is expressed in mitogen-stimulated quiescent fibroblasts. The biological effects of CSF-1 are multifaceted and include stimulation of the proliferation and differentiation of myeloid progenitors and activity of circulating monocytes and tissue-specific macrophages. Ablation of circulating levels of biologically active CSF-1 in mice leads to osteopetrosis and sterility, thus implicating a role for CSF-1 in bone remodeling and implantation. Identification of regulatory elements and cognate transcription factors that bind the csf-1 promoter and mediate such diverse expression patterns is of great interest. We identified a sequence element at -273 to -265 (relative to the transcription initiation site) in the murine csf-1 promoter, which contains overlapping consensus sequences for the Wilms' tumor protein (WT1), EGR-1, SP1, and SP3 proteins. WT1 and EGR-1 proteins produced in vitro bound to this sequence, and co-transfection of wt1 with a csf-1-cat reporter plasmid resulted in repression of promoter activity. Interestingly, nuclear extracts prepared from serum-stimulated C3H10T1/2 cells contained predominantly SP1 and SP3 binding activities, which recognized the -273 to -265 site. Thus repression of the csf-1 promoter by WT1 at this site may involve competition between SP1 family transcriptional activators and the WT1 repressor. Colony-stimulating factor-1 may be a physiologically relevant target gene for regulation by the WT1 transcription factor.

Modulation of myogenic determination factor 1 expression by cell-cell contact

Myogenic determination factor 1 (MyoD1) expression is modulated by a variety of agents including growth factors and activated cellular proto-oncogenes. However, little is known about the effect of cell-cell contact, which increases as myoblasts terminally differentiate, on the control of MyoD1 expression. Steady-state levels of MyoD1 transcripts decline over a 6-12 hour time period when myoblasts plated at a single cell density are incubated in media supplemented with 0.2% serum; by 48 hours MyoD1 mRNA levels have returned to the initial basal level. The decline in MyoD1 transcripts is diminished, but not prevented in myoblasts which maintain cell-cell contacts (at least 50% of cells with two or more sites of contact). MyoD1 transcript levels do not change if single cell cultures are maintained in 10% serum or are cocultured with fibroblasts. Analysis of conditioned media revealed that myoblasts plated at the single cell density or at a density which allowed multiple sites of cell-cell contact are not producing an activity(s) responsible for modulating MyoD1 mRNA levels. The changes in MyoD1 expression are mediated at the transcriptional level. Thus changes in the degree of cell-cell contact in cultures of myogenically determined cell lines effect changes in MyoD1 gene expression. Consequently when the influence of cytokines or other pharmacological agents on commitment to terminal myogenic differentiation is examined, the degree of cell-cell contact within the culture system may affect the response elicited.

Adeno-associated virus 2-mediated gene transfer in murine hematopoietic progenitor cells

Recombinant human adeno-associated virus 2 (AAV) virions were constructed containing a gene for resistance to neomycin (neoR), under the control of either the herpesvirus thymidine kinase (TK) promoter (vTK-Neo), the murine colony-stimulating factor-1 (CSF-1) promoter (vCSF1-Neo) or the CSF-1 promoter plus an upstream human erythroid cell-specific enhancer, HS-2 (vHS2-CSF1-Neo). Recombinant virions were used to infect low-density murine primary bone marrow cells. In hematopoietic progenitor cell assays initiated with cells infected with these recombinant virions, myeloid as well as erythroid cell colonies resistant to the drug G418, a neomycin analogue, were readily obtained, indicating that the murine hematopoietic progenitor cells were susceptible to infection by the recombinant AAV virions and that the transduced neo gene was functionally active in these cells. Whereas only approximately 10% of the colony-forming unit-granulocyte/macrophage (CFU-GM) colonies cloned from mock-infected cells survived the G418-selection at a final active concentration of 250 micrograms/mL of the drug, the extent of the CFU-GM colony formation initiated with the recombinant AAV-Neo virions was as follows: 15% with vTK-Neo, 22% with vCSF1-Neo and 49% with vHS2-CSF1-Neo. In addition, only 14% of the burst-forming unit-erythroid (BFU-E) colonies from mock-infected cells were resistant to G418, whereas 82% of the BFU-E colonies initiated with cells infected with vHS2-CSF1-Neo virions survived the drug selection, suggesting that a human erythroid cell-specific enhancer was able to potentiate expression of the transduced neoR gene from a murine promoter. Individual CFU-GM and BFU-E colonies from mock-infected or recombinant AAV-Neo virus-infected cultures were subjected to polymerase chain reaction (PCR) analysis using a neo-specific synthetic oligonucleotide primer-pair. A 276 bp DNA fragment that hybridized with a neo-specific DNA probe on Southern blots was detected only in colonies cloned from the recombinant virus-infected cells, indicating stable integration of the transduced neo gene. These studies suggest the feasibility of using the AAV-based vector system in an animal model as a prelude to evaluating its safety and efficacy in human gene therapy.

Regulation of myelopoiesis by murine fibroblastic and adipogenic cell lines

The regulation of hematopoiesis has been suggested to take place in close association with various cell types found in the bone marrow (BM) microenvironment. In the present study the role of fibroblasts, adipocytes and cell surface heparan sulfate in regulating hematopoiesis in an in vitro mouse system was examined. Mouse BM cells were allowed to adhere to a mouse embryo fibroblast cell line (C3H 10T1/2) or a clonally derived adipogenically determined derivative (Clone D) of the 10T1/2 cell line. Nonadherent cells were removed, cultures were overlaid with semisolid media supplemented with growth factors and colony formation by granulocyte-macrophage (CFU-GM), erythroid (BFU-E) and multipotential (CFU-GEMM) progenitor cells was quantitated. Adherence and co-culture of BM cells with the fibroblast cell line resulted in increased numbers of total CFU-GM and CFU-GEMM colonies. In contrast, adherence and co-culture of BM cells with the adipocytic cell line resulted in an increase only in CFU-GEMM colonies. Morphological analysis revealed a preferential adherence/growth of granulocyte and macrophage progenitors at the expense of bipotent granulocyte-macrophage progenitors to the fibroblastic cell line and an increase in the adherence/growth of granulocyte progenitors to the adipogenic cell line. Progenitor cell adherence was abolished when the fibroblastic or adipocytic cell lines were pretreated with heparitinase. These results demonstrate enhanced proliferation/differentiation of hematopoietic progenitor cells when there is direct contact between hematopoietic progenitors and cell types characteristic of those found in the microenvironment and that heparan sulfate and different types of stromal cells appear to play different roles in this interaction.

Geometric properties and the predicted mechanical behavior of adult human clavicles

An image processing system was used to examine histomorphometric properties of 15 adult male and female human clavicles. Variations in porosity, cross-sectional area, anatomic and principal moments of inertia were assessed at 2.5-5.0% increments along the length of the clavicles. The clavicle's biomechanical behavior (axial, flexural, and torsional rigidities and the critical force for buckling) was modeled from these data using beam theory. Over threefold variations in porosity and moments of inertia were found along the length of the s-shaped clavicle--the greatest porosity and moments of inertia were located in the variably shaped sternal and acromial thirds of the bone in contrast to the denser and smaller, more circulatory shaped central third of the bone. Clavicle orientation, as indicated by the direction of greatest resistance to bending (maximum principal moment of inertia), was found to rotate from a primarily cranio-caudal orientation at the sternum to a primarily anterior-posterior orientation at the acromion. Based on cross-sectional geometry, section moduli, and estimates of flexural and torsional rigidity, the clavicle was found to be weakest in the central third of its length. These data concur with the fracture location most commonly reported clinically. Analysis of Euler buckling predicted a minimum critical force for buckling during axial loading of approximately two to three body weights for an average adult. Thus, buckling, or a combination of axial loading and bending or torsional loading, must be considered as possible failure mechanisms for this commonly injured bone.

Detection of human myeloid progenitor cells in a murine background

Cell-mixing experiments were performed to determine whether human (hu) peripheral blood plasma would select for the growth of hu myeloid progenitor cells in vitro. Mixtures of hu male umbilical cord blood and murine (mu) female bone marrow (100% hu, 100% mu, 1.0% hu or 10% hu and 50% hu) were plated in methylcellulose cultures that contained either hu plasma or fetal bovine serum (FBS). Cultures were supplemented with recombinant (r) hu erythropoietin (Epo) alone or in combination with rhu granulocyte-macrophage colony stimulating factor (GM-CSF), rmuGM-CSF or rhu steel factor (SLF). DNA was extracted from day 14 colonies and clusters, and the polymerase chain reaction (PCR) was used to detect the hu Y-chromosome satellite DNA sequence. Results of these studies revealed that hu plasma used in combination with hu growth factors selected for the growth of hu progenitor cells. Mu cells grew in hu plasma only at high cell-plating concentrations. This selective effect was due to a heat labile factor or factors, since mu cells grew equally well in heat-inactivated hu plasma and FBS. Cells in individual progenitor cell colonies and clusters cultured in hu plasma contained hu Y-chromosome-specific DNA sequences that were detectable after PCR-mediated amplification, thus eliminating the need for time-consuming Southern transfer. This study describes a method whereby hu/immune-deficient mice can be screened rapidly for hu myeloid engraftment. These results also indicate that the hu identity of colonies and clusters cultured in hu plasma must be genetically confirmed, especially when hu cells may represent a low percentage of the total cells plated.

Molecular biology of serotonin receptors

The past decade has seen an explosive growth in our understanding of neurotransmitter receptors and the roles they play in neurotransmission. This is particularly true of the serotonin receptors where a synergy of basic science and clinical research has not only produced a deeper understanding of serotonin receptors and their actions but also resulted in the availability of new therapeutic agents useful for treating a number of psychiatric illnesses. This chapter details our current knowledge of the major subtypes of the serotonin receptor, including recent advances in the molecular biology, pharmacology, biochemistry, and clinical correlates of these receptors.

Interleukin 1 alpha mediated inhibition of myogenic terminal differentiation: increased sensitivity of Ha-ras transformed cultures

The commitment of myogenically determined cells to terminal differentiation can be modulated by a variety of agents, including growth factors and activated oncogenes. We have examined the effect of interleukin 1 alpha (IL-1 alpha) on the terminal differentiation of a normal myogenically determined cell line and two myogenically determined, differentiation competent cell lines which contain either one or six copies of the activated c-Ha-ras oncogene. Treatment of all cell lines with IL-1 alpha decreased but did not totally inhibit terminal myogenic differentiation. Over the range of IL-1 alpha concentrations assayed (1-40 ng/ml), the c-Ha-ras transformed cell lines demonstrated a significantly greater sensitivity to the inhibitory effects of IL-1 alpha. The inhibition of differentiation was not the result of enhanced proliferation. Interestingly, transformation with activated c-Ha-ras resulted in a decrease in IL-1 alpha receptor number and affinity. The enhanced IL-1 alpha responsiveness of the ras transformants was not the result of increased proliferation or changes in either ras gene expression or protein kinase C activity. IL-1 alpha treatment decreased the steady-state levels of both MyoD1 and myogenin transcripts in the c-Ha-ras transformed but not the normal myogenic cell line. Further studies are required to determine the mechanism(s) responsible for the increased sensitivity of the c-Ha-ras transformed cultures to the inhibitory effects of IL-1 alpha.

Differential transcriptional and posttranscriptional regulation of gene expression of the colony-stimulating factors by interleukin-1 and fetal bovine serum in murine fibroblasts

Colony-stimulating factors (CSF) are important factors in the proliferation and differentiation of hematopoietic progenitor cells (HPC), and in the survival and activation of mature blood cells. Interleukin-1 (IL-1) combined with fetal bovine serum (FBS) strongly induces the expression of macrophage-CSF (M-CSF), granulocyte-CSF (G-CSF), and granulocyte-macrophage-CSF (GM-CSF) in fibroblasts. Here, we report on the regulation of CSF gene expression in murine fibroblasts following IL-1 and FBS stimulation. We demonstrate that 10T1/2 murine fibroblasts induced by FBS or IL-1 accumulate M-CSF messenger RNA (mRNA). G-CSF mRNA expression was induced by IL-1, and not by FBS. For GM-CSF expression, induction with both FBS and IL-1 was required. Blocking studies with actinomycin-D showed that active transcription is essential for accumulation of all three CSF mRNAs. After blocking protein synthesis with cycloheximide, IL-1- or FBS-induced M-CSF expression and IL-1 plus FBS-induced GM-CSF expression still occurred and was increased. IL-1-induced G-CSF expression was completely prevented in these cells by pretreatment with cycloheximide, illustrating that, for this effect, intermediate protein synthesis was required. The half-lives of M-CSF transcripts were not substantially altered by addition of IL-1, FBS, or FBS plus IL-1. Using nuclear run-on assays, we demonstrated that the transcription rate of M-CSF was increased up to 20-fold by the addition of FBS, IL-1, or FBS plus IL-1. After blocking protein synthesis with cycloheximide, IL-1-or FBS-induced increase in M-CSF transcription rate was also observed. GM-CSF transcription increased up to fourfold after induction with FBS or IL-1. G-CSF transcription rate was not altered by FBS or IL-1. Our results indicate that M-CSF expression induced by FBS or IL-1 in these fibroblasts is primarily regulated at the transcriptional level. GM-CSF expression appears to be regulated both transcriptionally and posttranscriptionally, and G-CSF expression is regulated mainly at the posttranscriptional level.

Cloning and characterization of the murine promoter for the colony-stimulating factor-1-encoding gene

Colony-stimulating factor-1 (CSF-1 or M-CSF) is required for the growth and differentiation of macrophage progenitors, and for the survival of mature macrophages. Expression of the CSF-1 gene in monocytes and fibroblasts is controlled at both the transcriptional and post-transcriptional levels. To study the molecular mechanisms which mediate changes in CSF-1 expression, the 5' promoter region of the mouse CSF-1 gene was cloned. A high degree of structural and sequence similarity between the mouse and human CSF-1 genes was observed. A transcription start point was located 182 bp upstream from the start codon. Several sequences homologous to known cis-acting elements were identified in the 5'-flanking region. The CSF-1 promoter region was able to direct expression of a linked reporter gene in C3H10T1/2 mouse embryo fibroblasts. Deletion in the CSF-1 promoter region between bp -774 and -629 resulted in a significant decrease in promoter activity. The identification of a functional promoter for CSF-1 will serve as a valuable tool for studying the regulation of CSF-1 expression.

Effect of split low dose total body irradiation on SFFV mRNA, genomic DNA and protein expression in mice infected with the Friend virus complex

DBA/2 mice infected with lethal dosages of Friend virus complex (FVC) can be 100% cured by split-dose total body irradiation (TBI) at 150 cGy, an effect associated with the restoration of the cellular immunity which is compromised by the virus. The exact mechanism underlying the curative effect is unknown, but it may involve the interferon (IFN) system and interleukin-2 (IL-2) production. Initial studies indicated that TBI did not directly inactivate the virus, suggesting that irradiation either acted on the target cells for virus replication or on other cells mediating the effect. We have now examined the effect of this relatively low dose TBI on replication, transcription, and protein expression of the Friend virus. Northern blot analysis revealed that in FVC infected mice treated with curative low dose TBI, no spleen focus-forming virus (SFFV)-specific mRNA species were detected. Southern blot analysis revealed that a 6.0 kb SFFV fragment could be detected in infected, untreated spleen cells, but not in cells from FVC-infected mice treated with TBI, or in uninfected spleen cells. Western blot analysis revealed that the SFFV envelope glycoprotein was expressed in the spleen cells from untreated FVC infected mice, but not in the cells from TBI treated FVC infected mice. These results, consistent with our previous findings of greatly reduced spleen focus forming units in mice with FVC which had been treated with this regimen of TBI, suggest the possibility of using such treatments in other retroviral associated disorders.

Structural determinants of 5-HT1A versus 5-HT1D receptor binding site selectivity

A structure-activity analysis was used to identify selective 5-HT1A versus 5-HT1D receptor agents. An analysis of published data identified 13 drugs which display nanomolar affinity for the 5-HT1A receptor and that have been analyzed at 5-HT1D receptor binding sites. Four agents display greater than or equal to 100-fold selectivity for the 5-HT1A receptor. Two structural features were identified which hypothetically result in selectivity for 5-HT1A versus 5-HT1D binding sites. The linkage of an indole ring to a basic nitrogen atom via the 4 position on the indole ring or the absence of an indole ring are two features which lower the affinity for the 5-HT1D receptor, but do not necessarily lower the affinity for the 5-HT1A receptor. A series of 7 agents (5 indoles, 2 quinolines) was identified which met these hypothetical selectivity criteria. These compounds were then analyzed in radioligand binding studies. These 7 agents display affinities of 1.3-170 nM for the 5-HT1A receptor binding site, and 1,800-13,000 nM for the 5-HT1D receptor binding site. All 7 agents display greater than or equal to 47-fold selectivity for the 5-HT1A versus 5-HT1D site and 4 of the agents are greater than 100-fold selective. Compound No. 1 (N,N'-bis[3-(4-indolyloxy)-2-hydroxypropyl]-(Z)-1,8-diamino-p-meth ane) and compound No. 2 (N8-[3-(4-indolyloxy)-2-hydroxypropyl]-N1-(propioloyl)-(Z)-1 ,8-diamino-p-methane) are the most selective agents yet described for 5-HT1A versus 5-HT1D receptor binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of myogenic and adipogenic differentiation on expression of colony-stimulating factor genes

The influence of cellular differentiation on colony-stimulating factor gene expression was examined in myogenically and adipogenically determined cell lines derived from 5-azacytidine-treated C3H10T1/2 C18 (10T1/2) mouse embryo fibroblasts. These studies demonstrate that colony-stimulating factor gene expression can be modulated by myogenic and adipogenic determination and terminal differentiation.

Gene-expression and release of macrophage-colony stimulating factor in quiescent and proliferating fibroblasts. Effects of serum, fibroblast growth-promoting factors, and IL-1

Macrophage (M)-CSF induces the proliferation and differentiation of macrophage-precursor cells, and is an important factor in the survival and activation of mature mononuclear phagocytes. Several effector cell populations such as mononuclear phagocytes, endothelial cells, and fibroblasts, have been reported to produce M-CSF at high levels. We investigated the gene-expression and release of M-CSF in fibroblasts. Quiescent, growth-arrested, fibroblasts showed little expression of M-CSF as demonstrated by Northern blot analysis, and little production of M-CSF as measured in the murine bone marrow bioassay. Initiation of proliferation of fibroblasts by fetal bovine serum was followed by an increase in M-CSF transcription and release of the protein. Similarly, single factors (platelet-derived growth factor) or combinations of factors (epidermal growth factor (EGF) + insulin, platelet-derived growth factor + EGF + insulin, or fibroblast growth factor + EGF + insulin) that induced proliferation of the fibroblasts, also induced increased expression of M-CSF. As soon as 1 h after the addition of fetal bovine serum, M-CSF expression was increased, and reached a plateau at 2 to 8 h after induction. IL-1 increased M-CSF expression both in quiescent and proliferating fibroblasts, and induced the expression and release of granulocyte-, and granulocyte/macrophage-CSF. These results show that expression of M-CSF in fibroblasts is not constitutively at a high level, but undergoes regulation depending on the cellular proliferative state and on further activation by acute response proteins such as IL-1.

Gene-expression and release of macrophage-colony stimulating factor in quiescent and proliferating fibroblasts. Effects of serum, fibroblast growth-promoting factors, and IL-1

Macrophage (M)-CSF induces the proliferation and differentiation of macrophage-precursor cells, and is an important factor in the survival and activation of mature mononuclear phagocytes. Several effector cell populations such as mononuclear phagocytes, endothelial cells, and fibroblasts, have been reported to produce M-CSF at high levels. We investigated the gene-expression and release of M-CSF in fibroblasts. Quiescent, growth-arrested, fibroblasts showed little expression of M-CSF as demonstrated by Northern blot analysis, and little production of M-CSF as measured in the murine bone marrow bioassay. Initiation of proliferation of fibroblasts by fetal bovine serum was followed by an increase in M-CSF transcription and release of the protein. Similarly, single factors (platelet-derived growth factor) or combinations of factors (epidermal growth factor (EGF) + insulin, platelet-derived growth factor + EGF + insulin, or fibroblast growth factor + EGF + insulin) that induced proliferation of the fibroblasts, also induced increased expression of M-CSF. As soon as 1 h after the addition of fetal bovine serum, M-CSF expression was increased, and reached a plateau at 2 to 8 h after induction. IL-1 increased M-CSF expression both in quiescent and proliferating fibroblasts, and induced the expression and release of granulocyte-, and granulocyte/macrophage-CSF. These results show that expression of M-CSF in fibroblasts is not constitutively at a high level, but undergoes regulation depending on the cellular proliferative state and on further activation by acute response proteins such as IL-1.

A RAS oncogene imparts growth factor independence to myeloid cells that abnormally regulate protein kinase C: a nonautocrine transformation pathway

The factor-dependent cell line FDC-P1 has been utilized as a model of interleukin 3 (IL-3)-dependent myeloid cell proliferation. However, it has been recently observed that active phorbol esters (e.g., phorbol 12-myristate 13-acetate) may entirely replace IL-3 to promote its proliferation. These observations reveal abnormal regulation of protein kinase C (pkC) (absence of downregulation or overexpression). This property allowed a test of the hypothesis that the T24 RAS (codon 12) oncogene acts by constitutive and persistent pkC activation, driving proliferation. FDC-P1 cells were transfected by electroporation with the T24 RAS-containing vector pAL 8, or with a control vector pSVX Zip Neo, and neomycin-resistant clones were selected. Multiple RAS-transfectant clones were categorized for their growth factor requirement and incorporation of the 6.6-kb human mutant H-RAS genome. IL-3-independent clones had incorporated multiple (more than two) copies of the entire 6.6-kb RAS genome. The incorporation of multiple 6.6-kb RAS genomes was correlated with high-level p21 RAS expression. No evidence for autostimulatory growth factor production by clones containing the RAS oncogene was observed. Thus, acquisition of growth factor independence in myeloid cells by abundant expression of a RAS oncogene is linked, in part, to abnormal regulation of pkC, which acts as a collaborating oncogene.

Methylation and expression of the Myo D1 determination gene

Mouse embryo cells induced to differentiate with the demethylating agent 5-azacytidine represent an excellent model system to investigate the molecular control of development. Clonal derivatives of 10T1/2 cells that have become determined to the myogenic or adipogenic lineages can be isolated from the multipotential parental line after drug treatment. These determined derivatives can be cultured indefinitely and will differentiate into end-stage phenotypes on appropriate stimulation. A gene called Myo D1, recently isolated from such a myoblast line, will confer myogenesis when expressed in 10T1/2 or other cell types (Davis et al. 1987). The cDNA for Myo D1 contains a large number of CpG sequences and the gene is relatively methylated in 10T1/2 cells and an adipocyte derivative, but is demethylated in myogenic derivatives. Myo D1 may therefore be subject to methylation control in vitro. On the other hand, preliminary observations suggest that Myo D1 is not methylated at CCGG sites in vivo so that a de novo methylation event may have occurred in vitro. These observations may have significance in the establishment of immortal cell lines and tumours.

Differential modulation of 5-hydroxytryptamine1D binding sites by GTP and GTPgammaS

Incubation of bovine caudate membranes with 10(-4) M GTP results in a competitive inhibition of 5-hydroxytryptamine1D (5-HT1D) receptor binding sites labeled by [3H]5-HT. By contrast, incubation of bovine caudate membranes with 10(-4) M GTPgammaS, a non-hydrolyzable analog of GTP, results in a decrease in both the apparent affinity (Kd) and density (Bmax) of 5-HT1D binding sites. The Kd is increased by 67 +/- 8%, (P less than 0.01, n = 12) while the Bmax is reduced by 52 +/- 10% in comparison with control values (P less than 0.05, n = 12). Pre-incubation studies indicate that GTPgammaS-induced changes in 5-HT1D receptors are persistent and time-dependent. These results indicate that GTPgammaS induces non-competitive changes in 5-HT1D receptor-G-protein interactions that are reflected as a decrease in the affinity and density of binding sites labeled by [3H]5-HT.

Modulation of 5-hydroxytryptamine1A receptor density by nonhydrolyzable GTP analogues

Co-incubation of rat cortical membranes with 10(-4) M GTP results in a competitive inhibition of 5-hydroxytryptamine1A (5-HT1A) receptor binding sites labeled by [3H]8-hydroxy-2-(di-n-propylamino)tetralin [( 3H]8-OH-DPAT). Preincubation of cortical membranes with 10(-4) M GTP does not significantly change either KD or Bmax values, indicating that the effect of GTP is reversible. By contrast, GTP gamma S and 5'-guanylylimidodiphosphate (GppNHp) are nonhydrolyzable analogues of GTP which lengthen the time course of guanine nucleotide activation of guanine nucleotide binding proteins (G proteins) and thereby alter G protein-receptor interactions. These nonhydrolyzable GTP analogues were used to characterize the effects of persistent alterations in G proteins on [3H]8-OH-DPAT binding to 5-HT1A receptors. Co-incubation of rat cortical membranes with either 10(-4) M GTP gamma S or GppNHp results in a decrease in both the affinity and apparent density of 5-HT1A binding sites. Co-incubation with the nonhydrolyzable nucleotides reduces the affinity of [3H]8-OH-DPAT binding by 65-70% and lowers the density of the binding site by 53-61%. Similarly, preincubation of membranes with a 10(-4) M concentration of either GTP gamma S or GppNHp significantly increases the KD value and reduces the Bmax value of [3H]8-OH-DPAT binding. These results indicate that GTP gamma S and GppNHp induce persistent changes in 5-HT1A receptor-G protein interactions that are reflected as a decrease in the density of binding sites labeled by [3H]8-OH-DPAT.

6-substituted tricyclic partial ergoline compounds are selective and potent 5-hydroxytryptamine1A receptor agents

A series of 6 tricyclic partial ergoline derivatives was analyzed using radioligand binding assays. Four agents (LY 178210, LY 254089, LY 197205, and LY 197206) display high affinity (Ki less than or equal to 1.3 nM) for 5-hydroxytryptamine1A (5-HT1A) receptor binding sites labeled by [3H]8-hydroxy- 2-(di-n-propylamino) tetralin (8-OH-DPAT) and display greater than or equal to 150 fold selectivity for the 5-HT1A over the 5-HT1D receptor binding site. The most potent agent investigated, LY 178210, is essentially inactive (Ki greater than 1500 nM) at a total of 12 other neurotransmitter receptor binding sites in the brain. Using a forskolin-stimulated adenylate cyclase assay as a model of 5-HT1A receptor function, LY 178210 was found to display partial agonist activity which was blocked by 10(-5) M (-)pindolol. These data indicate that LY 178210 is a potent and selective 5-HT1A receptor partial agonist.

A mutant RAS gene acts through protein kinase C to augment interleukin-3 dependent proliferation in a fastidious immortal myeloid cell line

The functional role of a mutant RAS gene in immortal myeloid cell proliferation was examined in a fastidious interleukin-3 (IL-3) dependent cell line (NFS/N1.H7) formed by forced proliferation in IL-3 of marrow cells of the NFS/N mouse. The NFS/N1.H7 cell line was strictly dependent upon IL-3 for growth, and the cell line could be activated by phorbol esters (PMA) to augment IL-3 dependent proliferation, but when pKC was downregulated, diminished IL-3 proliferative response resulted. Transfection (electroporation) of the T24 RAS-containing vector pAL8 to NFS/N1.H7 led to clones (H7 NeoRas.F3, H7 NeoRas.E2) that had incorporated the entire 6.6 Kb human mutant H-RAS genome. The mutant RAS-containing clones demonstrated greater proliferation than parent cells or cells containing a control (neo-resistance) vector over a range of suboptimal IL-3 does and in optimal IL-3 concentrations had a faster doubling rate than parent cells. The clone H7 NeoRas.F3 was studied biochemically, and found to constitutively form 3-fold more 3H-diacylglycerol than the parent cell line upon exposure to 3H-glycerol. PMA could partially repair the proliferative defect of NFS/N1.H7 compared to the RAS-expressor. These studies affirm a secondary, accelerating role for a mutant RAS gene product acting through pKC to promote clonal expansion of immortal myeloid cells stimulated by IL-3.

Effect of cellular determination on oncogenic transformation by chemicals and oncogenes

Three developmentally determined myogenic cell lines derived from C3H 10T1/2 C18 (10T1/2) mouse embryo cells treated with 5-azacytidine were compared with the parental 10T1/2 line for their susceptibility to oncogenic transformation by 3-methylcholanthrene or the activated human c-Ha-ras oncogene. Neither the 10T1/2 cells nor the myogenic derivatives grew in soft agar or formed tumors in nude mice. In contrast to 10T1/2 cells, the three myogenic derivatives were not susceptible to transformation by 3-methylcholanthrene, so that cellular determination altered the response of 10T1/2 cells to chemical carcinogen. On the other hand, all cell types were transformed to a tumorigenic phenotype following transfection with the activated c-Ha-ras gene. The transfected myogenic cells expressed both the c-Ha-ras gene and the muscle determination gene MyoD1. In contrast to other reports, the presence of as many as six copies of the c-Ha-ras gene per genome did not prevent the formation of striated muscle cells which expressed immunologically detectable muscle-specific myosin. The expression of the c-Ha-ras gene does not therefore necessarily preclude the expression of the determination gene for myogenesis or prevent end-stage myogenic differentiation.

(R)-(-)-[77Br]4-bromo-2,5-dimethoxyamphetamine labels a novel 5-hydroxytryptamine binding site in brain membranes

(R)-(-)-[77Br]4-Bromo-2,5-dimethoxyamphetamine [(R)-(-)-[77Br] DOB] was synthesized to a high specific activity (1875 +/- 50 Ci/mmol) and used to label membrane-associated recognition sites in rat brain. (R)-(-)-[77Br]DOB displayed high affinity (KD = 0.60 +/- 0.08 nM) for a relatively low density of binding sites (Bmax = 1.2 +/- 0.08 pmol/g of tissue) in rat cortical membranes as compared with [3H]ketanserin (KD = 0.65 +/- 0.1 nM; Bmax = 6.2 +/- 0.6 pmol/g of tissue). Guanine, but not adenine, nucleotides were found to inhibit specific (R)-(-)-[77Br]DOB binding. GTP (10(-4) M) did not eliminate specific (R)-(-)-[77Br]DOB binding but caused a competitive inhibition of the radioligand. Drug competition studies of 5-hydroxytryptamine (5-HT) and related agents indicate that both putative agonists and antagonists display nanomolar potency for these sites. A significant correlation (p less than 0.01) exists between drug potencies for (R)-(-)-[77Br]DOB-labeled sites and both 5-HT2 (r = 0.64) and 5-HT1C (r = 0.68) binding sites. However, the sites do not appear to be identical. Moreover, a significant correlation exists between drug potencies for (R)-(-)-[77Br]DOB-labeled sites and human hallucinogenic drug potencies (r = 0.89; p less than 0.01). We conclude that (R)-(-)-[77Br]DOB labels a unique 5-HT recognition site in rat brain that does not coincide with previously described 5-HT binding site subtypes. The (R)-(-)-[77Br]DOB site does not appear to be a high affinity "state" of the 5-HT2 receptor but may label a subset of heterogeneous 5-HT2 recognition sites.