Ras activation of genes: Mob-1 as a model

CXCL9-11 chemokines and CXCR3 receptor in teleost fish species

The coordinated migration of immune cells from lymphoid organs to in or out of the bloodstream, and towards the site of infection or tissue damage is fundamental for an efficient innate and adaptive immune response. Interestingly, an essential part of this movement is mediated by chemoattractant cytokines called chemokines. Although the nature and function of chemokines and their receptors are well documented in mammals, much research is needed to accomplish a similar level of understanding of the role of chemokines in fish immunity. The first chemokine gene identified in teleosts (rainbow trout, Oncorhynchus mykiss) was CK1 in 1998. Since then, the identification of fish chemokine orthologue genes and characterization of their role has been more complex than expected, primarily because of the whole genome duplication processes occurring in fish, and because chemokines evolve faster than other immune genes. Some of the most studied chemokines are CXCL9, CXCL10, CXCL11, and the CXCR3 receptor, all involved in T cell migration and in the induction of the T helper 1 (Th1) immune response. Data from the zebrafish and rainbow trout CXCL9-11/CXCR3 axis suggest that these chemokines and the receptor arose early in evolution and must be present in most teleost fish. However, the pieces of knowledge also indicate that different numbers of gene copies can be present in different species, with distinct regulatory expression mechanisms and probably, also with different roles, as the differential expression in fish tissues suggest. Here, we revised the current knowledge of the CXCL9-11/CXCR3 axis in teleost fishes, identifying the gaps in knowledge, and raising some hypotheses for the role of CXCL9, CXCL10 CXCL11, and CXCR3 receptor axis in fish, which can encourage further studies in the field.

The Involvement of CXC Motif Chemokine Ligand 10 (CXCL10) and Its Related Chemokines in the Pathogenesis of Coronary Artery Disease and in the COVID-19 Vaccination: A Narrative Review

Coronary artery disease (CAD) and coronary heart disease (CHD) constitute two of the leading causes of death in Europe, USA and the rest of the world. According to the latest reports of the Iranian National Health Ministry, CAD is the main cause of death in Iranian patients with an age over 35 years despite a significant reduction in mortality due to early interventional treatments in the context of an acute coronary syndrome (ACS). Inflammation plays a fundamental role in coronary atherogenesis, atherosclerotic plaque formation, acute coronary thrombosis and CAD establishment. Chemokines are well-recognized mediators of inflammation involved in several bio-functions such as leucocyte migration in response to inflammatory signals and oxidative vascular injury. Different chemokines serve as chemo-attractants for a wide variety of cell types including immune cells. CXC motif chemokine ligand 10 (CXCL10), also known as interferon gamma-induced protein 10 (IP-10/CXLC10), is a chemokine with inflammatory features whereas CXC chemokine receptor 3 (CXCR3) serves as a shared receptor for CXCL9, 10 and 11. These chemokines mediate immune responses through the activation and recruitment of leukocytes, eosinophils, monocytes and natural killer (NK) cells. CXCL10, interleukin (IL-15) and interferon (IFN-g) are increased after a COVID-19 vaccination with a BNT162b2 mRNA (Pfizer/BioNTech) vaccine and are enriched by tumor necrosis factor alpha (TNF-α) and IL-6 after the second vaccination. The aim of the present study is the presentation of the elucidation of the crucial role of CXCL10 in the patho-physiology and pathogenesis of CAD and in identifying markers associated with the vaccination resulting in antibody development.

Ras-induced modulation of CXCL10 and its receptor splice variant CXCR3-B in MDA-MB-435 and MCF-7 cells: relevance for the development of human breast cancer

Interactions between chemokines and chemokine receptors have been proposed recently to be of importance in the development and progression of cancer. Human breast cancer cells express the chemokine CXCL10 (IP-10) and also its receptor CXCR3. In this study, we have investigated the role of Ras activation in the regulation of CXCL10 and its receptor splice variant CXCR3-B in two human breast cancer cell lines MDA-MB-435 and MCF-7. In cotransfection assays, using a full-length CXCL10 promoter-luciferase construct, we found that the activated form of Ras, Ha-Ras(12V), promoted CXCL10 transcriptional activation. Ras significantly increased CXCL10 mRNA and protein expression as observed by real-time PCR, fluorescence-activated cell sorting analysis, and ELISA. Selective inhibition of Ha-Ras by small interfering RNA (siRNA) decreased CXCL10 mRNA expression in a dose-dependent manner. Further, using effector domain mutants of Ras, we found that Ras-induced overexpression of CXCL10 is mediated primarily through the Raf and phosphatidylinositol 3-kinase signaling pathways. We also observed that the expression of the splice variant CXCR3-B, known to inhibit cell proliferation, was significantly down-regulated by Ras. Selective inhibition of CXCR3-B using siRNA resulted in an increase in CXCL10-mediated breast cancer cell proliferation through G(i) proteins and likely involving CXCR3-A. Finally, we observed intense expression of CXCL10 and CXCR3 in association with human breast cancer in situ, indicating that these observations may be of pathophysiologic significance. Together, these results suggest that activation of Ras plays a critical role in modulating the expression of both CXCL10 and CXCR3-B, which may have important consequences in the development of breast tumors through cancer cell proliferation.

Endo180 binds to the C-terminal region of type I collagen

Type I collagen is a fibril-forming heterotrimer composed of two alpha1 and one alpha2 chains and plays a crucial role in cell-matrix adhesion and cell differentiation. Through a comprehensive differential display screening of oncogenic ras target genes, we have shown that the alpha1 chain of type I collagen (col1a1) is markedly down-regulated by the ras oncogene through the mitogen-activated protein kinase pathway. Although ras-transformed cells are no longer able to produce and secrete endogenous collagen, they can still adhere to exogenous collagen, suggesting that the cells express a collagen binding factor(s) on the cell surface. When the region of col1a1 encompassing the C-terminal glycine repeat and C-prodomain (amino acids 1000-1453) was affinity-labeled with human placental alkaline phosphatase, the secreted trimeric fusion protein could bind to the surface of Ras-transformed cells. Using biochemical purification followed by matrix-assisted laser desorption/ionization mass spectrometry analysis, we identified this collagen binding factor as Endo180 (uPARAP, CD280), a member of the mannose receptor family. Ectopic expression of Endo180 in CosE5 cells followed by in situ staining and quantitative binding assays confirmed that Endo180 indeed recognizes and binds to placental alkaline phosphatase. The interaction between Endo180 and the C-terminal region of type I collagen appears to play an important role in cell-matrix adhesion.

Noise overstimulation induces immediate early genes in the rat cochlea

In mammals, exposure to intense noise produces a permanent hearing loss called permanent threshold shift (PTS), whereas a moderate noise produces only a temporary threshold shift (TTS). Little is known about the molecular responses to such high intensity noise exposures. In this study we used gene arrays to examine the early response to acoustic overstimulation in the rat cochlea. We compared cochlear RNA from noise-exposed rats with RNA from unexposed controls. The intense PTS noise induced several immediate early genes encoding both transcription factors (c-FOS, EGR1, NUR77/TR3) and cytokines (PC3/BTG2, LIF and IP10). In contrast, the TTS noise down-regulated the gene for growth hormone. The response of these genes to different noise intensities was examined by quantitative RT-PCR 2.5 h after the 90-min noise exposure. For most genes, the extent of induction correlates with the intensity of the noise exposure. Three proteins (EGR1, NUR77/TR3, and IP10) were detected in many regions of the unexposed cochlea. After exposure to 120 dB noise, these proteins were present at higher levels or showed extended expression in additional regions of the cochlea. LIF was undetectable in the cochlea of unexposed rats, but could be seen in the organ of Corti and spiral ganglion neurons following noise. NUR77/TR3 was a nuclear protein before noise, but following noise translocated to the cytoplasm. These studies provide new insights into the molecular response to noise overstimulation in the mammalian cochlea.

Regulation of the C-X-C chemokine, mob-1, gene expression in primary rat hepatocytes

The chemokine, mob-1, is involved in inflammatory and immune responses and may be an important mediator of the inflammatory response in the liver. Here, we investigated the upstream signal pathways that could be involved in the regulation of mob-1 expression. We have found that in primary rat hepatocytes the isolation and subsequent culture of these cells induced mob-1 expression. A similar induction of mob-1 mRNA was observed when the hepatocytes were stimulated with interferon-gamma (IFN-gamma). When hepatocytes were stimulated with IFN-gamma or cytokine mixture (IFN-gamma, interleukin-1beta and tumour necrosis factor-alpha), c-Jun N-terminal kinase (JNK), p38 and extracellular-regulated kinase (ERK) were phosphorylated, suggesting an involvement of the mitogen-activated protein kinases (MAPK) in the induction of mob-1 expression. The p38 kinase inhibitor, SB 203580, and the NF-kappaB inhibitor, MG-132, inhibited the induction of mob-1 mRNA and the effects were not additive. These results demonstrate that in primary rat hepatocytes the transient induction of mob-1 expression was regulated by p38 kinase and NF-kappaB through a common regulatory pathway.

Gene expression profiling by DNA microarray analysis in mouse embryonic fibroblasts transformed by rasV12 mutated protein and the E1A oncogene

BACKGROUND

Ras is an area of intensive biochemical and genetic studies and characterizing downstream components that relay ras-induced signals is clearly important. We used a systematic approach, based on DNA microarray technology to establish a first catalog of genes whose expression is altered by ras and, as such, potentially involved in the regulation of cell growth and transformation.

RESULTS

We used DNA microarrays to analyze gene expression profiles of rasV12/E1A-transformed mouse embryonic fibroblasts. Among the approximately 12,000 genes and ESTs analyzed, 815 showed altered expression in rasV12/E1A-transformed fibroblasts, compared to control fibroblasts, of which 203 corresponded to ESTs. Among known genes, 202 were up-regulated and 410 were down-regulated. About one half of genes encoding transcription factors, signaling proteins, membrane proteins, channels or apoptosis-related proteins was up-regulated whereas the other half was down-regulated. Interestingly, most of the genes encoding structural proteins, secretory proteins, receptors, extracellular matrix components, and cytosolic proteins were down-regulated whereas genes encoding DNA-associated proteins (involved in DNA replication and reparation) and cell growth-related proteins were up-regulated. These data may explain, at least in part, the behavior of transformed cells in that down-regulation of structural proteins, extracellular matrix components, secretory proteins and receptors is consistent with reversion of the phenotype of transformed cells towards a less differentiated phenotype, and up-regulation of cell growth-related proteins and DNA-associated proteins is consistent with their accelerated growth. Yet, we also found very unexpected results. For example, proteases and inhibitors of proteases as well as all 8 angiogenic factors present on the array were down-regulated in transformed fibroblasts although they are generally up-regulated in cancers. This observation suggests that, in human cancers, proteases, protease inhibitors and angiogenic factors could be regulated through a mechanism disconnected from ras activation.

CONCLUSIONS

This study established a first catalog of genes whose expression is altered upon fibroblast transformation by rasV12/E1A. This catalog is representative of the genome but not exhaustive, because only one third of expressed genes was examined. In addition, contribution to ras signaling of post-transcriptional and post-translational modifications was not addressed. Yet, the information gathered should be quite useful to future investigations on the molecular mechanisms of oncogenic transformation.

Gene expression profiling by DNA microarray analysis in mouse embryonic fibroblasts transformed by rasV12 mutated protein and the E1A oncogene

BACKGROUND

Ras is an area of intensive biochemical and genetic studies and characterizing downstream components that relay ras-induced signals is clearly important. We used a systematic approach, based on DNA microarray technology to establish a first catalog of genes whose expression is altered by ras and, as such, potentially involved in the regulation of cell growth and transformation.

RESULTS

We used DNA microarrays to analyze gene expression profiles of rasV12/E1A-transformed mouse embryonic fibroblasts. Among the approximately 12,000 genes and ESTs analyzed, 815 showed altered expression in rasV12/E1A-transformed fibroblasts, compared to control fibroblasts, of which 203 corresponded to ESTs. Among known genes, 202 were up-regulated and 410 were down-regulated. About one half of genes encoding transcription factors, signaling proteins, membrane proteins, channels or apoptosis-related proteins was up-regulated whereas the other half was down-regulated. Interestingly, most of the genes encoding structural proteins, secretory proteins, receptors, extracellular matrix components, and cytosolic proteins were down-regulated whereas genes encoding DNA-associated proteins (involved in DNA replication and reparation) and cell growth-related proteins were up-regulated. These data may explain, at least in part, the behavior of transformed cells in that down-regulation of structural proteins, extracellular matrix components, secretory proteins and receptors is consistent with reversion of the phenotype of transformed cells towards a less differentiated phenotype, and up-regulation of cell growth-related proteins and DNA-associated proteins is consistent with their accelerated growth. Yet, we also found very unexpected results. For example, proteases and inhibitors of proteases as well as all 8 angiogenic factors present on the array were down-regulated in transformed fibroblasts although they are generally up-regulated in cancers. This observation suggests that, in human cancers, proteases, protease inhibitors and angiogenic factors could be regulated through a mechanism disconnected from ras activation.

CONCLUSIONS

This study established a first catalog of genes whose expression is altered upon fibroblast transformation by rasV12/E1A. This catalog is representative of the genome but not exhaustive, because only one third of expressed genes was examined. In addition, contribution to ras signaling of post-transcriptional and post-translational modifications was not addressed. Yet, the information gathered should be quite useful to future investigations on the molecular mechanisms of oncogenic transformation.

Mammalian achaete scute homolog 2 is expressed in the adult sciatic nerve and regulates the expression of Krox24, Mob-1, CXCR4, and p57kip2 in Schwann cells

The molecular control mechanisms and regulatory molecules involved in nerve repair are not yet well known. Schwann cells have been attributed an important role in peripheral nerve regeneration; therefore, attention has been drawn to regulatory factors expressed by these glial cells. Here, we demonstrate that Mash2, a basic helix-loop-helix (bHLH) transcription factor previously shown to be crucial for placenta development, is expressed by Schwann cells of adult peripheral nerves. We observed that this gene is downregulated after nerve lesion and, using cDNA array hybridization technology, we could demonstrate that Mash2 is a regulator of Krox24, Mob-1, and CXCR4 expression in cultured Schwann cells. In addition, we provide strong evidence that Mash2 is a negative regulator of Schwann cell proliferation. Mash2 represents a first candidate for the missing class B bHLH proteins in peripheral nerves.

MOB-1 and TNF-alpha interact to induce microvascular lung injury

We have recently identified the alpha-chemokine mob-1 as a highly inducible gene in several rat models of microvascular lung injury, whose expression was suppressed by inhibition of tumor necrosis TNF-alpha (TNF-alpha). This work provides further insight into the relationship between mob-1 and TNF-alpha in the development of lung injury assessed by pulmonary edema and leukosequestration. First, pulmonary mob-1 and TNF-alpha were upregulated in animals subjected to lung injury produced by the intratracheal administration of recombinant TNF-alpha and recombinant mob-1, respectively. Second, mob-1 inhibition by intratracheal anti-mob-1 antibody attenuated lung injury induced by recombinant TNF-alpha. Third, pretreatment with anti-TNF-alpha monoclonal antibody administered intratracheally abrogated recombinant mob-1-induced microvascular lung injury. In vitro, mob-1 and TNF-alpha increased each other's production in RAW 264.7 cells and mob-1 or TNF-alpha inhibition prevented endotoxin-induced upregulation of TNF-alpha or mob-1, respectively, from these cells. Together, these data suggest that mob-1 and TNF-alpha interact to promote lung inflammation.

Mammalian achaete scute homolog 2 is expressed in the adult sciatic nerve and regulates the expression of Krox24, Mob-1, CXCR4, and p57kip2 in Schwann cells

The molecular control mechanisms and regulatory molecules involved in nerve repair are not yet well known. Schwann cells have been attributed an important role in peripheral nerve regeneration; therefore, attention has been drawn to regulatory factors expressed by these glial cells. Here, we demonstrate that Mash2, a basic helix-loop-helix (bHLH) transcription factor previously shown to be crucial for placenta development, is expressed by Schwann cells of adult peripheral nerves. We observed that this gene is downregulated after nerve lesion and, using cDNA array hybridization technology, we could demonstrate that Mash2 is a regulator of Krox24, Mob-1, and CXCR4 expression in cultured Schwann cells. In addition, we provide strong evidence that Mash2 is a negative regulator of Schwann cell proliferation. Mash2 represents a first candidate for the missing class B bHLH proteins in peripheral nerves.

Vascular endothelial growth factor induces IP-10 chemokine expression

We have previously shown that intracavernous injection of vascular endothelial growth factor (VEGF) improved the recovery of erectile function in an arteriogenic impotence rat mode. We wished to identify genes that are affected by VEGF treatment in the penis. Specifically we examined the induction of IP-10 chemokine. Male rats were subjected to pudendal arterial ligation or sham operation. They were then treated with intracavernous injection of 4 microg of VEGF in phosphate-buffered saline (PBS) or PBS alone. At 6 and 24 h after treatment, the erectile tissue was then harvested for RNA isolation. The isolated RNA was used for microarray and RT-PCR analyses. Cultured rat cavernous smooth muscle cells (CSMC) were treated with VEGF and then subjected to RT-PCR analysis. Cultured human CSMC were treated with VEGF and then subjected to ELISA analysis. Microarray analysis detected IP-10 as an abundantly induced message in 6-h VEGF-treated tissues. This was further confirmed by RT-PCR analysis. Using cultured rat CSMC, induction of IP-10 mRNA was detectable in 1 and 2 h, but not 24 h, VEGF-treated cells. Induction of IP-10 at the protein level was observed with cultured human CSMC. Secretion of IP-10 into culture medium peaked at 4 h after treatment of human CSMC with 10 ng/ml of VEGF. Optimal VEGF dosage for IP-10 induction was 50 ng/ml when assayed with cells that were treated for 8 h.

Interleukin 24 (MDA-7/MOB-5) signals through two heterodimeric receptors, IL-22R1/IL-20R2 and IL-20R1/IL-20R2

Interleukin 24 (IL-24) encodes a secreted protein that exhibits significant homology to the interleukin 10 (IL-10) family of cytokines. Here we show that the human IL-24 is secreted by activated peripheral blood mononuclear cells and is the ligand for two heterodimeric receptors, IL-22R1/IL-20R2 and IL-20R1/IL-20R2. The latter is also the receptor for IL-20. COS cells transfected with either IL-24 receptor heterodimers bind the ligand with similar saturation kinetics. IL-24 binding to either its endogenous receptors on human keratinocytes or to ectopically expressed receptors on baby hamster kidney cells leads to activation of the signal transducers and activators of transcription. Taken together, these results provide compelling evidence for IL-24 being the fourth member of IL-10 family of cytokines to which their specific receptors have been identified.

CCK independently activates intracellular trypsinogen and NF-kappaB in rat pancreatic acinar cells

In the cholecystokinin (CCK) hyperstimulation model of acute pancreatitis, two early intracellular events, activation of trypsinogen and activation of nuclear factor-kappaB (NF-kappaB), are thought to be important in the development of the disease. In this study, the relationship between these two events was investigated. NF-kappaB activity was monitored by using a DNA binding assay and mob-1 chemokine gene expression. Intracellular trypsin activity was measured by using a fluorogenic substrate. Protease inhibitors including FUT-175, Pefabloc, and E-64d prevented CCK stimulation of intracellular trypsinogen and NF-kappaB activation. Likewise, the NF-kappaB inhibitors pyrrolidine dithiocarbamate and N-acetyl-L-cysteine inhibited CCK stimulation of NF-kappaB and intracellular trypsinogen activation. These results suggested a possible codependency of these two events. However, CCK stimulated NF-kappaB activation in Chinese hamster ovary-CCK(A) cells, which do not express trypsinogen, indicating that trypsin is not necessary for CCK activation of NF-kappaB. Furthermore, adenovirus-mediated expression in acinar cells of active p65 subunits to stimulate NF-kappaB, or of inhibitory kappaB-alpha molecules to inhibit NF-kappaB, did not affect either basal or CCK-mediated trypsinogen activation. Thus trypsinogen and NF-kappaB activation are independent events stimulated by CCK.

Chemokine gene expression in astrocytes of Borna disease virus-infected rats and mice in the absence of inflammation

Borna disease virus (BDV) causes CD8(+) T-cell-mediated meningoencephalitis in immunocompetent mice and rats, thus providing a valuable animal model for studying the mechanisms of virus-induced central nervous system (CNS) immunopathology. Chemokine-mediated leukocyte recruitment to the CNS is a crucial step in the development of neurological disease. We found increased mRNA levels of IP-10 and other chemokines in brains of adult rats following infection with BDV. The marked increase in chemokine gene expression at about day 8 postinfection seemed to immediately precede the inflammatory process. In brains of rats infected as newborns, in which inflammation was only mild and transient, sustained expression of IP-10 and RANTES genes was observed. In situ hybridization studies revealed that astrocytes were the major source of IP-10 mRNAs in brains of rats infected as newborns and as adults. In brains of infected mice lacking CD8(+) T cells (beta2m(0/0)), transcripts encoding IP-10 and RANTES were also observed. IP-10 transcripts were also present in a small number of scattered astrocytes of infected knockout mice lacking mature B and T cells as well as functional alpha/beta and gamma interferon receptors, indicating that BDV can induce chemokine synthesis in the absence of interferons and other B- or T-cell-derived cytokines. These data provide strong evidence that CNS-resident cells are involved in the early localized host immune response to infection with BDV and support the concept that chemokines are pivotal for the initiation of virus-induced CNS inflammation.

Identification of a novel ligand-receptor pair constitutively activated by ras oncogenes

The Ras signaling pathway is thought to control the expression of a subset of yet to be defined genes that are crucial for cell growth and differentiation. Here we have identified by differential display a novel oncogenic Ras target, mob-5, encoding a 23-kDa cytokine-like secreted protein. Mob-5 expression could be induced by oncogenic Ha-ras and Ki-ras, but not by normal ras activation. Inhibitors of both Ha-Ras and mitogen-activated protein kinase kinase completely abolished the mob-5 expression in ras transformed cells, with concomitant loss of the transformation phenotype. Using an alkaline phosphatase-tagged Mob-5 as ligand, a putative Mob-5 receptor was identified on the cell surface of oncogenic ras transformed cells. Thus, the Mob-5/Mob-5 receptor may represent a novel putative autocrine loop coordinately activated by ras oncogenes.

NF-kappa B is required for H-ras oncogene induced abnormal cell proliferation and tumorigenesis

Oncogenic mutations in ras lead to constitutive activation of downstream signaling pathways that modulate the activities of transcription factors. In turn, these factors control the expression of a subset of genes responsible for neoplastic cell transformation. Recent studies suggest that transcription factor NF-kappa B contributes to cell transformation by inhibiting the cell death signal activated by oncogenic Ras. In this study, inhibition of NF-kappa B activity by forced expression of a super-repressor form of I kappa B alpha, the major inhibitor of NF-kappa B, markedly decreased the growth rate, saturation density and tumorigenicity of oncogenic H-Ras transformed rat embryo fibroblasts. Such clonally isolated cells overexpressing I kappa B alpha super-repressor not only were viable but also exhibited no sign of spontaneous apoptosis. Inhibition of NF-kappa B in these cells was functionally demonstrated by both the loss of cytokine induced DNA binding activity and a profoundly increased sensitivity to cell death in response to TNF-alpha treatment. In contrast, inhibition of NF-kappa B activity in non-transformed fibroblasts had minimal effect on growth, but rendered the cells resistant to a subsequent transformation by H-ras oncogene. Similar results were also obtained with rat intestinal epithelial cells harboring an inducible ras oncogene. Taken together, these findings suggest that NF-kappa B activity is essential for abnormal cell proliferation and tumorigenicity activated by the ras oncogene and highlight an alternative functional role for NF-kappa B in oncogenic Ras-mediated cell transformation that is distinct from its anti-apoptotic activity. Oncogene (2000) 19, 841 - 849.

CCK stimulates mob-1 expression and NF-kappaB activation via protein kinase C and intracellular Ca(2+)

Supraphysiological concentrations of cholecystokinin (CCK) induce chemokine expression in rat pancreatic acini through the activation of the transcription factor NF-kappaB. In the current study, the intracellular signals involved in these pathophysiological effects of CCK were investigated. CCK induction of mob-1 expression in isolated rat pancreatic acini was blocked by the protein kinase C (PKC) inhibitors GF-109203X and Ro-32-0432 and by the intracellular Ca(2+) chelator BAPTA. CCK induced NF-kappaB nuclear translocation, and DNA binding was also blocked by GF-109203X and BAPTA. Direct activation of PKC with TPA induced mob-1 chemokine expression and activated NF-kappaB DNA binding to a similar extent as did CCK. Increasing intracellular Ca(2+) using ionomycin had no effect on mob-1 mRNA levels or NF-kappaB activity. Both CCK and TPA treatments decreased inhibitory kappaB-alpha (IkappaB-alpha) levels, whereas ionomycin had no effect. However, the effects of TPA on IkappaB-alpha degradation were less complete than for CCK. In combination, TPA and ionomycin degraded IkappaB-alpha to a similar extent as CCK. Therefore, activation of NF-kappaB and mob-1 expression by supraphysiological CCK is likely mediated by both PKC activation and elevated intracellular Ca(2+).

[Rheumatoid arthritis: new molecular and cellular aspects]

BACKGROUND

Rheumatoid arthritis is a chronic systemic disorder of unknown etiology, that is characterized by inflammation, synovial hyperplasia and destruction of the affected joints. Novel molecular biology techniques have identified important cellular and molecular pathways in the pathogenesis of rheumatoid arthritis during the last years.

RESULTS

The cellular activation of aggressively growing, matrix-degrading synovial fibroblasts is a key event in the pathogenesis of rheumatoid arthritis. The cellular activation results in an altered expression of apoptosis regulating molecules (for example CD 95 and Sentrin) as well as of protooncogenes (for example RAS and MYC). Important extracellular stimuli such as the pro-inflammatory cytokines interleukin-1 and TNF-alpha are overexpressed in the rheumatoid arthritis synovium. First clinical trials with cytokine inhibiting molecules (interleukin-1 receptor antagonist, recombinant soluble TNF-alpha receptor/Etanercept and monoclonal TNF-alpha antibodies/Remicade) revealed promising results. Etanercept is now available for the treatment of rheumatoid arthritis in the USA. In addition, gene transfer methods could help to overcome the problem of a continuous expression of therapeutic molecules in the affected joints; gene delivery of the interleukin-1 receptor antagonist is currently tested in a human trial. Finally, the inhibition of matrix degrading enzymes such as matrix metalloproteinases, that mediate the joint destructive features of the activated synovial fibroblasts, could be another therapeutic approach.

CONCLUSIONS

The elucidation of important molecular and cellular pathways in the pathogenesis resulted in novel concepts in the therapy of rheumatoid arthritis. Gene transfer methods are of importance in studying the pathogenesis of the disease, however, their clinical safety and usefulness have to be proven in additional studies.

Cholecystokinin induction of mob-1 chemokine expression in pancreatic acinar cells requires NF-kappaB activation

Inflammatory mediators are involved in the early phase of acute pancreatitis, but the cellular mechanisms responsible for their generation within pancreatic cells are unknown. We examined the role of nuclear factor-kappaB (NF-kappaB) in cholecystokinin octapeptide (CCK-8)-induced mob-1 chemokine expression in pancreatic acinar cells in vitro. Supraphysiological, but not physiological, concentrations of CCK-8 increased inhibitory kappaB (IkappaB-alpha) degradation, NF-kappaB activation, and mob-1 gene expression in isolated pancreatic acinar cells. CCK-8-induced IkappaB-alpha degradation was maximal within 1 h. Expression of mob-1 was maximal within 2 h. Neither bombesin nor carbachol significantly increased mob-1 mRNA or induced IkappaB-alpha degradation. Thus the concentration, time, and secretagogue dependence of mob-1 gene expression and IkappaB-alpha degradation were similar. Inhibition of NF-kappaB with pharmacological agents or by adenovirus-mediated expression of the inhibitory protein IkappaB-alpha also inhibited mob-1 gene expression. These data indicate that the NF-kappaB signaling pathway is required for CCK-8-mediated induction of mob-1 chemokine expression in pancreatic acinar cells. This supports the hypothesis that NF-kappaB signaling is of central importance in the initiation of acute pancreatitis.

Induction of globin synthesis in K562 cells is associated with differential expression of transcription factor genes

Globin gene switching may be mediated by proteins expressed during different stages of development. Their identification may clarify the mechanisms of the conversion from fetal to adult globin production and lead to new approaches to reversing or retarding the gamma- to beta-globin gene switch. To explore this hypothesis, K562 erythroleukemia cells were induced to differentiate with 1.25, 2.5, and 5 mM sodium butyrate and gene expression was studied after 24, 48, and 72 h. Erythroid differentiation was verified by benzidine staining and by measuring the activity of a transduced A gamma-globin gene promoter linked to a luciferase reporter gene. Using differential display polymerase chain reaction (PCR), total mRNA extracted from induced cells at each time point of induction was reverse transcribed in the presence of A, G, and C anchored primers and 16 arbitrary primers, calculated to amplify approximately 50% of expressed genes. Amplified mRNAs from induced and uninduced cells were separated in polyacrylamide gels and compared. More than 110 cDNA fragments which appeared to represent either up- or downregulated mRNA species in induced K562 cells were identified. Sixty-four of these fragments had more than 95% homology to known GenBank sequences. Seventeen fragments with characteristics of transcription factors were cloned. These include differentiation-related gene-1 (drg-1), PAX 3/forkhead transcription factor, HZF2 which is a Kruppel-related zinc finger protein, three helix-loop-helix proteins (heir-1, Id3, and GOS8), alpha-NAC transcriptional coactivator, LIM domain protein, and trophoblast hypoxia regulating factor. Differential expression of all 17 fragments over 72 h was confirmed by reverse Northern dot blot analysis, semiquantitative PCR using nested primers, and Northern analysis. Erythroid maturation in induced K562 cells is associated with differential expression of numerous genes. Some encode transcription factors that could effect the initiation of HbF synthesis. Almost half of the differentially expressed clones contained cDNAs of unidentified open reading frames and these are the object of continued study.

Differential expression of RAB5A in human lung adenocarcinoma cells with different metastasis potential

For the sake of better understanding the molecular mechanism of neoplasia, we have used the mRNA differential display technique to analyze two human lung adenocarcinoma cell lines, AGZY83-a and Anip973. Anip973 was isolated from AGZY83-a, but manifested much higher metastatic potential than the parent line. We found that a significant differential cDNA fragment in Anip973 was over-expressed, then over-expressed cDNA fragment was cloned and sequenced. It showed that the over-expressed cDNA in Anip973 was RAB5A cDNA. And the RAB5A cDNA sequence was corresponding between the two cells. To determine whether RAB5A may be differentially expressed in the two human lung adenocarcinoma cells at protein level, we further detected RAB5A protein in the two cells by using immunofluorescent method. RAB5A protein was upregulated in highly metastatic Anip973. We also detected the difference in RAB5A gene expression at RNA level in human non-small cell lung carcinoma by RT-PCR. Using immunohistochemical staining, we also examined RAB5A change at protein level in 45 cases human non-small cell lung carcinoma paraffin sections. The results proved the evidence of upregulation of RAB5A in malignant tumor, indicated over-expression of RAB5A gene was correlated with the malignant degree and metastatic potential of lung cancer(chi2 test, p < 0.01). The RAB5A gene is a member of RAS superfamily, which can transcribe GTP-binding protein that plays an important role in signal transduction of protein trafficking at the cell surface and GDP/GTP cycle in the regulation of endocytotic membrane traffic. Thus our results indicated that overexpression of the RAB5A gene was involved in the process of transformation from AGZY83-a to the higher metastatic cell line Anip973. The result may be a powerful experimental evidence that over-expression of RAB5A gene associated with neoplasia metastasis.

Presence of P210bcrabl is associated with decreased expression of a beta chemokine C10 gene in a P210bcrabl-positive myeloid leukemia cell line

BACKGROUND

Chronic myelogenous leukemia (CML) is thought to start with the acquisition of the t(9;22) chromosomal translocation that codes for the P210bcrabl tyrosine-specific protein kinase. The CML cells exhibit anchorage-independent cell growth and genetic instability. After the initial phase, the cells acquire the phenotype of growth factor-independent growth. After the chronic phase, the disease evolves into the accelerated and blastic phases through the process of sequential random mutation.

MATERIALS AND METHODS

To identify some of the genetic changes that contribute to the phenotype of blastic and accelerated phase cells, we used differential display PCR to compare levels of cDNA reverse transcripts of mRNA in 32Dc13 cells and 32Dc13 cells that were stably transfected with a bcrabl cDNA plasmid in a constitutively expressed transcription unit. These cells were designated 32Dc13P210bcrabl. For these studies, we used the 32D myeloid leukemia cell line, which depends on IL-3 for growth.

RESULTS

Following introduction of the bcr-abl cDNA through transfection, the cell line became growth factor independent, mimicking the change in phenotype that occurs during the later phases of CML. These differential display screening assays detected altered levels of transcripts for 28 genes. Of interest to the biology of growth factor-independent growth in the bcrabl-positive 32D cells was the fact that the C10 beta chemokine gene was expressed at higher levels in the 32Dc13 cells than in the 32Dc13P210bcrabl cells.

CONCLUSIONS

These studies show that a C10 beta chemokine gene was expressed at different levels with or without P210bcrabl.

Identification of rCop-1, a new member of the CCN protein family, as a negative regulator for cell transformation

By using a model system for cell transformation mediated by the cooperation of the activated H-ras oncogene and the inactivated p53 tumor suppressor gene, rCop-1 was identified by mRNA differential display as a gene whose expression became lost after cell transformation. Homology analysis indicates that rCop-1 belongs to an emerging cysteine-rich growth regulator family called CCN, which includes connective-tissue growth factor, CYR61, CEF10 (v-src inducible), and the product of the nov proto-oncogene. Unlike the other members of the CCN gene family, rCop-1 is not an immediate-early gene, it lacks the conserved C-terminal domain which was shown to confer both growth-stimulating and heparin-binding activities, and its expression is lost in cells transformed by a variety of mechanisms. Ectopic expression of rCop-1 by retroviral gene transfers led to cell death in a transformation-specific manner. These results suggest that rCop-1 represents a new class of CCN family proteins that have functions opposing those of the previously identified members.

Lipopolysaccharide-induced expression of IP-10 mRNA in rat brain and in cultured rat astrocytes and microglia

Using mRNA differential display technique, we have found a differentially expressed band in rat brain, designated HAP2G1, which was the strongest one induced in response to peripheral administration of lipopolysaccharide (LPS). Sequence analysis showed that HAP2G1 cDNA is the rat homologue of the human alpha-chemokine IP-10. Using RT-PCR technique and in situ hybridization, we demonstrate that IP-10 mRNA was expressed only in brain tissue of rats treated with LPS and not in control brain tissue. Using semi-quantitative PCR, we found that both cultured astrocytes and microglia express IP-10 mRNA after treatment with LPS. LPS-induced IP-10 mRNA reached peak levels in rat brain and in cultured microglia at approximately 3 h after treatment with LPS. At 10 h, IP-10 mRNA was markedly decreased, and at 24 h it was low but still detectable by PCR or in situ hybridization. In contrast to unstimulated microglia, unstimulated astrocytes constitutively expressed IP-10 mRNA at a low level. Increased IP-10 expression could possibly be involved in the microglia response to inflammatory stimuli in vivo.

Expression and regulation of interferon-gamma-inducible protein 10 gene in rat Leydig cells

In the present study, we report the cloning of a gene that is differentially expressed in normal adult rat Leydig cells and whose expression is inhibited by hCG but is induced by interferon-gamma (IFNgamma). DNA sequence analysis identified this gene as rat IFNgamma-inducible protein 10 (IP-10), a member of the -C-X-C- chemokine superfamily of proinflammatory cytokines. High levels of IP-10 messenger RNA (mRNA) were constitutively expressed in freshly isolated and primary cultured Leydig cells. hCG inhibited this expression in a dose-dependent manner. The addition of 1 ng/ml hCG inhibited IP-10 mRNA levels more than 80%. Conversely, IP-10 mRNA levels were markedly increased in response to murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma by 3.3-, 10-, and 26-fold, respectively. Concomitant addition of murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma synergistically increased IP-10 mRNA levels by 58-fold. Furthermore, in addition to one previously described rat IP-10 mRNA transcript (1.5 kb), another larger transcript (2.7 kb) was identified by Northern blot in rat Leydig cells. After screening a rat testis complementary DNA library, we obtained a partial structural gene and an intron sequence, which possibly originated from the larger transcript of rat IP-10 mRNA. Histochemical and immunocytochemical staining revealed that purified cells were positive for 3beta-hydroxysteroid dehydrogenase and IP-10, confirming that IP-10 is indeed present in Leydig cells. IP-10 antisense oligonucleotides enhanced basal and hCG-induced testosterone formation. This suggests that endogenous IP-10 has an inhibitory effect on Leydig cell steroidogenesis. In conclusion, IP-10 is expressed in rat Leydig cells and may have paracrine and autocrine effects on testicular function.

Differentially expressed genes in head and neck cancer

Carcinogenesis is considered a multistep process. To further elucidate involved genetic changes, the differential display method was applied to compare gene expression of head and neck carcinoma cells and normal keratinocytes from the upper aerodigestive tract. Total RNA was extracted from cultured squamous carcinoma cells and keratinocytes. mRNA was reverse transcribed into cDNA, amplified by PCR, and separated on a gel. Currently three DNA transcripts were identified with a length of 191 to 336 base pairs (bp) that were either expressed only by the keratinocytes or by the malignant cells. Differentially expressed DNA fragments of the carcinoma cells and the keratinocytes were cloned and sequenced. A gene bank database search identified one fragment expressed by the carcinoma cells as an unknown gene, another one found in the keratinocytes as probably a part of the human cell attachment domain, and the third one with homology to the mRNA of the human epidermal growth factor receptor (EGFR). Northern blot analysis confirmed the differential expression in the malignant cells or the keratinocytes. Differential display seems to confirm the well-known overexpression and up-regulation of the EGFR, the differential expression of the cell attachment domain may play a role as a cofactor in carcinogenesis of head and neck cancer, and the third unknown fragment is still under investigation to elucidate the role in carcinogenesis.

Identification of glucocorticoid- and adenovirus E1A-regulated genes in lung epithelial cells by differential display

Adenovirus infection has been implicated in the pathogenesis of lung inflammatory diseases for which glucocorticoids provide effective antiinflammatory treatment. In this study, the differential display assay was used to identify messenger RNAs (mRNAs) differentially expressed in dexamethasone (1 microM for 24 h)-treated A549 lung epithelial cells compared to A549 cells transfected with the adenoviral E1A gene. Thirty-seven complimentary DNAs (cDNAs) (15 glucocorticoid-regulated, 22 adenovirus E1A-regulated) were isolated. DNA sequence analysis showed that 35 of these were unique, 2 were identical with each other, and 3 were common to the glucocorticoid- and E1A-regulated groups. Genes identified included those involved in transcription/translation, cytoskeletal/contractile element genes, metabolic enzyme genes, and genes associated with cell regulation/signal transduction. After further analysis of the isolated clones by Northern blotting, ribonuclease protection, and semiquantitative RT-PCR (reverse transcriptase-polymerase chain reaction), 10 of the 14 glucocorticoid-regulated and one of the three common to both the adenovirus E1A- and glucocorticoid-regulated cDNAs were confirmed for this control of their expression. We conclude that the strategy of identifying cDNAs regulated by both adenovirus E1A and glucocorticoids provides a promising approach for identifying genes that may be important in the pathogenesis of lung inflammation and therefore targets for glucocorticoid treatment.

Differentially expressed olfactomedin-related glycoproteins (Pancortins) in the brain

Messenger RNA differential display is conducted to search for genes that are expressed in a region-specific pattern in the rodent brain. Eleven novel gene fragments are isolated. One of these genes which we call pancortin, based on its predominant mRNA expression in the cerebral cortex of the adult, is studied. These pancortin cDNA clones are grouped into four different types of cDNA, designated as pancortin-1 to -4. All pancortin cDNAs share a common sequence in the middle of their structure, having two alternative sequences at both 5'- and 3'-ends, respectively. Deduced amino acid sequence shows that all pancortins have sequences of hydrophobic amino acids at N-terminus and no obvious membrane spanning regions. In situ hybridization histochemistry using oligonucleotide probes specific for 5'- and 3'-end variable parts has revealed that these four pancortin mRNAs are expressed differentially in the adult rodent brain. Robust expression of pancortin-1 and -2 mRNA is observed in the cerebral cortex (including the hippocampus and the olfactory bulb). However, little of pancortin-3 and -4 mRNA is observed there. In the cortex, some neurons are stained by an antibody raised against Pancortin. Immuno-electron microscopic study has revealed that Pancortin-like immunoreactive products are localized mainly in the endoplasmic reticulum and not in the Golgi apparatus indicating that Pancortins are the endoplasmic reticulum-anchored proteins. Our results suggest that each Pancortin is differentially regulated and may perform different functions in the brain.

IL-1 beta alters the expression of the receptor tyrosine kinase gene r-EphA3 in neonatal rat cardiomyocytes

To identify proinflammatory cytokine responsive genes in the myocardium, we used differential display to study RNA isolated from neonatal rat cardiac myocytes treated with tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). Sequence analysis of differential display products confirmed by reverse Northern blots revealed one clone as the partial sequence of an Eph-related receptor tyrosine kinase (r-EphA3). In cardiac myocytes, 36-h exposure to TNF-alpha and IL-1 beta reduced r-EphA3 transcripts to 59.9% (P < 0.01) of control levels; this effect was largely dependent on IL-1 beta. Western blot analysis showed that changes in r-EphA3 protein levels reflect that seen for transcripts. Cardiac nonmyocytes expressed substantially lower levels of r-EphA3. Full-length r-EphA3 cDNA clone (3,077 base pair) yielded an amino acid sequence with 90-98% homology to the Eph receptor human EphA3, chick EphA3, and mouse EphA3. In the adult rat, r-EphA3 transcripts were most abundant in the heart, brain, and lung. These results suggest that IL-1 beta may exert its effect on cardiac myocytes at least in part by altering r-EphA3 expression.

Identification and cloning of differentially expressed genes

Only a few of the methods currently used for identification of differentially expressed genes take advantage of the fact that (near) complete sets of cDNA clones and sequences representing all human and mouse genes will be available for high throughput survey of gene expression. Accordingly, strategies based on hybridization of complex (cDNA or RNA) probes to cDNA microarrays, either on glass slides or on chips, are likely to become increasingly more advantageous. Recognizing, however, that the power of these methods depends upon the availability of such resources, strategies are being pursued to facilitate completion of the ongoing efforts to identify all human and mouse genes.

[cDNAs encoding the antigenic proteins in pathogenic strain of Entamoeba histolytica]

The differential display reverse transcription polymerase chain reaction (DDRT-PCR) analysis was performed to identify the pathogenic strain specific amplicons. mRNAs were purified from the trophozoites of the pathogenic strain YS-27 and the non-pathogenic strain S 16, respectively. Three kinds of first stranded cDNAs were reverse transcribed from the mRNAs by one base anchored oligo-dT11M (M: A, C, or G) primers. Each cDNA template was used for DDRT-PCR analysis. A total of 144 pathogenic strain specific amplicons was observed in DDRT-PCR analysis using primer combinations of the 11 arbitrary primers and the 3 one base anchored oligo-dT11M primers. Of these, 31 amplicons were verified as the amplicons amplified only from the mRNAs of the pathogenic strain by DNA slot blot hybridization. Further characterization of the 31 pathogenic strain specific amplicons by DNA slot blot hybridization analysis using biotin labeled probes of the PCR amplified DNA of cysteine proteinase genes revealed that 21 of them were amplified from the mRNAs of the cysteine proteinase genes. Four randomly selected amplicons out of the rest 10 amplicons were used for screening of cDNA library followed by immunoscreening and all of them were turned out to be amplified from the mRNA.

H-ras oncogene point mutations in arthritic synovium

OBJECTIVE

To examine mutational activation of ras proto-oncogenes in synovial tissue from patients with rheumatoid arthritis (RA) compared with synovial specimens from patients with osteoarthritis (OA) or other arthropathies. Synovial samples from cadavers, without any signs of joint disease, were used as control material.

METHODS

Using a combination of polymerase chain reaction (PCR) and automated sequencing of the amplified PCR product, regions around codons 12, 13, and 61 of the H-, K-, and N-ras proto-oncogenes were analyzed. Confirmation of mutations was based on restriction fragment length polymorphism analysis and/or oligonucleotide hybridization.

RESULTS

Four (6%) of 72 patients with RA, 2 (13%) of 16 with OA, and 1 (8%) of 12 with other arthropathies harbored mutant H-ras proto-oncogenes, and were heterozygous at codon 13 for the GGT-->GAT (Gly-->Asp) change. An unexpected mutation was found in the H-ras gene, in which a heterozygous GTG-->ATG (Val-->Met) mutation was observed over codon 14. The incidence for this mutation was 39% (28 of 72) in RA patients, 94% (15 of 16) in OA patients, and 42% (5 of 12) in patients with other arthropathies. All samples carrying the codon 13 mutation of H-ras were also codon 14-mutated, i.e., double mutations existed. Identical point mutations were also detected in a few synovial specimens obtained from cadavers (n = 8), including a single case of double mutation. All specimens showed normal K- and N-ras loci.

CONCLUSION

Activation of proto-oncogene H-ras by point mutation in codons 13 and 14 occurred in the synovial tissue of patients with RA, OA, or other arthropathies, as well as, to some extent, in the control synovia, indicating that the phenomenon is not specific for RA. In codon 14, incidence of the H-ras point mutation was highest in OA tissue. The possible significance of this codon 14-mutated H-ras gene needs to be clarified.

Representational difference analysis of cDNA of genes expressed in embryonic kidney

Representational difference analysis of cDNA (cDNA-RDA) is a PCR-based differential cloning method. It involves hybridization of two populations of cDNA with selective amplification of differentially expressed genes. To isolate the differentially expressed genes during renal development, mRNAs from embryonic kidneys at day 13 (E13) and postnatal kidneys from three-week-old (P3) mice were extracted, and double stranded cDNAs prepared. Double stranded cDNAs were digested with DpnII, adaptor-ligated, and amplified by PCR, using adaptor primer to generate "representative amplicons." These reflect the "representation" of most of the cDNA population. The term "amplicons" denotes amplified PCR product. Among the two populations of cDNA, E13 kidney cDNA was used as a "tester," containing target genes, and P3 kidney cDNA as a "driver," driving the process of subtraction, following which, they were subjected to cDNA-RDA under low stringency conditions. During the first round of cDNA-RDA embryonic globin genes were isolated. To competitively eliminate these genes, plasmid DNAs of globin genes were supplemented into driver, and subjected to the second round of cDNA-RDA. This resulted in the isolation of four cDNA clones: H19 gene, mesoderm-specific cDNA, COL2A1 gene, and a novel cDNA. By Northern blot analyses, the H19 gene and mesoderm-specific cDNA exhibited a high degree of developmental regulation, that is, they were abundantly expressed in E13 kidney, and their expression was barely detectable in P3 kidney. The differential developmental regulation of mesoderm-specific cDNA was confirmed by tissue in situ hybridization experiments. The COL2A1 and novel cDNA were rare transcripts in the embryonic Kidney. However, Southern blot analyses of representations indicated their up-regulated expressions in E13 kidneys. The novel gene was differentially expressed in 13-day embryonic lung, and Northern blot analysis revealed an approximately 10 Kb transcript. These results indicate that cDNA-RDA is a sensitive technique to identify rare transcripts with differential expression, and since there is a minimal chance to isolate false positive clones, cDNA-RDA may serve as a powerful tool for delineating up- or down-regulation of the genes involved in various pathological or physiological states of the kidney.

TRA1, a Novel mRNA Highly Expressed in Leukemogenic Mouse Monocytic Sublines But Not in Nonleukemogenic Sublines

Mouse monocytic Mm-A, Mm-P, Mm-S1, and Mm-S2 cells are sublines of mouse monocytic and immortalized Mm-1 cells derived from spontaneously differentiated, mouse myeloblastic M1 cells. Although these subline cells retain their monocytic characteristics in vitro, Mm-A and Mm-P cells are highly leukemogenic to syngeneic SL mice and athymic nude mice, whereas Mm-S1 and Mm-S2 cells are not or are only slightly leukemogenic. To better understand the molecular mechanisms of these levels of leukemogenicity, we investigated putative leukemogenesis-associated genes or oncogenes involved in the maintenance of growth, especially in vivo, by means of differential mRNA display. We isolated a fragment clone (15T01) from Mm-P cells. The mRNA probed with 15T01 was expressed at high levels in leukemogenic Mm-P and Mm-A cells but not in nonleukemogenic Mm-S1 and Mm-S2 cells. The gene corresponding to 15T01, named TRA1, was isolated from an Mm-P cDNA library. The longest open reading frame of the TRA1 clone predicts a peptide containing 204 amino acids with a calculated molecular weight of 23,049 D. The predicted TRA1 protein is cysteine-rich and contains multiple cysteine doublets. A putative normal counterpart gene, named NOR1, was also isolated from a normal mouse kidney cDNA library and sequenced. NOR1 cDNA predicts a peptide containing 234 amino acids. The sequence of 201 amino acids from the C-terminal NOR1 was completely identical to that of TRA1, whereas the remaining N-terminal amino acids (33 amino acids) were longer than that (3 amino acids) of TRA1 and the N-terminus of NOR1 protein contained proline-rich sequence. A similarity search against current nucleotide and protein sequence databases indicated that the NOR1/TRA1 gene(s) is conserved in a wide range of eukaryotes, because apparently homologous genes were identified in Caenorhabditis elegans and Saccharomyces cerevisiae genomes. Northern blotting using TRA1-specific and NOR1-specific probes indicated that TRA1 mRNA is exclusively expressed in leukemogenic but not in nonleukemogenic Mm sublines and normal tissues and also indicated that NOR1 mRNA is expressed in normal tissues, especially in kidney, lung, liver, and bone marrow cells but not in any Mm sublines. After leukemogenic Mm-P cells were induced to differentiate into normal macrophages by sodium butyrate, the normal counterpart, NOR1, was expressed, whereas the TRA1 level decreased. Furthermore, transfection of TRA1 converted nonleukemogenic Mm-S1 cells into leukemogenic cells. These results indicate that the TRA1 gene is associated at least in part with the leukemogenesis of monocytic Mm sublines.

Intrinsic responses to Borna disease virus infection of the central nervous system

Immune cells invading the central nervous system (CNS) in response to Borna disease virus (BDV) antigens are central to the pathogenesis of Borna disease (BD). We speculate that the response of the resident cells of the brain to infection may be involved in the sensitization and recruitment of these inflammatory cells. To separate the responses of resident cells from those of cells infiltrating from the periphery, we used dexamethasone to inhibit inflammatory reactions in BD. Treatment with dexamethasone prevented the development of clinical signs of BD, and the brains of treated animals showed no neuropathological lesions and a virtual absence of markers of inflammation, cell infiltration, or activation normally seen in the CNS of BDV-infected rats. In contrast, treatment with dexamethasone exacerbated the expression of BDV RNA, which was paralleled by a similarly elevated expression of mRNAs for egr-1, c-fos, and c-jun. Furthermore, dexamethasone failed to inhibit the increase in expression of mRNAs for tumor necrosis factor alpha, macrophage inflammatory protein 1 beta, interleukin 6, and mob-1, which occurs in the CNS of animals infected with BDV. Our findings suggest that these genes, encoding transcription factors, chemokines, and proinflammatory cytokines, might be directly activated in CNS resident cells by BDV. This result supports the hypothesis that the initial phase of the inflammatory response to BDV infection in the brain may be dependent upon virus-induced activation of CNS resident cells.

Use of messenger RNA differential display to identify interleukin-11-responsive genes in human umbilical cord blood mononuclear cells: IL-11 upregulates the expression of the hMAL gene

Human umbilical cord blood (HUCB) mononuclear cells represent a source of hematopoietic stem and progenitor cells, including cells responsive to interleukin-11 (IL-11). To investigate the molecular mechanisms associated with IL-11 action, we have used HUCB mononuclear cells as a model system to identify genes that are transcriptional targets of IL-11. Using the technique of messenger RNA differential display, we have identified 17 candidate cDNA differentially expressed in mononuclear cells incubated without and with IL-11. Fifteen of these cDNA were recovered, and 11 were sequenced. DNA sequence analysis has identified one of these cDNA as being the human MAL gene, originally identified as a marker for intermediate stages of T cell differentiation. Northern analysis using a MAL-specific probe confirms the upregulation of MAL by IL-11 in HUCB cells.

Interferon-inducible protein-10 involves vascular smooth muscle cell migration, proliferation, and inflammatory response

Interferon-inducible protein-10 (IP-10) is a member of the C-X-C chemokine family. Using mRNA differential display, we isolated a rat homologue to murine and human IP-10 from lipopolysaccharide-stimulated carotid arteries. Our studies demonstrated that IP-10 is a potent mitogenic and chemotactic factor for vascular smooth muscle cells, the critical features of smooth muscle cells for their contribution to the pathogenesis of atherosclerosis and restenosis. IP-10 induced a concentration-dependent stimulation of DNA synthesis, cell proliferation, and cell migration of rat aortic smooth muscle cells. A concentration- and time-dependent IP-10 mRNA induction was observed in lipopolysaccharide- or interferon-gamma-stimulated, but not interleukin-1beta- or tumor necrosis factor-alpha-stimulated smooth muscle cells. A marked synergistic effect on IP-10 mRNA expression was observed when smooth muscle cells were challenged with interferon-gamma together with interleukin-1beta or tumor necrosis factor-alpha. Furthermore, IP-10 mRNA expression was induced in the rat carotid artery after balloon angioplasty. The mitogenic and chemotactic features of IP-10 for smooth muscle cells, along with its discrete induction in cultured vascular smooth muscle cells and in carotid arteries after balloon angioplasty (neointima formation) suggest that IP-10 may play an active and distinct role in vascular remodeling processes.

Identification of mRNAs differentially expressed in quiescence or in late G1 phase of the cell cycle in human breast cancer cells by using the differential display method

BACKGROUND

The decision for a cell to enter the DNA synthesis (S) phase of the cell cycle or to arrest in quiescence is likely to be determined by genes expressed in the late G1 phase, at the restriction point. Loss of restriction point control is associated with malignant cellular transformation and cancer. For this reason, identifying genes that are differentially expressed in late G1 phase versus quiescence is important for understanding the molecular basis of normal and malignant growth.

MATERIALS AND METHODS

The differential display (DD) method detects mRNA species that are different between sets of mammalian cells, allowing their recovery and cloning of the corresponding cDNAs. Using this technique, we compared mRNAs from synchronized human breast cancer cells (21 PT) in quiescence and in late G1.

RESULTS

Six mRNAs differentially expressed in late G1 or in quiescence were identified. One mRNA expressed 10 hr after serum induction showed 99% homology to a peptide transporter involved in antigen presentation of the class I major histocompatibility complex (TAP-1) mRNA. Another mRNA expressed specifically in quiescence and down-regulated 2 hr following serum induction showed 98% homology to human NADP+ -dependent cytoplasmic malic enzyme (EC1.1.1.40) mRNA, which is an important enzyme in fatty acid synthesis and lipogenesis. Three others showed high homology to different mRNAs in the GeneBank, corresponding to genes having unknown functions. Finally, one mRNA revealed no significant homology to known genes in the GeneBank.

CONCLUSIONS

We conclude that DD is an efficient and powerful method for the identification of growth-related genes which may have a role in cancer development.

AdipoQ is a novel adipose-specific gene dysregulated in obesity

Adipose differentiation is accompanied by changes in cellular morphology, a dramatic accumulation of intracellular lipid and activation of a specific program of gene expression. Using an mRNA differential display technique, we have isolated a novel adipose cDNA, termed adipoQ. The adipoQ cDNA encodes a polypeptide of 247 amino acids with a secretory signal sequence at the amino terminus, a collagenous region (Gly-X-Y repeats), and a globular domain. The globular domain of adipoQ shares significant homology with subunits of complement factor C1q, collagen alpha 1(X), and the brain-specific factor cerebellin. The expression of adipoQ is highly specific to adipose tissue in both mouse and rat. Expression of adipoQ is observed exclusively in mature fat cells as the stromal-vascular fraction of fat tissue does not contain adipoQ mRNA. In cultured 3T3-F442A and 3T3-L1 preadipocytes, hormone-induced differentiation dramatically increases the level of expression for adipoQ. Furthermore, the expression of adipoQ mRNA is significantly reduced in the adipose tissues from obese mice and humans. Whereas the biological function of this polypeptide is presently unknown, the tissue-specific expression of a putative secreted protein suggests that this factor may function as a novel signaling molecule for adipose tissue.

Identifying changes in gene expression in the nervous system: mRNA differential display

The majority of cellular and developmental processes are characterized by changes in gene expression. Recently, several polymerase chain reaction-based methods have been introduced for detecting genes whose expressions differ between cells or tissues. It is now possible to investigate whether novel gene expression occurs within many systems as a response to extracellular signals, and to identify systematically those genes. The characterization of cell-, tissue- or stage-specific gene expression will broaden our understanding of many complex biological processes.

Molecular dissection of quantitative traits: progress and prospects

QTL mapping is an increasingly useful approach to the study and manipulation of complex traits important in agriculture, evolution, and medicine. The molecular dissection of quantitative phenotypes, supplementing the principles of classical quantitative genetics, is accelerating progress in the manipulation of plant and animal genomes. A growing appreciation of the similarities among different organisms and the usefulness of comparative genetic information is making genome analysis more efficient, and providing new opportunities for using model systems to overcome the limitations of less-favorable systems. The expanding repertoire of techniques and information available for studying heredity is removing obstacles to the cloning of QTLs. Although QTL mapping alone is limited to a resolution of 0.1%-1.0% of a genome, use of QTL mapping in conjunction with a search for mapped candidate genes, with emerging technologies for isolation of genes expressed under conditions likely to account for the quantitative phenotype, and with ever more efficient megabase DNA manipulation and characterization bodes well for the prospect of isolating the genetic determinants of QTLs in the foreseeable future. In the words of Thoday (1961), "An extensive attack on quantitative genetics made from this point of view as well as the biometric approach should be a great help in answering questions concerning the nature of polygenes...."