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Expression pattern of a hematopoietic proteoglycan core protein gene during human hematopoiesis.

Expression of the hematopoietic proteoglycan core protein (HpPG) gene was examined in normal peripheral blood, normal bone marrow, and leukemic peripheral blood leukocytes samples to assess the expression pattern of the HpPG gene in these cells and to ascertain points of regulation of this gene during hematopoiesis. In situ hybridization to normal bone marrow and peripheral blood leukocytes demonstrated that the gene was expressed in the promyelocytes at a approximately two fold greater level than in the segmented neutrophils and the expression decreased as the granulocytes matured. The ratio of expression in the other leukocytes to expression in the segmented neutrophils were as follows: eosinophils/basophils approximately 7; monocytes approximately 2; lymphocytes less than 1. Expression of the HpPG gene during myeloblast differentiation was assessed by Northern blot analysis of acute myelogenous leukemia (AML) RNA samples. The expression of this gene, when compared to the levels in HL-60 cells, was approximately ten fold lower in the poorly differentiated blast cells obtained from three AML patients classified M"0". Conversely, the expression in the more differentiated blast cells obtained from 10 of 11 AML patients classified as M1 and M2 were at levels similar to the levels in HL-60 cells. The expression level found in eight lymphoid leukemias was approximately ten fold or more lower than in HL-60 cells. Gene copy number determination confirmed that the HpPG gene is present in one copy per haploid genome. Thus the HpPG gene's expression pattern denotes a single copy gene being differentially expressed during hematopoiesis with initial regulation occurring very early in this developmental process and an additional up-regulatory event occurring during granule genesis.

Aggrecans↗

Identification of a short nuclear lamin protein selectively expressed during meiotic stages of rat spermatogenesis.

The nuclear lamina is a karyoskeletal structure located at the nuclear periphery and intimately associated with the inner nuclear membrane. It is composed of a multigene family of proteins, the lamins, which show a conspicuous cell type-specific expression pattern. The functional role of lamins has not been definitively established but available information indicates that they are involved in the organization of nuclear envelope and interphase chromatin. Spermatogenesis is characterized, among other features, by stage-specific changes in chromatin organization and function. These changes are accompanied by modifications in the organization and composition of the nuclear lamina. In previous experiments we have determined that rat spermatogenic cells express a lamin closely related, if not identical, to lamin B1 of somatic cells; whereas rat somatic lamins A, C, D and E were not detected. Considering that chromatin reorganizations during spermatogenesis may be directly or indirectly related to changes of the nuclear lamina we have decided to further investigate lamin expression during this process. Here we report on the identification of a 52 kDa protein of the rat which, according to immunocytochemical and biochemical data, appears to be a novel nuclear lamin. Using meiotic stage-specific markers, we have also demonstrated that this short lamin is selectively expressed during meiotic stages of spermatogenesis.

Animals↗

Molecular cloning and expression of an interferon-inducible protein encoded by gene 203 from the gene 200 cluster.

We report here the complete coding sequence of a 203 cDNA, a member of the interferon-inducible Ifi 200 gene family. By combining reverse-transcriptase PCR and rapid amplification of cDNA ends (RACE) techniques we have obtained a 3.8-kb cDNA corresponding to a 203 mRNA. When used as a probe in northern analysis, its 3' segment hybridized to a 3.8-kb interferon-inducible mRNA, whereas the 5'-end additionally hybridized to a less abundant interferon-inducible 1.8-kb mRNA. Nucleotide sequence analysis revealed that the two mRNAs share the 5'-untranslated region and the same open reading frame, which encodes a hydrophilic protein composed of 408 amino acids. The difference between them is due to a 3'-untranslated region extended by alternative polyadenylation site selection. Furthermore, 203 mRNA was found to be inducible by interferon-alpha in various murine cell lines. Using polyclonal antibodies raised against a segment specific for the 203 protein, we established that p203 protein levels increase on treatment with interferon-alpha in murine fibroblasts and that p203 is located in the nucleus.

3T3 Cells↗

Skeletal muscle dictates the fibrinolytic state after exercise training in overweight men with characteristics of metabolic syndrome.

While there is indisputable evidence supporting the beneficial role of aerobic exercise in reducing cardiovascular risk factors, there are few dose-response studies of this relationship. Increasingly, it is thought that the cardiovascular benefits of exercise are significantly influenced by adaptations within skeletal muscle and its vasculature. However, little is known about the molecular mechanisms underlying these adaptations. To address this need, we initiated a study utilizing longitudinal, microarray-based gene expression profiling of serial skeletal muscle biopsies obtained from the study of targeted risk reduction intervention through defined exercise (STRRIDE). STRRIDE participants were overweight and exhibited symptoms characteristic of the metabolic syndrome that typically precedes type II diabetes such as insulin resistance, abnormal lipids and glucose intolerance. Expression data were statistically filtered and sorted into exercise training-responsive clusters based on gene product knowledge. One such cluster included genes that promote the degradation of fibrin clots such as tissue plasminogen activator (t-PA), connective tissue activation peptide III (CTAP III) and tetranectin. The fibrinolytic activity and protein levels of tetranectin, and t-PA and its endogenous inhibitor PAI-1, were subsequently shown to change significantly in both skeletal muscle and serum in response to exercise training. Our data show that the rigors of exercise directly induce fibrinolytic genes and protein cascades, both within muscle, and in the systemic circulation. This finding is particularly significant given that the metabolic syndrome is an independent risk factor for peripheral vascular disease and thrombotic events within the heart and brain. We conclude that aerobic exercise training induces both local and systemic changes in fibrinolysis and vascular homeostasis that are probably protective against cardiovascular disease.

Adaptation, Physiological↗

Evidence for mating of the "asexual" yeast Candida albicans in a mammalian host.

Since its classification nearly 80 years ago, the human pathogen Candida albicans has been designated as an asexual yeast. In this report, we describe the construction of C. albicans strains that were subtly altered at the mating-type-like (MTL) locus, a cluster of genes that resembles the mating-type loci of other fungi. These derivatives were capable of mating after inoculation into a mammalian host. C. albicans is a diploid organism, but most of the mating products isolated from a mouse host were tetrasomic for the two chromosomes that could be rigorously monitored and, overall, exhibited substantially higher than 2n DNA content. These observations demonstrated that C. albicans can recombine sexually.

Animals↗

Sequence analysis of the rfb loci, encoding proteins involved in the biosynthesis of the Salmonella enterica O17 and O18 antigens: serogroup-specific identification by PCR.

We report sequencing of the O antigen encoded by the rfb gene cluster of Salmonella enterica serotype Jangwani (O17) and Salmonella serotype Cerro (O18). We developed serogroup O17- and O18-specific PCR assays based on rfb gene targets and found them to be sensitive and specific for rapid identification of Salmonella serogroups O17 and O18.

Bacterial Proteins↗

The tryptophanase gene cluster of Haemophilus influenzae type b: evidence for horizontal gene transfer.

Among strains of Haemophilus influenzae, the ability to catabolize tryptophan (as detected by indole production) varies and is correlated with pathogenicity. Tryptophan catabolism is widespread (70 to 75%) among harmless respiratory isolates but is nearly universal (94 to 100%) among strains causing serious disease, including meningitis. As a first step in investigating the relationship between tryptophan catabolism and virulence, we have identified genes in pathogenic H. influenzae which are homologous to the tryptophanase (tna) operon of Escherichia coli. The tna genes are located on a 3.1-kb fragment between nlpD and mutS in the H. influenzae type b (Eagan) genome, are flanked by 43-bp direct repeats of an uptake signal sequence downstream from nlpD, and appear to have been inserted as a mobile unit within this sequence. The organization of this insertion is reminiscent of pathogenicity islands. The tna cluster is found at the same map location in all indole-positive strains of H. influenzae surveyed and is absent from reference type d and e genomes. In contrast to H. influenzae, most other Haemophilus species lack tna genes. Phylogenetic comparisons suggest that the tna cluster was acquired by intergeneric lateral transfer, either by H. influenzae or a recent ancestor, and that E. coli may have acquired its tnaA gene from a related source. Genomes of virulent H. influenzae resemble those of pathogenic enterics in having an island of laterally transferred DNA next to mutS.

Amino Acid Sequence↗

Activating receptors and coreceptors involved in human natural killer cell-mediated cytolysis.

Natural killer cells can discriminate between normal cells and cells that do not express adequate amounts of major histocompatibility complex (MHC) class I molecules. The discovery, both in mouse and in human, of MHC-specific inhibitory receptors clarified the molecular basis of this important NK cell function. However, the triggering receptors responsible for positive NK cell stimulation remained elusive until recently. Some of these receptors have now been identified in humans, thus shedding some light on the molecular mechanisms involved in NK cell activation during the process of natural cytotoxicity. Three novel, NK-specific, triggering surface molecules (NKp46, NKp30, and NKp44) have been identified. They represent the first members of a novel emerging group of receptors collectively termed natural cytotoxicity receptors (NCR). Monoclonal antibodies (mAbs) to NCR block to differing extents the NK-mediated lysis of various tumors. Moreover, lysis of certain tumors can be virtually abrogated by the simultaneous masking of the three NCRs. There is a coordinated surface expression of the three NCRs, their surface density varying in different individuals and also in the NK cells isolated from a given individual. A direct correlation exists between the surface density of NCR and the ability of NK cells to kill various tumors. NKp46 is the only NCR involved in human NK-mediated killing of murine target cells. Accordingly, a homologue of NKp46 has been detected in mouse. Molecular cloning of NCR revealed novel members of the Ig superfamily displaying a low degree of similarity to each other and to known human molecules. NCRs are coupled to different signal transducing adaptor proteins, including CD3 zeta, Fc epsilon RI gamma, and KARAP/DAP12. Another triggering NK receptor is NKG2D. It appears to play either a complementary or a synergistic role with NCRs. Thus, the triggering of NK cells in the process of tumor cell lysis may often depend on the concerted action of NCR and NKG2D. In some instances, however, it may uniquely depend upon the activity of NCR or NKG2D only. Strict NKG2D-dependency can be appreciated using clones that, in spite of their NCR(dull) phenotype, efficiently lyse certain epithelial tumors or leukemic cell lines. Other triggering surface molecules including 2B4 and the novel NKp80 appear to function as coreceptors rather than as true receptors. Indeed, they can induce natural cytotoxicity only when co-engaged with a triggering receptor. While an altered expression or function of NCR or NKG2D is being explored as a possible cause of immunological disorders, 2B4 dysfunction has already been associated with a severe form of immunodeficiency. Indeed, in patients with the X-linked lymphoproliferative disease, the inability to control Epstein-Barr virus infections may be consequent to a major dysfunction of 2B4 that exerts inhibitory instead of activating functions.

Adaptor Proteins, Signal Transducing↗

Interferon-alpha/beta receptor-mediated selective induction of a gene cluster by CpG oligodeoxynucleotide 2006.

BACKGROUND: Oligodeoxynucleotides containing unmethylated CpG motifs (CpG ODN) are known to exert a strong adjuvant effect on Th1 immune responses. Although several genes have been reported, no comprehensive study of the gene expression profiles in human cells after stimulation with CpG ODN has been reported. RESULTS: This study was designed to identify a CpG-inducible gene cluster that potentially predicts for the molecular mechanisms of clinical efficacy of CpG ODN, by determining mRNA expression in human PBMC after stimulation with CpG ODN. PBMCs were obtained from the peripheral blood of healthy volunteers and cultured in the presence or absence of CpG ODN 2006 for up to 24 hours. The mRNA expression profile was evaluated using a high-density oligonucleotide probe array, GeneChip. Using hierarchical clustering-analysis, out of a total of 10,000 genes we identified a cluster containing 77 genes as having been up-regulated by CpG ODN. This cluster was further divided into two sub-clusters by means of time-kinetics. (1) Inflammatory cytokines such as IL-6 and GM-CSF were up-regulated predominantly 3 to 6 hours after stimulation with CpG ODN, presumably through activation of a transcription factor, NF-kappaB. (2) Interferon (IFN)-inducible anti-viral proteins, including IFIT1, OAS1 and Mx1, and Th1 chemoattractant IP-10, were up-regulated predominantly 6 to 24 hours after stimulation. Blocking with mAb against IFN-alpha/beta receptor strongly inhibited the induction of these IFN-inducible genes by CpG ODN. CONCLUSION: This study provides new information regarding the possible immunomodulatory effects of CpG ODN in vivo via an IFN-alpha/beta receptor-mediated paracrine pathway.

Antibodies, Monoclonal↗

Presence of a nuclear lamina in pachytene spermatocytes of the rat.

The nuclear lamina is a karyoskeletal structure located at the periphery of cell nuclei. The major constituents are the lamins, which belong to the evolutionarily conserved multigene family of intermediate filament proteins. Lamins show a conspicuous cell type-specific expression pattern. The majority of somatic cells of vertebrates express A-type (lamins A and C) as well as B-type (lamins B1 and B2) lamins. Although a lamina structure has been demonstrated to be a ubiquitous component of somatic nuclei its existence in certain meiotic stages during spermatogenesis has been a matter of debate. In this study, we investigated the expression of lamins in rat spermatogenic cells using immunological and protein-chemical methods. We report on the presence of a nuclear lamina structure in rat pachytene spermatocytes. With the aid of a novel broad-reacting lamin antibody we have demonstrated the expression of a protein that is closely related, if not identical, to lamin B1.

Animals↗

Molecular diversity of cytokeratins: significance for cell and tumor differentiation.

Normal and transformed epithelial cells are characterized by the expression of a distinct class of intermediate filaments (IFs), the cytokeratin (CK) filaments. Their constituents, the CKs, comprise a complex multigene family of related proteins which can be subdivided into two sequence types (I and II). In the various epithelial cell types (excluding trichocytes), 19 different CK polypeptides (CKs 1-19) have been distinguished until recently. An additional cytoskeletal polypeptide of Mr 46,000 has been detected, by gel electrophoresis and by immunocytochemistry, in certain types of epithelia including gastric foveolar epithelium, small and large intestinal epithelium, urothelium, and epidermal Merkel cells. On the basis of its biochemical properties and considerable sequence homologies with several type I CKs, this new cytoskeletal protein is suggested to be included in the catalogue of human CKs as CK 20. The various CK polypeptides, as detected by gel electrophoretic and/or immunocytochemical analysis, are expressed in different epithelia and carcinomas in various combinations in a differentiation-dependent manner. Moreover, co-expressions of CKs with other IF classes (vimentin, neurofilaments, glial filaments) are also characteristic of certain epithelial differentiation lineages. Both non-neoplastic epithelial alterations as well as malignant transformation may result in similar modifications of the IF expression profiles although there is a considerable tendency of conservativity. In several instances, a reduced degree of differentiation is paralleled by an increased complexity of the IF protein pattern. CK (and IF) typing can be successfully used in the tracing of developmental lineages as well as in the histological differential diagnosis of primary and metastatic carcinomas. Certain CK polypeptides (CKs 5, 6, 14, 16, 17) identify squamous cell carcinomas including poorly differentiated ones, while other CKs, including CK 20, are typical of primary and metastatic urothelium-derived carcinomas. Among simple-epithelial tumors, CK analysis is of potential diagnostic value in the distinction of mesotheliomas from adenocarcinomas, the discrimination of different carcinomas within the gastrointestinal tract, and the distinction of certain gastrointestinal carcinomas from other adenocarcinoma types including breast and lung carcinomas. Among the individual CKs, CKs 5, 7, 13, 14, 19, and 20 appear to be particularly useful for diagnostic purposes. An important task in the future will be the development of additional monospecific CK-antibodies, particularly such which work on routine paraffin sections.

Cell Differentiation↗

Isolation and expression of an IFN-responsive Ly-6C chromosomal gene.

The Ly-6 locus controls the expression of genes whose products in lymphoid cells are involved in the process of Ag-independent T cell activation. The Ly-6 locus contains multiple tightly linked genes which have been mapped to a specific region on murine chromosome 15. The present approach to further define the Ly-6 Ag is based on the transfection of cloned genes and identification of the expressed products by using mAb. Screening of Ly-6 related chromosomal clones revealed one that contains a gene that is closely related to yet distinct from that of the previously characterized Ly-6E.1 protein. Transfection of this chromosomal clone into COS cells shows that it contains the gene encoding Ly-6C.1 determinants. The expression of the transfected Ly-6C.1 gene is enhanced in COS cells following treatment with mouse IFN. Characterization of the DNA sequence of the Ly-6C.1 gene has established that it consists of four exons, the first of which is untranslated. Several possible regulatory elements have been identified in the putative promoter region of this gene (5' to the first exon), including a 28-base sequence closely resembling the consensus IFN-responsive sequence found in the promoter regions of other IFN-responsive genes.

Animals↗

Structural organization of the human gene encoding nuclear lamin A and nuclear lamin C.

We have determined the structural organization of the human gene that encodes nuclear lamins A and C, intermediate filament proteins of the nuclear lamina. Sequencing and restriction mapping show that the coding region spans approximately 24 kilobases. The 5'-proximal promoter region contains several GC-rich stretches, a CCAAT box, and a TATA-like element of sequence TATTA. The lamin A/C gene contains 12 exons. Alternative splicing within exon 10 gives rise to two different mRNAs that code for pre-lamin A and lamin C. Consequently, two proteins are generated, only one of which, pre-lamin A, can be modified by isoprenylation. The intron positions in the human lamin A/C gene are generally conserved in the previously characterized genes for Xenopus lamin LIII and mouse lamin B2, but different from those in a Drosophila lamin gene. In the regions coding for the central rod domains, the intron positions are also conserved when compared with the intron positions in the genes for most cytoplasmic intermediate filament proteins except those for nestin and neurofilaments. Analysis of the intron positions in these genes supports the hypothesis that the nuclear lamins and other intermediate filament proteins arose from a common ancestor.

Amino Acid Sequence↗

Analysis of MAGE-3-specific cytolytic T lymphocytes in human leukocyte antigen-A2 melanoma patients.

The MAGE-3 gene is a member of a multigene family that is selectively expressed by subsets of different human tumor types, including malignant melanoma, but not by normal tissues except for testis and placenta. A cytolytic T lymphocyte (CTL)-defined MAGE-3 antigen, corresponding to the MAGE-3 peptide 271-279 associated with the human leukocyte antigen (HLA)-A2 molecule, has been recently identified using T lymphocytes from a normal individual stimulated in vitro with peptide-pulsed autologous antigen-presenting cells. Because MAGE-3 is expressed in 76% of metastatic melanomas, the HLA-A2-restricted MAGE-3 antigen should be expressed by approximately 37% of Caucasians bearing a metastatic melanoma tumor, thus representing an attractive candidate for the elicitation of specific CTL immune responses in vivo. In this study, we determined the proportion of HLA-A2+ melanoma patients displaying detectable MAGE-3 peptide 271-279-specific CTL precursors in peripheral blood. Peptide-specific CTL populations were obtained from at least 4 of 11 HLA-A2+ patients. Peptide-specific CTL lines derived from these populations readily lysed HLA-A2-positive target cells that were pulsed with MAGE-3 peptide 271-279 at nanomolar concentrations yet were unable to recognize (as assessed by cytolysis and cytokine production) MAGE-3-expressing autologous or allogeneic HLA-A2-positive melanoma lines. Similarly, the CTL lines failed to recognize MAGE-3-negative HLA-A2-positive tumor lines after transfection with the MAGE-3 gene, although they were able to recognize COS-7 cells transfected with MAGE-3. In contrast, HLA-A1-positive melanoma lines transfected with MAGE-3 were efficiently recognized by CTL lines directed against the MAGE-3 peptide 168-176, a known HLA-A1-restricted CTL epitope. These results suggest that the expression level of the MAGE-3 peptide 271-279, unlike that of MAGE-3 peptide 168-176, in melanomas may be too low to allow efficient recognition by specific CTLs. Thus, it appears that despite the presence of CTL precursors against MAGE-3 peptide 271-279 in some HLA-A2+ melanoma patients, the usefulness of this peptide for specific immunotherapy of melanoma may be limited.

Adult↗

New genes and new biological roles for expansins.

Expansins are extracellular proteins that loosen plant cell walls in novel ways. They are thought to function in cell enlargement, pollen tube invasion of the stigma (in grasses), wall disassembly during fruit ripening, abscission and other cell separation events. Expansins are encoded by two multigene families and each gene is often expressed in highly specific locations and cell types. Structural analysis indicates that one expansin region resembles the catalytic domain of family-45 endoglucanases but glucanase activity has not been detected. The genome projects have revealed numerous expansin-related sequences but their putative wall-loosening functions remain to be assessed.

Amino Acid Sequence↗

Insect glycobiology: a lectin multigene family in Drosophila melanogaster.

Glycodeterminants play an important role in mediating cellular and cell-substrate interactions during development and immune-related reactions enabling an organism to distinguish self determinants from non-self or modified-self determinants. One of the hallmarks of sugar recognition molecules (lectins) is their wide range of binding activities and their organisation in multigene families. Here we describe a group of Drosophila genes that are possible members of the C-type lectin family.

Amino Acid Sequence↗

Regulation of GmNRT2 expression and nitrate transport activity in roots of soybean (Glycine max).

A full-length cDNA, GmNRT2, encoding a putative high-affinity nitrate transporter was isolated from a Glycine max (L.) root cDNA library and sequenced. The deduced GmNRT2 protein is 530 amino acids in length and contains 12 putative membrane-spanning domains and a long, hydrophilic C-terminal domain. GmNRT2 is related to high-affinity nitrate transporters in the eukaryotes Chlamydomonas reinhardtii and Aspergillus nidulans, and to putative high-affinity nitrate transporters in barley and tobacco. Southern blot analysis indicated that GmNRT2 is part of a small, multigene family in soybean. Expression of GmNRT2 in roots was regulated by the type of nitrogen source provided to plants: GmNRT2 mRNA levels were barely detectable in ammonium-grown plants, higher in nitrogen-deprived plants, and highest in nitrate-grown plants. Induction of GmNRT2 mRNA levels in roots occurred within 1 h after exposure of plants to nitrate. Nitrate induction of GmNRT2 mRNA levels was accompanied by a fourfold increase in net nitrate uptake by soybean roots at 100 microM external nitrate. The molecular and physiological evidence indicates that GmNRT2 is probably a high-affinity nitrate transporter involved in nitrate uptake by soybean roots.

Amino Acid Sequence↗

Biochemical and topological properties of type A MGDG synthase, a spinach chloroplast envelope enzyme catalyzing the synthesis of both prokaryotic and eukaryotic MGDG.

MGDG synthase, the enzyme that catalyzes the synthesis of the major chloroplast membrane lipid monogalactosyldiacylglycerol (MGDG), is encoded by a multigenic family. We have analyzed the biochemical properties, subcellular localization and membrane topology of a spinach chloroplast MGDG synthase, a representative member of the type A family from Spinacia oleracea (soMGD A), using a recombinant protein that was functionally overexpressed in Escherichia coli and specific polyclonal antibodies. We demonstrated that soMGD A could catalyze the synthesis of both 'prokaryotic' and 'eukaryotic' MGDG molecular species in vitro, with a selectivity for diacylglycerol similar to that of purified chloroplast envelope MGDG synthase activity. Furthermore, soMGD A was shown to be sensitive to chemical reagents (dithiothreitol, N-ethylmaleimide and o-phenanthroline) known to affect MGDG synthesis by the partially purified enzyme, as well as in isolated chloroplast envelope membranes. In spinach chloroplasts, soMGD A was localized by Western blot analysis in the inner envelope membrane. Topological studies demonstrated that soMGD A is a monotopic enzyme, embedded within one leaflet of the inner envelope membrane from spinach chloroplasts, a structure which may involve amphipathic alpha helices. We further demonstrated that in vitro, soMGD A precursor is imported and processed to its correct mature form in intact chloroplasts. These results show that soMGD A corresponds to a mature polypeptide of approximately 45 kDa. In addition, inactivation kinetics after gamma-ray irradiation strongly suggest that both native chloroplast envelope MGDG synthase and recombinant soMGD A have a functional molecular mass of 95-100 kDa, indicating that they are probably active as homodimers made of two 45-kDa subunits. This study suggests that, in spite of the growing evidence that MGDG synthesis is catalyzed by a multigenic family of enzymes, in spinach leaves both prokaryotic and eukaryotic MGDG syntheses could be attributable to a unique dimeric enzyme, provided that diacylglycerol is transported from the outer membrane to the inner membrane of the chloroplast envelope.

Amino Acid Sequence↗