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Results for “evolutionary conservation”

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At least 1,189 records · Page 66Linked to original sources
PubMed2000

Identification of a novel putative Ran-binding protein and its close homologue.

In the process of cloning genes at the breakpoint of t(5;14) (q34;q11), a recurring translocation in acute lymphoblastic leukemia, we isolated and characterized a novel gene at 5q34, and a close human homologue (66% amino acid identity) located at 8p11-12. The presence of an importin-beta N-terminal domain at their N-terminus, their size of approximately 110 kD, their nuclear localization and the identity of the homologue to a gene of a recently submitted RanGTP binding protein (RanBP16), suggest that its protein is a novel member of the importin-beta superfamily of nuclear transport receptors, therefore called RanBP17. Northern blot analysis of human tissues revealed a ubiquitous expression pattern of the RanBP16 gene and a very restricted expression pattern of the RanBP17 gene, showing high expression in testis and pancreas. Both genes are evolutionary conserved and show a high (99 and 94%) amino acid conservation with their murine counterparts and a striking similarity (40%) to a protein product of Caenorhabditis elegans (C35A5.8).

Amino Acid Sequence↗
PubMed2001

Expression of p40/Epstein-Barr virus nuclear antigen 1 binding protein 2.

Nucleolar protein p40/EBP2 is a proliferation-associated antigen that interacts with Epstein-Barr virus nuclear antigen 1 (EBNA1) to maintain the Epstein-Barr virus (EBV) episomes. The yeast p40/EBP2 functions in the processing of 27S-A into 27S-B ribosomal RNA. The present study reports high evolutionary conservation of the cDNA-derived amino acid sequences of p40/EBP2 from frog, chicken, pig, rat, mouse, bovine, and human. p40/EBP2 is ubiquitously expressed in human tissues. It is highly expressed in myelogenous leukemia K-562 compared to other cell lines tested. The human p40/EBP2 gene is located in chromosome 1 with nine exons and eight introns. The minimal promoter region resides 300 nucleotides upstream of a putative ATG initiation codon preceded by a pyrimidine-rich region. These two regions contain eight Sp1 and four c-Ets-1 putative binding sites. Analysis of the p40/EBP2 gene and its promoter region will facilitate studies on the regulation of its expression in EBV-infected and noninfected cells.

Amino Acid Sequence↗
PubMed2001

The sea urchin sns insulator blocks CMV enhancer following integration in human cells.

Insulators are a new class of genetic elements that attenuate enhancer function directionally. Previously, we characterized in sea urchin a 265-bp-long insulator, termed sns. To test insulator activity following stable integration in human cells, we placed sns between the CMV enhancer and a tk promoter upstream of a GFP transgene of plasmid or retroviral vectors. In contrast to controls, cells transfected or transduced with insulated constructs displayed a barely detectable fluorescence. Southern blot and PCR ruled out vector rearrangement following integration into host DNA; RNase protection confirmed the enhancer blocking activity. Finally, we demonstrate that two cis-acting sequences, previously characterized in sea urchin, are also specific binding sites for human proteins. We conclude that sns interferes with enhancer promoter interaction also in a human chromatin context. The relatively small size, evolutionary conservation and apparent lack of enhancer specificity might result useful in gene transfer experiments in human cells.

Animals↗
PubMed2002

Structural domains of vault proteins: a role for the coiled coil domain in vault assembly.

Vaults consist of multiple copies of three proteins (MVP, VPARP, and TEP1) and several untranslated RNAs. The function of vaults is unknown but the typical and evolutionary conserved structure indicates a role in intracellular transport. Although all vault components have been identified and characterized, not much is known about vault protein assembly. In this study we identified and analyzed structural domains involved in vault assembly with emphasis on protein-protein interactions. Using a yeast two-hybrid system, we demonstrate within MVP an intramolecular binding site and show that MVP molecules interact with each other via their coiled coil domain. We show that purified MVP is able to bind calcium, most likely at calcium-binding EF-hands. No interactions could be detected between TEP1 and other vault proteins. However, the N-terminal half of MVP binds to a specific domain in the C-terminus of VPARP. Furthermore, VPARP contains amino acid stretches mediating intramolecular binding.

Amino Acid Sequence↗
PubMedDate not supplied

Cloning and characterization of Hepp, a novel gene expressed preferentially in hematopoietic progenitors and mature blood cells.

Through differential screening of mouse hematopoietic stem cell (HSC) and progenitor-subtracted cDNA libraries we have identified a progenitor cell-specific transcript that represents a novel gene, named Hepp (hematopoietic progenitor protein). The mouse Hepp gene encodes a protein of 237 amino acids with no detectable known functional domains or motifs. Lack of invertebrate orthologs and a high degree of evolutionary conservation of the peptide sequence in vertebrate species (zebrafish, mouse, human) suggest that the Hepp gene could have conserved although as yet unknown function in vertebrates. Mouse Hepp shows a restricted expression pattern in adult tissues and is transcribed at a very low level in heart, lung, spleen, and thymus and at a higher level in muscle. During embryonic hematopoiesis Hepp is not expressed in mouse fetal liver HSC (Sca-1(+)c-kit(+)AA4.1(+)Lin(-) cells), but is abundantly transcribed in the population of hematopoietic progenitors (AA4.1(-) cells). Similarly, during adult hematopoiesis Hepp is not transcribed in the highly enriched population of bone marrow HSC (Rh-123(low)Sca-1(+)c-kit(+)Lin(-) cells), but its expression is upregulated as a greater heterogeneous population of bone marrow HSC (Lin(-)Sca-1(+) cells) differentiates into progenitors (Lin(-)Sca-1(-) cells) and more mature lymphoid and myeloid cell types. A restricted pattern of expression in adult tissues and preferential expression in both fetal and adult hematopoietic progenitors and mature blood cells suggest that Hepp could be involved in molecular regulation of HSC and progenitor cell lineage commitment and differentiation.

Animals↗
PubMed1996

The mechanism of action of cyclosporin A and FK506.

The immunosuppressants cyclosporin A (CsA), FK506, and rapamycin suppress the immune response by inhibiting evolutionary conserved signal transduction pathways. CsA, FK506, and rapamycin bind to their intracellular receptors, immunophilins, creating composite surfaces that block the activity of specific targets. For CsA/cyclophilin and FK506/FKBP the target is calcineurin. Because of the large surface area of interaction of the drug-immunophilin complex with calcineurin, FK506 and CsA have a specificity for their biologic targets that is equivalent to growth factor-receptor interactions. To date, all the therapeutic as well as toxic effects of these drugs have been shown to be due to inhibition of calcineurin. Inhibition of the action of calcineurin results in a complete block in the translocation of the cytosolic component of the nuclear factor of activated T cells (NF-AT), resulting in a failure to activate the genes regulated by the NF-AT transcription factor. These genes include those required for B-cell help such as interleukin (IL-4) and CD40 ligand as well as those necessary for T-cell proliferation such as IL-2. The purpose of this article is to illustrate the means by which these drugs produce immunosuppression.

Animals↗
PubMed1994

Analysis of the developmental and transcriptional potentiation functions of 5'HS2 of the murine beta-globin locus control region in transgenic mice.

We analyze the role of 5'HS2 of the mouse beta-globin LCR in the transcriptional and developmental regulation of beta-globin gene expression. Previous studies have shown that the human beta-globin gene behaves as an adult gene in transgenic mice, being expressed in fetal liver and bone marrow-derived erythroblasts but not in yolk sac-derived embryonic erythroid cells. We show that linkage of mLCR5'HS2 to a human beta-globin gene alters this pattern of expression during ontogeny, resulting in expression of the linked beta-globin gene at all stages of murine erythroid development. Expression was independent of integration position and correlated with transgene copy number. Our results provide the first test of a phylogenetically homologous LCR in transgenic mice and demonstrate evolutionary conservation of both developmental and transcriptional potentiation functions between mammalian beta-globin LCRs.

Animals↗
PubMed1996

Identification of cis-acting sequences that control nanos RNA localization.

The generation of anterior-posterior polarity during development in Drosophila requires the localization of determinant molecules to the anterior and posterior poles of the embryo. Localization of the maternally synthesized nanos RNA to the posterior pole of the embryo is essential to provide a source for a gradient of Nanos protein that directs abdomen formation. nanos RNA localization occurs during oogenesis and requires the function of at least nine genes. cis-acting sequences that direct nanos RNA localization lie within the nanos 3'UTR. In this analysis, we have used nanos 3'UTR deletion mutants to define the localization signal more precisely. Our results indicate that the nanos RNA localization signal is large and complex and that targeting of nanos RNA may be achieved by the combined effects of multiple, partially independent sequences. This idea is supported by evolutionary conservation, both in sequence and in function, of the nanos 3'UTRs of Drosophila melanogaster and Drosophila virilis.

Animals↗
PubMed1997

Interspecies exchange of a Hoxd enhancer in vivo induces premature transcription and anterior shift of the sacrum.

The precise activation, in space and time, of vertebrate Hox genes is an essential requirement for normal morphogenesis. In order to assess for the functional potential of evolutionary conserved Hox regulatory sequences, a phylogenetically conserved bipartite regulatory element necessary for proper spatial and temporal activation of the Hoxd-11 gene was replaced by its fish counterpart in the HoxD complex of mice, using an ES cell-based targeted exchange. Fetuses carrying this replacement activated Hoxd-11 transcription prematurely, which led to a rostral shift of its expression boundary and a consequent anterior transposition of the sacrum. These results demonstrate the high phylogenetic conservation of regulatory mechanisms acting over vertebrate Hox complexes and suggest that minor time difference (heterochronies) in Hox gene activation may have contributed to important morphological variations in the course of evolution.

Animals↗
PubMed2002

Essential function of Wnt-4 for tubulogenesis in the Xenopus pronephric kidney.

In the vertebrate embryo, development of the excretory system is characterized by the successive formation of three distinct kidneys: the pronephros, mesonephros, and metanephros. While tubulogenesis in the metanephric kidney is critically dependent on the signaling molecule Wnt-4, it is unknown whether Wnt signaling is equally required for the formation of renal epithelia in the other embryonic kidney forms. We therefore investigated the expression of Wnt genes during the pronephric kidney development in Xenopus. Wnt4 was found to be associated with developing pronephric tubules, but was absent from the pronephric duct. Onset of pronephric Wnt-4 expression coincided with mesenchyme-to-epithelium transformation. To investigate Wnt-4 gene function, we performed gain- and loss-of-function experiments. Misexpression of Wnt4 in the intermediate and lateral mesoderm caused abnormal morphogenesis of the pronephric tubules, but was not sufficient to initiate ectopic tubule formation. We used a morpholino antisense oligonucleotide-based gene knockdown strategy to disrupt Wnt-4 gene function. Xenopus embryos injected with antisense Wnt-4 morpholinos developed normally, but marker gene and morphological analysis revealed a complete absence of pronephric tubules. Pronephric duct development was largely unaffected, indicating that ductogenesis may occur normally in the absence of pronephric tubules. Our results show that, as in the metanephric kidney, Wnt-4 is critically required for tubulogenesis in the pronephric kidney, indicating that a common, evolutionary conserved gene regulatory network may control tubulogenesis in different vertebrate excretory organs.

Animals↗
PubMed1997

The high-mobility group protein T160 binds to both linear and cruciform DNA and mediates DNA bending as determined by ring closure.

The high-mobility group protein T160 was isolated by screening a phage library from a murine pre-B-cell line L1210. South-Western experiments have previously shown that this protein binds to V-(D)-J recombination signal sequences, suggesting that it may be a sequence-specific DNA-binding protein. However, neither gel-shift nor footprinting analyses have been successfully employed with the T160 protein, despite an extensive effort. In this study, the T160 protein or truncated forms made soluble through denaturing and renaturing cycles in urea were successfully used in gel-shift experiments showing that T160 binds to cruci-form or linear duplex DNA with no apparent sequence specificity. Furthermore, fragments longer than 100 bp efficiently formed covalently closed circular monomers in the presence of T160 and T4 DNA ligase, indicating that the protein is capable of introducing bends into the duplex. Last, tissue distribution by Western blotting analysis showed that the T160 protein is expressed in various murine tissues in addition to those of lymphoid origin. Considering its broad evolutionary conservation (from plants to mammals) also, these results suggest that the functional role of the T160 protein is not limited to V-(D)-J recombination, but might be involved in basic processes such as DNA replication and repairing, where irregular DNA structures are generated and very likely recognized by HMG domain proteins.

Animals↗
PubMed1998

The expression of heat shock protein 70 decreases with cellular senescence in vitro and in cells derived from young and old human subjects.

Because heat shock proteins have been shown to play a critical role in protecting cells from hyperthermia and other types of stresses, it was of interest to determine what effect cellular senescence in vitro and cells cultured in vitro from young and old human donors have on the ability of cells to regulate the expression of heat shock protein 70 (hsp70), the most prominent and most evolutionary conserved of the heat shock proteins. The ability of early and late passage IMR-90 lung fibroblasts and epidermal melanocytes and skin fibroblasts obtained from young and old human donors to express hsp70 was determined after a brief heat shock. We found that the levels of hsp70 protein and mRNA were lower in late passage cells and cells from old donors than in early passage cells and cells from young donors. The binding activity of the heat shock transcription factor HSF1, as measured by a gel shift assay, was significantly higher in early passage cells and cells from young donors in comparison to late passage cells and cells from old donors. In addition, the levels of HSF1 decreased significantly in late passage cells and cells from old donors in comparison to early passage cells and cells from young donors. Thus, our study demonstrates that the induction of hsp70 by hyperthermia in fibroblasts is significantly lower in late passage fibroblasts and in fibroblasts from old donors. In addition, our study shows that the decline in hsp70 expression during cellular senescence in vitro and in cells derived from old human subjects is paralleled by a decrease in the levels of HSF1.

Adult↗
PubMed1999

SNAREs and the secretory pathway-lessons from yeast.

SNARE proteins lie at the heart of the membrane fusion events in the secretory and endocytic pathways. Physical interactions between them are thought not only to provide the driving force for bringing membranes together, but also to contribute to the specificity of vesicle targeting. Completion of the yeast genome sequence has allowed the full set of SNAREs to be identified. Characterization of these helps to define the number of distinct compartments and the nature of the transport steps between them, but also shows that SNAREs are by no means the sole determinants of fusion specificity. Evolutionary conservation of SNAREs suggests that despite the differences in scale and morphology, many features of membrane organization are similar in yeast and animal cells. This review summarizes current knowledge of the yeast SNAREs and the picture of the secretory pathway that emerges from such studies.

Animals↗
PubMed1999

The EH network.

The EH domain is an evolutionary conserved protein-protein interaction domain present in a growing number of proteins from yeast to mammals. Even though the domain was discovered just 5 years ago, a great deal has been learned regarding its three-dimensional structure and binding specificities. Moreover, a number of cellular ligands of the domain have been identified and demonstrated to define a complex network of protein-protein interactions in the eukaryotic cell. Interestingly, many of the EH-containing and EH-binding proteins display characteristics of endocytic "accessory" proteins, suggesting that the principal function of the EH network is to regulate various steps in endocytosis. In addition, recent evidence suggests that the EH network might work as an "integrator" of signals controlling cellular pathways as diverse as endocytosis, nucleocytosolic export, and ultimately cell proliferation.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Immunohistochemical localization of insulin-like growth factor I and II in the endocrine pancreas of birds, reptiles, and amphibia.

Immunoreactive insulin-like growth factors I and II (IGF-I, IGF-II) were sought in the endocrine pancreas of representative birds, reptiles, and amphibia using antisera specific for mammalian IGF-I and IGF-II and the classical islet hormones insulin (INS), glucagon (GLUC), somatostatin (SOM), and pancreatic polypeptide (PP) in double immunofluorescence. Both IGF-I and IGF-II immunoreactivities were present in the endocrine pancreas of all species. IGF-II immunoreactivity was exclusively found in INS-immunoreactive (-IR) cells, indicating evolutionary conservation of the islet IGF-II system. In contrast, IGF-I immunoreactivity was distributed differently among the species and never occurred in INS-IR cells. In the anuran Xenopus laevis, IGF-I immunoreactivity was present in islet cells showing coexistence of GLUC and PP immunoreactivities. In reptiles, the lizards (Lacerta viridis, Scincus officinalis) exhibited IGF-I immunoreactivity in PP-IR and SOM-IR cells and the snakes (Psamophis leniolatum, Coluber ravergieri) in SOM-IR and GLUC-IR cells. In birds, IGF-I immunoreactivity was located either in SOM-IR cells only (Gallus g. domesticus, Streptopelia roseogrisea) or in PP-IR and SOM-IR cells (Coturnix c. japonica). Thus, the distribution patterns of islet IGF-I immunoreactivities in birds, reptiles, and amphibia are equivalent to those in mammals and most bony fish. They differ, however, from those found in cartilaginous fish, cyclostomes, and protochordates, where a total or partial coexistence of IGF-I and INS immunoreactivities has been obtained. Therefore, the divergence of IGF-I and INS seems to have occurred early in vertebrate phylogeny. Furthermore, the existence of IGF-I immunoreactivity likely is common in the islets of all vertebrates. Finally, no phylogenetic trend to concentrate IGF-I immunoreactivity in a particular islet cell type is apparent.

Animals↗
PubMed1993

Mapping on human and mouse chromosomes of the gene for the beta-galactoside-binding protein, an autocrine-negative growth factor.

The structural gene for beta-galactoside-binding protein (Lgals-1), a cell growth regulatory molecule and cystostatic factor, is assigned to the E-region of mouse chromosome 15 and to the region q12-q13.1 of human chromosome 22. The evolutionary conservation of these two regions has been previously suggested from comparative mapping of several loci. These include the murine SIS oncogene (Pdgfb) and its human homolog, the platelet-derived growth factor-beta polypeptide, PDGFB. The findings presented here extend the genetic homology of the two regions.

Animals↗
PubMed1993

Spectrum of mutations in CRM-positive and CRM-reduced hemophilia A.

Hemophilia A is due to the functional deficiency of factor VII (FVIII, gene locus F8C). Although half the patients have no detectable FVIII protein in their plasma, the more rare patients (approximately 5%) have normal levels of a dysfunctional FVIII and are termed cross-reacting material (CRM)-positive. More commonly (approximately 45%), patients have plasma FVIII protein reduced to an extent roughly comparable to the level of FVIII activity and are designated CRM-reduced. We used denaturing gradient gel electrophoresis to screen for mutations within the F8C gene of 11 patients (6 CRM-positive, 5 CRM-reduced) and identified 9 different mutations in 9 patients after analyses of all 26 exons, the promoter region, and the polyadenylation site. Six mutations have not been described previously. Five were missense (Ser289Leu, Ser558Phe, Val634Ala, Val634-Met, Asn1441Lys), and the sixth was a 3-bp deletion (delta Phe652). A review of the literature and the assay of FVIII antigen in 5 hemophilia A patients with previously identified missense mutations from this laboratory yielded a total of 20 other unique CRM-reduced and CRM-positive mutations. Almost all CRM-positive/reduced mutations (24/26) were missense, and many (12/26) occurred at CpG dinucleotides. We examined 19 missense mutations for evolutionary conservation using the portions of the porcine and murine F8C sequences that are known, and 18/19 amino acid residues altered by mutation in these patients were conserved. Almost 50% of mutations (11/26) clustered in the A2 domain, suggesting that this region is critical for the function of FVIII.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Isolation and chromosomal mapping of the human immunoglobulin-associated B29 gene (IGB).

The B29 gene encodes a B-cell-specific membrane protein in the immunoglobulin antigen receptor complex. B29 is a crucial member of this receptor complex and is believed to function as an effector of signal transduction in a manner analogous to that of the CD3 components of the T cell antigen receptor. We have isolated a full-length human B29 cDNA clone by using a murine B29 cDNA probe. We show that there is an extremely high degree of evolutionary conservation between the human and mouse proteins, particularly in the transmembrane and intracytoplasmic regions, where the identity is 96%. In addition, the intracytoplasmic region in both proteins contains an identical peptide motif that is present in a number of molecules involved in lymphocyte activation. Genomic Southern blot analysis of human cell lines hybridized with both murine and human B29 cDNAs gives patterns consistent with a single-copy gene occupying a small region of the genomic sequence. Using human B29 cosmid DNA, we have localized the B29 gene to human chromosome 17q23 via fluorescence in situ hybridization. B29 is the first gene localized to this area of the genome. Interestingly, a subset of human B cell chronic lymphocytic leukemias (CLL) has translocations in this locus on chromosome 17.

Amino Acid Sequence↗