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At least 1,135 records · Page 63Linked to original sources
PubMed2000

Overexpression of the homeobox gene DLX-7 inhibits apoptosis by induced expression of intercellular adhesion molecule-1.

OBJECTIVE: DLX genes constitute a subfamily of divergent homeobox genes. We have previously reported that inhibition of DLX-7 expression by an antisense oligonucleotide caused apoptosis in the K562 erythroleukemia cell line, which highly expresses DLX-7. In this study, we have constructed an expression vector encoding human DLX-7, and examined the effects of overexpression of DLX-7 in the IL-3-dependent lymphoid precursor cell line Ba/F3. METHODS: DLX-7 expression vector was electroporated into Ba/F3 cells, and generate a DLX-7 expressing Ba/F3 cells. Northern blot analysis was performed to determine DLX-7 gene expression. WST-1 assay was used to cell proliferation assay. To detect apoptosis, we performed TUNEL assay. Expression of cell surface adhesion molecules was examined by FACS analysis. RESULTS: Growth properties of DLX-7-transfected Ba/F3 cells in the presence of IL-3, did not differ from those of control Ba/F3 cells. However, in the absence of IL-3, DLX-7-transfected cells abrogated growth dependence on cytokines due to inhibition of apoptosis. Because adhesion properties of DLX-7-transfected cells increase, we examined expression of adhesion molecules in these cells. Expression of intercellular adhesion molecule (ICAM)-1 and ICAM-2 were markedly upregulated in DLX-7-transfected cells. Both anti-ICAM-1 antibody and anti-LFA-1 antibody blocked the aggregation of DLX-7-transfected cells. Moreover, in the absence of IL-3, cytokine-independent cell growth was blocked by anti-ICAM-1 antibody. CONCLUSION: These results indicate that DLX-7 overexpression blocks apoptosis and that ICAM-1 expression induced by DLX-7 contributes to this antiapoptotic effect.

Animals↗
PubMed1985

Independent control elements that determine yolk protein gene expression in alternative Drosophila tissues.

The adjacent and divergently transcribed yp1 and yp2 genes of Drosophila were separated at a site that is 342 base pairs upstream of yp2 and 883 base pairs upstream of yp1. Each gene was separately used to transform Drosophila germ-line-producing flies with a single copy of the introduced gene. Transcripts from the introduced genes were found only in adult females. Thus, the introduced genes maintain the sex- and time-specific expression pattern of the endogenous yp genes. However, the pattern of tissue-specific expression differed among the two introduced genes and the endogenous genes. Transcripts from both of the endogenous genes are found in fat bodies and ovaries. In contrast, transcripts from the introduced yp1 gene are found only in fat bodies, and those from the introduced yp2 gene are found only in ovaries. Thus, each introduced DNA segment lacks at least one of the cis-acting elements required for the normal pattern of tissue-specific expression. These results indicate that the expression of a yp gene in different tissues is determined by different cis-acting elements.

Adipose Tissue↗
PubMed2003

Distinct expression patterns of splicing isoforms of mNumb in the endocrine lineage of developing pancreas.

The pancreas is composed of three tissues: endocrine, exocrine, and duct. The endocrine/exocrine lineages diverge from the ductal lineage before E12.5 in mice, and then further separate into endocrine and exocrine precursors. These processes are regulated by differential activation of Notch1-mediated signaling, which is required to repress the expression of the pro-endocrine gene neurogenin3 (ngn3) in the exocrine lineage. Mammalian Numb (mNumb) is an ortholog of Drosophila Numb (dNumb), which is likely to be an intracellular inhibitor of Notch signaling, and has four splicing isoforms: PTBS-PRRS, PTBL-PRRS, PTBS-PRRL, and PTBL-PRRL. Here we developed an anti-PRRL antibody, which recognizes only the PRRL forms of mNumb. We then performed immunohistochemical analyses using anti-PRRL together with anti-pan Numb, which recognizes all the isoforms of mNumb, antibodies that determine the spatio-temporal expression pattern of mNumb in the mouse fetal pancreas. mNumb PRRS and PRRL were first expressed in identical cells in the early stage of pancreatic development (i.e., E10.5), but gradually became biased. At the stage of endocrine and exocrine divergence, mNumb PRRS continued to be expressed in endocrine lineage cells, whereas PRRL was down-regulated during endocrine differentiation. Even after the endocrine/exocrine divergence, notch1 expression was sustained in endocrine lineage, where ngn3 was expressed. These results agree with the notion that mNumb PRRS has an inhibitory effect on Notch signaling, indicating its potential roles in the differentiation of pancreatic endocrine lineage. In addition, islet cells, which are produced from ductal tissue, were immunostained by the anti-panNb antibody. Our present results will contribute to the understanding of the mechanisms of islet development from ductal tissue.

Alternative Splicing↗
PubMed2003

Evolution and divergence of the MADS-box gene family based on genome-wide expression analyses.

MADS-box genes encode transcription factors involved in various important aspects of development and differentiation in land plants, metazoans, and other organisms. Three types of land plant MADS-box genes have been reported. MIKCC- and MIKC*-type genes both contain conserved MADS and K domains but have different exon/intron structures. M-type genes lack a K domain. Most MADS-box genes previously analyzed in land plants are expressed in the sporophyte (diploid plant body); few are expressed in the gametophyte (haploid plant body). Land plants are believed to have evolved from a gametophyte (haploid)-dominant ancestor without a multicellular sporophyte (diploid plant body); most genes expressed in the sporophyte probably originated from those used in the gametophyte during the evolution of land plants. To analyze the evolution and diversification of MADS-box genes in land plants, gametophytic MADS-box genes were screened using macroarray analyses for 105 MADS-box genes found in the Arabidopsis genome. Eight MADS-box genes were predominantly expressed in pollen, the male gametophyte; all but one of their expression patterns was confirmed by Northern analyses. Analyses of the exon/intron structure of these seven genes revealed that they included two MIKCC-type, one M-type, and four MIKC*-type MADS-box genes. Previously, MIKC*-type genes have been reported only from a moss and a club moss, and this is the first record in seed plants. These genes can be used to investigate the unknown ancestral functions of MADS-box genes in land plants. The macroarray analyses did not detect expression of 56 of 61 M-type MADS-box genes in any tissues examined. A phylogenetic tree including all three types of Arabidopsis MADS-box genes with representative genes from other organisms showed that M-type genes were polyphyletic and that their branch lengths were much longer than for the other genes. This finding suggests that most M-type genes are pseudogenes, although further experiments are necessary to confirm this possibility. Our global phylogenetic analyses of MADS-box genes did not support the previous classification of MADS-box genes into type I and II groups, based on smaller scale analyses. An evolutionary scenario for the evolution of MADS-box genes in land plants is discussed.

Arabidopsis↗
PubMed1990

Divergent effects of insulin on insulin-like growth factor-II gene expression in the rat hypothalamus.

The effect of peripheral insulin treatment on brain content and synthesis of insulin-like growth factor-II (IGF-II) was studied in acute and chronic conditions. After a 3-h hyperinsulinemic/euglycemic clamp, rats were killed, and brains were removed for IGF-II analysis. Insulin infusion elevated IGF-II concentrations in the dorsomedial hypothalamus (DMH) and suprachiasmatic nucleus, but decreased IGF-II in the paraventricular nucleus, lateral hypothalamus (LtH), and supraoptic nucleus compared to values in control animals. In separate parallel studies, the effects of 4 days of insulin injection (1 U insulin/rat, sc, twice daily) on brain IGF-II mRNA and peptide were determined. For RNA analysis the hypothalamus was divided into three regions (lateral, ventral, and dorsal). IGF-II mRNA content was shown to vary by an order of magnitude within the adult rat hypothalamus under control conditions, and there appeared to be a differential region-dependent response to insulin treatment. Relative abundance of IGF-II mRNA in control hypothalami was VH much greater than cortex greater than or equal to LtH greater than DMH. IGF-II mRNA content declined after insulin treatment in the VH, but rose in all other regions. Insulin increased IGF-II peptide content in the paraventricular nucleus, LtH, and VMH but decreased IGF-II in the DMH and suprachiasmatic nucleus. These results indicate that peripheral insulin status may be an important factor in the synthesis and secretion of IGF-II in the brain.

Animals↗
PubMed1999

Coordinate and divergent regulation of corticotropin-releasing factor (CRF) and CRF-binding protein expression in an immortalized amygdalar neuronal cell line.

CRF is a 41-amino acid neuropeptide best known for its hypophysiotropic actions. CRF is widely distributed in the central nervous system in areas beyond the hypothalamus. CRF-binding protein (CRF-BP) regulates the bioavailability of CRF, and knowledge of the regulation of CRF-BP synthesis is an integral component of understanding the actions of CRF. To better study the regulation of CRF and CRF-BP, primary amygdalar cultures were immortalized by transfection with the SV 40 large T antigen. A clonal line that expresses CRF immunoreactivity and messenger RNA was selected. The production of CRF peptide and message by this line is regulated in a manner indistinguishable from primary cultures. We also observed that the immortalized cells express CRF-BP immunoreactivity and messenger RNA. The expression of both CRF and CRF-BP is positively regulated by forskolin and interleukin-6. Unlike CRF, the expression of CRF-BP message and peptide was increased by phorbol 12-myristate 13-acetate or dexamethasone. These results demonstrate that the synthesis of CRF and CRF-BP in this clonal cell line may be regulated in parallel by some agents but not by others. These data also suggest that dexamethasone may decrease the biological availability of CRF in the amygdala by increasing the expression of CRF-BP, rather than by decreasing CRF expression.

Amygdala↗
PubMed2001

Lysyl oxidases: expression in the fetal membranes and placenta.

The cross-linking of the connective tissues in the fetal membranes and placenta is important for their tensile strength and elasticity. We have studied the expression of lysyl oxidase (LOX) because it is the classical enzyme responsible for the cross-linking of collagen and elastin. We have also studied the two recently described, genetically distinct lysyl oxidase-like genes and proteins, lysyl oxidase-like (LOXL) and lysyl oxidase-like 2 (LOXL2), of unknown functions. Specific antisera have been used for immunolocalization in fetal membranes and placentae from early pregnancy terminations and after caesarean section at both preterm and term, prior to labour. In addition, the steady state mRNA levels of the three genes has been quantitated in separated amnion, chorion, decidua and placentae collected at term before labour. The immunocytochemistry shows that the spatial expression of the three lysyl oxidases is similar in early pregnancy in both the fetal membranes and placentae. However, by preterm this pattern had diverged and becomes greatest at term. The expression of the genes found at term was similar to the results of protein expression obtained by immunocytochemistry, with the exception of LOXL which had high placental gene expression, but low levels of immunolocalized protein. Thus by term, LOX was expressed predominantly in the amniotic epithelium, with little expression in the placenta, while LOXL showed highest gene expression in the placenta and lowest expression in the amnion. LOXL2 expression was again different and was expressed predominantly in the chorionic cytotrophoblast of the membranes with low expression in both the amnion and placentae. These results suggest that these three members of the lysyl oxidase family may have similar roles in early pregnancy during the development of the placenta and fetal membranes, but their divergence as pregnancy advances to term, may reflect changes in substrate specificity and connective tissue composition.

Abortion, Legal↗
PubMed2000

Genome-wide expression profiling of mid-gestation placenta and embryo using a 15,000 mouse developmental cDNA microarray.

cDNA microarray technology has been increasingly used to monitor global gene expression patterns in various tissues and cell types. However, applications to mammalian development have been hampered by the lack of appropriate cDNA collections, particularly for early developmental stages. To overcome this problem, a PCR-based cDNA library construction method was used to derive 52,374 expressed sequence tags from pre- and peri-implantation embryos, embryonic day (E) 12.5 female gonad/mesonephros, and newborn ovary. From these cDNA collections, a microarray representing 15,264 unique genes (78% novel and 22% known) was assembled. In initial applications, the divergence of placental and embryonic gene expression profiles was assessed. At stage E12.5 of development, based on triplicate experiments, 720 genes (6.5%) displayed statistically significant differences in expression between placenta and embryo. Among 289 more highly expressed in placenta, 61 placenta-specific genes encoded, for example, a novel prolactin-like protein. The number of genes highly expressed (and frequently specific) for placenta has thereby been increased 5-fold over the total previously reported, illustrating the potential of the microarrays for tissue-specific gene discovery and analysis of mammalian developmental programs.

Amino Acid Sequence↗
PubMed2005

A functional survey of the enhancer activity of conserved non-coding sequences from vertebrate Iroquois cluster gene deserts.

Recent studies of the genome architecture of vertebrates have uncovered two unforeseen aspects of its organization. First, large regions of the genome, called gene deserts, are devoid of protein-coding sequences and have no obvious biological role. Second, comparative genomics has highlighted the existence of an array of highly conserved non-coding regions (HCNRs) in all vertebrates. Most surprisingly, these structural features are strongly associated with genes that have essential functions during development. Among these, the vertebrate Iroquois (Irx) genes stand out on both fronts. Mammalian Irx genes are organized in two clusters (IrxA and IrxB) that span >1 Mb each with no other genes interspersed. Additionally, a large number of HCNRs exist within Irx clusters. We have systematically examined the enhancer activity of HCNRs from the IrxB cluster using transgenic Xenopus and zebrafish embryos. Most of these HCNRs are active in subdomains of endogenous Irx expression, and some are candidates to contain shared enhancers of neighboring genes, which could explain the evolutionary conservation of Irx clusters. Furthermore, HCNRs present in tetrapod IrxB but not in fish may be responsible for novel Irx expression domains that appeared after their divergence. Finally, we have performed a more detailed analysis on two IrxB ultraconserved non-coding regions (UCRs) duplicated in IrxA clusters in similar relative positions. These four regions share a core region highly conserved among all of them and drive expression in similar domains. However, inter-species conserved sequences surrounding the core, specific for each of these UCRs, are able to modulate their expression.

Animals↗
PubMed1986

An ecdysterone-responsive puff site in Drosophila contains a cluster of seven differentially regulated genes.

We have determined the molecular organization of an ecdysterone-responsive puff site in Drosophila melanogaster. The 71E puff site contains a tightly linked cluster of at least seven genes within a neighborhood of 10 X 10(3) base-pairs. All the genes are expressed in a tissue-specific manner in either the larval or the prepupal salivary gland. However, these genes can be divided into two groups on the basis of their temporal pattern of transcription. Six of the genes are expressed only in prepupal salivary glands and are arranged as three divergently transcribed pairs. Nestled within this region is one gene expressed primarily in late third-instar salivary glands. We conclude that this developmentally complex puff site contains six members of the ecdysterone-induced "late"-gene set and one member of the ecdysterone-regulated "intermolt" -gene set. Additional complexity is found at the transcript level: a heterogeneously sized population of RNA molecules arises from each of the seven genes.

Animals↗
PubMed1983

Characterization of the operator sites of the exu regulon in Escherichia coli K-12 by operator-constitutive mutations and repressor titration.

In Escherichia coli, the exu regulon of the hexuronate system involves the three exuT, uxaCA and uxaB operons and is under the negative control of the exuR regulatory gene product. The technique developed by Casadaban, Chou and Cohen was employed to construct two plasmids containing operon fusions in which the lactose genes were fused to the uxaCA and exuT operons. These fusions were transferred into the chromosome by a reciprocal recombination event, and the resulting strains were used for isolation of mutants defective in repression. Two types of operator-constitutive mutants were obtained: one specific for the uxaCA operon expression and the other affecting the exuT gene expression. This genetic evidence confirms that these two operons which are divergently transcribed each possess their own operator site.--The derepressed expression of the two exuT-lac and uxaCA-lac operons and the uxaB gene was also examined upon introduction of plasmids bearing various operators of the exu regulon. The results of testing exuR repressor titration by multiple copies of the exu operators allowed us to show a gradation in the affinity degrees for the three exu operators: uxaBo has the strongest affinity for the exuR repressor and uxaCo the weakest, although that of exuTo seems to be just slightly greater. This gradation may play a role in the control of the exu regulon expression.

Chromosomes, Bacterial↗
PubMed2002

Divergent members of a soybean (Glycine max L.) 4-coumarate:coenzyme A ligase gene family.

4-Coumarate:CoA ligase (4CL) is involved in the formation of coenzyme A thioesters of hydroxycinnamic acids that are central substrates for subsequent condensation, reduction, and transfer reactions in the biosynthesis of plant phenylpropanoids. Previous studies of 4CL appear to suggest that many isoenzymes are functionally equivalent in supplying substrates to various subsequent branches of phenylpropanoid biosyntheses. In contrast, divergent members of a 4CL gene family were identified in soybean (Glycine max L.). We isolated three structurally and functionally distinct 4CL cDNAs encoding 4CL1, 4CL2, and 4CL3 and the gene Gm4CL3. A fourth cDNA encoding 4CL4 had high similarity with 4CL3. The recombinant proteins expressed in Escherichia coli possessed highly divergent catalytic efficiency with various hydroxycinnamic acids. Remarkably, one isoenzyme (4CL1) was able to convert sinapate; thus the first cDNA encoding a 4CL that accepts highly substituted cinnamic acids is available for further studies on branches of phenylpropanoid metabolism that probably lead to the precursors of lignin. Surprisingly, the activity levels of the four isoenzymes and steady-state levels of their transcripts were differently affected after elicitor treatment of soybean cell cultures with a beta-glucan elicitor of Phytophthora sojae, revealing the down-regulation of 4CL1 vs. up-regulation of 4CL3/4. A similar regulation of the transcript levels of the different 4CL isoforms was observed in soybean seedlings after infection with Phytophthora sojae zoospores. Thus, partitioning of cinnamic acid building units between phenylpropanoid branch pathways in soybean could be regulated at the level of catalytic specificity and the level of expression of the 4CL isoenzymes.

Coenzyme A Ligases↗
PubMed2003

Genome duplication, subfunction partitioning, and lineage divergence: Sox9 in stickleback and zebrafish.

Teleosts are the most species-rich group of vertebrates, and a genome duplication (tetraploidization) event in ray-fin fish appears to have preceded this remarkable explosion of biodiversity. What is the relationship of the ray-fin genome duplication to the teleost radiation? Genome duplication may have facilitated lineage divergence by partitioning different ancestral gene subfunctions among co-orthologs of tetrapod genes in different teleost lineages. To test this hypothesis, we investigated gene expression patterns for Sox9 gene duplicates in stickleback and zebrafish, teleosts whose lineages diverged early in Euteleost evolution. Most expression domains appear to have been partitioned between Sox9a and Sox9b before the divergence of stickleback and zebrafish lineages, but some ancestral expression domains were distributed differentially in each lineage. We conclude that some gene subfunctions, as represented by lineage-specific expression domains, may have assorted differently in separate lineages and that these may have contributed to lineage diversification during teleost evolution.

Animals↗
PubMed2001

Characterization of steroidogenic factor 1 during sexual differentiation in a marsupial.

In eutherian mammals, such as mice and humans, steroidogenic factor 1 (SF1) plays important roles in the development of the gonad and in its steroidogenic activity. Marsupial and eutherian mammals have been evolving independently for at least 100 million years and so we were interested in comparing SF1 of a marsupial with that of eutherians. To this end, we have cloned SF1 from an Australian marsupial, the tammar wallaby. Although the amino acid sequence of SF1 is highly conserved among vertebrate species, tammar SF1 appears to have diverged less from the ancestral SF1 than have eutherian SF1 proteins. Tammar SF1 is expressed by both ovaries and testes on the day of birth, just prior to the onset of testicular differentiation, until at least 8 days after birth by which time the ovary also has begun to sexually differentiate. SF1 transcripts are localized predominantly to the pre-granulosa and Sertoli cells of the ovary and testis, respectively. In the testis SF1 transcripts are also present in the interstitial cells, although at a lower level than that which is observed in the Sertoli cells. SF1 is also transcribed in adult testis and ovary. In the adult ovary SF1 is expressed in the interstitial gland, and in the granulosa cells and theca interna of small to medium-sized antral follicles, but is not expressed in large antral follicles. Thus, although the structure of tammar SF1 is divergent from that of eutherians, its expression profile is similar, supporting a conserved role in gonadal development and steroidogenesis.

Amino Acid Sequence↗
PubMed2006

Distinctive repertoire of contingency genes conferring mutation- based phase variation and combinatorial expression of surface lipoproteins in Mycoplasma capricolum subsp. capricolum of the Mycoplasma mycoides phylogenetic cluster.

The generation of surface variation among many divergent species of Mollicutes (mycoplasmas) occurs through stochastic expression patterns of diverse lipoprotein genes. The size and wide distribution of such variable gene sets in minimal (approximately 0.6- to 1.4-Mb) mycoplasmal genomes suggest their key role in the adaptation and survival of these wall-less monoderms. Diversity through variable genes is less clearly established among phylogenetically similar mycoplasmas, such as the Mycoplasma mycoides cluster of ruminant pathogens, which vary widely in host range and pathobiology. Using (i) genome sequences from two members of this clade, Mycoplasma capricolum subsp. capricolum and M. mycoides subsp. mycoides small colony biotype (SC), (ii) antibodies to specific peptide determinants of predicted M. capricolum subsp. capricolum gene products, and (iii) analysis of the membrane-associated proteome of M. capricolum subsp. capricolum, a novel set of six genes (vmcA to vmcF) expressing distinct Vmc (variable M. capricolum subsp. capricolum) lipoproteins is demonstrated. These occur at two separate loci in the M. capricolum subsp. capricolum genome, which shares striking overall similarity and gene synteny with the M. mycoides subsp. mycoides SC genome. Collectively, Vmc expression is noncoordinate and combinatorial, subject to a single-unit insertion/deletion in a 5' flanking dinucleotide repeat that governs expression of each vmc gene. All vmc genes share modular regions affecting expression and membrane translocation. In contrast, vmcA to vmcD genes at one locus express surface proteins with highly structured size-variable repeating domains, whereas vmcE to vmcF genes express products with short repeats devoid of predicted structure. These genes confer a distinctive, dynamic surface architecture that may represent adaptive differences within this important group of pathogens as well as exploitable diagnostic targets.

5' Flanking Region↗
PubMed1993

Salivary proline-rich proteins: biochemistry, molecular biology, and regulation of expression.

The proline-rich proteins (PRPs) in mammalian salivary glands are encoded by tissue-specific multigene families whose members have diverged with respect to structure and regulation of expression. PRPs are expressed constitutively in humans, and comprise about [70%] of the total salivary proteins. Families of similar proteins are dramatically increased or induced in parotid and submandibular glands of rats, mice and hamsters by treatment with the [beta-] agonist isoproterenol. Feeding tannins to rats and mice mimics the effects of isoproterenol on the parotid glands. Salivary PRPs may constitute a defense mechanism against tannins and other polyhydroxylated phenols ingested. Putative transcriptional regulatory sequences have been identified in mouse PRP genes.

Amino Acid Sequence↗
PubMed1991

The three major immediate-early transcripts of bovine herpesvirus 1 arise from two divergent and spliced transcription units.

Among 54 transcripts expressed in a temporal cascade during lytic infection with bovine herpesvirus 1, we have previously identified three major immediate-early (IE) RNAs, IER4.2 (4.2 kb), IER2.9 (2.9 kb), and IER1.7 (1.6 to 1.8 kb depending on the virus strain) transcribed from the HindIII C genome region (U. V. Wirth, K. Gunkel, M. Engels, and M. Schwyzer, J. Virol. 63:4882-4889, 1989). Northern (RNA) blot, S1 nuclease protection, and primer extension analysis used in the present study demonstrated that all three IE transcripts were spliced and originated from two divergent transcription units with start sites located in the inverted repeat. Transcription unit 1 encoded two alternative spliced transcripts, IER4.2 and IER2.9, with a common exon 1 located at 0.797 to 0.795 map units (m.u.) and an exon 2 for IER4.2 (0.792 to 0.762 m.u.) in the inverted repeat; exon 2 for IER2.9 (0.754 to 0.738 m.u.) was located in the unique long sequence and transcribed in antisense orientation to latency-related RNA. Transcription unit 2 (0.818 to 0.836 m.u.), further characterized by cDNA cloning, encoded the spliced IER1.7 with three exons in the inverted repeat. Additional minor IE transcripts were interpreted as unspliced precursors and splicing variants. With regard to the number and layout of IE genes, bovine herpesvirus 1 occupies an intermediate position between pseudorabies virus and equine herpesvirus 1 on the one hand and varicella-zoster virus and herpes simplex virus type 1 on the other.

Animals↗