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PubMed1995

LRP1, a gene expressed in lateral and adventitious root primordia of arabidopsis.

We describe a gene that is expressed in lateral and adventitious root primordia of Arabidopsis. The gene was identified by expression of a transposon-borne promoterless beta-glucuronidase gene in lateral root primordia. The gene, designated LRP1 for lateral root primordium 1, and its corresponding cDNA were cloned and sequenced. The expression pattern of the gene in lateral root primordia was confirmed by in situ hybridization with LRP1 cDNA probes. The LRP1 gene encodes a novel protein. LRP1 expression is activated during the early stages of root primordium development and is turned off prior to the emergence of lateral roots from the parent root. Insertion of the transposon in the LRP1 gene disrupted its expression. To evaluate the homozygous insertion line for a mutant phenotype, several aspects of wild-type lateral root development were analyzed. A mutant phenotype has not yet been identified in the insertion line; however, there is evidence that the gene belongs to a small gene family. LRP1 provides a molecular marker to study the early stages of lateral and adventitious root primordium development.

Amino Acid Sequence↗
PubMed1995

Molecular characterization of BET1, a gene expressed in the endosperm transfer cells of maize.

A cDNA clone, BET1 (for basal endosperm transfer layer), was isolated from a cDNA bank prepared from 10-days after pollination (DAP) maize endosperm mRNA. BET1 mRNA was shown to encode a 7-kD cell wall polypeptide. Both the mRNA and protein were restricted in their distribution to the basal endosperm transfer layer and were not expressed elsewhere in the plant. BET1 expression commenced at 9 DAP, reached a maximum between 12 and 16 DAP, and declined after 16 DAP. The initial accumulation of the BET1 polypeptide reached a plateau by 16 DAP and declined thereafter, becoming undetectable by 20 DAP. The antibody raised against the BET1 protein reacted with a number of polypeptides of higher molecular mass than the BET1 monomer. Most of these were present in cytosolic fractions and were found in nonbasal cell endosperm extracts, but three species appeared to be basal cell specific. This result and the reactivity of exhaustively extracted cell wall material with the BET1 antibody suggest that a fraction of the protein is deposited in a covalently bound form in the extracellular matrix. We propose that the BET1 protein plays a role in the structural specialization of the transfer cells. In addition, BET1 provides a new molecular marker for the development of this endosperm domain.

Amino Acid Sequence↗
PubMed1995

Adenovirus E1A functions as a cofactor for retinoic acid receptor beta (RAR beta) through direct interaction with RAR beta.

Transcription regulation by DNA-bound activators is thought to be mediated by a direct interaction between these proteins and TATA-binding protein (TBP), TFIIB, or TBP-associated factors, although occasionally cofactors or adapters are required. For ligand-induced activation by the retinoic acid receptor-retinoid X receptor (RAR-RXR) heterodimer, the RAR beta 2 promoter is dependent on the presence of E1A or E1A-like activity, since this promoter is activated by retinoic acid only in cells expressing such proteins. The mechanism underlying this E1A requirement is largely unknown. We now show that direct interaction between RAR and E1A is a requirement for retinoic acid-induced RAR beta 2 activation. The activity of the hormone-dependent activation function 2 (AF-2) of RAR beta is upregulated by E1A, and an interaction between this region and E1A was observed, but not with AF-1 or AF-2 of RXR alpha. This interaction is dependent on conserved region III (CRIII), the 13S mRNA-specific region of E1A. Deletion analysis within this region indicated that the complete CRIII is needed for activation. The putative zinc finger region is crucial, probably as a consequence of interaction with TBP. Furthermore, the region surrounding amino acid 178, partially overlapping with the TBP binding region, is involved in both binding to and activation by AF-2. We propose that E1A functions as a cofactor by interacting with both TBP and RAR, thereby stabilizing the preinitiation complex.

Adenovirus E1A Proteins↗
PubMed1995

The activity of transcription factor PBP, which binds to the proximal sequence element of mammalian U6 genes, is regulated during differentiation of F9 cells.

Mouse F9 embryonic carcinoma (EC) cells differentiate in culture to parietal endoderm (PE) cells upon induction with retinoic acid and cyclic AMP. In the course of this process, the expression of polymerase III transcripts, e.g., 5S rRNA and U6 small nuclear RNA, is dramatically reduced. This reduction of endogenous RNA content is accompanied by a loss of transcriptional capacity in cell extracts from PE cells. Partial purification of such extracts reveals that the DNA-binding activity of transcription factor PBP, binding specifically to the proximal sequence element (PSE) sequence of vertebrate U6 genes, is significantly reduced. This finding is corroborated by a loss in the transcriptional activity of this factor in reconstitution assays with partially purified polymerase III transcription components. In contrast, the activity of TFIIIA and TFIIIB and the amount of free TATA-binding protein remain unchanged during the differentiation process analyzed here. These data show for the first time that the PSE-binding protein PBP is essentially involved in the differential regulation of polymerase III genes governed by external promoters.

Animals↗
PubMed1994

The in situ localization of Adh transcripts in Drosophila species reveals evolved regulatory differences in spatially restricted expression.

Spatial and temporal aspects of Adh expression were examined during oogenesis and embryogenesis of Drosophila melanogaster, D. simulans, and D. virilis by in situ hybridization. In stage 14 and 15 embryos, differences in zygotic expression of Adh in the primordia of the gastric caecae of D. simulans and in the fat body of D. virilis were observed. These zygotic differences appear to be transient because Adh expression is seen in the gastric caecae of stage 16 embryos of D. simulans and in the fat body of stage 17 embryos of D. virilis. Analysis of D. melanogaster x D. simulans hybrids revealed that the parental difference for transcriptional activity of Adh in the primordia of the gastric caecae is under dominant control. These results provide the basis for exploring evolved regulatory differences in Adh expression during oogenesis and embryogenesis of Drosophila, which are until now unexplored. The potential of in situ hybridization in analyzing evolved regulatory differences in gene expression is briefly discussed.

Alcohol Dehydrogenase↗
PubMed1995

Cholesterol side-chain cleavage cytochrome P450 gene expression in the primitive gut of the mouse embryo does not require steroidogenic factor 1.

In situ hybridization studies reveal novel sites of expression of cholesterol side-chain cleavage cytochrome P450 (P450scc) during murine embryonic development. In addition to fetal adrenals and testes, P450scc transcripts localize in situ to the primitive gut and to a subset of unidentified cells in the dermal mesenchyme of embryonic skin. In the gut, transcripts are most abundant in luminal epithelia of the hindgut, which will form the colon. P450scc transcript abundance at these novel sites is a fraction of that in fetal adrenals or testes, suggesting a local rather than an endocrine function. Immunocytochemical analyses localize P450scc protein to the fetal hindgut, indicating that the transcripts are translated in vivo. RNA isolated from microdissected embryonic hindgut and skin was reverse transcribed and amplified by polymerase chain reaction. DNA sequence analyses of polymerase chain reaction products confirmed that specific hybridization in situ represents authentic P450scc gene (Cyp11A) transcripts and that 3 beta-hydroxysteroid dehydrogenase/delta 5-->delta 4-isomerase transcripts are also present, demonstrating the potential of these fetal tissues to produce pregnenolone and progesterone. P450scc transcripts are also detectable by in situ hybridization in primitive gut and skin of Fushi tarazu factor 1 null mice, which lack the nuclear receptor steroidogenic factor 1, proving that steroidogenic factor 1 is not required for steroid hydroxylase gene expression at these sites. The capacity for C21 steroid biosynthesis in primitive gut and skin during organogenesis raises the question whether local production of steroid hormones may be required for normal cellular growth and differentiation of these tissues during embryogenesis.

Animals↗
PubMedDate not supplied

Perspectives in steroid hydroxylase gene expression: novel sites of expression during embryonic development.

CYP17 is not expressed in adult mouse adrenal glands but is expressed in a subset of fetal adrenocortical cells, indicating the potential to produce both corticosterone and cortisol during murine embryogenesis. CYP11A is expressed in the fetal adrenal but also in developing hindgut, which will form the colon, and in cells located beneath the skin of the embryo. Novel sites of expression of CYP17 and CYP11A in the mouse embryo suggest potential physiological roles for local production of steroids in diverse organs systems during development.

Adrenal Glands↗
PubMed1994

Proliferative and metabolic capacity of rat embryo fibroblasts immortalized by c-myc depends on cellular age at oncogenic transfection.

It is well known that secondary rat embryo fibroblasts are immortalized and transformed with respect to requirements of growth factors by transfection with an overexpressed c-myc protooncogene. On the other hand, c-myc expression of nontransformed cells was shown to be independent of cellular age in vitro. In order to elucidate further the role of the c-myc protooncogene in the process of aging of rat embryo fibroblasts, we have transfected these cells at low (< or = 2) and at high (> or = 16) cumulative population doublings with SV40-promoter/enhancer-driven murine c-myc. These cells transformed young or aged, as well as their nontransformed, young and aged controls, were characterized with respect to their expression of c-myc at the mRNA and the protein level. Furthermore, we have investigated in detail their cell density-dependent growth, dependence of cell proliferation on stimulation by combinations of growth factors, and dependence of entry into cell cycle on cell size. In addition, we have measured rates of synthesis and degradation of cellular RNA and protein. The main result was that cells transformed at old age cannot be distinguished from nontransformed old cells by any of the characteristics investigated except by their immortalization. Thus, the cell lines overexpressing c-myc are immortalized and fixed in the proliferative/metabolic state achieved at the time of transfection. It is concluded that the intracellular effects of c-myc depend on the epigenetic status of the cells.

Animals↗
PubMed1995

Studies of cloning, chromosomal mapping, and embryonic expression of the mouse Rab geranylgeranyl transferase beta subunit.

The mouse Rab geranylgeranyl transferase beta subunit has been cloned from a mouse E8.5 embryonic cDNA library. Sequence comparison reveals 97.4% sequence identity at the amino acid level to the rat clone isolated from an adult rat brain cDNA library. This gene, given a gene symbol of Rabggtb, is mapped in the distal region of mouse chromosome 3. It is ubiquitously expressed in adult animals but displays an interesting pattern of expression during a specific time of embryonic development. The expression of this gene can be detected in the whole embryos during early embryonic stages and is specifically concentrated in the developing brain, heart, and liver between gestation stages of E11.5 and E13.5. In addition, the expression of this gene is induced by retinoic acid in a mouse embryonal carcinoma cell line, P19.

Animals↗
PubMed1994

Expression of the acetylcholinesterase gene during development of drosophila embryos.

The acetylcholinesterase (AChE) forms and the expression of the AChE mRNA in situ have been shown during the embryonic development of Drosophila melanogaster. The enzyme and its transcript were present well before the differentiation of the first neuroblasts. The non-CNS- specific AChE forms were responsible for the early AChE activity, and specific AChE form to the central nervous system (CNS) appeared when the CNS started to condense. Embryos deficient for the 5' end of the AChE gene expressed only the non-CNS-specific AChE forms,-- interestingly, the AChE transcript was present only in their CNS. The elimination of half of the CNS-specific AChE elevated the acetylcholine (ACh) level in the flies. These results imply that the non-CNS-specific AChE can also be non-neural, it is dispensable for the late embryonic development, and it does not substitute for the ACh hydrolysing capacity of the CNS- specific enzyme.

Acetylcholinesterase↗
PubMedDate not supplied

Expression of the transcription factor c-Ets1 correlates with the occurrence of invasive processes during normal and pathological development.

The protein encoded by the c-ets1 proto-oncogene is a member of a new family of transcription factors. Cellular regulatory sequences responsive to the c-Ets1 proteins include a urokinase-type plasminogen activator (uPA) gene enhancer, the stromelysin 1 and the collagenase 1 gene promoters. During normal as well as pathological development, the expression of c-ets1 is associated with the occurrence of invasive processes, either in invading cells or in the invaded tissue. Since these invasive processes are thought to require the remodeling of the extracellular matrix, we investigate the relationships between c-Ets1 and the expression patterns of transcripts encoding the matrix-degrading proteases uPA, stromelysin 1 and collagenase 1, in embryos and in solid tumors.

Animals↗
PubMed1994

Mouse dioxin-inducible NAD(P)H: menadione oxidoreductase: NMO1 cDNA sequence and genetic differences in mRNA levels.

We have cloned and sequenced the mouse NMO1 cDNA, which encodes the NAD(P)H:menadione oxidoreductase [also called NAD(P)H:(quinone acceptor) oxidoreductase; quinone reductase; azo dye reductase; DT diaphorase; EC 1.6.99.2]. The cDNA is 1528 bp in length excluding the poly(A+) tail, and has 5' and 3' nontranslated regions of 108 bp and 595 bp, respectively. The deduced protein contains 274 amino acids, including the first methionine (M(r) = 30,959). The mouse NMO1 protein is: 94% similar to the rat NMO1 and 86.5% to the human NMO1 proteins; 49.3% identical to the human NQO2 protein; and < 20% similar to several dozen other proteins in the quinone oxidoreductase superfamily. Southern hybridization analysis of mouse DNA reveals that the Nmo1 gene is likely to span less than a total of 20 kb. The Nmo1 gene is highly inducible by 2,3,7,8,-tetrachlorodibenzo-p-dioxin (dioxin; TCDD) in mouse liver and mouse cell cultures. TCDD inducibility of NMO1 is detectable at 12 and 18 days of gestation, but markedly elevated at 1-3 weeks post partum as compared with the 6- and 12-week-old mouse. NMO1 mRNA levels are strikingly elevated in the untreated mouse hepatoma Hepa-1c1c7 mutant line c37 lacking CYP1A1 (aryl hydrocarbon hydroxylase) activity, and in the untreated 14CoS/14CoS mouse cell line having an 'oxidative stress response' caused by homozygous deletion of about 3800 kb on chromosome 7. Previous work and the data in this report show that the murine Nmo1 gene is regulated by three distinct mechanisms: CYP1A1 metabolism-dependent repression, Ah receptor-mediated induction by TCDD, and activation by the chromosome 7-mediated oxidative stress response.

3T3 Cells↗
PubMed1995

Molecular cloning and expression of hardening-induced genes in Chlorella vulgaris C-27: the most abundant clone encodes a late embryogenesis abundant protein.

To investigate the effects of hardening on gene expression in Chlorella vulgaris Beijerink IAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27), a frost-hardy strain, 17 cDNA clones corresponding to hardening-induced Chlorella (hiC) genes were isolated by differential screening of a cDNA library from 6-h hardened cells. Northern blot analysis of transcripts of hiC genes showed that these genes are specifically induced by hardening and that their patterns of induction vary. Southern blots of genomic DNAs from two strains (Chlorella ellipsoidea Gerneck IAM C-102, chilling-sensitive; and C. vulgaris C-27, frost-hardy) of Chlorella indicated that ten hiC clones out of 17 hybridized only with DNA of strain C-27 and the other seven clones hybridized with DNA of both strains. However, of these seven clones, transcripts corresponding to six clones did not accumulate in strain C-102 at low temperatures. The sequence of a deduced protein encoded by the most abundant clone, hiC6, exhibited homology to sequences of Group III LEA (late embryogenesis abundant) proteins and had an amino-terminal amino acid sequence that was similar to the sequences of chloroplast transit peptides.

Acclimatization↗
PubMed1994

neu and ras initiate murine mammary tumors that share genetic markers generally absent in c-myc and int-2-initiated tumors.

We have previously shown that each of four activated oncogenes (c-myc, neu, ras, and int-2) can serve as transgenic initiators of morphologically distinct adenocarcinomas of the murine mammary gland. Since abnormalities of these oncogenes are found frequently in human breast cancers, such differences are of particular interest. Thus, the distinctiveness of each murine tumor type might reflect a relationship between a specific oncogene and a susceptible target cell or might reflect distinctive changes brought about by the idiosyncratic action of each oncogene. We have identified six genes (two of them novel) expressed in tumors initiated by neu, but usually absent from tumors initiated by c-myc. The expression of these genes (kappa-casein, transferrin, cellular retinol binding protein I (CRBPI), WDNM1, and the two novel ones) cannot be induced in c-myc-initiated tumors by the introduction of an activated neu oncogene nor can their expression be inhibited in neu-initiated tumors by the introduction of c-myc. Therefore, these genes appear to represent markers of a cell type preferentially transformed by neu. Further analysis reveals that the six markers are also expressed by ras-initiated mammary tumors, but not by int-2-initiated tumors suggesting that neu/ras-initiated tumors share a common cellular lineage and/or a common signal transduction pathway. Interestingly, one of the novel marker genes (Mat-8) appears to encode a cell-surface chloride channel and the other, a secreted protein with homologies to glycosyl hydrolases, both of which might be useful for the diagnosis and treatment of specific mammary tumors.

Amino Acid Sequence↗
PubMed1994

Cloning and sequencing of the Atlantic salmon (Salmo salar) cytochrome c oxidase subunit III gene (coxIII) and analysis of coxIII expression during parr-smolt transformation.

Smoltification is the process whereby salmon alter their metabolism in preparation for movement from freshwater to seawater. Differential screening of a cDNA library prepared from post-smolt salmon liver mRNA led to the selection of a smoltification-induced sequence. Analysis of this cDNA revealed that it partially encoded subunit III of the enzyme cytochrome c oxidase. The complete coxIII sequence was amplified from salmon genomic DNA using consensus oligonucleotides based on ATPase 6 and tRNA(GLY) sequences from Pacific salmonid species. Cytochrome c oxidase subunit III liver mRNA levels were found to be significantly increased in salmon smolts. Northern blot analysis revealed a coxIII transcript of approximately 750 bp in all salmon tissues tested except blood. The DNA sequence of coxIII employs the mammalian mitochondrial genetic code and is strongly conserved when compared with that of other species.

Amino Acid Sequence↗
PubMed1994

Extracellular cAMP can restore development in Dictyostelium cells lacking one, but not two subtypes of early cAMP receptors (cARs). Evidence for involvement of cAR1 in aggregative gene expression.

Extracellular cAMP induces expression of several classes of developmentally regulated genes in Dictyostelium. Four highly homologous surface cAMP receptors (cARs) were identified earlier, but involvement of specific cARs in gene regulation has not been clarified. Cells lacking the chemotactic receptor, cAR1, neither aggregate nor express developmentally regulated genes. Expression of aggregative genes is in wild-type cells induced by nanomolar cAMP pulses and repressed by persistent micromolar cAMP stimuli, which induce expression of prespore and prestalk-enriched genes during the postaggregative stages of development. We show here that in cell lines carrying a cAR1 gene disruption, nanomolar pulses cannot induce aggregative gene expression. Remarkably, micromolar cAMP can induce expression of aggregative genes in car1- cells as well as expression of prespore and prestalk-enriched genes, and furthermore restores their ability to form normal slugs and fruiting bodies. These data indicate that cAR1 mediates aggregative but not postaggregative gene expression and morphogenesis, and suggest that after gene disruption, its function is partially taken over by a lower affinity receptor that is not subjected to desensitization. The absence of another early cAMP receptor, cAR3, does not affect development. However, in a car1-/car3- double mutant, cAMP stimulation cannot restore any developmental gene expression, indicating that cAR3 may have substituted for cAR1 in car1- cell lines.

Animals↗
PubMed1989

Rat lung lectin gene expression is regulated developmentally and by dexamethasone.

The cell-agglutinating activity of soluble beta-galactoside-binding proteins (lectins) is developmentally regulated in several mammalian organs. Little is known of the alterations in gene expression that underlie this developmental regulation. Rat lung contains a dimeric beta-galactoside-binding protein that exhibits a postnatal peak of hemagglutination activity caused in part by an increased rate of lectin synthesis. We now report rat lung lectin mRNA concentration increased to a peak at age 6 days; dexamethasone treatment aborted this increase. Southern blot analysis is compatible with the presence of more than one lectin gene. However, two lines of evidence indicate that we measured a single gene product: 1) only one lectin of subunit Mr 14,000 is present in rat lung (Biochemistry 27: 692-699, 1988), and 2) in Northern blot analysis of RNA, the lectin cDNA hybridized with only one mRNA species. Our present findings, taken with prior studies of lectin synthesis, indicate that the postnatal increase in lectin synthesis is mediated pretranslationally and by an increased efficiency of translation. Dexamethasone treatment impairs the increase of lectin mRNA concentration but increases translational efficiency.

Aging↗