scholarly journals Ingrowth by photoreceptor axons induces transcription of a retrotransposon in the developing Drosophila brain

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1049-1058 ◽  
Author(s):  
B.A. Mozer ◽  
S. Benzer
Keyword(s):  
P Element ◽  
Regulatory Sequences ◽  
Lacz Expression ◽  
Specific Expression ◽  
Enhancer Element ◽  
Drosophila Brain ◽  
First Optic Ganglion ◽  
Combined Action ◽  
Eye Imaginal Disc ◽  
The Brain

The development of the lamina, the first optic ganglion of the fly visual system, depends on inductive cues from the innervating photoreceptor axons. lacZ expression from a P-element insertion, A72, occurs in the anlage of the lamina coincident with axon ingrowth from the eye imaginal disc. In eyeless mutants lacking photoreceptor axons, lacZ expression did not occur. The P-element was found to have inserted within the 3′ long terminal repeat (LTR) of a ‘17.6′ type retrotransposon. The expression pattern of 17.6 transcripts in the brain in wild-type and eyeless mutants paralleled the expression of the lacZ reporter. Analysis of 17.6 cis-regulatory sequences indicates that the lamina-specific expression is due to the combined action of an enhancer element in the LTR and a repressor element within the internal body of the retrotransposon. The regulation of the 17.6 retrotransposon provides a model for the study of innervation-dependent gene expression in postsynaptic cells during neurogenesis.

scholarly journals Identification and characterization of a neuroretina-specific enhancer element in the quail Pax-6 (Pax-QNR) gene.

1995 ◽  
Vol 15 (2) ◽  
pp. 892-903 ◽  
Author(s):  
S Plaza ◽  
C Dozier ◽  
M C Langlois ◽  
S Saule
Keyword(s):  
Specific Activity ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Transcriptional Level ◽  
Regulatory Sequences ◽  
Independent Manner ◽  
Specific Expression ◽  
Enhancer Activity ◽  
Enhancer Element

Using nuclear run-on assays, we showed that the tissue-specific expression of quail Pax-6 (Pax-QNR) P0-initiated mRNAs is due in part to regulation of the gene at the transcriptional level. Regulatory sequences governing neuroretina-specific expression of the P0-initiated mRNAs were investigated. By using reporter-based expression assays, we characterized a region within the Pax-QNR gene, located 7.5 kbp downstream from the P0 promoter, that functions as an enhancer in neuroretina cells but not in nonexpressing P0-initiated mRNA cells (quail embryo cells and quail retinal pigment epithelial cells). This enhancer element functioned in a position- and orientation-independent manner both on the Pax-QNR P0 promoter and the heterologous thymidine kinase promoter. Moreover, this enhancer element exhibited a developmental stage-specific activity during embryonic neuroretina development: in contrast to activity at day E7, the enhancer activity was very weak at day E5. This paralleled the level of expression of P0-initiated mRNAs observed at the same stages. Using footprinting, gel retardation, and Southwestern (DNA-protein) analysis, we demonstrated the existence of four neuroretina-specific nuclear protein-binding sites, involving multiple unknown factors. In addition we showed that the quail enhancer element is structurally and functionally conserved in mice. All of these results strongly suggest that this enhancer element may contribute to the neuroretina-specific transcriptional regulation of the Pax-6 gene in vivo.

scholarly journals The l(3)S12 locus of Drosophila melanogaster: heterochromatic position effects and stage-specific misexpression of the gene in P element transposons.

Genetics ◽  
1991 ◽  
Vol 128 (1) ◽  
pp. 103-118
Author(s):  
F L Dutton ◽  
A Chovnick
Keyword(s):  
Position Effect ◽  
Fusion Transcript ◽  
P Element ◽  
Female Sterility ◽  
Specific Expression ◽  
Position Effects ◽  
Enhancer Element ◽  
Control Stage ◽  
Cold Sensitive ◽  
Sensitive Allele

Abstract l(3)S12 is a vital locus whose function is required in embryos, early larvae, late pupae and oogenesis. We have identified a cold-sensitive allele, l(3)S12(3), and characterized conditional misexpression of the gene associated with this mutation as well as with several euchromatic insertions of l(3)S12+ transposons. Surviving cold-sensitive mutants as well as underexpression variants generated by P element transformation display a phenotypic syndrome that can include delayed development, abnormal bristle morphology, and female sterility. Using these phenotypes, defects in putative "early" and "late" l(3)S12 expression can be identified. The sensitivity of certain l(3)S12+ insertions to site-specific euchromatic position effect appears to be due to separation of the gene from an endogenous enhancer element during cloning. This enhancerless construct can be used to identify and perhaps to select "permissive" euchromatic sites, presumably adjacent to enhancer elements, which in some cases permit elevated production not only of the l(3)S12 message, but also of a P element-l(3)S12 fusion transcript. Certain of these permissive sites appear to control stage-specific expression, and we propose that this system may be used to identify, clone, and characterize such loci. Heterochromatic position effect on this locus has been demonstrated. Available evidence suggests that the l(3)S12 gene may be involved in protein synthesis, perhaps encoding a ribosomal protein.

scholarly journals Analysis of the Promoter of the ninaE Opsin Gene in Drosophila melanogaster

Genetics ◽  
1987 ◽  
Vol 116 (4) ◽  
pp. 565-578 ◽  
Author(s):  
Drzislav Mismer ◽  
Gerald M Rubin
Keyword(s):  
Control Region ◽  
Photoreceptor Cells ◽  
P Element ◽  
Opsin Gene ◽  
Regulatory Sequences ◽  
Enhancer Element ◽  
Cis Acting ◽  
E Coli ◽  
Promoter Function ◽  
Control Regions

ABSTRACT We have analyzed the cis-acting regulatory sequences of the ninaE gene. This gene encodes the major Drosophila melanogasteropsin, the protein component of the primary chromophore of photoreceptor cells R1-R6 of the adult eye. DNA fragments containing the start point of transcription of the ninaE gene were fused to either the Escherichia coli chloramphenicol acetyltransferase or lacZ (β-galactosidase) gene and introduced into the Drosophila germline by P-element-mediated transformation. Expression of the E. coli genes was then used to assay the ability of various sequences from the ninaE gene to confer the ninaE pattern of expression. Fragments containing between 2.8 kb and 215 bp of the sequences upstream of the start of transcription plus the first 67 bp of the untranslated leader were able to direct nearly wild-type expression. We have identified three separable control regions in the ninaE promoter. The first, which has the properties of an enhancer element, is located between nucleotides -501 and -219. The removal of this sequence had little effect on promoter function; this sequence appears to be redundant. However, it appears to be able to substitute for the second control region which is located between nucleotides -215 and -162, and which also affects the level of output from this promoter. Removal of these two control regions resulted in a 30-fold decrease in expression; however tissue specificity was not affected. The third control region, located downstream from nucleotide -120, appears to be absolutely necessary for promoter function in the absence of the first two regulatory sequences. Examination of larvae containing fusion genes expressing β-galactosidase suggests that the ninaE gene is also expressed in a subset of cells in the larval photoreceptor organ.

scholarly journals Definition of cis-acting elements regulating expression of the Drosophila melanogaster ninaE opsin gene by oligonucleotide-directed mutagenesis.

Genetics ◽  
1989 ◽  
Vol 121 (1) ◽  
pp. 77-87 ◽  
Author(s):  
D Mismer ◽  
G M Rubin
Keyword(s):  
Drosophila Melanogaster ◽  
The Body ◽  
Drosophila Virilis ◽  
P Element ◽  
Opsin Gene ◽  
Directed Mutagenesis ◽  
Homologous Gene ◽  
Regulatory Sequences ◽  
Specific Expression ◽  
Cis Acting

Abstract We have analyzed the cis-acting regulatory sequences of the Rh1 (ninaE) gene in Drosophila melanogaster by P-element-mediated germline transformation of indicator genes transcribed from mutant ninaE promoter sequences. We have previously shown that a 200-bp region extending from -120 to +67 relative to the transcription start site is sufficient to obtain eye-specific expression from the ninaE promoter. In the present study, 22 different 4-13-bp sequences in the -120/+67 promoter region were altered by oligonucleotide-directed mutagenesis. Several of these sequences were found to be required for proper promoter function; two of these are conserved in the promoter of the homologous gene isolated from the related species Drosophila virilis. Alteration of a conserved 9-bp sequence results in aberrant, low level expression in the body. Alteration of a separate 11-bp sequence, found in the promoter regions of several photoreceptor-specific genes of Drosophila, results in an approximately 15-fold reduction in promoter efficiency but without apparent alteration of tissue-specificity. A protein factor capable of interacting with this 11-bp sequence has been detected by DNaseI footprinting in embryonic nuclear extracts. Finally, we have further characterized two separable enhancer sequences previously shown to be required for normal levels of expression from this promoter.

Analysis of the promoter of the Rh2 opsin gene in Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 120 (1) ◽  
pp. 173-180
Author(s):  
D Mismer ◽  
W M Michael ◽  
T R Laverty ◽  
G M Rubin
Keyword(s):  
Drosophila Melanogaster ◽  
Fusion Gene ◽  
Photoreceptor Cells ◽  
Histochemical Staining ◽  
P Element ◽  
Opsin Gene ◽  
Regulatory Sequences ◽  
Specific Expression ◽  
Beta Galactosidase ◽  
Cat Expression

Abstract We have analyzed the cis-acting regulatory sequences of the Drosophila melanogaster Rh2 gene that encodes the protein component of a rhodopsin which is expressed in ocellar photoreceptor cells. DNA fragments containing the start point of transcription of the Rh2 gene were fused to either the Escherichia coli chloramphenicol acetyltransferase (CAT) or lacZ (beta-galactosidase) genes and introduced into the Drosophila germline by P-element-mediated transformation. Expression of the E. coli genes was then used to assay the ability of various sequences from the Rh2 gene to confer upon the indicator genes the Rh2 pattern of expression. Fragments containing between 4.3 kb and 183 bp upstream of the start of transcription plus the first 32 bp of the 5'-untranslated leader were found to result in nearly identical levels of head-specific CAT expression. Deletion of Rh2 sequences distal to position -112 bp resulted in loss of detectable CAT expression from these Rh2/CAT fusion constructs. We have, therefore, defined a region essential for head-specific expression of the Rh2 gene to a region extending from -183 to -112. We have determined the DNA sequence of the Rh2 promoter from -448 to +32 and have found an 11-bp sequence which is also present in the upstream flanking sequences of two other photoreceptor-specific genes (ninaE and ninaC). By histochemical staining of beta-galactosidase expressed under the control of the Rh2 promoter and by analyzing the effect of the ocelliless mutation on the expression of an Rh2/CAT fusion gene, we have been able to demonstrate that this promoter is active in ocelli.

Molecular biology of the renin-angiotensin system

1988 ◽  
Vol 255 (4) ◽  
pp. F563-F573 ◽  
Author(s):  
V. J. Dzau ◽  
D. W. Burt ◽  
R. E. Pratt
Keyword(s):  
Molecular Biology ◽  
Physiological Role ◽  
Renin Angiotensin System ◽  
Regulatory Sequences ◽  
Specific Expression ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Molecular Approaches ◽  
Combined Action

This paper reviews the molecular biology of the renin-angiotensin system. The renin gene structure is analyzed in detail, including an examination of the putative regulatory regions. The combined action of these regulatory sequences would result in the complex, tissue-specific expression and regulation observed in vivo. The expression of the tissue renin-angiotensin systems, which may have important physiological functions, is also described. In addition, the pathway of renin biosynthesis and secretion is reviewed. This includes speculation on the fate of circulating prorenin and the physiological role of multiple renin forms and secretory pathways. The molecular approaches described in this paper have greatly advanced our knowledge of the biology of the renin-angiotensin system. Future studies using these and other approaches should provide further insight into this complex system.

Segmental expression of the EphA4 (Sek-1) receptor tyrosine kinase in the hindbrain is under direct transcriptional control of Krox-20

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 443-452 ◽  
Author(s):  
T. Theil ◽  
M. Frain ◽  
P. Gilardi-Hebenstreit ◽  
A. Flenniken ◽  
P. Charnay ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Binding Sites ◽  
Cell Signalling ◽  
Ectopic Expression ◽  
Regulatory Sequences ◽  
Kinase Gene ◽  
Specific Expression ◽  
Enhancer Activity ◽  
Enhancer Element

Segmentation of the vertebrate hindbrain leads to the formation of a series of rhombomeres (r) with distinct identities. Recent studies have uncovered regulatory links between transcription factors governing this process, but little is known of how these relate to molecules mediating cell-cell signalling. The Eph receptor tyrosine kinase gene EphA4 (Sek-1) is expressed in r3 and r5, and function-blocking experiments suggest that it is involved in restricting intermingling of cells between odd- and even-numbered rhombomeres. We have analysed the cis-acting regulatory sequences of the EphA4 gene in transgenic mice and identified a 470 bp enhancer element that drives specific expression in r3 and r5. Within this element, we have identified eight binding sites for the Krox-20 transcription factor that is also expressed in r3 and r5. Mutation of these binding sites abolishes r3/r5 enhancer activity and ectopic expression of Krox-20 leads to ectopic activation of the enhancer. These data indicate that Krox-20 is a direct transcriptional activator of EphA4. Together with evidence that Krox-20 regulates Hox gene expression, our findings reveal a mechanism by which the identity and movement of cells are coupled such that sharply restricted segmental domains are generated.

Positive and negative transcriptional elements of the human type IV collagenase gene

1990 ◽  
Vol 10 (12) ◽  
pp. 6524-6532
Author(s):  
S M Frisch ◽  
J H Morisaki
Keyword(s):  
Core Promoter ◽  
Type Iv Collagenase ◽  
Mobility Shift ◽  
Specific Expression ◽  
Enhancer Element ◽  
Type Iv ◽  
Dnase I Footprinting ◽  
Gel Mobility Shift ◽  
Transcriptional Elements ◽  
Mcf 7

Proteolysis by type IV collagenase (T4) has been implicated in the process of tumor metastasis. The T4 gene is expressed in fibroblasts, but not in normal epithelial cells, and its expression is specifically repressed by the E1A oncogene of adenovirus. We present an investigation of the transcriptional elements responsible for basal, E1A-repressible, and tissue-specific expression. 5'-Deletion analysis, DNase I footprinting, and gel mobility shift assays revealed a strong, E1A-repressible enhancer element, r2, located about 1,650 bp upstream of the start site. This enhancer bound a protein with binding specificity very similar to that of the transcription factor AP-2. A potent silencer sequence was found 2 to 5 bp downstream of this enhancer. The silencer repressed transcription from either r2 or AP-1 enhancer elements and in the context of either type IV collagenase or thymidine kinase (tk) gene core promoters; enhancerless transcription from the latter core promoter was also repressed. Comprising the silencer were two contiguous, autonomously functioning silencer elements. Negative regulation of T4 transcription by at least two factors was demonstrated. mcf-7 proteins specifically binding both elements were detected by gel mobility shift assays; a protein of approximately 185 kDa that bound to one of these elements was detected by DNA-protein cross-linking. The silencer repressed transcription, in an r2 enhancer-tk promoter context, much more efficiently in T4-nonproducing cells (mcf-7 or HeLa) than in T4-producing cells (HT1080), suggesting that cell type-specific silencing may contribute to the regulation of this gene.

Stable transfer and restricted expression of a cloned class I gene encoding a secreted transplantation-like antigen

1985 ◽  
Vol 5 (6) ◽  
pp. 1295-1300
Author(s):  
Y Barra ◽  
K Tanaka ◽  
K J Isselbacher ◽  
G Khoury ◽  
G Jay
Keyword(s):  
Molecular Mechanisms ◽  
Cell Types ◽  
Class I ◽  
Regulatory Sequences ◽  
Transcriptional Enhancer ◽  
Gene Encoding ◽  
Specific Expression ◽  
Tissue Specific ◽  
Functional Studies ◽  
I Gene

The identification of a unique major histocompatibility complex class I gene, designated Q10, which encodes a secreted rather than a cell surface antigen has led to questions regarding its potential role in regulating immunological functions. Since the Q10 gene is specifically activated only in the liver, we sought to define the molecular mechanisms which control its expression in a tissue-specific fashion. Results obtained by transfection of the cloned Q10 gene, either in the absence or presence of a heterologous transcriptional enhancer, into a variety of cell types of different tissue derivations are consistent with the Q10 gene being regulated at two levels. The first is by a cis-dependent mechanism which appears to involve site-specific DNA methylation. The second is by a trans-acting mechanism which would include the possibility of an enhancer binding factor. The ability to efficiently express the Q10 gene in certain transfected cell lines offers an opportunity to obtain this secreted class I antigen in quantities sufficient for functional studies; this should also make it possible to define regulatory sequences which may be responsible for the tissue-specific expression of Q10.

Generation and early differentiation of glial cells in the first optic ganglion of Drosophila melanogaster

Development ◽  
1992 ◽  
Vol 115 (4) ◽  
pp. 903-911 ◽  
Author(s):  
M.L. Winberg ◽  
S.E. Perez ◽  
H. Steller
Keyword(s):  
Drosophila Melanogaster ◽  
Glial Cells ◽  
Enhancer Trap ◽  
P Element ◽  
Cell Divisions ◽  
Genetic Mosaic ◽  
First Optic Ganglion ◽  
Optic Ganglion ◽  
Glial Lineage ◽  
Enhancer Trap Lines

We have examined the generation and development of glial cells in the first optic ganglion, the lamina, of Drosophila melanogaster. Previous work has shown that the growth of retinal axons into the developing optic lobes induces the terminal cell divisions that generate the lamina monopolar neurons. We investigated whether photoreceptor ingrowth also influences the development of lamina glial cells, using P element enhancer trap lines, genetic mosaics and birthdating analysis. Enhancer trap lines that mark the differentiating lamina glial cells were found to require retinal innervation for expression. In mutants with only a few photoreceptors, only the few glial cells near ingrowing axons expressed the marker. Genetic mosaic analysis indicates that the lamina neurons and glial cells are readily separable, suggesting that these are derived from distinct lineages. Additionally, BrdU pulse-chase experiments showed that the cell divisions that produce lamina glia, unlike those producing lamina neurons, are not spatially or temporally correlated with the retinal axon ingrowth. Finally, in mutants lacking photoreceptors, cell divisions in the glial lineage appeared normal. We conclude that the lamina glial cells derive from a lineage that is distinct from that of the L-neurons, that glia are generated independently of photoreceptor input, and that completion of the terminal glial differentiation program depends, directly or indirectly, on an inductive signal from photoreceptor axons.

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