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R Hen

Publications and source records attributed to R Hen.

At least 109 records · Page 6Linked to original sources
PubMed1993

Gene in the region of the Friedreich ataxia locus encodes a putative transmembrane protein expressed in the nervous system.

Friedreich ataxia (FRDA) is an autosomal recessive degenerative disorder that affects the cerebellum, spinal cord, and peripheral nerves. The FRDA gene was localized in 9q13-q21 within 0.7 centimorgan of the D9S5 and D9S15 loci. One recently reported recombination event and haplotype analysis in a population with a founder effect suggested that the FRDA locus is on the D9S5 side. Using a conserved probe from the D9S5 locus, we have now identified an approximately 7-kilobase (kb) transcript and report cloning of its cDNA. The corresponding gene, X11, extends at least 80 kb in a direction opposite D9S15. The gene is expressed in the brain, including the cerebellum, but is not detectable in several nonneuronal tissues and cell lines. In situ hybridization of adult mouse brain sections showed prominant expression in the granular layer of the cerebellum. Expression was also found in the spinal cord. The cDNA contains an open reading frame encoding a 708-amino acid sequence that shows no significant similarity to other known proteins but contains a unique, 24-residue-long, putative transmembrane segment. On the basis of its genomic localization and its neuronal site of expression, particularly in the cerebellum, this "pioneer" gene represents a candidate for FRDA. Direct evidence of its involvement in FRDA will require a search for causative point mutations in patients.

Adaptor Proteins, Signal Transducing↗
PubMed1993

Structural and functional conservation of serotonin receptors throughout evolution.

Pharmacological studies as well as molecular cloning of serotonin receptors have revealed a multiplicity of receptor subtypes not only in mammals but also in molluscs and arthropods. Most of these receptors belong to the G protein-coupled receptor family and modulate levels of second messengers such as cAMP, IP3 and calcium. Rather than being specialized in a particular physiological function, a given receptor may be expressed in multiple neurons throughout the brain but always in the same compartment of these neurons. The 5HT1B receptor for example, is generally localized presynaptically on neuronal terminals where it inhibits neurotransmitter release. A widespread distribution of 5-HT receptors might explain how serotonin can modulate the multiple neuronal circuits which underlie complex behaviors.

Amino Acid Sequence↗
PubMed1993

Molecular cloning of a mammalian serotonin receptor that activates adenylate cyclase.

Serotonin modulates a wide range of physiological functions by activating multiple receptors, which are coupled to various effector systems. Using a strategy based on amino acid sequence homology between 5-hydroxytryptamine (5-HT) receptors, we have isolated from a mouse brain library a cDNA encoding a new 5-HT receptor, 5-HTx, that activates adenylate cyclase. Amino acid sequence comparisons revealed that the 5-HTx receptor was a distant relative of previously cloned 5-HT receptors, with the highest percentage of homology (42%) being with the 5-HTdro1 receptor, a Drosophila 5-HT receptor positively coupled to adenylate cyclase. In COS-7 cells transiently expressing the 5-HTx receptor, 5-HT induced an increase in cAMP levels that was dose dependent and saturable (EC50 = 45 nM). Agonists displayed the following rank order of potencies: 5-carboxamidotryptamine > 5-methoxytryptamine > 5-HT > RU 24969 > 8-hydroxy-2-(di-n-propylamino)tetralin. The most efficient antagonists in inhibiting the stimulatory effect of 5-HT were methysergide, methiothepin, mesulergine, metergoline, clozapine, ergotamine, and (+)-butaclamol. Membranes of COS-7 cells expressing the 5-HTx receptor displayed a single saturable binding site for [3H]5-HT. The order of potencies of various drugs in displacing [3H]5-HT binding was similar to the order obtained in cAMP experiments. The pharmacological profile of this receptor does not correspond to the profile of any of the classic 5-HT receptor subtypes. Expression of 5-HTx mRNA was highest in brainstem and lower in forebrain, cerebellum, intestine, and heart. The 5-HTx receptor might therefore correspond to 5-HT1-like receptors that have been shown to induce relaxation in porcine vena cava and guinea pig ileum as well as tachycardia in cat heart. The high affinity of the 5-HTx receptor for neuroleptic agents such as (+)-butaclamol and clozapine suggests also that this receptor might play a role in certain neuropsychiatric disorders.

Adenylyl Cyclases↗
PubMed1993

Mouse 5-hydroxytryptamine5A and 5-hydroxytryptamine5B receptors define a new family of serotonin receptors: cloning, functional expression, and chromosomal localization.

Serotonin [5-hydroxytryptamine (5-HT)] is a neuromodulator that mediates a wide range of physiological functions by activating multiple receptors. Using a strategy based on amino acid sequence homology between 5-HT receptors that interact with guanine nucleotide-binding proteins, we have isolated from a mouse brain library a cDNA encoding a new serotonin receptor. Amino acid sequence comparisons revealed that this receptor was a close relative of the previously identified 5-HT5 receptor but was distant from all other 5-HT receptor subtypes; we therefore named it 5-HT5B. When expressed in COS-7 cells, the 5-HT5B receptor displayed a high affinity for the serotonergic radioligand 125I-lysergic acid diethylamide. Its pharmacological profile was distinct from that of all classic 5-HT receptor subtypes. However, the high affinity of the 5-HT5B receptor for 5-carboxamidotryptamine and its low affinity for sumatriptan indicated that it might correspond to recently described 5-HT1D-like binding sites that were labeled with [3H]5-carboxamidotryptamine and insensitive to sumatriptan. In situ hybridization experiments revealed that the 5-HT5B mRNA was expressed predominantly in the habenula and in the CA1 field of the hippocampus. We also determined the chromosomal localization of the 5-HT5A and 5-HT5B genes and of their human counterparts. The 5-HT5A gene colocalized with the mouse mutation reeler and the human mutation holoprosencephaly type 3, which both result in abnormal brain development, raising the possibility that the 5-HT5A receptor plays a role in brain development.

Amino Acid Sequence↗
PubMed1992

Isolation of a mouse "5HT1E-like" serotonin receptor expressed predominantly in hippocampus.

Using a strategy based on amino acid sequence homology between 5-hydroxytryptamine (5-HT) receptors that interact with G proteins, we have isolated from a mouse brain library a cDNA encoding a new serotonin receptor, the 5HT1E beta receptor. Amino acid sequence comparisons revealed that its closest relatives were the recently characterized 5HT1E receptor (S31) and the 5HT1B and 5HT1D receptors. When expressed transiently in Cos-7 cells, the 5HT1E beta receptor displayed a high affinity for the nonspecific serotonergic radioligand 2-[125I]iodolysergic acid diethylamide (Kd = 980 pM). The pharmacological profile of the 5HT1E beta receptor resembled that of previously reported 5HT1E sites that have a low affinity for 5-carboxamidotryptamine and that have been found in human and rat brain. When stably expressed in NIH-3T3 cells, the 5HT1E beta receptor was negatively coupled to adenylate cyclase. In situ hybridization experiments revealed that the 5HT1E beta transcripts were detected only in the CA1, CA2, and CA3 layers of the hippocampus. Our results therefore demonstrate that the 5HT1E receptors constitute a heterogeneous family of receptors.

3T3 Cells↗
PubMed1992

Mouse 5HT1B serotonin receptor: cloning, functional expression, and localization in motor control centers.

Serotonin is a neuromodulator that mediates a wide range of effects by interacting with multiple receptors. Using a strategy based on nucleotide sequence homology between genes encoding receptors that interact with guanine nucleotide-binding proteins, we have isolated a mouse gene encoding an additional serotonin receptor. When expressed in cultured cells, it displayed the pharmacological profile and coupling with adenylate cyclase characteristic of the 5HT1B receptor subtype. In NIH 3T3 cells expressing this receptor, serotonin induced a decrease in forskolin-stimulated cAMP levels. This effect was blocked by pertussis toxin, indicating that the 5HT1B receptor interacts with a pertussis toxin-sensitive guanine nucleotide-binding protein. To obtain clues as to the possible function of the 5HT1B receptor, we have analyzed its pattern of expression in the adult mouse brain by in situ hybridization. Our results, together with previous autoradiographic studies, suggest that the 5HT1B receptors are localized presynaptically on the terminals of striatal neurons and Purkinje cells and that they might modulate the release of neurotransmitters such as gamma-aminobutyric acid. The predominant expression of the 5HT1B receptor in the striatum and cerebellum points to an involvement of this receptor in motor control.

3T3 Cells↗
PubMed1992

NKD, a developmentally regulated tachykinin receptor in Drosophila.

A number of neuropeptides have been described which are present in the insect nervous system. The physiological role of these neuropeptides has not yet been clarified. We have characterized a Drosophila melanogaster cDNA coding for a protein, NKD, whose sequence resembles that of mammalian G protein-coupled neuropeptide receptors. This protein shows 38% homology with the mammalian tachykinin NK3 receptor within the transmembrane domain region. Stable cell lines expressing this cDNA are responsive to Locusta migratoria tachykinin but not to other peptides of the tachykinin family. The expression of this gene is detected principally in adult fly heads, but also in the adult body and in embryos. Interestingly, NKD mRNA is detected at very early stages of Drosophila embryonic development (3 h) and reaches the highest level of expression at 12-16 h, a time which correlates with the period of major neuronal development. In situ hybridization experiments demonstrate that NKD is expressed in the central nervous system, as well as in subsets of neurons in each segment of the developing ventral ganglia. The cytological localization of this gene is at position 86C on the Drosophila third chromosome.

3T3 Cells↗
PubMed1992

A family of Drosophila serotonin receptors with distinct intracellular signalling properties and expression patterns.

Biogenic amines such as serotonin elicit or modulate a wide range of behaviours by interacting with multiple receptor subtypes. We have isolated cDNA clones encoding three distinct Drosophila serotonin receptors which belong to the G protein-coupled receptor family. When expressed in mammalian cells, these receptors activate different intracellular effector systems. The 5HT-dro1 receptor stimulates adenylate cyclase while the 5HT-dro2A and the 5HT-dro2B receptors inhibit adenylate cyclase and activate phospholipase C. Expression of all three receptors starts in late embryos and is restricted to distinct populations of cells in the central nervous system. The 5HT-dro2A receptor is predominantly expressed in midline motor neurons (VUM neurons) that innervate larval muscles thus suggesting a role for this receptor in motor control.

Adenylyl Cyclases↗
PubMed1992

The mouse 5HT5 receptor reveals a remarkable heterogeneity within the 5HT1D receptor family.

Serotonin (5-HT) is a neuromodulator that mediates a wide range of physiological functions by activating multiple receptors. Using a strategy based on amino acid sequence homology between 5-HT receptors that interact with G proteins, we have isolated a cDNA encoding a new serotonin receptor from a mouse brain library. Amino acid sequence comparisons revealed that this receptor was a distant relative of all previously identified 5-HT receptors; we therefore named it 5HT5. When expressed in Cos-7 cells and NIH-3T3 cells, the 5HT5 receptor displayed a high affinity for the serotonergic radioligand [125I]LSD. Surprisingly, its pharmacological profile resembled that of the 5HT1D receptor, which is a 5-HT receptor subtype which has been shown to inhibit adenylate cyclase and which is predominantly expressed in basal ganglia. However, unlike 5HT1D receptors, the 5HT5 receptor did not inhibit adenylate cyclase and its mRNA was not found in basal ganglia. On the contrary, in situ hybridization experiments revealed that the 5HT5 mRNA was expressed predominantly in cerebral cortex, hippocampus, habenula, olfactory bulb and granular layer of the cerebellum. Our results therefore demonstrate that the 5HT1D receptors constitute a heterogeneous family of receptors with distinct intracellular signalling properties and expression patterns.

3T3 Cells↗
PubMed1992

Of mice and flies: commonalities among 5-HT receptors.

Pharmacological studies as well as molecular cloning of 5-HT receptors have revealed a multiplicity of receptor subtypes, not only in mammals but, as discussed in this review by René Hen, also in molluscs and arthropods. Most of these receptors belong to the G protein-coupled receptor family, and their mechanism of action involves modulating levels of second messengers such as cAMP, IP3 and Ca2+. Rather than being specialized in a particular physiological function, a given receptor may be expressed in multiple neurons throughout the brain but always in the same compartment in these neurons. The 5-HT1B receptor, for example, is generally localized presynaptically on neuronal terminals, where it inhibits neurotransmitter release. A widespread distribution of 5-HT receptors might explain how 5-HT can modulate the multiple neuronal circuits that underlie complex behaviours.

Amino Acid Sequence↗
PubMed1991

Differential expression of the mouse D2 dopamine receptor isoforms.

We have identified and characterized the cDNAs corresponding to the mouse D2 dopamine receptors. We show that in the mouse the D2 dopamine receptor is found in two forms, generated by alternative splicing of the same gene, mRNA distribution analysis of areas expressing the D2 receptors shows that the larger form is the most abundant, except in the brain stem where the shorter form is predominant. Membranes of mammalian cells transiently transfected with both forms of D2 receptor bind [3H]spiperone with a high affinity.

Amino Acid Sequence↗
PubMed1990

Cloning and characterization of a Drosophila tyramine receptor.

Receptors for biogenic amines such as dopamine, serotonin and epinephrine belong to the family of receptors that interact with G proteins and share a putative seven transmembrane domain structure. Using a strategy based on nucleotide sequence homology between the corresponding genes, we have isolated Drosophila cDNA clones encoding a new member of the G protein-coupled receptor family. This protein exhibits highest homology to the human alpha 2 adrenergic receptors, the human 5HT1A receptor and a recently cloned Drosophila serotonin receptor. The corresponding mRNA is found predominantly in adult Drosophila heads. Membranes from mammalian cells expressing this receptor displayed high affinity binding sites for [3H]yohimbine, an alpha 2 adrenergic receptor antagonist (Kd = 4.45 x 10(-9) M). Tyramine was the most efficient of the putative Drosophila neurotransmitters at displacing [3H]yohimbine binding (EC50 = 1.25 x 10(-6) M). Furthermore tyramine induced an inhibition of adenylate cyclase activity in NIH 3T3 cells expressing this receptor. The Drosophila tyramine receptor that we have isolated might therefore be an invertebrate equivalent of the mammalian alpha 2 adrenergic receptors.

Amino Acid Sequence↗
PubMed1990

Cloning and characterization of a Drosophila serotonin receptor that activates adenylate cyclase.

Using a strategy based on nucleotide sequence homology between genes encoding receptors that interact with guanine nucleotide-binding proteins, we have isolated Drosophila genomic and cDNA clones encoding a functional serotonin receptor (5HT-dro receptor). This protein is expressed predominantly in Drosophila heads and exhibits highest homology with the human 5HT1A receptor. The predicted structure of the 5HT-dro receptor reveals two unusual features: (i) eight putative transmembrane domains instead of the expected seven and (ii) a Gly-Ser repeat that is a potential glycosaminoglycan attachment site. When stably introduced into mouse NIH 3T3 cells, the 5HT-dro receptor activates adenylate cyclase in response to serotonin and is inhibited by serotonin receptor antagonists such as dihydroergocryptine. The 5HT-dro receptor or closely related receptors might be responsible for the serotonin-sensitive cyclase that has been suggested to play a role in learning and modulation of circadian rhythm in a number of invertebrate systems.

Adenylyl Cyclases↗
PubMed1989

Activation of the beta 2-adrenergic receptor promotes growth and differentiation in thyroid cells.

We have introduced the beta 2-adrenergic receptor into the unnatural environment of a thyroid cell to demonstrate that the activation of this receptor initiates diverse cellular programs in different cell types. The thyroid-stimulating hormone (TSH) receptor and the beta 2-adrenergic receptor stimulate a common signaling pathway in distinct populations of cells. In this study, we demonstrate that the activation of the beta 2-adrenergic receptor, transfected into a thyroid epithelial cell, elicits a program of growth and differentiation normally observed with TSH. In thyroid cells expressing beta 2 receptors, the beta 2 agonist isoproterenol activates adenylate cyclase, induces the expression of a thyroid-specific iodide carrier system, and can substitute for TSH to promote growth. Thus, in thyroid cells expressing beta 2-adrenergic receptors, isoproterenol elicits the entire array of thyroid-specific functions normally activated by TSH.

1-Methyl-3-isobutylxanthine↗
PubMed1986

The immunoglobulin heavy chain enhancer is stimulated by the adenovirus type 2 E1A products in mouse fibroblasts.

In contrast with our previous results (Hen, R., Borrelli, E. & Chambon, P. (1985) Science 230, 1391-1394), which demonstrated that the mouse immunoglobulin heavy chain transcriptional enhancer is repressed in lymphoid cells by the products of the adenovirus type 2 E1A transcription unit, we show here that these products activate the same enhancer in mouse fibroblast L cell lines that contain stably integrated copies of a recombinant in which the enhancer is inserted upstream from the chicken conalbumin promoter. In addition, competition experiments suggest that the activity of the heavy chain enhancer may be repressed by a trans-acting factor in mouse L cells. We speculate that the E1A products may prevent the action of this cellular repressor in these cells.

Adenovirus Early Proteins↗
PubMed1985

Repression of the immunoglobulin heavy chain enhancer by the adenovirus-2 E1A products.

The products of the adenovirus-2 (Ad2) immortalizing oncogene E1A repress the activity of the SV40, polyoma virus and E1A enhancers. Evidence is presented that Ad2 infection of MPC11 plasmocytoma cells results in an inhibition of transcription of both the gamma 2b heavy chain (IgH) and the kappa light chain immunoglobulin genes. This inhibition is caused by the Ad2 E1A products. Furthermore, the Ad2 E1A products repress transcription activated by the immunoglobulin heavy chain enhancer in chimeric recombinants, which are either stably integrated in the genome of lymphoid cells or are present as episomes. The implications of negative regulation of cellular enhancers are discussed.

Adenoviruses, Human↗
PubMed1984

Stimulation of in vitro transcription by the upstream element of the adenovirus-2 major late promoter involves a specific factor.

We have previously reported that sequences located upstream from the TATA box of the Adenovirus-2 major late promoter (Ad2MLP), between -34 and -97, are necessary for efficient transcription in vivo and in vitro (1). We have utilized an in vitro competition assay to demonstrate that the upstream element requirement involves the binding of a specific factor(s), which results in stimulation of in vitro transcription from the Ad2MLP. DNA fragments prepared from Ad2MLP upstream sequence mutants which are transcribed much less efficiently than the wild-type promoter both in vivo and in vitro were shown to be unable to bind this factor. We have also constructed chimeric promoter recombinants containing the 21bp repeat upstream element of the SV40 early promoter inserted upstream from the Ad2MLP TATA box. The SV40 upstream element stimulates in vitro transcription from the heterologous Ad2MLP TATA box element; competition experiments show that the Ad2MLP upstream element-specific factor is different from the SV40-specific factor Sp1.

Adenoviruses, Human↗