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F L Margolis

Publications and source records attributed to F L Margolis.

At least 37 records · Page 2Linked to original sources
PubMed1998

Identification of a long variant of mRNA encoding the NR3 subunit of the NMDA receptor: its regional distribution and developmental expression in the rat brain.

A longer variant of rat mRNA encoding the NR3 subunit of the NMDA receptor has been identified. It contains a 60-bp insertion at the nucleotide position 3007 in the intracellular domain of the C-terminal of the previously cloned variant. Therefore, the NR3 mRNA exists in at least two variants--with the insert (NR3-long; NR3-l) and without the insert (NR3-short; NR3-s). The NR3-l variant is expressed throughout the adult rat brain. Moreover, this variant predominates in the occipital and entorhinal cortices, thalamus and cerebellum. Analysis of NR3-l development indicates that it is regulated in a region-specific manner.

Animals↗
PubMed1998

Does olfactory marker protein participate in olfactory neurogenesis?

Olfactory marker protein (OMP) is a phylogenetically conserved, 19-kDa, acidic, soluble protein found abundantly in mature olfactory sensory neurons. Its function has been enigmatic although recent evidence from studies on OMP null mice suggests that neurons lacking OMP exhibit altered physiological activity, including prolonged onset and recovery kinetics following stimulation. We have reported increased expression of OMP in individual surviving sensory neurons that have been deprived of their target, the olfactory bulb. Because olfactory epithelia deprived of their target also exhibit an increased rate of cell division we investigated the effect of recombinant OMP on cell division in organotypic cultures of fetal rat (embryonic day 19) epithelium grown for 3 days in vitro. After 3 days, cultures were given a 1-hr pulse of a mitotic marker, bromodeoxyuridine (BrdU), fixed and prepared for immunohistochemistry to determine the number of proliferating cells. We found a dose-dependent increase in the number of BrdU-positive cells/100-mm length of epithelium. The number of labeled cells increased incrementally, reached a plateau at 25 pM OMP/ml culture medium, 50% higher than in cultures with no OMP added, and remained at that level at 50 and 100 pM doses. Controls included trypsinized OMP and addition of equivalent volumes of TRIS buffer lacking OMP. These results, taken together with previous studies on several growth factors indicate that regulation of neurogenesis in olfactory tissue is a multifactorial process and that OMP may play a role.

Animals↗
PubMed1998

Effects of mutation of the Olf-1 motif on transgene expression in olfactory receptor neurons.

We have examined the effect of mutating the Olf-1 binding motif of the olfactory marker protein (OMP) promoter in determining olfactory neuron-specific gene expression in adult tissues and during embryonic development. The proximal Olf-1 motif located 170 nucleotides upstream of the transcription start site of the OMP gene was mutated to prevent its interaction with the Olf-1 factor in vitro. The wild-type and mutated fragments of the OMP gene extending from -239 to +55 nucleotides relative to the transcription start site were used to direct expression of a lacZ reporter gene in transgenic mice. The transgenic animals were analyzed for cell-specific and developmental expression of the reporter gene. We demonstrate that the mutation that prevents interaction of Olf-1 with its binding site does not alter the temporal and spatial patterns of gene expression in olfactory sensory neurons but does alter the specificity and level of expression in other neuronal populations. These observations are consistent with our demonstration that the mutated Olf-1 site interacts with nuclear proteins present in the central nervous system (CNS).

Animals↗
PubMed1998

Prenatal differentiation of mouse vomeronasal neurones.

The vomeronasal organ (VNO) subserves basic chemosensory functions in rodents, mainly related to sexual behaviour. In order to understand early stages of the VNO structural maturation, we have undertaken an immunocytochemical analysis of the VNO of fetal mice. Our results demonstrate that Olfactory Marker Protein (OMP), a marker of differentiated chemosensory cells, is already expressed in vomeronasal neurones and their fibres projecting to the accessory olfactory bulb during the last week of gestation. However, in contrast to the adult, where its expression is restricted to the medial sensory neuronal component of the VNO, during fetal development OMP is also present in cells located in the lateral non-sensory epithelial component. Some other markers of nasal chemosensory neurones, such as GAP-43/B-50, Protein Gene Product 9.5 (PGP 9.5) and carnosine are also transiently expressed in this ectopic site. These results indicate that (i) significant morphological and biochemical maturation of the VNO is achieved before birth; (ii) transient cell populations, sharing the biochemical profile of the vomeronasal chemosensory receptors, occur in ectopic areas during fetal development.

Animals↗
PubMed1998

An enhanced olfactory marker protein immunoreactivity in individual olfactory receptor neurons following olfactory bulbectomy may be related to increased neurogenesis.

Olfactory marker protein (OMP) is a 19-kD acidic protein found throughout the cytoplasm of mature olfactory receptor neurons (ORNs). Its function remains unknown. Following olfactory bulbectomy, the proportion of ORNs mature enough to express OMP declines greatly. However, in the few remaining mature ORNs, it has been observed that the intensity of OMP immunoreactivity (IR) appears to increase over that of ORNs on the unoperated side. We have now investigated this phenomenon quantitatively in rats subjected to unilateral olfactory bulbectomy. Results show that at all postbulbectomy survival periods examined quantitatively (3 days to 6 months), a significant decrease (19-37%) occurs in the transmission of incident light through OMP(+)-ORNs in bulbectomized versus unoperated olfactory epithelium (OE). Further, we also observed a consistent side-to-side difference in OMP IR in control unoperated animals. Possible explanations for these observations and their relation to the still unknown function of OMP are discussed. To test the possibility that OMP might serve a mitogenic role in the OE, recombinant OMP was added to organotypic explant cultures of fetal olfactory mucosa. Addition of OMP resulted in a dose-dependent increase in the density of bromodeoxyuridine-positive cells in the cultures, with a 50% increase occurring at the plateau OMP concentration of 25 pM.

Amino Acid Sequence↗
PubMed1997

Chemically defined neuron groups and their subpopulations in the glomerular layer of the rat main olfactory bulb--II. Prominent differences in the intraglomerular dendritic arborization and their relationship to olfactory nerve terminals.

In the glomerular layer of the rat main olfactory bulb, we previously reported three chemically defined interneuron groups: GABA-like immunoreactive, calretinin-immunoreactive and Calbindin-D28k-immunoreactive groups [Kosaka K. et al. (1995) Neurosci. Res. 23, 73-88]. In the present study, we analysed the structural features of these three neuron groups using confocal laser scanning light microscopy, focusing on their dendritic arborization pattern, especially on their close apposition to olfactory receptor terminals labeled by olfactory marker protein. Each glomerulus consisted of two zones, the olfactory nerve zone and the non-olfactory nerve zone. The former was mainly occupied by olfactory nerve preterminals and terminals as well as their targets, postsynaptic fine dendritic portions of intrinsic neurons. The latter non-olfactory nerve zone was occupied mainly by olfactory marker protein-negative profiles. Processes of GABAergic neurons and those of one of their subpopulations, tyrosine hydroxylase-immunoreactive neurons, were numerous both in the olfactory nerve and non-olfactory nerve zones, resulting in their frequent close apposition to olfactory marker protein-immunoreactive elements. Combined confocal laser scanning light microscopic electron microscopic examination revealed synaptic contacts from olfactory nerve terminals on tyrosine hydroxylase-immunoreactive processes at these sites of close apposition. In contrast, calretinin-immunoreactive and Calbindin-D28k-immunoreactive processes, particularly Calbindin-D28k-immunoreactive ones, were distributed almost exclusively in the non-olfactory nerve zone, as if they avoided the olfactory nerve zone, showing a net or honeycomb pattern. Thus, calretinin-immunoreactive and Calbindin-D28k-immunoreactive processes were not or very rarely closely apposed to olfactory nerve terminals. These findings suggested that there might be some differences among chemically defined interneuronal groups in their synaptic contacts from olfactory nerves. Further quantitative image analysis clearly exhibited the prominent differences among these neuron groups in their intraglomerular dendritic arborization in relation with the olfactory nerve zone, i.e. the percentages of the area in the olfactory nerve zone occupied by GABAergic and tyrosine hydroxylase-immunoreactive processes were about 10%, respectively, whereas those of calretinin-immunoreactive and Calbindin-D28k-immunoreactive processes were only about 1% and 0.3%, respectively. These findings suggested that so-called periglomerular cells in glomeruli might be heterogeneous not only in their chemical nature, but also in their dendritic arborization pattern and synaptic contacts from olfactory nerve terminals.

Animals↗
PubMed1996

Molecular cloning of ictacalcin: a novel calcium-binding protein from the channel catfish, Ictalurus punctatus.

Calcium is essential for a variety of functions in animals, including signal transduction, transmission of nerve impulses, and bone and scale growth. In freshwater adapted teleosts, blood calcium levels are maintained constant (2-4 mM) even at low external calcium concentration (< 0.01 mM). Epithelial cells in skin and gill have been implicated in calcium homeostasis. We have cloned a cDNA from Ictalurus punctatus, the channel catfish, that codes for ictacalcin, a novel member of the S100 family of calcium-binding protein. In-situ hybridization demonstrates ictacalcin mRNA is abundant in epithelial cells of olfactory rosette, barbel, skin and gill but not brain or muscle. The presence of ictacalcin protein in these tissues was confirmed by immuno-blot analysis. Tissue extracts and recombinant ictacalcin bind calcium with attendant changes in electrophoretic mobility indicative of changes in protein conformation. The calcium-binding activity and abundant localization of ictacalcin in epithelial cells of several tissues indicates that this protein plays an important role in catfish calcium homeostasis.

Amino Acid Sequence↗
PubMed1996

Olfactory marker protein (OMP) gene deletion causes altered physiological activity of olfactory sensory neurons.

Olfactory marker protein (OMP) is an abundant, phylogentically conserved, cytoplasmic protein of unknown function expressed almost exclusively in mature olfactory sensory neurons. To address its function, we generated OMP-deficient mice by gene targeting in embryonic stem cells. We report that these OMP-null mice are compromised in their ability to respond to odor stimull, providing insight to OMP function. The maximal electroolfactogram response of the olfactory neuroepithelium to several odorants was 20-40% smaller in the mutants compared with controls. In addition, the onset and recovery kinetics following isoamyl acetate stimulation are prolonged in the null mice. Furthermore, the ability of the mutants to respond to the second odor pulse of a pair is impaired, over a range of concentrations, compared with controls. These results imply that neural activity directed toward the olfactory bulb is also reduced. The bulbar phenotype observed in the OMP-null mouse is consistent with this hypothesis. Bulbar activity of tyrosine hydroxylase, the rate limiting enzyme of catecholamine biosynthesis, and content of the neuropeptide cholecystokinin are reduced by 65% and 50%, respectively. This similarity to postsynaptic changes in gene expression induced by peripheral olfactory deafferentation or naris blockade confirms that functional neural activity is reduced in both the olfactory neuroepithelium and the olfactory nerve projection to the bulb in the OMP-null mouse. These observations provide strong support for the conclusion that OMP is a novel modulatory component of the odor detection/signal transduction cascade.

Animals↗
PubMed1996

Proximal regions of the olfactory marker protein gene promoter direct olfactory neuron-specific expression in transgenic mice.

Olfactory marker protein (OMP) expression is highly restricted to mature olfactory neurons (ON). Less than 0.3 kb of upstream 5' flanking sequence of the OMP gene directs lacZ expression preferentially to ON in several independently derived lines of transgenic mice. A larger transgene with 0.8 kb of upstream flanking sequence also gave lacZ expression in ON and in a few ectopic sites in the central nervous system (CNS). In addition to the main olfactory epithelium, endogenous OMP is also expressed in chemosensory neurons of the vomeronasal and septal organs, and lacZ expression was detected in neurons of these sites as well. This confirmed the presence of regulatory sequences in the proximal portion of the OMP gene. Endogenous OMP expression in ON was normal in all transgenic lines. Strikingly, in several transgenic lines lacZ expression was restricted to subsets of ON. In one such line, ON axons were intensely stained for lacZ and projected to a subset of olfactory bulb glomeruli. Although identifiable subsets of ON and their termination fields have been described previously, this is the first demonstration of this phenomenon in transgenic mice. These lines of transgenic mice thus provide in vivo models for characterization of genetic elements regulating developmental and functional organization of the olfactory neuroepithelium.

Animals↗
PubMed1996

LacZ and OMP are co-expressed during ontogeny and regeneration in olfactory receptor neurons of OMP promoter-lacZ transgenic mice.

The ontogeny and cellular specificity of expression of beta-galactosidase activity and olfactory marker protein (OMP) are compared in olfactory tissue of the H-OMP-lacZ-3 line of transgenic mice. In this line the expression of lacZ is driven by a 0.3 kb fragment of the rat OMP promoter. During fetal development, lacZ expression is detectable in olfactory receptor neurons (ORNs) shortly after the initial appearance of endogenous OMP. The beta-galactosidase marker was observed only in mature olfactory receptor neurons where it co-localized with endogenous OMP. It was absent from immature neurons that express the growth associated phosphoprotein B50/GAP43. Lesion of the peripheral olfactory pathway by intranasal irrigation with Triton X-100 eliminated expression of both OMP and lacZ in the olfactory neuroepithelium. Subsequent regeneration of the full complement of olfactory receptor neurons was associated with co-expression of both OMP and beta-galactosidase activity. Neither OMP nor beta-galactosidase activity was induced in any other cell type of the regenerating olfactory mucosa. Thus, as little as 0.3 kb of the OMP promoter has the ability to target lacZ expression to olfactory receptor neurons in a temporally and spatially defined manner. We discuss the potential utility of this transgenic line for future studies of the olfactory system.

Animals↗
PubMed1995

Human olfactory receptor neurons contain OMP mRNA in their dendritic and axonal processes.

The cellular expression of olfactory marker protein (OMP) mRNA and protein was investigated in the olfactory mucosa of humans ranging in age from 26 weeks of gestation to 85 years using in situ hybridization and immunocytochemistry. OMP mRNA and protein were most abundant in the somas of olfactory receptor neurons (ORNs). The hybridization signal over the ORN somal layer was greater in older subjects than in younger ones, reflecting either a higher neuronal density or more OMP mRNA per cell. In contrast, it was significantly lower in subjects with Alzheimer's disease when compared with an age-matched control. Characteristics of older subjects were patchiness in the distribution of OMP-expressing ORNs and the occurrence of subepithelial invaginations containing OMP-positive neurons. In addition, a significant hybridization signal was detected in the apical olfactory epithelium containing the dendrites, dendritic knobs, and cilia of ORNS, and over olfactory nerve bundles in the lamina propria, indicating the occurrence of OMP mRNA in dendritic and axonal domains.

Adult↗
PubMed1995

Differential expression of vomeromodulin and odorant-binding protein, putative pheromone and odorant transporters, in the developing rat nasal chemosensory mucosae.

Expression of the putative pheromone and odorant transporter, vomeromodulin, was characterized in developing rat nasal mucosae using in situ hybridization and immunocytochemistry. Initial expression of vomeromodulin mRNA and protein was detected at embryonic day (E)16 in the maxillary sinus component of the lateral nasal glands. The abundance of mRNA and protein in the lateral nasal glands increased with age and reached a peak at postnatal day (P)27. Also at P27, vomeromodulin mRNA and protein expression was initiated in vomeronasal glands and posterior glands of the nasal septum. Comparison of the developmental expression of odorant-binding protein, another carrier protein synthesized in the lateral nasal glands, with that of vomeromodulin demonstrated major differences. In contrast to vomeromodulin, odorant-binding protein was not detected until postnatal day 2 in the ventral component of the lateral nasal glands and anterior glands of the nasal septum. These results suggest that the expression of vomeromodulin and odorant-binding protein is developmentally and differentially regulated and confirms the suggestion that vomeromodulin may function in olfactory and vomeronasal perireceptor processes as a transporter for pheromones and odorants. In addition, the embryonic expression of vomeromodulin suggests its involvement in olfactory perireceptor processes in utero.

Animals↗
PubMed1995

Expression of the human Achaete-scute 1 gene in olfactory neuroblastoma (esthesioneuroblastoma).

Olfactory neuroblastoma (ONB) is a rare neuronal malignancy of the olfactory mucosal. Markers used in the diagnosis of ONB do not distinguish ONB from other neuronal tumors or tumors with neuroendocrine features thus making the diagnosis of ONB difficult. Using a modified RT-PCR technique, we show that the human homologue of the Drosophila achaete-scute gene HASH1 is expressed in 6 primary and one metastatic ONB specimens, whereas Olfactory Marker Protein (OMP) is not. Previous studies have shown that HASH1 is expressed in immature olfactory neurons and is required for their development. OMP, whose function is unknown, is expressed exclusively in mature olfactory neurons. Together, these data suggest that ONB is derived from immature olfactory neurons of neuroectodermal origin. Analysis of RNA expression in primary tumor specimens and in an established cell line make this an ideal system to study olfactory growth and differentiation. Furthermore, these studies represent the first molecular genetic analysis of this rare and unusual neuronal tumor.

Adolescent↗
PubMed1995

Molecular cloning of a phosphoinositide-specific phospholipase C from catfish olfactory rosettes.

A 2.7 kb clone encoding the partial (about 66%) sequence of a phosphoinositide-specific phospholipase C (PLC) was isolated from a cDNA library constructed from channel catfish (Ictalurus punctatus) olfactory rosettes. The clone, designated 30c7, was completely sequenced by automated DNA sequencing and was found to share significant homology with rat and bovine PLCs of the delta 1 isotype. In situ hybridization showed that 30c7 transcripts were expressed in a small subpopulation of olfactory neurons, as well as in other cell types in the olfactory epithelium. Polymerase chain reaction (PCR) analysis indicated that the enzyme was also expressed in several additional tissues, including brain, gill, heart, liver and skeletal muscle. These results suggest that the PLC encoded by clone 30c7 is expressed in several tissues and therefore may have a role in mediating transduction events in diverse tissues as well as in a small group of olfactory neurons.

Amino Acid Sequence↗
PubMed1995

Olfactory marker protein mRNA is found in axons of olfactory receptor neurons.

The separation between the cell bodies of olfactory receptor neurons in the nasal cavity and their axon terminals in the olfactory bulb make them attractive for studying axonal transport. Although high molecular weight RNAs are generally believed to be excluded from axons of mature neurons, we demonstrate here that mRNA for olfactory marker protein (OMP), an abundant cytoplasmic protein selectively expressed in mature receptor cells, is present in rodent olfactory receptor axons. OMP RNA was detected by in situ hybridization at the light microscope level in axons and in terminals. By nuclease protection, the level of OMP RNA in the olfactory bulb was 5-10% of that in the olfactory epithelium where the cell bodies reside. In contrast to axonally transported vasopressin and oxytocin mRNAs, which are deficient in their 3' polyA tails, axonal OMP RNA fractionated as polyA+. OMP RNA was lost from axons and terminals after deafferentation, suggesting that OMP RNA was synthesized in receptor cell bodies in the epithelium and was transported into axons and terminals in the olfactory bulb. RNA for G(olf), a G-protein highly expressed in dendrites of mature olfactory receptor neurons, was not detected in the olfactory bulb. We hypothesize that the immature nature of the cytoskeleton and, specifically, the lack of tightly bundled microtubules allows transport of particular mRNAs in olfactory receptor axons.

Afferent Pathways↗
PubMed1995

Directed expression of the growth-associated protein B-50/GAP-43 to olfactory neurons in transgenic mice results in changes in axon morphology and extraglomerular fiber growth.

B-50/GAP-43, a neural growth-associated phosphoprotein, is thought to play a role in neuronal plasticity and nerve fiber formation since it is expressed at high levels in developing and regenerating neurons and in growth cones. Using a construct containing the coding sequence of B-50/GAP-43 under the control of regulatory elements of the olfactory marker protein (OMP) gene, transgenic mice were generated to study the effect of directed expression of B-50/GAP-43 in a class of neurons that does not normally express B-50/GAP-43, namely, mature OMP-positive olfactory neurons. Olfactory neurons have a limited lifespan and are replaced throughout adulthood by new neurons that migrate into the upper compartment of the epithelium following their formation from stem cells in the basal portion of this neuroepithelium. Thus, the primary olfactory pathway is exquisitely suited to examine a role of B-50/GAP-43 in neuronal migration, lifespan, and nerve fiber growth. We find that B-50/GAP-43 expression in adult olfactory neurons results in numerous primary olfactory axons with enlarged endings preferentially located at the rim of individual glomeruli. Furthermore, ectopic olfactory nerve fibers in between the juxtaglomerular neurons or in close approximation to blood vessels were frequently observed. This suggests that expression of B-50/GAP-43 in mature olfactory neurons alters their response to signals in the bulb. Other parameters examined, that is, migration and lifespan of olfactory neurons are normal in B-50/GAP-43 transgenic mice. These observations provide direct in vivo evidence for a role of B-50/GAP-43 in nerve fiber formation and in the determination of the morphology of axons.

Animals↗
PubMed1994

Human and rodent OMP genes: conservation of structural and regulatory motifs and cellular localization.

Immunocytochemical analysis has demonstrated that expression of the olfactory marker protein (OMP) is highly restricted to mature olfactory receptor neurons in virtually all vertebrate species from fish to man. We have now cloned the OMP gene from human and mouse and demonstrated conservation of gene structure, protein sequence, and Olf-1 and upstream binding region (UBE) regulatory domains. The OMP gene in all species studied lacks canonical TATA and CAAT motifs and introns. The deduced protein sequence is 88.4% identical between mouse and human, and most of the differences observed are conservative changes. The proximal Olf-1 binding sites differ by two purine-purine replacements and effectively cross-compete in mobility shift assays. The distal Olf-1 binding site is also highly conserved in terms of both sequence and binding activity. The availability of sequence from multiple species has permitted us to determine that the UBE site has close similarity to motifs that bind members of the NF-1 family of transcription factors. Gel mobility shift assays confirm this prediction, providing additional insight into mechanisms that may participate in the stringent regulation of the expression of this neuronal-specific protein. Furthermore, we demonstrate the in situ localization of OMP mRNA in human olfactory neuro-epithelium and its colocalization to immunocytochemically identified human olfactory receptor neurons.

Amino Acid Sequence↗