Human Tra2 proteins are sequence-specific activators of pre-mRNA splicing

The RNA-binding protein Tra2 is an important regulator of sex determination in Drosophila. Recently, two mammalian Tra2 homologs of unknown function have been described. Here, we show that human Tra2 proteins are present in HeLa cell nuclear extracts and that they bind efficiently and specifically to a previously characterized pre-mRNA splicing enhancer element. Indeed, both purified proteins bound preferentially to RNA sequences containing GAA repeats, characteristic of many enhancer elements. Neither Tra2 protein functioned in constitutive splicing in vitro, but both activated enhancer-dependent splicing in a sequence-specific manner and restored it after inhibition with competitor RNA. Our findings indicate that mammalian Tra2 proteins are sequence-specific splicing activators that likely participate in the control of cell-specific splicing patterns.

Increased transcription of glutamate-aspartate transporter (GLAST/GluT-1) mRNA following kainic acid-induced limbic seizure

Expression of mRNA for glutamate-aspartate transporter (GLAST/GluT-1/EAAT1) was studied in the brain of the rat which presented recurrent limbic seizure following systemic administration of kainic acid (KA) by in situ hybridization and Northern blot analysis. The expression of GLAST mRNA was markedly increased after 12 h and peaked after 48 h in animals which demonstrated limbic seizure. The induction of the mRNA were observed in the small non-neuronal cells in the hippocampus, especially around CA3 region and hilus. In contrast, there was no change in GLAST mRNA levels in KA injected seizure-free animals. These findings suggest that GLAST mRNA is induced by seizure and increased extracellular glutamate levels during seizure may be important for induction of GLAST mRNA.

Ketamine inhibits monoamine transporters expressed in human embryonic kidney 293 cells

BACKGROUND

Ketamine has been characterized as having psychotomimetic and sympathomimetic effects. These symptoms have raised the possibility that ketamine affects monoaminergic neurotransmission. To elucidate the relation between ketamine and monoamine transporters, the authors constructed three cell lines that stably express the norepinephrine, dopamine, and serotonin transporters and investigated the effects of ketamine on these transporters.

METHODS

Human embryonic kidney cells were transfected using the Chen-Okayama method with the human norepinephrine, rat dopamine, and rat serotonin transporter cDNA subcloned into the eukaryotic expression vector. Using cells stably expressing these transporters, the authors investigated the effects of ketamine on the uptake of these compounds and compared them with those of pentobarbital.

RESULTS

Inhibition analysis showed that ketamine significantly inhibited the uptake of all three monoamine transporters in a dose-dependent manner. The Ki (inhibition constant) values of ketamine on the norepinephrine, dopamine, and serotonin transporters were 66.8 microM, 62.9 microM, and 162 microM, respectively. Pentobarbital, a typical general anesthetic agent with no psychotic symptoms, did not affect the uptake of monoamines, however. Further, neither the glycine transporter 1 nor the glutamate/aspartate transporter was affected by ketamine, indicating that ketamine preferentially inhibits monoamine transporters.

CONCLUSIONS

Ketamine inhibited monoamine transporters expressed in human embryonic kidney cells in a dose-dependent manner. This result suggests that the ketamine-induced inhibition of monoamine transporters might contribute to its psychotomimetic and sympathomimetic effects through potentiating monoaminergic neurotransmission.

Alzheimer-associated presenilin-1 gene is induced in gerbil hippocampus after transient ischemia

To investigate the biological roles of the presenilin-1 (PS-1) gene after neuronal injury, the changes of PS-1 mRNA expression in the gerbil hippocampus after transient ischemia were examined. From 1 day to 3 day-reperfusion after 5 min-ischemia, PS-1 mRNA was induced in the hippocampus compared with the sham-operated control. The cells which induced the PS-1 genes were neurons of CA3 and dentate gyrus, the region relatively resistant to ischemic stress. These findings suggest that the induction of PS-1 genes may be associated with some responses of neurons damaged by transient ischemia.

Expression pattern of a novel death-promoting gene, DP5, in the developing murine nervous system

We examined the expression patterns of the DP5 gene, which encodes a protein with apoptosis-inducing activity, in the developing nervous system of mice. This gene was primarily expressed in the spinal motor neurons and peripheral sensory ganglia of mouse embryos and transiently in the postnatal brain, particularly in the entorhinal cortex and hippocampus. These expression patterns suggest that the DP5 gene may be involved in the apoptosis, if not all, of the developing nervous system.

MK-801 blocks monoamine transporters expressed in HEK cells

(+)-MK-801 is known to be a specific non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors. However, besides having an anticonvulsant effect, this compound possesses a central sympathomimetic effect and an anxiolytic-like action, raising the possibility that (+)-MK-801 might affect monoamine uptake systems. To elucidate this possibility, we investigated the effects of (+)-MK-801 on monoamine transporters expressed in HEK cells. (+)-MK-801 significantly inhibited the uptake of all three monoamine transporters in a dose-dependent manner and the inhibitions were competitive with respect to monoamines. The Ki values of (+)-MK-801 on the norepinephrine, dopamine and serotonin transporters were 3.2 microM, 40 microM and 43 microM, respectively. In addition, (-)-MK-801, a less potent antagonist of NMDA receptors, also inhibited monoamine transporters with a similar potency as that of (+)-MK-801. These results clearly indicate that MK-801, a non-competitive antagonist of NMDA receptors, competitively inhibits monoamine transporters without stereoselectivity.

Induction of 72-kDa inducible heat shock protein (HSP72) in cultured rat astrocytes after energy depletion

Protein synthesis is important in the readaptive processes for cultured astrocytes after hypoxia and subsequent reoxygenation. We have identified 72-kDa inducible heat shock protein (HSP72) as a major stress protein in reoxygenated astrocytes. To assess the mechanism for reoxygenation-mediated induction of HSP72, a reporter gene that consists of a human HSP promoter fused to the luciferase gene was transfected into cultured astrocytes. Analysis of cellular energy nucleotides showed an increase of the ADP/ATP ratio after reoxygenation, which synchronized with activation of the HSP promoter. Activation of the HSP promoter was also observed after an addition of iodoacetic acid to hypoxic astrocytes, which reached the maximum when the ADP/ATP ratio reached 50%, but further decline in the energy profile caused inactivation of this promoter. Inhibition of protein synthesis after reoxygenation resulted in temporary restoration of the energy profile and suppression of the DNA binding activity of the heat shock factor. Addition of quercetin greatly decreased the [3H]leucine incorporation in the polysome fraction without any effect on the mature mRNA formation. These data suggest that the energy depletion in reoxygenation triggers induction of HSP72 after reoxygenation, which may act as a pivotal mediator in the stress response of reoxygenated astrocytes by facilitating protein synthesis.

Inhibition of myo-inositol transport causes acute renal failure with selective medullary injury in the rat

Myo-inositol is a major compatible osmolyte in the renal medulla that is accumulated under hypertonic conditions via the Na+/myo-inositol cotransporter (SMIT). We have recently reported that SMIT is predominantly present in the thick ascending limb of Henle (TAL) and is strongly induced by acute NaCl loading, suggesting an important role of myo-inositol in this nephron segment. In the present study, we sought to examine in vivo effects of inhibition of myo-inositol transport using a transport inhibitor, 2-O, C-methylene-myo-inositol (MMI). Intraperitoneal injection of MMI caused acute renal failure in the rats. Serum creatinine and urea nitrogen were significantly increased 12 hours after MMI injection. Morphologic study revealed that the tubular cells were extensively injured in the outer medulla. A considerable number of the tubular cells were injured in the cortex as well. Immunohistochemical study for Tamm-Horsfall protein (THP), which was used for identification of the TAL cells, showed that THP-positive cells were predominantly injured. The tubular injury apparently appeared to worsen when high concentration of NaCl was injected with MMI. Administration of myo-inositol prevented acute renal failure and improved the tubular injury after MMI injection. Furthermore, supplementation of betaine, another osmolyte in the TAL cells, partially prevented the toxic effects of MMI. These results suggest that myo-inositol play a crucial role in the TAL regarding osmoregulation of the cells.

Assessment of affinities of beta-CIT, beta-CIT-FE, and beta-CIT-FP for monoamine transporters permanently expressed in cell lines

We investigated the effects of three cocaine analogs, beta-CIT (2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane), beta-CIT-FE (2-beta-carbomethoxy-3-beta-(4-iodophenyl)-N-(2.fluoroethyl)-nortropa ne), and beta-CIT-FP (2-beta-carbomethoxy-3-beta-(4-iodophenyl)-N-(3-fluoropropyl)-n ortropane), on the uptake of [3H]dopamine(DA), serotonin(5-HT), and 1-norepinephrine (NE) using cell lines permanently expressing DA, 5-HT, and NE transporters, respectively, to determine their affinities for these three transporters. We generated cell lines stably expressing DA, 5-HT, and NE transporters, respectively, by the Chen-Okayama method, and then tested the abilities of (-)cocaine, beta-CIT, beta-CIT-FE, beta-CIT-FP, and clomipramine to inhibit the uptake of [3H]DA, 5-HT, and 2-NE. Ki values of beta-CIT, beta-CIT-FE, and beta-CIT-FP for [3H]DA, 5-HT, 1-NE uptake were 6, 29, and 33 nM, 91, 133, and 130 nM, and 28, 113 and 70 nM, respectively, whereas those of cocaine and clomipramine were 316, 581, and 176 nM and > 10,000, 437, and 851 nM, respectively. Beta-CIT, beta-CIT-FE, and beta-CIT-FP were shown to be potent DA, 5-HT, and NE uptake inhibitors. Beta-CIT and beta-CIT-FP were highly potent and selective dopamine uptake inhibitors, and therefore might be useful for imaging of DA transporter with single photon emission computed tomography (SPECT) or positron emission tomography (PET).

Tetrahydropapaveroline and its derivatives inhibit dopamine uptake through dopamine transporter expressed in HEK293 cells

Tetrahydropapaveroline (THP), an isoquinoline alkaloid, has been detected in brain and urine of Parkinsonian patients on L-dopa medication, and in the urine and brain of rats after L-dopa or acute ethanol administration. Since THP is considered to be synthesized from dopamine, it may affect dopaminergic neurons through the reuptake system, i.e. dopamine transporter (DAT). To determine whether THP has affinity for DAT, we generated a cell line which stably expresses DAT and examined whether THP and its derivatives could inhibit [3H]DA uptake in these cells. Ki of THP and three derivatives (1-benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ), 1-(3',4'-dibydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline (3',4' DHBnTIQ) and 6,7-dihydroxy-1-benzyl-1,2,3,4-tetrahydroisoquinoline (6,7 DHBnTIQ)) for inhibition of [3H]DA uptake were about 41, 35, 23 and 93 microM, respectively, which were similar to the Ki of 1-methyl-4-phenylpyridinium ion (MPP+) (28 microM). These results suggest that THP and its derivatives might be uptaken through DAT and be involved in Parkinson's disease and/or alcohol addiction.

Cloning of a gene, YT521, for a novel RNA splicing-related protein induced by hypoxia/reoxygenation

To elucidate the role of astrocytes in the stress response of the central nervous system to ischemia, early gene expression was examined in rat cultured astrocytes after the exposure to hypoxia/reoxygenation, and we have previously cloned a novel RNA binding protein, RA301, from the reoxygenated astrocytes. Furthermore, we have now cloned a new gene for RA301 binding protein, termed YT521, by a yeast two-hybrid screening technique to explore RA301 functions. The YT521 cDNA is about 3200 bp long with an open reading frame encoding 712 amino acids. This amino acid sequence contains arginine-aspartic acid-glutamic acid rich region and glutamic acid rich one, and has a low degree of homology with RNA binding proteins such as U1-70k. Northern blot analysis revealed that YT521 mRNA expression was up-regulated in reoxygenated astrocytes. Induction of YT521 mRNA was mediated by endogenously generated reactive oxygen species, as it was suppressed by treatment of the cells with diphenyl iodonium which blocks oxygen-free radical formation by astrocytes. These expression patterns resembled those of RA301 mRNA. Far Western blot analysis showed that YT521 protein was not only interacting with RA301 protein, but also with SC35 and SF2, both of which are splicing factors. These results suggest that YT521 is a novel candidate for RNA splicing-related protein.

Developmental regulation of Na+ / myo-inositol cotransporter gene expression

myo-Inositol plays a role in many important aspects of cellular regulation including membrane structure, signal transduction and osmoregulation. It is taken up into the cells by the Na+ / myo-inositol cotransporter (SMIT). We investigated developmental changes in the expression of SMIT mRNA and protein in the rat. In the fetal rat brain, SMIT mRNA was abundantly and diffusely expressed throughout the whole brain and the spinal cord. Positive signals were expressed in neuronal and non-neuronal cells in these regions. SMIT is gradually down-regulated nearer birth, but intense signals were still detected in the brain at postnatal day one. In the adult rat brain, very weak hybridization signals were detected throughout whole brain except for the choroid plexus where SMIT mRNA expression remained high. In contrast, the pattern of developmental regulation of SMIT gene expression in the kidney was opposite to that seen in the brain. Signals in the kidney were very weak during embryonic stages, whereas SMIT expression increased significantly after birth. These results suggest that myo-inositol and its transporter play an important role in the CNS developmental stage.

Expression of c-fos and c-jun mRNA following transient retinal ischemia: an approach using ligation of the retinal central artery in the rat

The expression of the proto-oncogenes c-fos and c-jun was examined by in situ hybridization at various timepoints following transient retinal ischemia by means of ligation of the retinal central artery in the rat. Ischemia of 90-minute duration resulted in the degeneration of neurons in both the ganglion cell layer and the inner nuclear layer at 48 hours after reperfusion. The expression of c-fos and c-jun messenger RNA throughout the entire inner nuclear layer was transiently coinduced following 90-minute retinal ischemia with a peak at 1 hour after reperfusion. This expression was also found in the ganglion cell layer at 3 hours after reperfusion. Weak signals for c-fos and c-jun mRNA were observed at 24 hours after reperfusion and returned to near control levels by 48 hours. c-jun protein expression was detected in the ganglion cell layer, the middle of the inner nuclear layer, and optic nerve head at 3 hours, but not 1 hour, after lethal ischemia/reperfusion; however, c-fos protein expression was not detected after reperfusion. Whereas no neuronal degenerative changes were found at 7 days after 30-minute ischemic retina, c-fos and c-jun messenger RNA were also induced at 1 hour postreperfusion. To our knowledge, this study is the first report to show expression patterns of immediate-early genes after retinal ischemia/reperfusion. These results suggest that changes in expression of c-fos and c-jun after transient retinal ischemia are similar to those after transient brain ischemia, and the selective occlusion of the central retinal artery will provide a useful model for studying ischemic neuronal degeneration in vivo in the rat retina.

An intracellular protein that binds amyloid-beta peptide and mediates neurotoxicity in Alzheimer's disease

Amyloid-beta is a neurotoxic peptide which is implicated in the pathogenesis of Alzheimer's disease. It binds an intracellular polypeptide known as ERAB, thought to be a hydroxysteroid dehydrogenase enzyme, which is expressed in normal tissues, but is overexpressed in neurons affected in Alzheimer's disease. ERAB immunoprecipitates with amyloid-beta, and when cell cultures are exposed to amyloid-beta, ERAB inside the cell is rapidly redistributed to the plasma membrane. The toxic effect of amyloid-beta on these cells is prevented by blocking ERAB and is enhanced by overexpression of ERAB. By interacting with intracellular amyloid-beta, ERAB may therefore contribute to the neuronal dysfunction associated with Alzheimer's disease.

Characterization of glycine release mediated by glycine transporter 1 stably expressed in HEK-293 cells

We constructed a cell line which stably expresses glycine transporter 1 (GlyT1) proteins. The cell line showed significant [14C]glycine uptake and could keep steep glycine concentration gradient between intracellular and extracellular space (in > out). Using this cell line, we investigated glycine release mediated by this transporter. The [14C]glycine release was enhanced by extracellular glycine and sarcosine, a selective inhibitor of the transporter, in a dose-dependent manner. In addition, the replacement of extracellular Na+ with Li+ or extracellular Cl- with acetate- markedly increased the release. Furthermore, we investigated the effects of extracellular Ca2+ and K+. The removal of these ions also showed enhancement of the release. These results suggest that glycine transporter 1 protein, which might be involved in the NMDA receptor neurotransmission, can release glycine into the extracellular space in the vicinity of synapses, and that the release might be influenced by the extracellular substrate concentration and ion composition in the synaptic cleft.

[A case of pulmonary sarcoidosis mimicking relapse of pulmonary tuberculosis]

A 61-year-old woman was suspected of relapse of pulmonary tuberculosis. A chest X-ray film taken at a regular health check-up suggested relapse of pulmonary tuberculosis in a 61-year-old woman. Chest X-ray revealed irregular shadow with calcification in the upper lobe of the left lung and pulmonary tuberculosis was initially diagnosed a despite a negative reaction for acid-fast bacilli on examination of her sputum and bronchial lavage. Chest CT revealed thickened bronchi and blood vessels and nodules in the lung field. Transbronchial by biopsy failed to reveal caseating epithelioid cell granulomas transbronchial lung biopsy. Past history of facial palsy, uveitis, high plasma levels of angiotensin-converting enzyme (31.6IU/L), and abnormal HRCT levels. Bronchoalveolar lavage analysis revealed an increase in lymphocytes and a CD4/CD8 ratio of 8.67. Sarcoidosis was diagnosed after a liver biopsy. This appears that HRCT findings are useful in the diagnosis of pulmonary sarcoidosis.

Isolation of a cDNA encoding a photoreceptor cell-specific actin-bundling protein: retinal fascin

We have isolated a novel retina-specific gene, retinal fascin, encoding a new member of actin-bundling protein gene family, from a bovine retina cDNA library. The cDNA encodes a 492 amino acid protein which shows 36-57% amino acid identity with three vertebrate fascins, echinoid fascin and Drosophila singed gene. Northern blot analysis revealed that retinal fascin mRNA was exclusively expressed in the eye and not seen in other tissues examined. In situ hybridization analysis indicated that retinal fascin mRNA signals were found only in the inner segment of the photoreceptor layer and outer nuclear layer, indicating that retinal fascin was specifically expressed in photoreceptor cells. As fascins are actin-bundling proteins important for constructing several intracellular structures, retinal fascin might play a pivotal role in photoreceptor cell-specific events, such as disk morphogenesis.

Expression of zinc transporter gene, ZnT-1, is induced after transient forebrain ischemia in the gerbil

To elucidate the molecular mechanisms underlying neuronal death after transient forebrain ischemia, we cloned genes expressed after transient forebrain ischemia in the Mongolian gerbil by a differential display method. A gerbil homolog of rat zinc transporter, ZnT-1, which transports intracellular Zn2+ out of cells, was isolated. Its expression became detectable exclusively in pyramidal neurons of the CA1 region 12 hr after ischemia and reached a maximum from day 1 to day 2 as shown by in situ hybridization. By day 7, expression had disappeared entirely from the cells in the CA1 region, because the neurons had died. No other brain regions exhibited such a significant level of ZnT-1 mRNA expression during this period. Zn2+ was shown to accumulate in CA1 pyramidal neurons expressing ZnT-1 mRNA after the ischemia by using zinquin, a zinc-specific fluorescent dye. When primary hippocampal neurons were exposed to a high dose of Zn2+, ZnT-1 mRNA accumulated. These results suggest that the induction of ZnT-1 mRNA observed in CA1 neurons was caused by an increase in the intracellular Zn2+ concentration. It was reported recently that Zn2+ chelator blocked neuronal death after ischemia and that the influx of Zn2+ might be a key mechanism underlying neuronal death. The induction of ZnT-1 mRNA in CA1 pyramidal neurons fated to die after transient ischemia is of interest to the study of postischemic events and the molecular mechanisms underlying delayed neuronal death.

Molecular cloning of a novel polypeptide, DP5, induced during programmed neuronal death

To study the molecular mechanisms underlying neuronal programmed cell death (PCD), we performed differential display screening for genes, the expression of which was induced during PCD in the sympathetic neuron culture model deprived of NGF. We cloned a gene encoding a novel polypeptide (DP5) which consisted of 92 amino acids. DP5 polypeptide had no homology with any other known protein and contained no motif that would indicate its putative biochemical functions. DP5 mRNA levels peaked at 15 h after nerve growth factor withdrawal, concurrent with the time at which neurons were committed to die. The induction of DP5 gene expression was blocked when cell death was rescued by treatment with cycloheximide, KCl, or the cyclic AMP analogue CPTcAMP. Overexpression of the full-length DP5 in cultured sympathetic neurons was in itself sufficient to induce apoptosis. These results suggest that DP5 plays a role in programmed neuronal death.

Cloning of a putative vesicle transport-related protein, RA410, from cultured rat astrocytes and its expression in ischemic rat brain

To elucidate the role of astrocytes in the stress response of the central nervous system to ischemia, early gene expression was evaluated in cultured rat astrocytes subjected to hypoxia/reoxygenation. Using differential display, a novel putative vesicle transport-related factor (RA410) was cloned from reoxygenated astrocytes. Analysis of the deduced amino acid sequence showed RA410 to be composed of domains common to vesicle transport-related proteins of the Sec1/Unc18 family, including Sly1p and Sec1p (yeast), Rop (Drosophila), Unc18 (Caenorhabditis elegans), and Munc18 (mammalian), suggesting its possible role in vesicular transport. Northern analysis of normal rat tissues showed the highest expression of RA410 transcripts in testis. When astrocyte cultures were subjected to a period of hypoxia followed by reoxygenation, induction of RA410 mRNA was observed within 15 min of reoxygenation, reaching a maximum by 60 min. At the start of reoxygenation, the addition of diphenyl iodonium, an NADPH oxidase inhibitor, blocked in parallel astrocyte generation of reactive oxygen intermediates and expression of RA410 message. In contrast, cycloheximide did not affect RA410 mRNA levels, indicating that RA410 is an immediate-early gene in the setting of reoxygenation. Using polyclonal antibody raised against an RA410-derived synthetic peptide, Western blotting of lysates from reoxygenated astrocytes displayed an immunoreactive band of approximately 70 kDa, the expression of which followed induction of the mRNA. Fractionation of astrocyte lysates on sucrose gradients showed RA410 antigen to be predominantly in the plasma membrane. Immunoelectron microscopic analysis demonstrated RA410 in large vesicles associated with the Golgi, but not in the Golgi apparatus itself, consistent with its participation in post-Golgi transport. Consistent with these in vitro data, RA410 expression was observed in rat brain astrocytes following transient occlusion of the middle cerebral artery. These data provide insight into a new protein (RA410) that participates in the ischemia-related stress response in astrocytes.

Coordinate expression of alpha-tropomyosin and caldesmon isoforms in association with phenotypic modulation of smooth muscle cells

Isoform diversity of tropomyosin is generated from the limited genes by a combination of differential transcription and alternative splicing. In the case of the alpha-tropomyosin (alpha-TM) gene, exon 2a rather than exon 2b is specifically spliced in alpha-TM-SM mRNA, which is one of the major tropomyosin isoforms in smooth muscle cells. Here we demonstrate that expressions of alpha-tropomyosin and caldesmon isoforms are coordinately regulated in association with phenotypic modulation of smooth muscle cells. Molecular cloning and Western and Northern blottings have revealed that in addition to the down-regulation of beta-TM-SM, alpha-TM-SM converted to alpha-TM-F1 and alpha-TM-F2 by a selectional change from exon 2a to exon 2b during dedifferentiation of smooth muscle cells in culture. Simultaneously, a change of caldesmon isoforms from high Mr type to low Mr type was also observed by alternative selection between exons 3b and 4 in the caldesmon gene during this process. In contrast, cultured smooth muscle cells maintaining a differentiated phenotype continued to express alpha-TM-SM, beta-TM-SM, and high Mr caldesmon. In situ hybridization revealed specific coexpression of alpha-TM-SM and high Mr caldesmon in smooth muscle in developing embryos. These results suggest a common splicing mechanism for phenotype-dependent expression of tropomyosin and caldesmon isoforms in both visceral and vascular smooth muscle cells.

Effects of partial nephrectomy on the expression of osmolyte transporters

Na+/myo-inositol cotransporter (SMIT) and Na+/Cl-/betaine-gamma-amino-n-butyric acid transporter (BGT-1) are the major osmolyte transporters that are regulated by extracellular osmolarity. We have recently shown localization and rapid regulation of the mRNAs for these transporters in rat kidney. In the present study, we examined the expression of SMIT and BGT-1 in partial nephrectomized rats in order to assess the change in local osmolarity following reduction of renal mass. Four weeks after 5/6 nephrectomy (NX), the rats were compared to sham-operated control animals (CONT). Northern analysis using RNA of whole kidney indicated that there were little differences in the levels of SMIT and BGT-1 mRNAs between the two groups. In situ hybridization revealed that signals for both transporter mRNAs were markedly reduced in the inner medulla of the remnant kidney. In contrast, these signals in the outer medulla increased following nephrectomy. SMIT signals in the cortex increased as well. Grain density, determined by counting grain number per cell, revealed that the signals in the inner medullary collecting ducts were markedly reduced whereas those in the thick ascending limbs of Henle (TAL) as well as macula densa cells were significantly increased. The signals in the TAL and macula densa were reduced by furosemide administration. The increased expression in NX rats may reflect the increased NaCl transport and high local osmolarity in this segment.

Induction of Na+/myo-inositol co-transporter mRNA after rat cryogenic injury

Myo-inositol is one of the major organic osmolytes in the brain. It is stored in the cells by the Na+/myo-inositol co-transporter (SMIT) which is regulated by extracellular osmolality. First, in order to confirm that local change of the osmolality induces alteration of the SMIT mRNA in brain, we examined change of SMIT mRNA of the animals with hypertonic NaCl application to the cortex. Application of hypertonic NaCl up-regulated the SMIT mRNA expression widely surrounding the application site. We next investigated the role of SMIT in brain during vasogenic edema, we examined expression of SMIT mRNA in the rat brain after cryogenic injury. The expression of SMIT mRNA was markedly increased 12 h after surgery and the induction of the mRNA extended to the entire cortex of the affected side. Up-regulated expression was found predominantly in the neurons in remote areas. The induction of SMIT mRNA was found until the 3rd day after surgery. These findings suggest that osmotic stress may spread over a wide area in the cortex in case of vasogenic edema produced by cryogenic injury and that the cells respond to this stress by increasing SMIT expression.

Distribution of mRNAs for pituitary adenylate cyclase-activating polypeptide (PACAP), PACAP receptor, vasoactive intestinal polypeptide (VIP), and VIP receptors in the rat superior cervical ganglion

The distribution of mRNAs for pituitary adenylate cyclase-activating polypeptide (PACAP), PACAP receptor (PACAP-R), vasoactive intestinal polypeptide (VIP) and two subtypes of VIP receptors (VIP1-R and VIP2-R) was examined by in situ hybridization in the superior cervical ganglion (SCG) of the adult rat. PACAP-R mRNA was expressed intensely in virtually all principal neurons. PACAP mRNA was expressed in approximately half of the principal neurons, where the levels of expression vary extensively. Intense expression of VIP mRNA was observed only in a few principal neurons. Neither VIP1-R mRNA nor VIP2-R mRNA was detected in SCG cells. These findings suggest that PACAP, but not VIP, may function as a paracrine or autocrine regulatory factor through PACAP-R in the principal neurons of the SCG.

Differential expression patterns of GABA transporters (GAT1-3) in the rat olfactory bulb

The localization of GABA transporters 1-3 (GAT1-3) was investigated in the rat olfactory bulb by using in situ hybridization and immunohistochemistry. In the glomerular and the internal granular layers, GAT1 mRNA was expressed in most of periglomerular and granule cells, which are known to be GABAergic. In addition, we compared GAT1 mRNA expression with that of glutamic acid decarboxylase67 (GAD67) mRNA. The expressions were very similar in these two layers, indicating that GAT1 mRNA is mainly expressed in GABAergic neurons. However, in the external plexiform and the olfactory nerve layers, we observed more GAT1 mRNA-positive cells than GAD67 ones, suggesting that GAT1 mRNA is also expressed in non-GABAergic neurons and in glial cells. GAT3 mRNA expression was observed in small glial-like cells which might be involved in GABAergic neurotransmission throughout the olfactory bulb. This was confirmed by double-immunostaining studies which showed the expression of both GAT3 and glial fibrillary acidic protein (GFAP) mRNAs in astrocytes. Moreover, GAT2 mRNA was expressed only in the ependyma and arachnoid. These findings suggest that the expression patterns of GABA transporters differ with the type of cells in the rat olfactory bulb where GAT1 and GAT3 may play an imporatant role in GABA-mediated transmission, such as lateral inhibition.

Comparison of tissue distribution of two novel serine/threonine kinase genes containing the LIM motif (LIMK-1 and LIMK-2) in the developing rat

We previously isolated two novel serine/threonine kinase genes containing the LIM motif (LIMK-1 and LIMK-2) from a rat cDNA library. To examine the functions of these genes, we performed in situ hybridization in the developing rat nervous system. LIMK-1 and LIMK-2 mRNAs mostly co-localized during development and are expressed preferentially in the central nervous system during mid-to-late gestation but the signals decreased during the post-natal period. However, differential gene expression was observed in some nuclei in the CNS; LIMK-1 mRNA was intensely expressed in the facial motor nucleus, the hypoglossal nucleus, deep nuclei of the cerebellum and the layers 3, 5 and 6 of the adult cerebral cortex while only LIMK-2 mRNA was preferentially expressed in the some parts of the epithelium. In the nasal cavity, LIMK-1 and LIMK-2 mRNAs were expressed complementarily. Our results suggest that LIMK-1 and LIMK-2 may have different functions in these regions during development.

Cloning and functional expression of a brain peptide/histidine transporter

Here we report the cloning and functional characterization of a rat novel peptide/histidine transporter (PHT1), which was expressed in the brain and the retina. The cDNA encodes the predicted protein of 572 amino acid residues with 12 putative membrane-spanning domains. The amino acid sequence has moderate homology with a nonspecific peptide transporter found in the plant. When expressed in Xenopus laevis oocytes, PHT1 cRNA induced high affinity proton-dependent histidine transport activity. This transport process was inhibited by dipeptides and tripeptides but not by free amino acids such as glutamate, glycine, leucine, methionine, and aspartate. Dipeptide carnosine transport activity was also confirmed by direct uptake measurement. By in situ hybridization analysis, PHT1 mRNA was widely distributed throughout whole brain. Especially, intense hybridization signals were found in the hippocampus, choroid plexus, cerebellum, and pontine nucleus. Signals were located in both the neuronal and small nonneuronal cells in these areas. PHT1 protein could contribute to uptake of oligopeptides, which function as neuromodulators, and clearance of degraded neuropeptides and be a new member in the growing superfamily of proton-coupled peptide and nitrate transporters, although its structure, localization, and pharmacological characteristics are unique among these members.

Expression of cytokines and inducible nitric oxide synthase mRNA in the lungs of mice infected with Cryptococcus neoformans: effects of interleukin-12

We have recently established a murine model of pulmonary and disseminated infection with a highly virulent strain of Cryptococcus neoformans and demonstrated that administration of interleukin-12 (IL-12) protected the animals against infection. In this study, we extended these studies by investigating the host defense mechanisms. In particular, we examined the expression of mRNA for helper T-cell 1 (Th1) cytokines (IL-2, lymphotoxin, and gamma interferon [IFN-gamma]), Th2 cytokines (IL-4, -6, and -10), macrophage-derived cytokines (tumor necrosis factor alpha [TNF-alpha], IL-1beta, transforming growth factor beta [TGF-beta, IL-12p40, and IFN-gamma-inducing factor [IGIF]), and inducible nitric oxide synthase (iNOS) in the lungs on days 1, 3, 7, and 14 after infection and following treatment with IL-12. There was little or no expression of mRNAs for Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS in the infected mice, but expression increased markedly after treatment with IL-12. In contrast, the mRNAs for Th2 cytokines, IL-1beta, and TGF-beta were detected at considerable levels during the early stages of infection, and, interestingly, expression was not suppressed by IL-12 but rather augmented, particularly during the late stage. Similar results were also obtained for IFN-gamma, IL-4, IL-10, and TNF-alpha measured in the lung homogenates by enzyme-linked immunosorbent assay. These results suggest that the predominance of expression of Th2 cytokines and TGF-beta over Th1 cytokines, TNF-alpha, IL-12p40, IGIF, and iNOS is associated with severe lethal infection in mice and that administration of IL-12 protects infected animals by stimulating Th1 cytokines.

[Stress response of cultured astrocytes to hypoxia/reoxygenation]

As the most abundant cell type in the central nervous system (CNS), astrocytes play a major role in the host defense mechanism even in situations associated with ischemic cerebrovascular diseases. Cultured rat astrocytes exposed to hypoxia (pO2 = 8-10 torr) expressed a set of stress proteins whose Mrs are 28, 33, 78, 94, and 150 kDa. Northern/western blot analysis indicated that these stress proteins are identical to heme oxygenase-1 (33 kDa), 78-kDa glucose regulated protein (GRP78) and GRP94 (94 kDa), respectively. The amino acid sequence analysis of the 150-kDa protein revealed that it (ORP150: oxygen regulated protein) is a novel stress protein belonging to the heat shock protein family. The induction of this stress protein was seen in the endoplasmic reticulum (ER) and mainly regulated by the decline of atmospheric oxygen tension, not by other chemical stimuli. The abundant expression of these ER-localized stress proteins (ORP150, GRP94 and GRP78) suggest that the stress response of these astrocytes to hypoxia may focus on the restoration of ER function. The unique expression of these stress proteins may provide a clue to understand the role of this cell type in ischemic cerebrovascular accidents.

Regional distribution of GABA transporter 1 (GAT1) mRNA in the rat brain: comparison with glutamic acid decarboxylase67 (GAD67) mRNA localization

The mRNA expression of GABA transporter 1 (GAT1) was investigated in the rat brain by in situ hybridization histochemistry using an oligonucleotide probe specific to the mRNA. The pattern of GABA transporter 1 mRNA expression was well coincident with that of GABAergic terminals detected by using glutamic acid decarboxylase (GAD) as a marker. In addition, we compared the GAT1 mRNA expression with that of glutamic acid decarboxylase67 (GAD67) mRNA positive neurons. Although the expression patterns of both mRNAs were similar in most nuclei, the number of GABA transporter 1 mRNA positive cells were higher than that of GAD67 mRNA positive cells in some nuclei, such as the inferior colliculus, cerebellar nuclei and cerebral cortex. Furthermore the subthalamic nucleus and inferior olive nucleus, which lacked GAD67 mRNA expression, showed intense GABA transporter 1 mRNA expression. These data suggest that GABA transporter 1 mRNA is expressed not only in GABAergic neurons but also in non-GABAergic neurons and/or glial cells which are involved in GABAergic neurotransmission.

Molecular cloning of mouse Doc2alpha and distribution of its mRNA in adult mouse brain

We have previously isolated from a human brain cDNA library, a new protein having two C2-like domains which interact with Ca2+ and phospholipid, and named Doc2alpha. Doc2alpha is abundantly expressed in brain, where it is highly concentrated on the synaptic vesicle fraction, and is implicated in Ca2(+)-dependent exocytosis. We have isolated here a mouse Doc2alpha cDNA and determined the localization of its mRNA in adult mouse brain. The amino acid sequence of the mouse Doc2alpha cDNA is 92% identical with that of the human counterpart. Northern blot analysis and in situ hybridization on adult mouse brain sections have revealed that Doc2alpha is predominantly expressed in mouse brain, where it is expressed in neuronal cells, but not in non-neuronal cells. Doc2alpha is highly expressed in the olfactory bulb, cerebral cortex, hippocampus, amygdaloid complex, and ventromedial hypothalamus nucleus, but not in the cerebellum, caudate-putamen, or ventral thalamus. These results indicate that Doc2alpha is expressed heterogeneously in mouse brain, where it is predominantly expressed in neuronal cells, and suggest that Doc2alpha plays a specific role in the area where it is expressed.

Expression of vasoactive intestinal polypeptide receptor mRNA and secretory regulation by vasoactive intestinal polypeptide in rat submandibular and sublingual salivary glands

Vasoactive intestinal polypeptide (VIP)-receptor mRNA was strongly expressed in the acinar cells in the submandibular gland but not in the sublingual gland. VIP-containing nerve fibres were richly distributed around acini in the submandibular gland but were rare around acini of the sublingual gland. In the submandibular gland, the chorda was stimulated at various frequencies (1-40 Hz) together with an infusion of (N-Ac-Tyr1, D-Phe2)-GRF(1-29)-NH2 (109 M), VIP antagonist, which reduced salivary flow from the submandibular gland only at high-frequency stimulation (> 20 Hz), and more markedly reduced the salivary protein concentration. When the chorda was continuously stimulated the antagonist reduced the salivary flow only during the initial 5 min. Exogenous VIP 10(-12) - 10(-8) M) infusion at the same time as chorda stimulation caused no increase in salivary flow, but the salivary protein concentration was increased in a dose-dependent manner. In the sublingual gland, neither VIP nor the VIP antagonist affected chorda-evoked salivary flow and protein concentration. Thus, endogenous VIP may play a part in the regulation of both fluid and protein secretion, especially of protein, evoked by chorda stimulation at high frequency in the submandibular gland. These phenomena occurred only in the initial phase of secretion. In the sublingual gland, it seems likely that VIP plays no part in the regulatory mechanism, at least with regard to salivary fluid secretion in the acinar cells.

The differential osmoregulation and localization of taurine transporter mRNA and Na+/myo-inositol cotransporter mRNA in rat eyes

We studied the cellular localization and osmotic regulation of taurine transporter (TauT) mRNA in the rat eyes using in situ hybridization. TauT mRNA signals were expressed in the ciliary body, and the outer part of the inner nuclear layer (INL), the outer nuclear layer (ONL) and the inner segment (IS) of the adult rat retina. Chronic hypernatrema, induced by gavaging with 1 ml/100 g body weight of 5% NaCl every other day for 7 days, markedly increased in TauT mRNA in the retina compared with control rats. However, there was little change in TauT mRNA in the eyes in acute hypernatremic state that is induced by single injection of high concentration of NaCl. On the contrary, acute hypernatremic rats displayed markedly elevated Na+/myo-inositol cotransporter (SMIT) mRNA in the retina and the iris-ciliary body and the lens epithelium. Under chronic hypernatremic conditions, there was no significant increase in SMIT mRNA in rat eyes. These findings suggest that TauT mRNA is osmotically regulated in vivo to protect retinal neuronal function, especially against chronic hypernatremic conditions, in contrast to rapid up-regulation of SMIT mRNA in acute hypernatremic rats.

Localization of molecules involved in cytokine receptor signaling in the rat trigeminal ganglion

The localization of some cytokine receptors and their downstream intracellular signaling molecules was examined in the trigeminal ganglia of rats. Among cytokine receptor components, we examined signal transduction subchain, gp130, IL-2Rgamma and IL-5Rbeta, which are common to respective groups of cytokine receptors. Most of the sensory ganglion neurons expressed gp130, but not IL-2Rgamma nor IL-5Rbeta. We further examined the localization of Janus kinase (JAK) family members which were reported to be associated with various kind of cytokine receptors and are thought to be implicated in major cytokine receptor-signaling pathways [6,9,11,13]. While JAK1 and Tyk2 were expressed in all the type of neurons, JAK2 was predominantly expressed in the small neurons. In addition, JAK3 immunoreactivity was only found in satellite cells. The present results indicate that most of neurons express gp130, and that the localization of JAK family members differs with the cell type. This also suggests that the cytokine receptor-signaling pathway may be different in neuronal and glial cells.

LIM-homeodomain gene family in neural development

In the present study, we isolated five murine LIM-homeodomain (LH) genes including a novel gene designated as L3 which is expressed specifically in the medial ganglionic eminence of the embryonic brain and the mesenchyme surrounding the oral cavity. The comparison of the expression domains in the embryonic forebrain using in situ hybridization histochemistry proved that three LH genes (LH-2, lim-1, and L3) share sharp boundaries. In addition to the prosomeric boundaries in the diencephalon, this gene family defines novel boundaries in the basal telencephalon, the mesencephalon, and the rhombencephalon. These mutually exclusive expression domains suggest that this family might be involved in controlling the early compartmentalization and boundary formation of the developing central nervous system.

Identification of a novel transmembrane semaphorin expressed on lymphocytes

Semaphorin (also known as collapsin) members are thought to be involved in axon guidance during neural network formation. Here, we report the isolation of a novel member, mouse semaphorin G (M-sema G), which encodes a semaphorin domain followed by a single putative immunoglobulin-like domain, a transmembrane domain, and a cytoplasmic domain. M-sema G is most closely related to M-sema F, which we previously reported, and semB and semC. These four members appear to constitute a transmembrane type subfamily in mouse semaphorins. In contrast to the predominant expression of M-sema F mRNAs in the nervous tissues, M-sema G mRNAs are strongly expressed in lymphoid tissues, especially in the thymus, as well as in the nervous tissues. The mRNAs are also detected in various cell lines from hematopoietic cells. By generating specific antibodies, we confirmed the strong expression of M-Sema G proteins on the surface of lymphocytes. These results provide the first evidence that semaphorin is expressed on lymphocytes and suggest that semaphorins may play an important role in the immune system, as well as in the nervous system.

Contribution of tumour necrosis factor-alpha (TNF-alpha) in host defence mechanism against Cryptococcus neoformans

We investigated the role of TNF-alpha in the host defence mechanism against infection with a virulent strain of Cryptococcus neoformans. Administration of exogenous recombinant human TNF-alpha significantly prolonged the survival time of mice infected by intratracheal instillation of the organism. Surprisingly, neutralizing MoAb to murine TNF-alpha did not shorten their survival time, a finding inconsistent with previous results. To investigate the cause of this inconsistency, we examined the production of TNF-alpha in the lungs of infected mice. During the course of cryptococcosis, there was little or no generation of TNF-alpha mRNA in the lung. This might be partly due to a direct inhibitory action of the fungal microorganism of TNF-alpha production by macrophages. In vitro production of TNF-alpha by murine interferon-gamma (IFN-gamma)- and lipopolysaccharide (LPS)-stimulated macrophages was strongly inhibited by co-culturing with the whole yeast cells. In contrast, administration of recombinant murine IL-12 markedly induced TNF-alpha production and the neutralizing anti-TNF-alpha MoAb strongly blocked IL-12-induced protection of mice against cryptococcal infection. These results indicate that endogenously synthesized TNF-alpha has the potential to contribute to the elimination of C. neoformans and partly mediates the protective effect of IL-12.

GLAST mRNA expression in the periventricular area of experimental hydrocephalus

Glutamate transporters play an important role in maintaining the extracellular glutamate concentration below the neurotoxic level. We investigated the expression of glutamate/aspartate transporter (GLAST) mRNA in the periventricular region of rats with kaolin-induced hydrocephalus by in situ hybridization (ISH). The density of GLAST mRNA-positive cells and the level of hybridization signals per positive cell significantly increased in the acute stage of hydrocephalus. We also demonstrated co-localization of GLAST mRNA and GFAP immunoreactivity in a single cell using the combined methods of ISH and immunohistochemistry. These findings suggest that GLAST is expressed in the reactive astrocytes of the periventricular area and regulates extracellular glutamate concentration after hydrocephalic brain injury.

Induction of Na+/myo-inositol cotransporter mRNA after focal cerebral ischemia: evidence for extensive osmotic stress in remote areas

Myo-inositol is one of the major organic osmolytes in the brain. It is accumulated into cells through an Na+/ myo-inositol cotransporter (SMIT) that is regulated by extracellular tonicity. To investigate the role of SMIT in the brain after cerebral ischemia, we examined expression of SMIT mRNA in the rat brain after middle cerebral artery occlusion, which would reflect alteration of extracellular tonicity. The expression of SMIT mRNA was markedly increased 12 h after surgery in the cortex of the affected side and lasted until the second day. Increased expression was also found in the contralateral cingulate cortex. Up-regulated expression was found predominantly in the neurons in remote areas, although nonneuronal cells adjacent to the ischemic core also expressed this mRNA. These results suggest that cerebral ischemia causes extensive osmotic stress in brain and that the neuronal cells respond to this stress by increasing SMIT expression.

cDNA cloning of a novel membrane glycoprotein that is expressed specifically in glial cells in the mouse brain. LIG-1, a protein with leucine-rich repeats and immunoglobulin-like domains

A cDNA encoding a protein designated as LIG-1 has been cloned and characterized. A fragment of this cDNA was found previously in a screen for genes up-regulated during neural differentiation in mouse P19 embryonal carcinoma cells. Comparative sequence analysis revealed LIG-1 to be a novel integral membrane glycoprotein (1091 amino acids) containing an extracellular region (794 amino acids) with a potential signal peptide, 15 leucine-rich repeats, 3 immnunoglobulin-like domains, and 7 potential N-glycosylation sites, a transmembrane region of 23 amino acids, and a cytoplasmic region of 274 amino acids. This protein, therefore, is a new member of both the leucine-rich repeat and the immunoglobulin superfamilies. Furthermore, Northern blot and in situ hybridization analyses showed LIG-1 gene expression to be predominantly in the brain, restricted to a small subset of glial cells such as Bergmann glial cells of the cerebellum and glial cells in the nerve fiber layer of the olfactory bulb. On the basis of its structural features and expression pattern, we propose that LIG-1 functions as a cell type-specific adhesion molecule or receptor at the glial cell surface, and plays a role in the nervous system in for example neuroglial differentiation, development, and/or maintenance of neural functions where it is expressed.

Expression of betaine transporter mRNA: its unique localization and rapid regulation in rat kidney

Betaine is a major compatible osmolyte in the renal medulla. It is taken up into cells via the betaine gamma-amino-n-butyric acid transporter (BGT-1). We investigated the localization of BGT-1 mRNA and its acute regulation by NaCl and furosemide administration. In situ hybridization revealed that BGT-1 mRNA is predominantly present in the outer medulla and papilla. Less intense signals were seen in the inner medulla and no signals were found in the cortex. Microscopic examination suggested that intense signals were present in the medullary thick ascending limbs of Henle's loop (MTAL) and the inner medullary collecting ducts (IMCD). A reverse transcription and polymerase chain reaction assay of individual microdissected segments along the nephron confirmed its localization. Intraperitoneal administration of NaCl rapidly increased the signal in the MTAL, and furosemide prevented the increase in BGT-1 mRNA by NaCl loading. In contrast, BGT-1 mRNA in the IMCD is less sensitive to these kinds of acute regulation. These results suggest that BGT-1 expression in the MTAL is rapidly regulated in response to the magnitude of NaCl absorption, as suggested for the expression of Na+/myo-inositol cotransporter.

Rapid and transient up-regulation of Na+/myo-inositol cotransporter transcription in the brain of acute hypernatremic rats

The osmoregulatory system is well developed in the brain. Osmolytes contribute to maintenance of cell volume and cellular functions without changing intracellular ionic composition. Myo-inositol is regarded as one of the major osmolytes in the brain. In the present study, we investigated the changes in expressions of sodium myo-inositol cotransporter (SMIT) mRNA in the brain of acute hypernatremic rats by in-situ hybridization and Northern blot methods. Under moderate acute hypernatremic conditions, SMIT mRNA level increased markedly at 1 h and returned to almost control levels at 3 h, in accordance with plasma Na+ concentrations. Especially, distinct increases in SMIT mRNA expression were observed in the granule cells and glial cells in the cerebellum. These findings indicate that SMIT plays an important role in osmoregulation, especially in the early stages of acute hypernatremia in the brain.

Anticryptococcal effect of amphotericin B is mediated through macrophage production of nitric oxide

Amphotericin B (AmB) is a classical antifungal drug and one of the most effective antifungal drugs for the treatment of systemic fungal infection. It is also known to have various immunomodulating activities other than its direct antifungal effect. In the present study, we demonstrated that AmB augmented gamma interferon (IFN-gamma)-induced killing potentials of murine peritoneal macrophages against Cryptococcus neoformans in a dose-dependent manner. This effect was strongly blocked by NG-monomethyl-L-arginine, a competitive inhibitor of nitric oxide (NO) synthesis. In addition, AmB markedly augmented macrophage NO production induced by IFN-gamma with a dose-response curve similar to that seen with its effect on the anticryptococcal activity. These effects were partially mediated by either tumor necrosis factor alpha or interleukin-1, because AmB enhanced IFN-gamma-induced production of these cytokines by macrophages and their specific antibodies partially inhibited the AmB-induced enhancement of NO generation when they were used separately. Our results indicate that AmB induces the production of tumor necrosis factor alpha and IL-1 by macrophages and augments their anticryptococcal activity through triggering the NO-dependent pathway.

Increased expression of NLRR-3 mRNA after cortical brain injury in mouse

In Drosophila, members of the leucine-rich repeat (LRR) family have significant functions in neural development. We have isolated mouse brain cDNAs which encode three new independent LRR proteins (neuronal leucine-rich repeat: NLRR-1, NLRR-2, NLRR-3). Levels of expression of these NLRR mRNAs were measured in a unilateral cortical injury model by in-situ hybridization and Northern blot analysis. In the injured cerebral cortex, only NLRR-3 mRNA increased in layers 2-3, while the other two genes showed no up-regulation. The level of NLRR-3 mRNA induction peaked around 7-10 days postinjury. This study suggests that NLRR-3 may be an important component of the pathophysiological response to brain injury.

Localization of bcl-2, bax, and bcl-x mRNAs in the developing inner ear of the mouse

In situ hybridization was employed to study the expression of bcl-2 mRNA and its family members, bax and bcl-x mRNAs, in the developing inner ear. We found that in the cochlear structure, sensory epithelial cells, the spiral ganglion and stria vascularis expressed these mRNAs in postnatal period in a temporally similar manner, but in embryos, neither bax nor bcl-x mRNA were expressed in the sensory epithelium from embryonic day (E) 13 to 19. In contrast to these patterns, bcl-2 mRNA was expressed by E15 to E19, and the expression at E13 was below the lower limit of detection. Non-neuronal tissue (stria vascularis) also expressed these three transcripts during development. These results suggest that bcl-2 family members may be differentially involved in the differentiation of sensory epithelial cells, spiral ganglia, and stria vascularis. In particular, the differential expression patterns in the cochleovestibular neurons suggest that proliferating and differentiating neurons utilize distinct members of the bcl-2 family.

Expression of dopamine transporter mRNA and its binding site in fetal nigral cells transplanted into the striatum of 6-OHDA lesioned rat

Neurological disorders in rat model of hemi-Parkinson's disease can be compensated by the transplantation of fetal nigral cells. However, the role of the dopamine transporter (DAT) in this recovery has not been clarified. To clarify this mechanism, we examined the expression of DAT in the caudate putamen (CPu) by in situ hybridization histochemistry (mRNA) and autoradiography (using the ligand [125I] beta-CIT, which labels DAT) and compared them with the recovery of motor disturbance revealed with methamphetamine-induced rotation. Models were made with the stereotaxic injection of 6-hydroxydopamine into the left side of the substantia nigra pars compacta. Cell suspensions from rat fetus (embryonic day 14-15) were transplanted into the lesioned side of CPu. Methamphetamine-induced rotation, expression of DAT mRNA, and [125I] beta-CIT binding were evaluated 2, 4 and 12 weeks after the transplantation. Methamphetamine-induced rotation recovered partly in the 2nd week and significantly in the 4th week. [125I] beta-CIT binding increased with time and the dense binding was detected 4 and 12 weeks after the transplantation. In all transplanted rats, cells expressing DAT mRNA were found in CPu. These results indicated that transplanted fetal dopaminergic cells maturated in CPu of host animals and extended nerve terminals where high density of DAT binding sites were found.

Visualization of ischemic insult in caudate putamen with beta-CIT

Dopamine (DA) has been considered to play an important role in the development of ischemic neuronal injury in the caudate putamen (CPu). The goal of this study was to examine the change in the dopamine transporter (DAT) after ischemic insult in CPu.

METHODS

Male Mongolian gerbils (n = 10) were exposed to 10-min forebrain ischemia. Animals were decapitated 24 hr (n = 5) and 96 hr (n = 5) after ischemia. The change in the amount of DAT binding sites in CPu was evaluated by in vitro autoradiography with [125I]-beta-CIT (3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid methyl ester). In addition, the expression of DAT mRNA in CPu and the substantia nigra pars compacta (SNC) was examined.

RESULTS

Iodine-125-beta-CIT specific binding was significantly increased in dorsolateral CPu with ischemic damage both 24 hr and 96 hr after ischemia, with greater increase at 96 hr. DAT mRNA in SNC was also significantly increased 96 hr after ischemia, which corresponded with the increase of [125I] beta-CIT binding. However, DAT mRNA in SNC was decreased 24 hr after ischemia. In the ischemic lesion in CPu, no expression of DAT mRNA could be detected both 24 hr and 96 hr after ischemia.

CONCLUSION

The change in DAT after ischemic insult is clarified with [125I] beta-CIT. This increase of [125I] beta-CIT binding does not come from de novo expression of DAT in glial cells in the damaged area in CPu. This increase of beta-CIT binding reflects increase of DAT synthesis in DA neurons in SNC (96 hr) or other factors such as the impairment of the degradation of DAT in the damaged area in CPu.

Reg gene expression is increased in rat gastric enterochromaffin-like cells following water immersion stress

BACKGROUND & AIMS

Reg gene has been isolated from regenerating rat pancreatic islets, and subsequent studies have shown a trophic effect of Reg protein on islet cells. However, little is known about the role of Reg protein in the stomach. The aim of this study was to clarify the localization of Reg messenger RNA (mRNA) and its product in the stomach and to examine changes in the level of their expression during regeneration of gastric mucosal cells.

METHODS

Gastric lesions were experimentally induced in Sprague-Dawley rats by water immersion stress. Northern blot analysis and in situ hybridization studies were performed to examine changes in mRNA levels. Immunohistochemical studies were performed to identify the cellular localization and to investigate the change in Reg protein level.

RESULTS

Reg mRNA and its product were distributed in the basal part of the oxyntic mucosa and were expressed mainly in enterochromaffin-like cells. Levels of both Reg mRNA and its product were markedly increased in the water immersion-induced gastric lesions.

CONCLUSIONS

Reg mRNA and its product are expressed in gastric enterochromaffin-like cells, and their levels are increased during the healing process of water immersion-induced gastric lesions.