Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We analyzed the developmental regulation and role of the neurotrophins during metanephric kidney morphogenesis. RNase protection assay revealed the presence of nerve growth factor, neurotrophin 3 (NT-3), and brain-derived neurotrophic factor mRNAs and the regulation of their expression during embryonic development of rat metanephros. NT-3 induced differentiation (neurite outgrowth) and survival (inhibition of apoptosis) of the neuronal precursors in cultured nephrogenic mesenchymes and neuronal differentiation in cultured whole kidneys, whereas NT-4/5, brain-derived neurotrophic factor, and nerve growth factor were without effect. The neurotrophins did not trigger tubular differentiation of isolated nephrogenic cells, which underwent apoptosis when cultured with or without the neurotrophins. NT-3 is thus an inducer of differentiation and a survival factor for renal neuronal cells, but none of the neurotrophins is a morphogen in kidney tubule induction.
...
PMID:Neurotrophin 3 rescues neuronal precursors from apoptosis and promotes neuronal differentiation in the embryonic metanephric kidney. 747 79

By northern blot analysis and ribonuclease protection assay, we observed the presence of a high level of trkB mRNA in primary brain cultures devoid of neuronal cells and highly enriched in glial fibrillary acidic protein-positive astroglial cells prepared from newborn rat cerebral hemispheres, cerebral cortex, hippocampus, and striatum. In primary astroglial cultures, the more abundant trkB transcripts code for the truncated receptor without tyrosine kinase activity; probes specific for the full-length trkB mRNA did not detect any signal in northern blot analysis. By the sensitive ribonuclease protection assay, we could show the presence of trkC mRNA in cultured astrocytes, whereas no trkA mRNA was detected. We confirmed the presence of relatively high levels of nerve growth factor and neurotrophin-3 mRNA, and very low basal level of brain-derived neurotrophic factor mRNA. Moreover, we demonstrated that another member of the neurotrophin family, neurotrophin-4, is also expressed in cultured astroglial cells. In view of the fact that many functional receptors for conventional neurotransmitters or neuropeptides present on astroglial cells may act via the adenylate cyclase system, we studied also the effect of agents able to increase the intracellular cyclic AMP concentration. A sharp increase in the trkB mRNA level was observed after treatment of primary astroglial cultures with dibutyryl cyclic AMP, 8-bromo-cyclic AMP, or the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine. On the contrary, trkC mRNA levels were unaffected by treatment with cyclic AMP-elevating agents. All the neurotrophin mRNAs examined, except neutrophin-4, were increased by 3-isobutyl-1-methylxanthine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Expression of neurotrophins and their receptors in primary astroglial cultures: induction by cyclic AMP-elevating agents. 751 99

The rat brain-derived neurotrophic factor (BDNF) gene consists of four 5' exons linked to separate promoters and one 3' exon encoding the prepro-BDNF protein. In the present study, using RNase protection analysis, we show that the same major transcription initiation sites are used for each BDNF exon mRNA in different brain regions and that in addition to hippocampus and cerebral cortex, kainate differentially induces the expression of BDNF exon mRNAs in thalamus, cerebellum and striatum. The 4.2 kb transcripts, are less enriched in the polysomal fraction of rat brain than the shorter 1.6 kb transcripts suggesting their translational discrimination.
...
PMID:Analysis of transcriptional initiation and translatability of brain-derived neurotrophic factor mRNAs in the rat brain. 782 76

The actions of the neurotrophins are mediated through specific receptors. Nerve growth factor (NGF), the prototypic neurotrophin, binds to receptors of both high and low affinity. A protein 75 kDa in size (p75NGFR) binds NGF, as well as brain-derived neurotrophic factor and neurotrophin 3, with low affinity. Recent investigations suggest that this protein may also be a component of the high affinity NGF receptor complex. To study gene expression of the p75NGFR molecule, we used a sensitive reverse transcription-polymerase chain reaction (RT-PCR) assay to measure levels of its messenger RNA (mRNA) in small samples of total RNA. The assay is based on using a shortened p75NGFR cRNA as an internal RNA standard to control for variability in reverse transcription and polymerase chain amplification. We measured p75NGFR mRNA levels in the rat cerebellum during ontogeny to further study the transient developmental increase in receptor gene expression known to occur in this brain region during the early postnatal period. We found that p75NGFR mRNA levels were most abundant at postnatal day 2, and then declined to lower levels throughout postnatal development and in the adult. Northern blot analysis of the same total RNA samples used in our RT-PCR assay verified that p75NGFR expression is highest in the early postnatal period. These results confirm those of previous studies accomplished with much larger amounts of RNA using ribonuclease protection or northern blot assays. The use of an RT-PCR assay that utilized an internal standard also controls against changes in RNA complexity which can affect the measurement of message abundance across developmental stages.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:A reverse transcription-polymerase chain reaction study of p75 nerve growth factor receptor gene expression in developing rat cerebellum. 797 82

The expression of neurotrophin and neurotrophin receptor mRNAs was examined using RNase protection assays and Northern-blot analysis in rat thymus, spleen tissue and immunocompetent mononuclear cells purified from these two organs. Nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 mRNAs were all expressed in thymus and spleen tissue although at different levels, while immunocompetent cells expressed neurotrophin-3 and neurotrophin-4 mRNAs. Thymus and spleen tissue expressed mRNAs encoding the low-affinity nerve-growth-factor receptor, the non-neuronal TrkA I receptor, the truncated (kinase deficient) and full-length TrkB, and the TrkC receptor. Low-affinity nerve-growth-factor receptor and non-neuronal TrkA I mRNAs were detected in both thymus and spleen immunocompetent cells. In addition, thymus cells expressed neuronal TrkA II mRNA and spleen cells expressed truncated TrkB mRNA. The expression of TrkA I and TrkA II mRNAs was enhanced in both thymus and spleen cells after cell culture. Enhanced levels of neurotrophin-4 mRNA were observed in spleen immunocompetent cells after adrenalectomy. Moreover, the expression of neurotrophin-4 mRNA was up-regulated after stimulation of immune cells with the mitogens concanavalin A or lipopolysaccharide or with the inflammatory mediator leukotriene B4. This suggests that neurotrophin-4 could be secreted by immunocompetent cells and may be involved in inflammatory processes.
...
PMID:Expression of mRNA encoding neurotrophins and neurotrophin receptors in rat thymus, spleen tissue and immunocompetent cells. Regulation of neurotrophin-4 mRNA expression by mitogens and leukotriene B4. 805 49

The adult rat dorsal root ganglion (DRG) produces mRNA for the neurotrophic factors nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and contains large populations of neurons responsive to these factors. We report that following a focal crush injury of the sciatic nerve, NGF mRNA expression increases threefold and BDNF mRNA two-fold, in the ipsilateral L4 and L5 DRGs. The mRNAs encoding the cognate neurotrophin receptors, p75NGFR, trkA, and trkB were expressed in the DRG throughout the post-injury time course, suggesting that DRG neurons remain responsive to both NGF and BDNF. p75NGFR mRNA levels became transiently depressed in the DRG during the first several days after the lesion but returned to normal within 1 week. trkB mRNA was expressed in the normal sciatic nerve and levels were not altered by nerve crush. RNase protection assays detected both full-length and truncated trkB transcripts in the DRG, but only truncated trkB mRNA, lacking the tyrosine kinase domain, was detected in the sciatic nerve. Likewise, trkA transcripts were not detected by RNase protection in normal sciatic nerve or in a segment of nerve distal to the crush site. These results are consistent with a model in which regenerating sensory neurons are supported by neurotrophic factors synthesized within the DRG.
...
PMID:Expression of mRNA for neurotrophic factors and their receptors in the rat dorsal root ganglion and sciatic nerve following nerve injury. 827 14

The presence of the neurotrophin, nerve growth factor, brain derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 (NGF, BDNF, NT-3 and NT-4) and their receptors of the tyrosine kinase family (trkA, trkB and trkC) have been investigated in the choroid plexus and dura mater of the adult rat by ribonuclease protection assay. The choroid plexus contained high levels of mRNAs for NGF and NT-4, and low levels of NT-3 and BDNF mRNA; and high levels of trkB mRNA, and undetectable levels of trkA and trkC mRNA. In the dura mater there were high levels of NT-3 and NGF, and low levels of BDNF and NT-4 mRNAs; and high levels of trkC mRNA, and relatively high amount of trkB mRNA, while levels of trkA mRNA was undetectable. The present analysis revealed a different distribution of neurotrophins and their related receptors in the choroid plexus and dura mater.
...
PMID:Expression of mRNAs for neurotrophins and their receptors in the rat choroid plexus and dura mater. 858 Apr 26

Using the RNase protection assay, we have found that nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) are expressed in the avian retina during development. The expression peaks around embryonic days 12-15, with decreasing levels at later stages of development. Abundant levels of NGF and BDNF but low levels of NT-3 mRNA were found in the adult retina. We also found that light/darkness regulated the levels of NGF and BDNF mRNAs but not the levels of NT-3 mRNA in the 5-day-old chicken retina. It was demonstrated that NGF and BDNF mRNA levels were up-regulated by light exposure. The cellular localization of mRNA expression for the neurotrophins and neurotrophin receptors TrkA, TrkB, and TrkC in the retina was studied using in situ hybridization. The patterns of NGF and trkA mRNA expression were very similar and were localized to the external part of the inner nuclear layer on the border with the outer plexiform layer and corresponded to the localization of horizontal cells. NT-3 labeling was also found over the external part of the inner nuclear layer, whereas trkC mRNA was found over all layers in the retina. BDNF labeling was found over all layers in the retina, whereas TrkB labeling was intense over cells in the ganglion cell layer, which is in agreement with the response of ganglion cells to BDNF stimulation. Functional neurotrophin receptors were suggested by the response of retinal explants to neurotrophin stimulation. These data indicate that the neurotrophins play local roles in the retina that involve interactions between specific neuronal populations, which were identified by the localization of the Trk receptor expression. The data also suggest that NGF and BDNF expression is regulated by normal neuron usage in the retina.
...
PMID:Expression of neurotrophins and trk receptors in the avian retina. 882 53

Previous studies have analyzed the expression of different members of the neurotrophin family and their trk receptors in glial cultures composed mainly or exclusively of type-1 astrocytes, whereas only partial data have been published on other cultured glial types. In this article we compare the mRNA levels for neurotrophins (NGF, BDNF, NT-3, NT-4) and their high-affinity receptors (trkA, trkB, trkC) in cultures enriched in specific glial types, such as microglia, type-1 astroglia, and cells of the O/2A lineage (type-2 astroglia and oligodendroglia). Relatively high levels of NGF mRNA (comparable to those observed in adult rat cerebral cortex) are present in all types of cultured glial cells, except for a low level of expression in cultures enriched in microglial cells. In contrast, BDNF mRNA is undetectable in all cultures examined. NT-3 and NT-4 mRNA molecules, at a level equal to that observed in adult rat cerebral cortex, are easily detected in type-1 astrocyte cultures, whereas their hybridization signals are undetectable in cells of the O/2A lineage and in microglial cultures. The analysis of neurotrophin receptor mRNAs confirms the absence of trkA mRNA, the presence of relatively high levels of trkB mRNA (70-100% of cerebral cortex values), and low levels of trkC mRNA (10-18% of cerebral cortex values) in both cultured astroglial and oligodendroglial cells. Only very low levels of trkB and trkC mRNAs are observed in microglial cultures. Although cultured glial cells express mainly mRNAs encoding for the truncated form of trkB and trkC, a low level of mRNA encoding for the full-length catalytic form of these receptors is detected by the sensitive ribonuclease protection assay.
...
PMID:Neurotrophins and their trk receptors in cultured cells of the glial lineage and in white matter of the central nervous system. 886 Feb 35

The neurotrophins brain-derived neurotrophic factor (BDNF) and NT-4/5 exert their trophic effects on the nervous system via signaling through trkB receptors. These receptors occur as splice variants of the trkB gene that encodes a full-length receptor containing the signal transducing tyrosine kinase domain as well as truncated forms lacking this domain. Because the importance of the trkB isoforms for development and maturation of the nervous system is unknown, we have examined the expression of trkB receptor isoforms during development of the rat forebrain using 1) a sensitive ribonuclease protection assay to distinguish full-length and truncated trkB transcripts, 2) western blot analysis to characterize developmental changes in trkB proteins, and 3) immunohistochemistry to determine the cellular localization of trkB receptors. In the rat forebrain, adult mRNA levels for full-length trkB are reached by birth, whereas truncated trkB message does not peak until postnatal days 10-15. Western blot analysis indicates that full-length trkB protein is the major form during early development, whereas truncated trkB protein predominates in all forebrain regions of late postnatal and adult rats. These data also suggest that the glycosylation state of these receptors changes during postnatal maturation. TrkB immunoreactivity is present predominately within neurons, where it is localized to axons, cell soma, and dendrites. Strong dendritic immunostaining is particularly evident in certain neuronal populations, such as pyramidal neurons in the hippocampus and in layer V of the neocortex. The dendritic localization of trkB receptors supports the hypothesis that dendrites, as well as axons, are important sites for neurotrophin actions in the central nervous system.
...
PMID:Developmental and mature expression of full-length and truncated TrkB receptors in the rat forebrain. 889 44


1 2 3 4 Next >>

---