Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteolipid protein (PLP) is the major protein in the myelin sheath of the CNS. It was recently reported that PLP coding transcripts are also found in the PNS, although the protein was not detectable in peripheral nerve myelin. In the present investigation, levels of mRNA for PLP in sciatic nerve were studied during development and following transection and crush injury. Results were compared to those for P0, the major PNS myelin protein, and the myelin-associated glycoprotein (MAG). PLP transcript levels were very low at 21 days in sciatic nerve and remained unchanged in the adult sciatic nerve. This contrasts markedly with P0 and MAG mRNAs, which are expressed at high levels during development and decrease in content significantly by adulthood. The level of PLP messages was reduced approximately 40% in the quiescent Schwann cells in the distal segment of the sciatic nerve at 21 days after permanent transection, yet P0 mRNA levels were very low, and MAG mRNAs were undetectable in this tissue. The distal segment of the crush-injured sciatic nerve is characterized by transient demyelination followed by rapid myelination. PLP mRNA levels remained comparatively unaffected in the 3-week period following crush injury. RNase protection experiments using two antisense riboprobes confirmed that levels of PLP-derived protected fragments, corresponding to PLP and DM-20 messages, remained unchanged in the developing and adult sciatic nerve. These results indicate that myelin-specific P0 and MAG genes are tightly controlled at the level of transcription through Schwann cell-axonal interactions, whereas PLP transcription in the peripheral nerve remains nearly dissociated from axonal influences.
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PMID:Levels of proteolipid protein mRNAs in peripheral nerve are not under stringent axonal control. 170 41

Developmentally regulated action potentials are a hallmark of Rohon-Beard cells, a class of sensory neurons. In these neurons as well as other primary spinal neurons of Xenopus laevis, the functional differentiation of delayed-rectifier potassium current regulates the waveform of the action potential during the initial day of its appearance. Later, the acquisition of another voltage-dependent potassium current--the A current--plays a major role in regulating excitability. In order to understand the molecular basis of this functional differentiation, genes encoding voltage-dependent potassium currents expressed in the embryonic amphibian nervous system are being cloned. Here, we report the functional properties and developmental localization of a second Xenopus Shaker-like gene (Xenopus Kv 1.1; XSha1; GenBank accession number M94258) encoding a potassium current. Homology screening with the mouse gene MBK1 led to its isolation. Functional expression in oocytes identifies it as a delayed-rectifier current when assembled as a homooligomeric structure. Specific transcripts corresponding to XSha1 and to the previously cloned gene XSha2 are both detectable by RNase protection in RNA isolated from the embryonic nervous system. However, whole-mount in situ hybridization reveals the temporal pattern and cellular localization of XSha1 but not XSha2 mRNA, suggesting that the concentration of XSha2 transcripts in individual cells is lower than the threshold for detection by this method. Of particular interest, Rohon-Beard cells express XSha1 mRNA. In addition, XSha1 mRNA is detected in several structures containing neural crest derivatives including spinal ganglia, the trigeminal ganglion, and branchial arches; its presence in motor nerves and lateral spinal tracts suggests that both CNS and PNS glia express the mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Primary sensory neurons express a Shaker-like potassium channel gene. 822 10

Three major isoforms of the receptor protein tyrosine phosphatase HPTPzeta/RPTPbeta (RPTPzeta/beta) have been previously identified, two with identical transmembrane and intracellular catalytic domains that differ by virtue of a long cysteine-free extracellular region, and a soluble proteoglycan called phosphacan that lacks the transmembrane and carboxy-terminal catalytic domains. To determine whether these RPTPzeta/beta variants are produced by alternative mRNA splicing of a common primary transcript, we performed genomic Southern analysis and characterized several rat cDNA and genomic RPTPzeta/beta clones. These studies indicated that the three major transcripts which encode phosphacan and the two RPTPzeta/beta phosphatase variants are encoded by a single gene, and further that additional alternative mRNA splicing is likely to result in the deletion of a 7 amino acid insert from the intracellular juxtamembrane region of both long and short phosphatase isoforms. Simultaneous quantitation of the three major isoforms by RNase protection analysis indicated that the mRNA encoding phosphacan had the highest relative abundance in the CNS while that encoding the short phosphatase isoform was most abundant relative to the other RPTPzeta/beta variants in the PNS. Following peripheral nerve crush, all RPTPzeta/beta mRNAs, including phosphacan and the phosphatase variants with and without the 21 base insert, were significantly induced in the distal segments of the sciatic nerve with a time course that correlated well with the response of Schwann cells to this injury.
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PMID:Regulated expression during development and following sciatic nerve injury of mRNAs encoding the receptor tyrosine phosphatase HPTPzeta/RPTPbeta. 974 13