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

The intermediate filament protein composition in glial cells of goldfish optic nerve differs from that found in glial cells of the goldfish spinal cord and brain. Brain and spinal cord glial cells contain glial fibrillary acidic protein (GFAP), whereas glial cells in the optic nerve contain ON3. The ON3 protein of the goldfish optic nerve was recently identified as the goldfish equivalent to the mammalian type II keratin 8 protein. In addition to the ON3 protein, the goldfish optic nerve also contains a 48-kDa protein. Immunoblotting experiments suggest that this protein is equivalent to the mammalian type I keratin 18 protein, which typically pairs with keratin 8 to form filaments. We show that these proteins are not specific to the optic nerve. The ON3 and 48-kDa proteins of the goldfish optic nerve share common antigenic properties with the predominant keratin pair expressed in the goldfish liver. These proteins are also expressed at low levels in the goldfish brain and spinal cord. In addition RNase protection assays and Northern blots indicate that the mRNA for the ON3 protein in optic nerve is identical to the message found in other goldfish tissues. The expression of ON3 was also examined in cultured glial cells from goldfish spinal cord and optic nerve and cultured fibroblast cells. Analysis of intermediate filament protein expression in cultured glial cells taken from goldfish spinal cord demonstrated the absence of GFAP in these cells and the expression of ON3. This protein was also the predominant intermediate filament protein of cultured optic nerve glial cells and fibroblasts. The differences in the expression of intermediate filament proteins in mammals and lower vertebrates are discussed. In addition, we discuss how the expression of a simple epithelial keratin pair in glial cells of the goldfish optic nerve may be associated with this system's capacity for continuous growth and regeneration.
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PMID:Keratin 8 of simple epithelia is expressed in glia of the goldfish nervous system. 170 94

The goldfish visual pathway, unlike the visual pathway of higher vertebrates, retains continuous growth and development throughout life and is capable of functional regeneration. The structure and expression of proteins that support the physiological attributes of this system are of interest. Glial cells in this pathway express keratins as the predominant intermediate filament proteins rather than the expected glial fibrillary acidic protein. Previously we identified and characterized cDNA clones representing two type I keratins from the goldfish optic nerve, GK48 and GK49. The GK48 protein is the type I keratin partner to the type II keratin ON3, while the GK49 protein is expressed in a different cell type. Here, we extend our studies on the expression of mRNA for the GK48, GK49, and ON3 proteins at the early stages of optic nerve regeneration. RNase protection assays show that at 10 days post-crush, there is no overall change in levels of mRNA for these proteins as compared to uncrushed control nerves and nerves from unoperated fish. In addition, we show by in situ hybridization that the GK49 protein shows no changes in its distribution of mRNA in the optic nerve after crush. In contrast, the levels of GK48 and ON3 mRNA are greatly reduced within the crush zone. However, these two mRNAs are differentially expressed at different time points during regeneration, with GK48 mRNA appearing in the crush zone before ON3. These results indicate that the mRNA for the GK48 and ON3 proteins are differentially regulated during regeneration and that these two proteins are expressed in a different cell type from the GK49 protein.
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PMID:Differential expression of keratins in goldfish optic nerve during regeneration. 751 63