Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Telomerase is a ribonucleoprotein reverse transcriptase that synthesizes and maintains telomeric DNA. Studies of telomeres and telomerase are facilitated by the large number of linear DNA molecules found in ciliated protozoa, such as Tetrahymena thermophila. To examine the expression of telomerase, we investigated the transcription of the RNA polymerase III-directed gene encoding the RNA subunit (TER1) of this enzyme. A chimeric gene containing the Glaucoma chattoni TER1 transcribed region flanked by 5' and 3' Tetrahymena regions was used to identify promoter elements following transformation of Tetrahymena cells. Disruption of a conserved proximal sequence element (PSE) located at -55 in the Tetrahymena TER1 5' flanking region eliminated expression of the chimeric gene. In addition, mutation of an A/T-rich element at -25 decreased expression markedly. A gel mobility shift assay and protein-DNA cross-linking identified a PSE-binding polypeptide of 50-60 kDa in Tetrahymena extracts. Gel filtration analysis revealed a native molecular mass of approximately 160 kDa for this binding activity. Our results point to a similar architecture between ciliate telomerase RNA and metazoan U6 small nuclear RNA promoters.
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PMID:Identification of an essential proximal sequence element in the promoter of the telomerase RNA gene of Tetrahymena thermophila. 1051 20

To establish auto iris pigment epithelial (IPE) transplantation, we characterized the properties of IPE cells and the method of culture using auto serum. Monkey and human IPE cells were obtained and cultured in several conditions, using auto, mouse, rabbit, bovine, or human serum. Immunocytochemical study was performed to confirm that the cells were epithelial in origin. The proliferation rate of the IPE was also calculated from fresh human IPE cells, which were obtained during filtering glaucoma surgery. Proliferation rate was also compared to that of retinal pigment epithelial (RPE) cells. Reverse-transcriptase and polymerase chain reaction for melanogenesis was performed, and the amount of pigment in the IPE cells was also calculated. Mouse and rabbit sera were not effective for the monkey IPE cell culture. Conversely, the cells grew well in the medium with auto, bovine, or human serum. Human IPE cells grew exponentially by the described methods and reached to 60,000 cells after about 4-5 weeks. When we compared them by proliferation rate, IPE cells were less proliferative than RPE cells. The gene expression for melanogenesis and the amount of pigment in the IPE gradually decreased through successive passages. Transplantation has been tried for the treatment of age-related macular degeneration using RPE from fetus or from eye bank eyes. However, focal rejection may play an important role in the clinical results. The establishment of auto IPE cell transplantation may improve the problem of rejection. In the present study, we established auto IPE cell culture using auto serum. The cultured IPE cell showed pigment epithelial cell properties until around five passages in both human and monkey.
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PMID:Characterization of iris pigment epithelial cell for auto cell transplantation. 1058 Mar 44

Medical therapy of glaucoma commonly aims at slowing aqueous humor formation by the ocular ciliary epithelial bilayer, but underlying mechanisms are poorly understood. The first step in secretion is NaCl uptake from the stroma into the pigmented ciliary epithelial (PE) cell layer by electroneutral transporters. After crossing gap junctions into the nonpigmented ciliary epithelial (NPE) cell layer, solute is released into the aqueous humor. Published data have indicated that both paired Na+/H+ and Cl-/HCO3- antiporters and the Na+-K+-2Cl- symporter are involved in net uptake. The molecular identities of the paired antiporters have not been elucidated. We have studied continuously cultured bovine PE cells. Acid-activated 22Na+ uptake was inhibited by cariporide, EIPA (ethyl-isopropyl-amiloride) and amiloride, at concentrations characteristic of the NHE-1 isoform. Videomicroscopy of BCECF-loaded PE cells verified the presence of an EIPA-inhibitable Na+/H+ antiporter. Removing external Cl- also triggered an alkalinization, which was Na+-independent and could be inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Application of hypotonicity followed by return to isotonicity triggered a regulatory volume increase, which was pharmacologically similar to the uptake mechanisms described for intact rabbit ciliary epithelium. Reverse transcriptase polymerase chain reaction (RT-PCR) amplification of RNA from the human ciliary body detected expression of the AE2 Cl-/HCO3- exchanger, but not of AE1, cAE3 or bAE3. Immunostaining of bovine PE cells also revealed the presence of AE2 epitope. We conclude that paired NHE-1 Na+/H+ and AE2 Cl-/HCO3- antiporters are important components in the initial step in aqueous humor formation.
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PMID:Na+/H+ and CI-/HCO3-antiporters of bovine pigmented ciliary epithelial cells. 1100 5