Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta-subunit of cGMP-phosphodiesterase (beta-PDE) is a key protein in phototransduction expressed exclusively in rod photoreceptors. It is necessary for visual function and for structural integrity of the retina. beta-PDE promoter deletions showed that the -45/-23 region containing a consensus Crx-response element (CRE) was necessary for low level transcriptional activity. Overexpressed Crx modestly transactivated this promoter in 293 human embryonic kidney cells; however, mutation of CRE had no significant effect on transcription either in transfected Y79 retinoblastoma cells or Xenopus embryonic heads. Thus, Crx is unlikely to be a critical beta-PDE transcriptional regulator in vivo. Interestingly, although the beta/GC element (-59/-49) binds multiple Sp transcription factors in vitro, only Sp4, but not Sp1 or Sp3, significantly enhanced beta-PDE promoter activity. Thus, the Sp4-mediated differential activation of the beta-PDE transcription defines the first specific Sp4 target gene reported to date and implies the importance of Sp4 for retinal function. Further extensive mutagenesis of the beta-PDE upstream sequences showed no additional regulatory elements. Although this promoter lacks a canonical TATA box or Inr element, it has the (T/A)-rich beta/TA sequence located within the -45/-23 region. We found that it binds purified TBP and TFIIB in gel mobility shift assays with cooperative enhancement of binding affinity.
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PMID:The rod cGMP-phosphodiesterase beta-subunit promoter is a specific target for Sp4 and is not activated by other Sp proteins or CRX. 1194 74

We have studied retina-specific gene expression and gene promoter activity in WERI-Rb1 retinoblastoma cells. In general, the expression of endogenous genes matched the efficiency of promoter activity of the transfected gene: interphotoreceptor retinoid binding protein and phosphodiesterase-beta mRNAs and reporter activities were readily detected while other retina-specific messages were at or below the detection limit in WERI-Rb1 cells. Phosphodiesterase-beta promoter appeared active in all six cell lines tested. The viral SV40 promoter is very weak in WERI-Rb1 cells, which has implications for its use in gene constructs targeted to the photoreceptors. Our results also show that polyethyleneimine 25 is an efficient and simple carrier for DNA. The optimized transfection conditions permit the use of 24-well plates and low amounts of DNA for improved analysis of promoter activities, as compared to previous studies. Our results are expected to facilitate further research on retina-specific gene expression.
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PMID:Retina-specific gene expression and improved DNA transfection in WERI-Rb1 retinoblastoma cells. 1293 29

cGMP-phosphodiesterase (PDE) is a key component in visual phototransduction. Rod and cone photoreceptors each produce their unique cGMP-PDE subunits. The alpha' catalytic subunits are believed to be cone-specific. In this study, we report that transfection of the -132 to +139 sequence in the upstream region of the human alpha'-PDE gene fused to luciferase cDNA gives the highest level of reporter gene transcription in cultured retinoblastoma Y79 cells. Transgenic Xenopus laevis carrying this sequence fused to green fluorescent protein (GFP) expressed GFP in cones, suggesting a conserved regulatory mechanism for alpha'-PDE transcription in both human and frog.
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PMID:Conserved transcriptional regulation of a cone phototransduction gene in vertebrates. 1552 96


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