Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of different CC Ar GG boxes derived from either muscle-specific or serum-responsive genes, on the specificity of different promoters has been investigated. Inserted upstream from an 85 base-pair long minimal promoter of the human cardiac alpha-actin gene, a single copy of both the cognate CC Ar GG element (HCA1) and the c-fos gene serum response element (SRE) stimulate transcription four- to fivefold more efficiently in C2 myogenic cells than in L fibroblastic cells, SRE being two- to threefold more active than HCA1. Inserted upstream from the ubiquitous Herpes simplex thymidine kinase (HSV-tk) promoter, multimerized CC Ar GG boxes behave as strong muscle-specific activating elements, about 20-fold more active in myogenic C2 cells than in L fibroblasts and hepatoma HepG2 cells. They also confer serum responsiveness on the HSV-tk promoter. Efficiency of HCA1 and SRE tetramers in conferring both muscle specificity and serum responsiveness is roughly similar. It appears, therefore, that regardless of their origin (either muscle-specific or serum-responsive genes) CC Ar GG boxes behave by themselves as both muscle-specific activating and serum-responsive elements.
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PMID:CC Ar GG boxes, cis-acting elements with a dual specificity. Muscle-specific transcriptional activation and serum responsiveness. 216 66

CArG boxes (CC(A/T)6GG sequences) are present in various promoters and are able to confer two different types of transcriptional responsiveness: serum inducibility and muscle-specific activation. Inserted upstream from the ubiquitous HSV thymidine kinase promoter, multimerized HCA1 boxes (human cardiac alpha-actin proximal CArG box) behave as strong muscle-specific activating elements. Transient expression assay was used to determine whether the muscle-specific transcriptional activation by the CArG boxes depends on the presence in the vicinity of other specific cis-acting DNA elements. Our results show that no specific association between different regulatory binding sites is required for the myogenic activity of a CArG box and that CArG elements are able to stimulate transcription in myogenic cells through either homophilic or heterophilic interactions of the CArG box binding factors.
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PMID:Muscle-specific transcriptional activation by CArG box requires either homophilic or heterophilic interactions of the CArG box binding factors. 839 32

We have studied gene activation via CArG boxes in the context of myogenesis. The proximal CArG box of the human cardiac actin gene (HCA1) stimulates transcription from the herpes simplex virus thymidine kinase (TK) promoter in a tissue-specific fashion. Thus in transient transfection assays, when the expression of chloramphenicol acetyltransferase (CAT) from p(HCA1)4 TKCAT is compared to that derived from p(M1)4 TKCAT which contains an inactive mutated version (M1) of the HCA1 element, high levels of expression are seen in C2 mouse myoblasts and myotubes, and in the T4 myoblast cell line derived from the C3H10T1/2 cell line by 5-azacytidine treatment, whereas only low levels of expression are seen in the mouse L fibroblast cell line. The parental C3H10T1/2 cell line shows intermediate levels of expression. A similar situation is seen in stably transfected cell lines. Gene activation via CArG boxes was also analyzed in the course of myogenic conversion of C3H10T1/2 cells treated with 5-azacytidine. Our results indicate that activation of the CAT gene from the HCA1 element is slightly posterior to the appearance of the first MyoD1 and myogenin transcripts, concomitant with the appearance of cardiac alpha-actin transcripts, but clearly precedes the accumulation of myosin light-chain 1a transcripts and the appearance of troponin T-positive cells. These results further establish that CArG boxes can be seen as muscle-specific cis-acting regulatory element prior to terminal differentiation.
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PMID:Activation of gene expression via CArG boxes during myogenic differentiation. 845 94