Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA-binding proteins containing the basic helix-loop-helix (bHLH) domain have been implicated in lineage determination and the regulation of specific gene expression in a number of cell types. By oligonucleotide screening of an adipocyte cDNA expression library, we have identified a novel member of the bHLH-leucine zipper transcription factor family designated ADD1. ADD1 mRNA is expressed predominantly in brown adipose tissue in vivo and is regulated during both determination and differentiation of cultured adipocyte cell lines. ADD1 can function as a sequence-specific transcriptional activator in that it stimulates expression of a chloramphenicol acetyltransferase vector containing multiple ADD1 binding sequences but is unable to activate the myosin light-chain enhancer, which contains multiple binding sites for another bHLH factor, MyoD. ADD1 can also activate transcription through a binding site present in the 5'-flanking region of the fatty acid synthetase gene which is expressed in a differentiation-dependent manner in adipose cells. These data suggest that ADD1 plays a role in the regulation of determination- and differentiation-specific gene expression in adipocytes.
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PMID:ADD1: a novel helix-loop-helix transcription factor associated with adipocyte determination and differentiation. 833 13

ADD1 is a recently identified basic helix-loop-helix leucine zipper-type transcription factor that acts as a positive regulator of adipocyte-specific gene expression. Since adipocytes may share their precursor with osteoblasts, we examined the expression of ADD1 mRNA in osteoblast-like cells. In osteoblastic MC3T3-E1 cells, the level of the ADD1 mRNA expression was low at the early period of cultures while it subsequently increased with time up to more than 10-fold in the later period of cultures along with the expression of alkaline phosphatase, a differentiation marker of these cells. In ROS17/2.8 cells, which represent mature osteoblasts, ADD1 mRNA was expressed constitutively. Treatment with retinoic acid (RA) enhanced the ADD1 mRNA expression several fold in these cells within 4 h in a dose-dependent manner. This RA effect on the ADD1 mRNA expression was blocked by dichloro-D-ribofuranosylbenzimidazole but not by cycloheximide. RA treatment did not affect the ADD1 mRNA stability, suggesting the involvement of transcriptional control. Electrophoretic mobility shift assay revealed that proteins in the crude nuclear extracts prepared from ROS17/2.8 cells were bound to the E box-containing ADD1 recognition DNA sequence, E/C, and that this binding activity was enhanced by the RA treatment. Neither the E2A protein recognition sequence nor the Myo-D/E12 recognition sequence competed against the E/C sequence for the binding, indicating the sequence specificity of the binding activity. Furthermore, RA treatment enhanced the transactivation activity of the chloramphenicol acetyltransferase construct containing the E/C sequence in the transient transfection assay in ROS17/2.8 cells. RA treatment also enhanced the ADD1 mRNA expression in another rat calvaria-derived cell line, RCT1, and in the primary cultures of newborn rat calvaria cells. Overexpression of ADD1 in ROS17/2.8 enhanced the level of the osteocalcin mRNA expression. These results indicated that the adipogenic basic helix-loop-helix leucine zipper-type transcription factor (ADD1) mRNA was expressed in osteoblastic cells and that its expression was associated with the expression of an osteoblastic phenotype-related gene.
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PMID:An adipogenic basic helix-loop-helix-leucine zipper type transcription factor (ADD1) mRNA is expressed and regulated by retinoic acid in osteoblastic cells. 912 91