Cell type- and differentiation-dependent expression from the mouse acetylcholine receptor epsilon-subunit promoter.
The nicotinic acetylcholine receptor (AChR) in adult skeletal muscle is composed of alpha-, beta-, epsilon-, and delta-subunits and is localized at the neuromuscular junction; in contrast, the more diffusely distributed fetal form is composed of alpha-, beta-, gamma-, and delta-subunits. To define sequences necessary for the transcriptional regulation of the mouse epsilon-subunit gene, we sequenced and analyzed 1036 bp upstream of the transcription start site. Using deletion analysis of the 5'-flanking region linked to the bacterial chloramphenicol acetyltransferase (CAT) gene and transfection of the resulting constructs into established cell lines, we demonstrate that a 151 bp fragment exhibits cell type- and differentiation-specific promoter activity. This activity was independent of a myogenic factor putative binding site (E-box). However, transactivation experiments with recombinant myoD, myogenin, or MRF4 showed that the E-box was functional and that MRF4 preferentially transactivates the epsilon-promoter. Thus, like other AChR promoters, the proximal region of the epsilon-promoter contains information for cell type-specific and developmental regulation of CAT and can be transactivated by myogenic factors in cultured cell lines. Unlike the other AChR promoters characterized to date, epsilon-promoter function can be partially independent of myogenic factors of the helix-loop-helix class.
Sunyer
T
T
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri.
Merlie
J P
JP
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D015870:Gene Expression; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology / Q000378:metabolism; D009154:Mutation; D009469:Neuromuscular Junction / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011950:Receptors, Cholinergic / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
D011950:Receptors, Cholinergic; D004247:DNA