Cloning and characterization of the promoters of the maxiK channel α and β subunits
| Autor: | Michael I. Kotlikoff, Prasad Dhulipala |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Potassium Channels
Large-Conductance Calcium-Activated Potassium Channel beta Subunits TATA box Molecular Sequence Data Biophysics Biology Biochemistry Cell Line Potassium Channels Calcium-Activated Structural Biology Transcription (biology) Genetics Transcriptional regulation Humans Large-Conductance Calcium-Activated Potassium Channels Cloning Molecular Binding site Large-Conductance Calcium-Activated Potassium Channel alpha Subunits Muscle Skeletal Promoter Regions Genetic Gene G alpha subunit Genomic Library Base Sequence Muscle Smooth Promoter Molecular biology biology.protein ATP synthase alpha/beta subunits |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression. 1444:254-262 |
| ISSN: | 0167-4781 |
| DOI: | 10.1016/s0167-4781(98)00276-0 |
| Popis: | Large conductance, calcium-activated potassium (maxiK) channels are expressed in nerve, muscle, and other cell types and are important determinants of smooth muscle tone. To determine the mechanisms involved in the transcriptional regulation of maxiK channels, we characterized the promoter regions of the pore forming (alpha) and regulatory (beta) subunits of the human channel complex. Maximum promoter activity (up to 12.3-fold over control) occurred between nucleotides -567 and -220 for the alpha subunit (hSlo) gene. The minimal promoter is GC-rich with 5 Sp-1 binding sites and several TCC repeats. Other transcription factor-binding motifs, including c/EBP, NF-kB, PU.1, PEA-3, Myo-D, and E2A, were observed in the 5'-flanking sequence. Additionally, a CCTCCC sequence, which increases the transcriptional activity of the SM1/2 gene in smooth muscle, is located 27 bp upstream of the TATA-like sequence, a location identical to that found in the SM1/2 5'-flanking region. However, the promoter directed equivalent expression when transfected into smooth muscle and other cell types. Analysis of the hSlo beta subunit 5'-flanking region revealed a TATA box at position -77 and maximum promoter activity (up to 11.0-fold) in a 200 bp region upstream from the cap site. Binding sites for GATA-1, Myo-D, c-myb, Ets-1/Elk-1, Ap-1, and Ik-2 were identified within this sequence. Two CCTCCC elements are present in the hSlo beta subunit promoter, but tissue-specific transcriptional activity was not observed. The lack of tissue-specific promoter activity, particularly the finding of promoter activity in cells from tissues in which the maxiK gene is not expressed, suggests a complex channel regulatory mechanism for hSlo genes. Moreover, the lack of similarity of the promoters of the two genes suggests that regulation of coordinate expression of the subunits does not occur through equivalent cis-acting sequences. |
| Databáze: | OpenAIRE |
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