title: Transcriptional regulation of T-type calcium channel CaV3.2: bi-directionality by early growth response 1 (Egr1) and repressor element 1 (RE-1) protein-silencing transcription factor (REST).
abstract: The pore-forming Ca(2+) channel subunit Ca(V)3.2 mediates a low voltage-activated (T-type) Ca(2+) current (I(CaT)) that contributes pivotally to neuronal and cardiac pacemaker activity. Despite the importance of tightly regulated Ca(V)3.2 levels, the mechanisms regulating its transcriptional dynamics are not well understood. Here, we have identified two key factors that up- and down-regulate the expression of the gene encoding Ca(V)3.2 (Cacna1h). First, we determined the promoter region and observed several stimulatory and inhibitory clusters. Furthermore, we found binding sites for the transcription factor early growth response 1 (Egr1/Zif268/Krox-24) to be highly overrepresented within the Ca(V)3.2 promoter region. mRNA expression analyses and dual-luciferase promoter assays revealed that the Ca(V)3.2 promoter was strongly activated by Egr1 overexpression in vitro and in vivo. Subsequent chromatin immunoprecipitation assays in NG108-15 cells and mouse hippocampi confirmed specific Egr1 binding to the Ca(V)3.2 promoter. Congruently, whole-cell I(CaT) values were significantly larger after Egr1 overexpression. Intriguingly, Egr1-induced activation of the Ca(V)3.2 promoter was effectively counteracted by the repressor element 1-silencing transcription factor (REST). Thus, Egr1 and REST can bi-directionally regulate Ca(V)3.2 promoter activity and mRNA expression and, hence, the size of I(CaT). This mechanism has critical implications for the regulation of neuronal and cardiac Ca(2+) homeostasis under physiological conditions and in episodic disorders such as arrhythmias and epilepsy.
authors.affiliation: Department of Neuropathology, University of Bonn Medical Center, D-53105 Bonn, Germany. karen.van_loo@ukb.uni-bonn.de
authors.forename: Karen M J
authors.initials: KM
authors.lastname: van Loo
authors.forename: Christina
authors.initials: C
authors.lastname: Schaub
authors.forename: Katharina
authors.initials: K
authors.lastname: Pernhorst
authors.forename: Yoel
authors.initials: Y
authors.lastname: Yaari
authors.forename: Heinz
authors.initials: H
authors.lastname: Beck
authors.forename: Susanne
authors.initials: S
authors.lastname: Schoch
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Becker
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001921:Brain / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000235:genetics* / Q000502:physiology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials; D051379:Mice; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014162:Transfection; D000099229:RE1-Silencing Transcription Factor
chemical_list: D020747:Calcium Channels, T-Type; D051766:Early Growth Response Protein 1; D012097:Repressor Proteins; D000099229:RE1-Silencing Transcription Factor; C479952:CACNA1H protein, human; C497325:EGR1 protein, human