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The C terminus of the L-type voltage-gated calcium channel Ca(V)1.2 encodes a transcription factor.

ABSTRACT: Voltage-gated calcium channels play a central role in regulating the electrical and biochemical properties of neurons and muscle cells. One of the ways in which calcium channels regulate long-lasting neuronal properties is by activating signaling pathways that control gene expression, but the mechanisms that link calcium channels to the nucleus are not well understood. We report that a C-terminal fragment of Ca(V)1.2, an L-type voltage-gated calcium channel (LTC), translocates to the nucleus and regulates transcription. We show that this calcium channel associated transcription regulator (CCAT) binds to a nuclear protein, associates with an endogenous promoter, and regulates the expression of a wide variety of endogenous genes important for neuronal signaling and excitability. The nuclear localization of CCAT is regulated both developmentally and by changes in intracellular calcium. These findings provide evidence that voltage-gated calcium channels can directly activate transcription and suggest a mechanism linking voltage-gated channels to the function and differentiation of excitable cells.

SUBMITTER: Gomez-Ospina N

PROVIDER: S-EPMC1750862 | biostudies-literature | 2006 Nov

REPOSITORIES: biostudies-literature

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The C terminus of the L-type voltage-gated calcium channel Ca(V)1.2 encodes a transcription factor.

Gomez-Ospina Natalia N Tsuruta Fuminori F Barreto-Chang Odmara O Hu Linda L Dolmetsch Ricardo R

Cell 20061101 3

Voltage-gated calcium channels play a central role in regulating the electrical and biochemical properties of neurons and muscle cells. One of the ways in which calcium channels regulate long-lasting neuronal properties is by activating signaling pathways that control gene expression, but the mechanisms that link calcium channels to the nucleus are not well understood. We report that a C-terminal fragment of Ca(V)1.2, an L-type voltage-gated calcium channel (LTC), translocates to the nucleus and ...[more]

PMID: 17081980

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Project description:Calcium homeostasis is critical for cardiac myocyte function and must be tightly regulated. The guiding hypothesis of this study is that a carboxyl-terminal cleavage product of the cardiac L-type calcium channel (Ca(V)1.2) autoregulates expression. First, we confirmed that the Ca(V)1.2 C terminus (CCt) is cleaved in murine cardiac myocytes from mature and developing ventricle. Overexpression of full-length CCt caused a 34+/-8% decrease of Ca(V)1.2 promoter activity, and truncated CCt caused an 80+/-3% decrease of Ca(V)1.2 promoter (n=12). The full-length CCt distributes into cytosol and nucleus. A deletion mutant of CCt has a greater relative affinity for the nucleus than full-length CCt, and this is consistent with increased repression of Ca(V)1.2 promoter activity by truncated CCt. Chromatin immunoprecipitation analysis revealed that CCt interacts with the Ca(V)1.2 promoter in adult ventricular cardiac myocytes at promoter modules containing Nkx2.5/Mef2, C/EBp, and a cis regulatory module. The next hypothesis tested was that CCt contributes to transcriptional signaling associated with cellular hypertrophy. We explored whether fetal cardiac myocyte Ca(V)1.2 was regulated by serum in vitro. We tested atrial natriuretic factor promoter activity as a positive control and measured the serum response of Ca(V)1.2 promoter, protein, and L-type current (I(Ca,L)) from fetal mouse ventricular myocytes. Serum increased atrial natriuretic factor promoter activity and cell size as expected. Serum withdrawal increased Ca(V)1.2 promoter activity, mRNA, and I(Ca,L). Moreover, serum withdrawal decreased the relative nuclear localization of CCt. A combination of promoter deletion mutant analyses, and the response of promoter mutants to serum withdrawal support the conclusion that CCt, a proteolytic fragment of Ca(V)1.2, autoregulates Ca(V)1.2 expression in cardiac myocytes. These data support the novel mechanism that a mobile segment of Ca(V)1.2 links Ca handling to nuclear signaling.

Dataset Information

The C terminus of the L-type voltage-gated calcium channel Ca(V)1.2 encodes a transcription factor.

Publications

The C terminus of the L-type voltage-gated calcium channel Ca(V)1.2 encodes a transcription factor.

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