Regulation and function of AP-1 in insulinoma cells and pancreatic β-cells.

Ca1.2 L-type voltage-gated Ca channels play a central role in pancreatic β-cells by integrating extracellular signals with intracellular signaling events leading to insulin secretion and altered gene transcription. Here, we investigated the intracellular signaling pathway following stimulation of Ca1.

Ternary complex factor regulates pancreatic islet size and blood glucose homeostasis in transgenic mice.

A hallmark of diabetes mellitus is the inability of pancreatic β-cells to secrete sufficient amounts of insulin for maintaining normoglycemia. The formation of smaller islets may underlie the development of a diabetic phenotype, as a decreased β-cell mass will produce an insufficient amount of insulin. For a pharmacological intervention it is crucial to identify the proteins determining β-cell mass.

Regulation of Gene Transcription Following Stimulation of Transient Receptor Potential (TRP) Channels.

Transient receptor potential (TRP) channels belong to a heterogeneous superfamily of cation channels that are involved in the regulation of numerous biological functions, including regulation of Ca and glucose homeostasis, tumorigenesis, temperature, and pain sensation. To understand the functions of TRP channels, their associated intracellular signaling pathways and molecular targets have to be identified on the cellular level. Stimulation of TRP channels frequently induces an influx of Ca ions into the cells and the subsequent activation of protein kinases.

Stimulation of transient receptor potential M3 (TRPM3) channels increases interleukin-8 gene promoter activity involving AP-1 and extracellular signal-regulated protein kinase.

Stimulation of Ca permeable TRPM3 (transient receptor potential melastatin-3) channels with the steroid ligand pregnenolone sulfate activates stimulus-responsive transcription factors, including the transcription factor AP-1 (activator protein-1). As part of a search for AP-1-regulated target genes we analyzed the gene encoding interleukin-8 (IL-8) in HEK293 cells expressing TRPM3 channels. Here, we show that stimulation of TRPM3 channels activated transcription of an IL-8 promoter-controlled reporter gene that was embedded into the chromatin of the cells.

Transient receptor potential TRPM3 channels: Pharmacology, signaling, and biological functions.

The transient receptor potential melastatin-3 (TRPM3) channel belongs to the family of transient receptor potential (TRP) cation channels that are expressed in a variety of tissues and cell types, including dorsal root ganglia, cardiomyocytes and pancreatic beta-cells. Although its natural ligands are currently unknown, TRPM3 channels can be activated by the neurosteroid pregnenolone sulfate, the synthetic ligand CIM0216, and by noxious heat. TRPM3 channels are regulated by phosphoinositides, and perhaps by calmodulin.

Extracellular Signal-Regulated Protein Kinase, c-Jun N-Terminal Protein Kinase, and Calcineurin Regulate Transient Receptor Potential M3 (TRPM3) Induced Activation of AP-1.

Stimulation of transient receptor potential M3 (TRPM3) cation channels with pregnenolone sulfate induces an influx of Ca ions into the cells and a rise in the intracellular Ca concentration, leading to the activation of the activator protein-1 (AP-1) transcription factor. Here, we show that expression of a constitutively active mutant of the Ca /calmodulin-dependent protein phosphatase calcineurin attenuated pregnenolone sulfate-induced AP-1 activation in TRPM3-expressing cells. Likewise, expression of the regulatory B subunit of calcineurin reduced AP-1 activity in the cells following stimulation of TRPM3 channels.

Combining fibroblast isolation with lentiviral gene transfer to validate transgene expression in mice following pronucleus injection.

The binary tetracycline-based expression system in transgenic mice relies on the expression of the tetracycline transactivator (tTA or rtTA) in a particular cell type together with a transcription unit encoding the gene of interest under a tetracycline or doxycycline-responsive promoter. Transgenic mice containing this transcription unit are produced via pronucleus injection. As the chromosomal integration site of the injected DNA influences transgene expression, several founder lines have to be crossed with (r)tTA-expressing mice to find a line showing low background and high transgene expression following doxycycline stimulation.

Transient receptor potential melastatin-3 (TRPM3)-induced activation of AP-1 requires Ca2+ ions and the transcription factors c-Jun, ATF2, and ternary complex factor.

The steroid pregnenolone sulfate activates the transcription factor activator protein-1 (AP-1) via stimulation of transient receptor potential melastatin-3 (TRPM3) channels. Here, we show that the signaling pathway requires an influx of Ca(2+) ions into the cells and a rise in the intracellular Ca(2+) levels. The upregulation of AP-1 was attenuated in cells that overexpressed mitogen activated protein kinase phosphatase-1, indicating that Ca(2+) ions prolong the signaling cascade via activation of mitogen activated protein kinases.

Activation and inhibition of transient receptor potential TRPM3-induced gene transcription.

Background And Purpose: Transient receptor potential-3 (TRPM3) channels function as Ca2+ permeable cation channels. While the natural ligands for these channels are still unknown, several compounds have been described that either activate or inhibit TRPM3 channel activity. experimental approach: We assessed TRPM3-mediated gene transcription, which relies on the induction of intracellular signalling to the nucleus following activation of TRPM3 channels.

Transcriptional response to calcium-sensing receptor stimulation.

Elevated extracellular Ca(2+) concentrations stimulate the G-protein coupled receptor calcium-sensing receptor. Here we show that this stimulation induces the expression of biologically active early growth response protein 1 (Egr-1), a zinc finger transcription factor. Expression of a dominant-negative mutant of the ternary complex factor Ets-like protein-1 (Elk-1), a key transcriptional regulator of serum response element-driven gene transcription, prevented Egr-1 expression, indicating that Elk-1 or related ternary complex factors connect the intracellular signaling cascade elicited by activation of calcium-sensing receptors with transcription of the Egr-1 gene.