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Your search keyword '"Maria Hauge Pedersen"' showing total 3 results
Start Over Author "Maria Hauge Pedersen" Publisher elsevier
3 results on '"Maria Hauge Pedersen"'

1. Free fatty acid receptor 1 stimulates cAMP production and gut hormone secretion through Gq-mediated activation of adenylate cyclase 2

Author

Jacob Emil Petersen, Maria Hauge Pedersen, Oksana Dmytriyeva, Emilie Nellemose, Tulika Arora, Maja Storm Engelstoft, Wesley B. Asher, Jonathan A. Javitch, Thue W. Schwartz, and Mette Trauelsen

Subjects
FFAR1, GPR40, Adenylate cyclase 2, GLP-1, ADCY2, Gq, Internal medicine, RC31-1245
Abstract

Objective: Free fatty acid receptor 1 (FFAR1) is highly expressed in enteroendocrine cells of the small intestine and pancreatic beta cells, where FFAR1 agonists function as GLP-1 and insulin secretagogues, respectively. Most efficacious are so-called second-generation synthetic agonists such as AM5262, which, in contrast to endogenous long-chain fatty acids are able to signal through both IP3/Ca2+ and cAMP pathways. Whereas IP3 signaling is to be expected for the mainly Gq-coupled FFAR1, the mechanism behind FFAR1-induced cAMP accumulation remains unclear, although originally proposed to be Gs mediated. Methods and results: When stimulated with AM5262, we observe that FFAR1 can activate the majority of the Gα proteins, except - surprisingly - members of the Gs family. AM5262-induced FFAR1-mediated transcriptional activation through cAMP response element (CREB) was blocked by the specific Gq inhibitor, YM253890. Furthermore, in Gq-deficient cells no CREB signal was observed unless Gq or G11 was reintroduced by transfection. By qPCR we determined that adenylate cyclase 2 (Adcy2) was highly expressed and enriched relative to the nine other Adcys in pro-glucagon expressing enteroendocrine cells. Co-transfection with ADCY2 increased the FFAR1-induced cAMP response 4-5-fold in WT HEK293 cells, an effect fully inhibited by YM253890. Moreover, co-transfection with ADCY2 had no effect in Gq-deficient cells without reintroduction of either Gq or G11. Importantly, although both AM5262/FFAR1 and isoproterenol/β2 adrenergic receptor (β2AR) induced cAMP production was lost in Gs-deficient cells, only the β2AR response was rescued by Gs transfection, whereas co-transfection with ADCY2 was required to rescue the FFAR1 cAMP response. In situ hybridization demonstrated a high degree of co-expression of ADCY2 and FFAR1 in enteroendocrine cells throughout the intestine. Finally, in the enteroendocrine STC-1 and GLUTag cell lines AM5262-induced cAMP accumulation and GLP-1 secretion were both blocked by YM253890. Conclusions: Our results show that Gq signaling is responsible not only for the IP3/Ca2+ but also the cAMP response, which together are required for the highly efficacious hormone secretion induced by second-generation FFAR1 agonists - and that ADCY2 presumably mediates the Gq-driven cAMP response.

Published
2023
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2. Encephalopathy-causing mutations in Gβ1 (GNB1) alter regulation of neuronal GIRK channels

Author

Tal Keren-Raifman, Sophie Colombo, Amal Kanti Bera, Daniel Yakubovich, Jonathan A. Javitch, Nathan Dascal, Galit Tabak, Haritha P. Reddy, David Goldstein, Vladimir Tsemakhovich, Boris Shalomov, and Maria Hauge Pedersen

Subjects
STRUCTURAL BASIS, CALCIUM-CHANNELS, BASAL ACTIVITY, Science, Molecular neuroscience, Gating, Neurotransmitter receptor, MOLECULAR-BASIS, Heterotrimeric G protein, CA2+ CHANNEL, G-PROTEIN MODULATION, G protein-coupled inwardly-rectifying potassium channel, Ion channel, Multidisciplinary, Inward-rectifier potassium ion channel, Chemistry, G-BETA-GAMMA, Cell biology, Biological sciences, ACTIVATED K+-CHANNEL, POTASSIUM CHANNEL, C-TERMINUS, GNB1, Neuroscience
Abstract

Mutations in the GNB1 gene, encoding the G beta(1) subunit of heterotrimeric G proteins, cause GNB1 Encephalopathy. Patients experience seizures, pointing to abnormal activity of ion channels or neurotransmitter receptors. We studied three G beta(1) mutations (K78R, I80N and I80T) using computational and functional approaches. In heterologous expression models, these mutations did not alter the coupling between G protein-coupled receptors to G(i/o), or the G beta gamma regulation of the neuronal voltage-gated Ca2+ channel Ca(V)2.2. However, the mutations profoundly affected the G beta gamma regulation of the G protein-gated inwardly rectifying potassium channels (GIRK, or Kir3). Changes were observed in G beta(1) protein expression levels, G beta gamma binding to cytosolic segments of GIRK subunits, and in G beta gamma function, and included gain-of-function for K78R or loss-of-function for I80T/N, which were GIRK subunit-specific. Our findings offer new insights into subunit-dependent gating of GIRKs by G beta gamma, and indicate diverse etiology of GNB1 Encephalopathy cases, bearing a potential for personalized treatment.

Published
2021

3. Assays for detecting arrestin interaction with GPCRs

Author

Wesley B. Asher, Nicole A. Perry-Hauser, Maria Hauge Pedersen, and Jonathan A. Javitch

Subjects
Cell signaling, genetic structures, G protein, Drug discovery, media_common.quotation_subject, Biology, Cell biology, Rhodopsin, Arrestin, biology.protein, sense organs, Internalization, Receptor, media_common, G protein-coupled receptor
Abstract

The four vertebrate arrestins play a key role in the desensitization and internalization of G protein-coupled receptors (GPCRs) and also mediate receptor-dependent signaling. Recent work has shown that bias for arrestin vs G protein signaling could offer certain therapeutic advantages (or disadvantages) in different systems, making assays that measure arrestin binding to receptors important for drug discovery efforts. Herein, we briefly review several commonly used techniques for measuring arrestin binding to receptors, as well as provide an in-depth and methodologically focused review of two methods that do not require receptor modification. The first approach measures direct binding between purified arrestin and rhodopsin, and the second measures the recruitment of arrestin to receptors in living cells.

Published
2021

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