scholarly journals AKAP13 couples GPCR signaling to mTORC1 inhibition

PLoS Genetics ◽  
2021 ◽  
Vol 17 (10) ◽  
pp. e1009832
Author(s):  
Shihai Zhang ◽  
Huanyu Wang ◽  
Chase H. Melick ◽  
Mi-Hyeon Jeong ◽  
Adna Curukovic ◽  
...  
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
Human Diseases ◽  
Gpcr Signaling ◽  
Anchoring Protein ◽  
Lung Adenocarcinoma Patient ◽  
Important Player ◽  
Cancer Tumor ◽  
Mtorc1 Activation ◽  
G Protein Coupled

The mammalian target of rapamycin complex 1 (mTORC1) senses multiple stimuli to regulate anabolic and catabolic processes. mTORC1 is typically hyperactivated in multiple human diseases such as cancer and type 2 diabetes. Extensive research has focused on signaling pathways that can activate mTORC1 such as growth factors and amino acids. However, less is known about signaling cues that can directly inhibit mTORC1 activity. Here, we identify A-kinase anchoring protein 13 (AKAP13) as an mTORC1 binding protein, and a crucial regulator of mTORC1 inhibition by G-protein coupled receptor (GPCR) signaling. GPCRs paired to Gαs proteins increase cyclic adenosine 3’5’ monophosphate (cAMP) to activate protein kinase A (PKA). Mechanistically, AKAP13 acts as a scaffold for PKA and mTORC1, where PKA inhibits mTORC1 through the phosphorylation of Raptor on Ser 791. Importantly, AKAP13 mediates mTORC1-induced cell proliferation, cell size, and colony formation. AKAP13 expression correlates with mTORC1 activation and overall lung adenocarcinoma patient survival, as well as lung cancer tumor growth in vivo. Our study identifies AKAP13 as an important player in mTORC1 inhibition by GPCRs, and targeting this pathway may be beneficial for human diseases with hyperactivated mTORC1.

scholarly journals Leucyl-tRNA Synthetase Deficiency Systemically Induces Excessive Autophagy in Zebrafish

2021 ◽  
Author(s):  
Hiroshi Shiraishi ◽  
Nobuyuki Shimizu ◽  
Mika Tsumori ◽  
Kyoko Kiyota ◽  
Miwako Maeda ◽  
...  
Keyword(s):  
Liver Failure ◽  
Mammalian Target Of Rapamycin ◽  
Trna Synthetase ◽  
Biallelic Mutation ◽  
Synthetase Deficiency ◽  
Morpholino Knockdown ◽  
Mtorc1 Activation ◽  
Early Lethality

Abstract Leucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tRNA. LARS is also essential to sensitize the intracellular leucine concentration to the mammalian target of rapamycin complex 1 (mTORC1) activation. Biallelic mutation in the LARS gene causes infantile liver failure syndrome type 1 (ILFS1), which is characterized by acute liver failure, anaemia, and neurological disorders, including microcephaly and seizures. However, the molecular mechanism underlying ILFS1 under LARS deficiency has been elusive. Here, we generated Lars deficient (larsb-/-) zebrafish that showed progressive liver failure and anaemia, resulting in early lethality within 12 days post fertilization. The atg5-morpholino knockdown and bafilomycin treatment partially improved the size of the liver and survival rate in larsb-/- zebrafish. These findings indicate the involvement of autophagy in the pathogenesis of larsb-/- zebrafish. Indeed, excessive autophagy activation was observed in larsb-/- zebrafish. Therefore, our data clarify a mechanistic link between LARS and autophagy in vivo. Furthermore, autophagy regulation by LARS could lead to development of new therapeutics for IFLS1.

scholarly journals Rescue of defective G protein–coupled receptor function in vivo by intermolecular cooperation

2010 ◽  
Vol 107 (5) ◽  
pp. 2319-2324 ◽  
Author(s):  
Adolfo Rivero-Müller ◽  
Yen-Yin Chou ◽  
Inhae Ji ◽  
Svetlana Lajic ◽  
Aylin C. Hanyaloglu ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Luteinizing Hormone Receptor ◽  
Wild Type ◽  
Gpcr Signaling ◽  
Physiological Relevance ◽  
Biosynthesis Activation ◽  
Mutant Receptors ◽  
G Protein Coupled

G protein–coupled receptors (GPCRs) are ubiquitous mediators of signaling of hormones, neurotransmitters, and sensing. The old dogma is that a one ligand/one receptor complex constitutes the functional unit of GPCR signaling. However, there is mounting evidence that some GPCRs form dimers or oligomers during their biosynthesis, activation, inactivation, and/or internalization. This evidence has been obtained exclusively from cell culture experiments, and proof for the physiological significance of GPCR di/oligomerization in vivo is still missing. Using the mouse luteinizing hormone receptor (LHR) as a model GPCR, we demonstrate that transgenic mice coexpressing binding-deficient and signaling-deficient forms of LHR can reestablish normal LH actions through intermolecular functional complementation of the mutant receptors in the absence of functional wild-type receptors. These results provide compelling in vivo evidence for the physiological relevance of intermolecular cooperation in GPCR signaling.

scholarly journals A-Kinase Anchoring Protein 1: Emerging Roles in Regulating Mitochondrial Form and Function in Health and Disease

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 298 ◽  
Author(s):  
Yujia Liu ◽  
Ronald A. Merrill ◽  
Stefan Strack
Keyword(s):  
Cell Survival ◽  
Intracellular Signaling ◽  
Neuronal Cell ◽  
Supporting Cell ◽  
In Vivo Studies ◽  
Form And Function ◽  
Anchoring Protein ◽  
Cancer Tumor ◽  
And Function

Best known as the powerhouse of the cell, mitochondria have many other important functions such as buffering intracellular calcium and reactive oxygen species levels, initiating apoptosis and supporting cell proliferation and survival. Mitochondria are also dynamic organelles that are constantly undergoing fission and fusion to meet specific functional needs. These processes and functions are regulated by intracellular signaling at the mitochondria. A-kinase anchoring protein 1 (AKAP1) is a scaffold protein that recruits protein kinase A (PKA), other signaling proteins, as well as RNA to the outer mitochondrial membrane. Hence, AKAP1 can be considered a mitochondrial signaling hub. In this review, we discuss what is currently known about AKAP1′s function in health and diseases. We focus on the recent literature on AKAP1′s roles in metabolic homeostasis, cancer and cardiovascular and neurodegenerative diseases. In healthy tissues, AKAP1 has been shown to be important for driving mitochondrial respiration during exercise and for mitochondrial DNA replication and quality control. Several recent in vivo studies using AKAP1 knockout mice have elucidated the role of AKAP1 in supporting cardiovascular, lung and neuronal cell survival in the stressful post-ischemic environment. In addition, we discuss the unique involvement of AKAP1 in cancer tumor growth, metastasis and resistance to chemotherapy. Collectively, the data indicate that AKAP1 promotes cell survival throug regulating mitochondrial form and function. Lastly, we discuss the potential of targeting of AKAP1 for therapy of various disorders.

Cardiac hypertrophy and altered β-adrenergic signaling in transgenic mice that express the amino terminus of β-ARK1

2003 ◽  
Vol 285 (5) ◽  
pp. H2201-H2211 ◽  
Author(s):  
Janelle R. Keys ◽  
Emily A. Greene ◽  
Chris J. Cooper ◽  
Sathyamangla V. Naga Prasad ◽  
Howard A. Rockman ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Cardiac Hypertrophy ◽  
Protein Interactions ◽  
Amino Terminus ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Gpcr Signaling ◽  
Amino Terminal ◽  
G Protein Coupled

The G protein-coupled receptor (GPCR) kinase β-adrenergic receptor (β-AR) kinase-1 (β-ARK1) is elevated during heart failure; however, its role is not fully understood. β-ARK1 contains several domains that are capable of protein-protein interactions that may play critical roles in the regulation of GPCR signaling. In this study, we developed a novel line of transgenic mice that express an amino-terminal peptide of β-ARK1 that is comprised of amino acid residues 50–145 (β-ARKnt) in the heart to determine whether this domain has any functional significance in vivo. Surprisingly, the β-ARKnt transgenic mice presented with cardiac hypertrophy. Our data suggest that the phenotype was driven via an enhanced β-AR system, as β-ARKnt mice had elevated cardiac β-AR density. Moreover, administration of a β-AR antagonist reversed hypertrophy in these mice. Interestingly, signaling through the β-AR in response to agonist stimulation was not enhanced in these mice. Thus the amino terminus of β-ARK1 appears to be critical for normal β-AR regulation in vivo, which further supports the hypothesis that β-ARK1 plays a key role in normal and compromised cardiac GPCR signaling.

scholarly journals Sphingosine 1-phosphate-regulated transcriptomes in heterogenous arterial and lymphatic endothelium of the aorta

2019 ◽  
Author(s):  
Eric Engelbrecht ◽  
Michel V. Levesque ◽  
Liqun He ◽  
Michael Vanlandewijck ◽  
Anja Nitzsche ◽  
...  
Keyword(s):  
Cellular Heterogeneity ◽  
Dependent Manner ◽  
Branch Points ◽  
Transcriptional Responses ◽  
Gpcr Signaling ◽  
Aortic Endothelial Cells ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

AbstractDespite the medical importance of G protein-coupled receptors (GPCRs), in vivo cellular heterogeneity of GPCR signaling and downstream transcriptional responses are not understood. We report the comprehensive characterization of transcriptomes (bulk and single-cell) and chromatin domains regulated by sphingosine 1-phosphate receptor-1 (S1PR1) in adult mouse aortic endothelial cells. First, S1PR1 regulates NFkB and nuclear glucocorticoid receptor pathways to suppress inflammation-related mRNAs. Second, spatially distinct S1PR1 signaling in the aorta is associated with heterogenous endothelial cell (EC) subtypes. For example, a transcriptomically distinct arterial EC population at vascular branch points (aEC1) exhibits ligand- independent S1PR1/ß-arrestin coupling. In contrast, circulatory S1P-dependent S1PR1/ß-arrestin coupling was observed in non-branch point aEC2 cells that exhibit an inflammatory signature. Moreover, an adventitial lymphatic EC (LEC) population shows suppression of lymphangiogenic and inflammation-related transcripts in a S1P/S1PR1-dependent manner. These insights add resolution to existing concepts of GPCR signaling and S1P biology.

G-protein-coupled designer receptors – new chemical-genetic tools for signal transduction research

2013 ◽  
Vol 394 (12) ◽  
pp. 1615-1622 ◽  
Author(s):  
Gerald Thiel ◽  
Anke Kaufmann ◽  
Oliver G. Rössler
Keyword(s):  
Signal Transduction ◽  
Signaling Pathway ◽  
G Protein ◽  
Membrane Receptors ◽  
Designer Drugs ◽  
Gpcr Signaling ◽  
Chemical Genetic ◽  
G Protein Coupled

Abstract G-protein-coupled receptors (GPCRs) are the largest group of plasma membrane receptors in nature and are activated by a variety of different ligands. The biological outcome of GPCR stimulation is complex, as a plethora of signaling pathways are activated upon stimulation. These complexity and diversity of GPCR signaling make it difficult to manipulate the signaling pathway of a specific GPCR by natural ligands. To reduce the complexity in experimental settings, specific pharmacological ligands that preferentially activate one signaling pathway have been developed. In addition, G-protein-coupled designer receptors that are unresponsive to endogenous ligands but can be activated by otherwise pharmacologically inert compounds have been designed. These receptors have been termed designer receptors exclusively activated by designer drugs. The lack of constitutive activity of these designer receptors allows their use for in vitro and in vivo studies of GPCR-mediated signal transduction. The analysis of recently generated transgenic mice showed that the expression of G-protein-coupled designer receptors represents a powerful chemical-genetic tool to investigate GPCR signaling and function.

scholarly journals Cortical astrocytes independently regulate sleep depth and duration via separate GPCR pathways

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Trisha V Vaidyanathan ◽  
Max Collard ◽  
Sae Yokoyama ◽  
Michael E Reitman ◽  
Kira E Poskanzer
Keyword(s):  
Neuronal Activity ◽  
Population Level ◽  
Nrem Sleep ◽  
Gpcr Signaling ◽  
Natural Sleep ◽  
Electrophysiological Activity ◽  
Sleep Depth ◽  
Cortical Astrocyte ◽  
G Protein Coupled

Non-rapid eye movement (NREM) sleep, characterized by slow-wave electrophysiological activity, underlies several critical functions, including learning and memory. However, NREM sleep is heterogeneous, varying in duration, depth, and spatially across the cortex. While these NREM sleep features are thought to be largely independently regulated, there is also evidence that they are mechanistically coupled. To investigate how cortical NREM sleep features are controlled, we examined the astrocytic network, comprising a cortex-wide syncytium that influences population-level neuronal activity. We quantified endogenous astrocyte activity in mice over natural sleep and wake, then manipulated specific astrocytic G-protein-coupled receptor (GPCR) signaling pathways in vivo. We find that astrocytic Gi- and Gq-coupled GPCR signaling separately control NREM sleep depth and duration, respectively, and that astrocytic signaling causes differential changes in local and remote cortex. These data support a model in which the cortical astrocyte network serves as a hub for regulating distinct NREM sleep features.

scholarly journals Leucyl-tRNA synthetase deficiency systemically induces excessive autophagy in zebrafish

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masanori Inoue ◽  
Hiroaki Miyahara ◽  
Hiroshi Shiraishi ◽  
Nobuyuki Shimizu ◽  
Mika Tsumori ◽  
...  
Keyword(s):  
Liver Failure ◽  
Mammalian Target Of Rapamycin ◽  
Trna Synthetase ◽  
Biallelic Mutation ◽  
Synthetase Deficiency ◽  
Morpholino Knockdown ◽  
Mtorc1 Activation ◽  
Early Lethality

AbstractLeucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tRNA. LARS is also essential to sensitize the intracellular leucine concentration to the mammalian target of rapamycin complex 1 (mTORC1) activation. Biallelic mutation in the LARS gene causes infantile liver failure syndrome type 1 (ILFS1), which is characterized by acute liver failure, anaemia, and neurological disorders, including microcephaly and seizures. However, the molecular mechanism underlying ILFS1 under LARS deficiency has been elusive. Here, we generated Lars deficient (larsb−/−) zebrafish that showed progressive liver failure and anaemia, resulting in early lethality within 12 days post fertilization. The atg5-morpholino knockdown and bafilomycin treatment partially improved the size of the liver and survival rate in larsb−/− zebrafish. These findings indicate the involvement of autophagy in the pathogenesis of larsb−/− zebrafish. Indeed, excessive autophagy activation was observed in larsb−/− zebrafish. Therefore, our data clarify a mechanistic link between LARS and autophagy in vivo. Furthermore, autophagy regulation by LARS could lead to development of new therapeutics for IFLS1.

scholarly journals A Physiologically Required G Protein-coupled Receptor (GPCR)-Regulator of G Protein Signaling (RGS) Interaction That Compartmentalizes RGS Activity

2013 ◽  
Vol 288 (38) ◽  
pp. 27327-27342 ◽  
Author(s):  
Wayne Croft ◽  
Claire Hill ◽  
Eilish McCann ◽  
Michael Bond ◽  
Manuel Esparza-Franco ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Signaling ◽  
Rgs Proteins ◽  
Protein Signaling ◽  
Gpcr Signaling ◽  
Additional Layer ◽  
Physiological Relevance ◽  
Gtpase Cycle ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) can interact with regulator of G protein signaling (RGS) proteins. However, the effects of such interactions on signal transduction and their physiological relevance have been largely undetermined. Ligand-bound GPCRs initiate by promoting exchange of GDP for GTP on the Gα subunit of heterotrimeric G proteins. Signaling is terminated by hydrolysis of GTP to GDP through intrinsic GTPase activity of the Gα subunit, a reaction catalyzed by RGS proteins. Using yeast as a tool to study GPCR signaling in isolation, we define an interaction between the cognate GPCR (Mam2) and RGS (Rgs1), mapping the interaction domains. This reaction tethers Rgs1 at the plasma membrane and is essential for physiological signaling response. In vivo quantitative data inform the development of a kinetic model of the GTPase cycle, which extends previous attempts by including GPCR-RGS interactions. In vivo and in silico data confirm that GPCR-RGS interactions can impose an additional layer of regulation through mediating RGS subcellular localization to compartmentalize RGS activity within a cell, thus highlighting their importance as potential targets to modulate GPCR signaling pathways.

scholarly journals In vivo brain GPCR signaling elucidated by phosphoproteomics

Science ◽  
2018 ◽  
Vol 360 (6395) ◽  
pp. eaao4927 ◽  
Author(s):  
Jeffrey J. Liu ◽  
Kirti Sharma ◽  
Luca Zangrandi ◽  
Chongguang Chen ◽  
Sean J. Humphrey ◽  
...  
Keyword(s):  
High Throughput ◽  
Behavioral Outcomes ◽  
Brain Regions ◽  
Kappa Opioid Receptor ◽  
General Strategy ◽  
Mtor Inhibition ◽  
Gpcr Signaling ◽  
Systems View ◽  
G Protein Coupled

A systems view of G protein–coupled receptor (GPCR) signaling in its native environment is central to the development of GPCR therapeutics with fewer side effects. Using the kappa opioid receptor (KOR) as a model, we employed high-throughput phosphoproteomics to investigate signaling induced by structurally diverse agonists in five mouse brain regions. Quantification of 50,000 different phosphosites provided a systems view of KOR in vivo signaling, revealing novel mechanisms of drug action. Thus, we discovered enrichment of the mechanistic target of rapamycin (mTOR) pathway by U-50,488H, an agonist causing aversion, which is a typical KOR-mediated side effect. Consequently, mTOR inhibition during KOR activation abolished aversion while preserving beneficial antinociceptive and anticonvulsant effects. Our results establish high-throughput phosphoproteomics as a general strategy to investigate GPCR in vivo signaling, enabling prediction and modulation of behavioral outcomes.

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