Depletion of Gprc5a Promotes Development of Diabetic Nephropathy

Background Renal glomeruli are the primary target of injury in diabetic nephropathy (DN), and the glomerular podocyte has a key role in disease progression.Methods To identify potential novel therapeutic targets for DN, we performed high-throughput molecular profiling of G protein–coupled receptors (GPCRs) using human glomeruli.Results We identified an orphan GPCR, Gprc5a, as a highly podocyte-specific gene, the expression of which was significantly downregulated in glomeruli of patients with DN compared with those without DN. Inactivation of Gprc5a in mice resulted in thickening of the glomerular basement membrane and activation of mesangial cells, which are two hallmark features of DN in humans. Compared with wild-type mice, Gprc5a-deficient animals demonstrated increased albuminuria and more severe histologic changes after induction of diabetes with streptozotocin. Mechanistically, Gprc5a modulated TGF-β signaling and activation of the EGF receptor in cultured podocytes.Conclusions Gprc5a has an important role in the pathogenesis of DN, and further study of the podocyte-specific signaling activity of this protein is warranted.

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0906695106 ◽

2010 ◽

Vol 107 (5) ◽

pp. 2319-2324 ◽

Cited By ~ 141

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.

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Melatonin promotes sleep by activating the BK channel in C. elegans

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2010928117 ◽

2020 ◽

Vol 117 (40) ◽

pp. 25128-25137

Author(s):

Longgang Niu ◽

Yan Li ◽

Pengyu Zong ◽

Ping Liu ◽

Yuan Shui ◽

...

Keyword(s):

G Protein ◽

Neurotransmitter Release ◽

Expression System ◽

Molecular Target ◽

Bk Channel ◽

G Protein Coupled Receptors ◽

Wild Type ◽

Heterologous Expression System ◽

C Elegans ◽

G Protein Coupled

Melatonin (Mel) promotes sleep through G protein-coupled receptors. However, the downstream molecular target(s) is unknown. We identified the Caenorhabditis elegans BK channel SLO-1 as a molecular target of the Mel receptor PCDR-1-. Knockout of pcdr-1, slo-1, or homt-1 (a gene required for Mel synthesis) causes substantially increased neurotransmitter release and shortened sleep duration, and these effects are nonadditive in double knockouts. Exogenous Mel inhibits neurotransmitter release and promotes sleep in wild-type (WT) but not pcdr-1 and slo-1 mutants. In a heterologous expression system, Mel activates the human BK channel (hSlo1) in a membrane-delimited manner in the presence of the Mel receptor MT1 but not MT2. A peptide acting to release free Gβγ also activates hSlo1 in a MT1-dependent and membrane-delimited manner, whereas a Gβλ inhibitor abolishes the stimulating effect of Mel. Our results suggest that Mel promotes sleep by activating the BK channel through a specific Mel receptor and Gβλ.

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The metalloprotease Kuzbanian (ADAM10) mediates the transactivation of EGF receptor by G protein–coupled receptors

The Journal of Cell Biology ◽

10.1083/jcb.200112026 ◽

2002 ◽

Vol 158 (2) ◽

pp. 221-226 ◽

Cited By ~ 218

Author(s):

Yibing Yan ◽

Kyoko Shirakabe ◽

Zena Werb

Keyword(s):

Signaling Pathways ◽

G Protein ◽

Egf Receptor ◽

Critical Role ◽

G Protein Coupled Receptors ◽

Heparin Binding ◽

Egf Receptors ◽

Gpcr Activation ◽

G Protein Coupled ◽

Stimulation Of

Communication between different signaling pathways enables cells to coordinate the responses to diverse environmental signals. Activation of the transmembrane growth factor precursors plays a critical role in this communication and often involves metalloprotease-mediated proteolysis. Stimulation of G protein–coupled receptors (GPCR) transactivates the EGF receptors (EGFRs), which occurs via a metalloprotease-dependent cleavage of heparin-binding EGF (HB-EGF). However, the metalloprotease mediating the transactivation remains elusive. We show that the integral membrane metalloprotease Kuzbanian (KUZ; ADAM10), which controls Notch signaling in Drosophila, stimulates GPCR transactivation of EGFR. Upon stimulation of the bombesin receptors, KUZ increases the docking and activation of adaptors Src homology 2 domain–containing protein and Gab1 on the EGFR, and activation of Ras and Erk. In contrast, transfection of a protease domain–deleted KUZ, or blocking endogenous KUZ by morpholino antisense oligonucleotides, suppresses the transactivation. The effect of KUZ on shedding of HB-EGF and consequent transactivation of the EGFR depends on its metalloprotease activity. GPCR activation enhances the association of KUZ and its substrate HB-EGF with tetraspanin CD9. Thus, KUZ regulates the relay between the GPCR and EGFR signaling pathways.

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β-Arrestin–Dependent Endocytosis of Proteinase-Activated Receptor 2 Is Required for Intracellular Targeting of Activated Erk1/2

The Journal of Cell Biology ◽

10.1083/jcb.148.6.1267 ◽

2000 ◽

Vol 148 (6) ◽

pp. 1267-1282 ◽

Cited By ~ 571

Author(s):

K.A. DeFea ◽

J. Zalevsky ◽

M.S. Thoma ◽

O. Déry ◽

R.D. Mullins ◽

...

Keyword(s):

Gel Filtration ◽

G Protein Coupled Receptors ◽

Wild Type ◽

Signaling Complex ◽

Intracellular Targeting ◽

Extracellular Signal ◽

Mitogenic Potential ◽

Erk Activity ◽

G Protein Coupled ◽

Dependent Pathway

Recently, a requirement for β-arrestin–mediated endocytosis in the activation of extracellular signal–regulated kinases 1 and 2 (ERK1/2) by several G protein–coupled receptors (GPCRs) has been proposed. However, the importance of this requirement for function of ERK1/2 is unknown. We report that agonists of Gαq-coupled proteinase–activated receptor 2 (PAR2) stimulate formation of a multiprotein signaling complex, as detected by gel filtration, immunoprecipitation and immunofluorescence. The complex, which contains internalized receptor, β-arrestin, raf-1, and activated ERK, is required for ERK1/2 activation. However, ERK1/2 activity is retained in the cytosol and neither translocates to the nucleus nor causes proliferation. In contrast, a mutant PAR2 (PAR2δST363/6A), which is unable to interact with β-arrestin and, thus, does not desensitize or internalize, activates ERK1/2 by a distinct pathway, and fails to promote both complex formation and cytosolic retention of the activated ERK1/2. Whereas wild-type PAR2 activates ERK1/2 by a PKC-dependent and probably a ras-independent pathway, PAR2(δST363/6A) appears to activate ERK1/2 by a ras-dependent pathway, resulting in increased cell proliferation. Thus, formation of a signaling complex comprising PAR2, β-arrestin, raf-1, and activated ERK1/2 might ensure appropriate subcellular localization of PAR2-mediated ERK activity, and thereby determine the mitogenic potential of receptor agonists.

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Selective Modulation of Wild Type Receptor Functions by Mutants of G-Protein-coupled Receptors

Journal of Biological Chemistry ◽

10.1074/jbc.274.18.12548 ◽

1999 ◽

Vol 274 (18) ◽

pp. 12548-12554 ◽

Cited By ~ 39

Author(s):

Christian Le Gouill ◽

Jean-Luc Parent ◽

Carolyn-Ann Caron ◽

Rémi Gaudreau ◽

Léonid Volkov ◽

...

Keyword(s):

G Protein ◽

G Protein Coupled Receptors ◽

Wild Type ◽

Selective Modulation ◽

G Protein Coupled ◽

Type Receptor

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ADAMs as mediators of EGF receptor transactivation by G protein-coupled receptors

AJP Cell Physiology ◽

10.1152/ajpcell.00620.2005 ◽

2006 ◽

Vol 291 (1) ◽

pp. C1-C10 ◽

Cited By ~ 235

Author(s):

Haruhiko Ohtsu ◽

Peter J. Dempsey ◽

Satoru Eguchi

Keyword(s):

G Protein ◽

Egf Receptor ◽

Current Knowledge ◽

G Protein Coupled Receptors ◽

Surface Proteins ◽

Egf Receptors ◽

Cellular Functions ◽

Egfr Transactivation ◽

And Migration ◽

G Protein Coupled

A disintegrin and metalloprotease (ADAM) is a membrane-anchored metalloprotease implicated in the ectodomain shedding of cell surface proteins, including the ligands for epidermal growth factor (EGF) receptors (EGFR)/ErbB. It has been well documented that the transactivation of the EGFR plays critical roles for many cellular functions, such as proliferation and migration mediated through multiple G protein-coupled receptors (GPCRs). Recent accumulating evidence has suggested that ADAMs are the key metalloproteases activated by several GPCR agonists to produce a mature EGFR ligand leading to the EGFR transactivation. In this review, we describe the current knowledge on ADAMs implicated in mediating EGFR transactivation. The major focus of the review will be on the possible upstream mechanisms of ADAM activation by GPCRs as well as downstream signal transduction and the pathophysiological significances of ADAM-dependent EGFR transactivation.

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