G protein–coupled receptor Gpr115 (Adgrf4) is required for enamel mineralization mediated by ameloblasts

Dental enamel, the hardest tissue in the human body, is derived from dental epithelial cell ameloblast-secreted enamel matrices. Enamel mineralization occurs in a strictly synchronized manner along with ameloblast maturation in association with ion transport and pH balance, and any disruption of these processes results in enamel hypomineralization. G protein–coupled receptors (GPCRs) function as transducers of external signals by activating associated G proteins and regulate cellular physiology. Tissue-specific GPCRs play important roles in organ development, although their activities in tooth development remain poorly understood. The present results show that the adhesion GPCR Gpr115 (Adgrf4) is highly and preferentially expressed in mature ameloblasts and plays a crucial role during enamel mineralization. To investigate the in vivo function of Gpr115, knockout (Gpr115-KO) mice were created and found to develop hypomineralized enamel, with a larger acidic area because of the dysregulation of ion composition. Transcriptomic analysis also revealed that deletion of Gpr115 disrupted pH homeostasis and ion transport processes in enamel formation. In addition, in vitro analyses using the dental epithelial cell line cervical loop–derived dental epithelial (CLDE) cell demonstrated that Gpr115 is indispensable for the expression of carbonic anhydrase 6 (Car6), which has a critical role in enamel mineralization. Furthermore, an acidic condition induced Car6 expression under the regulation of Gpr115 in CLDE cells. Thus, we concluded that Gpr115 plays an important role in enamel mineralization via regulation of Car6 expression in ameloblasts. The present findings indicate a novel function of Gpr115 in ectodermal organ development and clarify the molecular mechanism of enamel formation.

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G-protein-coupled receptor kinase-2 is a critical regulator of TNFα signaling in colon epithelial cells

Biochemical Journal ◽

10.1042/bcj20170093 ◽

2017 ◽

Vol 474 (14) ◽

pp. 2301-2313 ◽

Cited By ~ 3

Author(s):

Michael D. Steury ◽

Peter C. Lucas ◽

Laura R. McCabe ◽

Narayanan Parameswaran

Keyword(s):

Wound Healing ◽

Epithelial Cell ◽

Epithelial Cells ◽

G Protein ◽

Critical Role ◽

Receptor Kinase ◽

G Protein Coupled Receptor ◽

G Protein Coupled

G-protein-coupled receptor kinase-2 (GRK2) belongs to the GRK family of serine/threonine protein kinases critical in the regulation of G-protein-coupled receptors. Apart from this canonical role, GRK2 is also involved in several signaling pathways via distinct intracellular interactomes. In the present study, we examined the role of GRK2 in TNFα signaling in colon epithelial cell–biological processes including wound healing, proliferation, apoptosis, and gene expression. Knockdown of GRK2 in the SW480 human colonic cells significantly enhanced TNFα-induced epithelial cell wound healing without any effect on apoptosis/proliferation. Consistent with wound-healing effects, GRK2 knockdown augmented TNFα-induced matrix metalloproteinases (MMPs) 7 and 9, as well as urokinase plasminogen activator (uPA; factors involved in cell migration and wound healing). To assess the mechanism by which GRK2 affects these physiological processes, we examined the role of GRK2 in TNFα-induced MAPK and NF-κB pathways. Our results demonstrate that while GRK2 knockdown inhibited TNFα-induced IκBα phosphorylation, activation of ERK was significantly enhanced in GRK2 knockdown cells. Our results further demonstrate that GRK2 inhibits TNFα-induced ERK activation by inhibiting generation of reactive oxygen species (ROS). Together, these data suggest that GRK2 plays a critical role in TNFα-induced wound healing by modulating MMP7 and 9 and uPA levels via the ROS–ERK pathway. Consistent with in vitro findings, GRK2 heterozygous mice exhibited enhanced intestinal wound healing. Together, our results identify a novel role for GRK2 in TNFα signaling in intestinal epithelial cells.

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Extracellular Acid-Base Balance and Ion Transport Between Body Fluid Compartments

Physiology ◽

10.1152/physiol.00007.2017 ◽

2017 ◽

Vol 32 (5) ◽

pp. 367-379 ◽

Cited By ~ 9

Author(s):

Julian L. Seifter ◽

Hsin-Yun Chang

Keyword(s):

Ion Transport ◽

Ph Regulation ◽

Extracellular Fluid ◽

Transport Processes ◽

Electrolyte Balance ◽

Ph Homeostasis ◽

Acid Base Balance ◽

Acid Base ◽

Base Balance ◽

Fluid Compartments

Clinical assessment of acid-base disorders depends on measurements made in the blood, part of the extracellular compartment. Yet much of the metabolic importance of these disorders concerns intracellular events. Intracellular and interstitial compartment acid-base balance is complex and heterogeneous. This review considers the determinants of the extracellular fluid pH related to the ion transport processes at the interface of cells and the interstitial fluid, and between epithelial cells lining the transcellular contents of the gastrointestinal and urinary tracts that open to the external environment. The generation of acid-base disorders and the associated disruption of electrolyte balance are considered in the context of these membrane transporters. This review suggests a process of internal and external balance for pH regulation, similar to that of potassium. The role of secretory gastrointestinal epithelia and renal epithelia with respect to normal pH homeostasis and clinical disorders are considered. Electroneutrality of electrolytes in the ECF is discussed in the context of reciprocal changes in Cl−or non Cl−anions and [Formula: see text].

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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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The G Protein‐coupled bile acid receptor, TGR5, is expressed on colonic epithelial cells and regulates ion transport

The FASEB Journal ◽

10.1096/fasebj.27.1_supplement.1162.10 ◽

2013 ◽

Vol 27 (S1) ◽

Author(s):

Joseph Bernard Jude Ward ◽

Magdalena Slawa Mróz ◽

Stephen J Keely

Keyword(s):

Bile Acid ◽

Epithelial Cells ◽

Ion Transport ◽

G Protein ◽

Colonic Epithelial Cells ◽

Acid Receptor ◽

Bile Acid Receptor ◽

G Protein Coupled

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Faculty Opinions recommendation of Bcl10 plays a critical role in NF-kappaB activation induced by G protein-coupled receptors.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1059041.511012 ◽

2007 ◽

Author(s):

Andrew Tobin

Keyword(s):

G Protein ◽

Critical Role ◽

G Protein Coupled Receptors ◽

Nf Kappab ◽

G Protein Coupled

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Abstract 3337: The G protein-coupled P2Y6pyrimidoceptor increases tumorigenesis potential of epithelial cell in colorectal cancer associated to colitis

10.1158/1538-7445.am2017-3337 ◽

2017 ◽

Author(s):

Morgane Placet ◽

Caroline M. Molle ◽

Djordje M. Grbic Grbic ◽

Guillaume Arguin ◽

Sameh Geha ◽

...

Keyword(s):

Colorectal Cancer ◽

Epithelial Cell ◽

G Protein ◽

G Protein Coupled

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Bcl10 plays a critical role in NF- B activation induced by G protein-coupled receptors

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0601894104 ◽

2006 ◽

Vol 104 (1) ◽

pp. 145-150 ◽

Cited By ~ 84

Author(s):

D. Wang ◽

Y. You ◽

P.-C. Lin ◽

L. Xue ◽

S. W. Morris ◽

...

Keyword(s):

G Protein ◽

Critical Role ◽

G Protein Coupled Receptors ◽

G Protein Coupled

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Inhibition of Ebola and Marburg Virus Entry by G Protein-Coupled Receptor Antagonists

Journal of Virology ◽

10.1128/jvi.01337-15 ◽

2015 ◽

Vol 89 (19) ◽

pp. 9932-9938 ◽

Cited By ~ 49

Author(s):

Han Cheng ◽

Calli M. Lear-Rooney ◽

Lisa Johansen ◽

Elizabeth Varhegyi ◽

Zheng W. Chen ◽

...

Keyword(s):

Antiviral Activity ◽

G Protein ◽

High Mortality ◽

Ebola Virus ◽

Critical Role ◽

Marburg Virus ◽

Severe Illness ◽

G Protein Coupled Receptor ◽

Chemical Library ◽

G Protein Coupled

ABSTRACTFiloviruses, consisting of Ebola virus (EBOV) and Marburg virus (MARV), are among the most lethal infectious threats to mankind. Infections by these viruses can cause severe hemorrhagic fevers in humans and nonhuman primates with high mortality rates. Since there is currently no vaccine or antiviral therapy approved for humans, there is an urgent need to develop prophylactic and therapeutic options for use during filoviral outbreaks and bioterrorist attacks. One of the ideal targets against filoviral infection and diseases is at the entry step, which is mediated by the filoviral glycoprotein (GP). In this report, we screened a chemical library of small molecules and identified numerous inhibitors, which are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs, including histamine receptors, 5-HT (serotonin) receptors, muscarinic acetylcholine receptor, and adrenergic receptor. These inhibitors can effectively block replication of both infectious EBOV and MARV, indicating a broad antiviral activity of the GPCR antagonists. The time-of-addition experiment and microscopic studies suggest that GPCR antagonists block filoviral entry at a step following the initial attachment but prior to viral/cell membrane fusion. These results strongly suggest that GPCRs play a critical role in filoviral entry and GPCR antagonists can be developed as an effective anti-EBOV/MARV therapy.IMPORTANCEInfection of Ebola virus and Marburg virus can cause severe illness in humans with a high mortality rate, and currently there is no FDA-approved vaccine or therapeutic treatment available. The 2013-2015 epidemic in West Africa underscores a lack of our understanding in the infection and pathogenesis of these viruses and the urgency of drug discovery and development. In this study, we have identified numerous inhibitors that are known G protein-coupled receptor (GPCR) antagonists targeting different GPCRs. These inhibitors can effectively block replication of both infectious EBOV and MARV, indicating a broad antiviral activity of the GPCR antagonists. Our results strongly suggest that GPCRs play a critical role in filoviral entry and GPCR antagonists can be developed as an effective anti-EBOV/MARV therapy.

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