Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo

Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.

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The G protein α subunit variant XLαspromotes inositol 1,4,5-trisphosphate signaling and mediates the renal actions of parathyroid hormone in vivo

Science Signaling ◽

10.1126/scisignal.aaa9953 ◽

2015 ◽

Vol 8 (391) ◽

pp. ra84-ra84 ◽

Cited By ~ 15

Author(s):

Qing He ◽

Yan Zhu ◽

Braden A. Corbin ◽

Antonius Plagge ◽

Murat Bastepe

Keyword(s):

Parathyroid Hormone ◽

G Protein ◽

Α Subunit ◽

Inositol 1,4,5 Trisphosphate ◽

G Protein Α Subunit

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Faculty Opinions recommendation of Structural basis for modulation of gating property of G protein-gated inwardly rectifying potassium ion channel (GIRK) by i/o-family G protein α subunit (Gαi/o).

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

10.3410/f.714397808.789952913 ◽

2012 ◽

Author(s):

Nathan Dascal

Keyword(s):

Ion Channel ◽

G Protein ◽

Potassium Ion ◽

Structural Basis ◽

Potassium Ion Channel ◽

Α Subunit ◽

G Protein Α Subunit ◽

Inwardly Rectifying

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The Natural Flavonoid Naringenin Inhibits the Cell Growth of WilmsTumorinChildren by Suppressing TLR4/NF-κB Signaling

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520620999200818155814 ◽

2020 ◽

Vol 20 ◽

Author(s):

Hongtao Li ◽

Peng Chen ◽

Lei Chen ◽

Xinning Wang

Keyword(s):

Cell Growth ◽

Western Blot ◽

Wilms Tumor ◽

Critical Role ◽

Time Dependent ◽

Luciferase Assay ◽

Dependent Manner ◽

Tlr4 Expression ◽

Protein Levels

Background: Nuclear factor kappa B (NF-κB) is usually activated in Wilms tumor (WT) cells and plays a critical role in WT development. Objective: The study purpose was to screen a NF-κB inhibitor from natural product library and explore its effects on WT development. Methods: Luciferase assay was employed to assess the effects of natural chemical son NF-κB activity. CCK-8 assay was conducted to assess cell growth in response to naringenin. WT xenograft model was established to analyze the effect of naringenin in vivo. Quantitative real-time PCR and Western blot were performed to examine the mRNA and protein levels of relative genes, respectively. Results: Naringenin displayed significant inhibitory effect on NF-κB activation in SK-NEP-1 cells. In SK-NEP-1 and G-401 cells, naringenin inhibited p65 phosphorylation. Moreover, naringenin suppressed TNF-α-induced p65 phosphorylation in WT cells. Naringenin inhibited TLR4 expression at both mRNA and protein levels in WT cells. CCK-8 staining showed that naringenin inhibited cell growth of the two above WT cells in dose-and time-dependent manner, whereas Toll-like receptor 4 (TLR4) over expression partially reversed the above phenomena. Besides, naringenin suppressed WT tumor growth in dose-and time-dependent manner in vivo. Western blot found that naringenin inhibited TLR4 expression and p65 phosphorylation in WT xenograft tumors. Conclusion: Naringenin inhibits WT development viasuppressing TLR4/NF-κB signaling

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Dominant-negative inhibition of pheromone receptor signaling by a single point mutation in the G protein α subunit. Vol. 279 (2004) 35287-35297

Journal of Biological Chemistry ◽

10.1016/s0021-9258(20)56430-2 ◽

2005 ◽

Vol 280 (33) ◽

pp. 29988

Author(s):

Yuh-Lin Wu ◽

Shelley B. Hooks ◽

T. Kendall Harden ◽

Henrik G. Dohlman

Keyword(s):

G Protein ◽

Point Mutation ◽

Single Point ◽

Dominant Negative ◽

Single Point Mutation ◽

Receptor Signaling ◽

Α Subunit ◽

Pheromone Receptor ◽

G Protein Α Subunit

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The G-Protein α-Subunit GasC Plays a Major Role in Germination in the Dimorphic FungusPenicillium marneffei

Genetics ◽

10.1093/genetics/164.2.487 ◽

2003 ◽

Vol 164 (2) ◽

pp. 487-499 ◽

Cited By ~ 2

Author(s):

Sophie Zuber ◽

Michael J Hynes ◽

Alex Andrianopoulos

Keyword(s):

G Protein ◽

Germination Rate ◽

Yeast Cells ◽

Class Iii ◽

Temperature Dependent ◽

Gene Encoding ◽

Α Subunit ◽

G Protein Α Subunit ◽

Opportunistic Human Pathogen

AbstractThe opportunistic human pathogen Penicillium marneffei exhibits a temperature-dependent dimorphic switch. At 25°, multinucleate, septate hyphae that can undergo differentiation to produce asexual spores (conidia) are produced. At 37° hyphae undergo arthroconidiation to produce uninucleate yeast cells that divide by fission. This work describes the cloning of the P. marneffei gasC gene encoding a G-protein α-subunit that shows high homology to members of the class III fungal Gα-subunits. Characterization of a ΔgasC mutant and strains carrying a dominant-activating gasCG45R or a dominant-interfering gasCG207R allele show that GasC is a crucial regulator of germination. A ΔgasC mutant is severely delayed in germination, whereas strains carrying a dominant-activating gasCG45R allele show a significantly accelerated germination rate. Additionally, GasC signaling positively affects the production of the red pigment by P. marneffei at 25° and negatively affects the onset of conidiation and the conidial yield, showing that GasC function overlaps with functions of the previously described Gα-subunit GasA. In contrast to the S. cerevisiae ortholog Gpa2, our data indicate that GasC is not involved in carbon or nitrogen source sensing and plays no major role in either hyphal or yeast growth or in the switch between these two forms.

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Role of Cathepsin S in Periodontal Inflammation and Infection

Mediators of Inflammation ◽

10.1155/2017/4786170 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 12

Author(s):

S. Memmert ◽

A. Damanaki ◽

A. V. B. Nogueira ◽

S. Eick ◽

M. Nokhbehsaim ◽

...

Keyword(s):

Periodontal Diseases ◽

Interleukin 1 ◽

Critical Role ◽

Gingival Tissue ◽

Cathepsin S ◽

Protein Levels ◽

Periodontal Inflammation

Cathepsin S is a cysteine protease and regulator of autophagy with possible involvement in periodontitis. The objective of this study was to investigate whether cathepsin S is involved in the pathogenesis of periodontal diseases. Human periodontal fibroblasts were cultured under inflammatory and infectious conditions elicited by interleukin-1β and Fusobacterium nucleatum, respectively. An array-based approach was used to analyze differential expression of autophagy-associated genes. Cathepsin S was upregulated most strongly and thus further studied in vitro at gene and protein levels. In vivo, gingival tissue biopsies from rats with ligature-induced periodontitis and from periodontitis patients were also analyzed at transcriptional and protein levels. Multiple gene expression changes due to interleukin-1β and F. nucleatum were observed in vitro. Both stimulants caused a significant cathepsin S upregulation. A significantly elevated cathepsin S expression in gingival biopsies from rats with experimental periodontitis was found in vivo, as compared to that from control. Gingival biopsies from periodontitis patients showed a significantly higher cathepsin S expression than those from healthy gingiva. Our findings provide original evidence that cathepsin S is increased in periodontal cells and tissues under inflammatory and infectious conditions, suggesting a critical role of this autophagy-associated molecule in the pathogenesis of periodontitis.

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Prep1 Deficiency Induces Protection from Diabetes and Increased Insulin Sensitivity through a p160-Mediated Mechanism

Molecular and Cellular Biology ◽

10.1128/mcb.00117-08 ◽

2008 ◽

Vol 28 (18) ◽

pp. 5634-5645 ◽

Cited By ~ 35

Author(s):

Francesco Oriente ◽

Luis Cesar Fernandez Diaz ◽

Claudia Miele ◽

Salvatore Iovino ◽

Silvia Mori ◽

...

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Glucose Uptake ◽

Normal Glucose Tolerance ◽

Glucose Disposal ◽

Protein Levels ◽

Normal Glucose ◽

Enhanced Expression ◽

The Stability

ABSTRACT We have examined glucose homeostasis in mice hypomorphic for the homeotic transcription factor gene Prep1. Prep1-hypomorphic (Prep1 i / i ) mice exhibit an absolute reduction in circulating insulin levels but normal glucose tolerance. In addition, these mice exhibit protection from streptozotocin-induced diabetes and enhanced insulin sensitivity with improved glucose uptake and insulin-dependent glucose disposal by skeletal muscle. This muscle phenotype does not depend on reduced expression of the known Prep1 transcription partner, Pbx1. Instead, in Prep1 i / i muscle, we find normal Pbx1 but reduced levels of the recently identified novel Prep1 interactor p160. Consistent with this reduction, we find a muscle-selective increase in mRNA and protein levels of PGC-1α, accompanied by enhanced expression of the GLUT4 transporter, responsible for insulin-stimulated glucose uptake in muscle. Indeed, using L6 skeletal muscle cells, we induced the opposite effects by overexpressing Prep1 or p160, but not Pbx1. In vivo skeletal muscle delivery of p160 cDNA in Prep1 i / i mice also reverses the molecular phenotype. Finally, we show that Prep1 controls the stability of the p160 protein. We conclude that Prep1 controls insulin sensitivity through the p160-GLUT4 pathway.

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