scholarly journals R-spondins engage heparan sulfate proteoglycans to potentiate WNT signaling

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ramin Dubey ◽  
Peter van Kerkhof ◽  
Ingrid Jordens ◽  
Tomas Malinauskas ◽  
Ganesh V Pusapati ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Wnt Signaling ◽  
Cultured Cells ◽  
Heparan Sulfate Proteoglycans ◽  
G Protein Coupled Receptors ◽  
Binding Domains ◽  
Genome Wide ◽  
A Genome ◽  
G Protein Coupled ◽  
In Cells

R-spondins (RSPOs) amplify WNT signaling during development and regenerative responses. We previously demonstrated that RSPOs 2 and 3 potentiate WNT/β-catenin signaling in cells lacking leucine-rich repeat-containing G-protein coupled receptors (LGRs) 4, 5 and 6 (Lebensohn and Rohatgi, 2018). We now show that heparan sulfate proteoglycans (HSPGs) act as alternative co-receptors for RSPO3 using a combination of ligand mutagenesis and ligand engineering. Mutations in RSPO3 residues predicted to contact HSPGs impair its signaling capacity. Conversely, the HSPG-binding domains of RSPO3 can be entirely replaced with an antibody that recognizes heparan sulfate (HS) chains attached to multiple HSPGs without diminishing WNT-potentiating activity in cultured cells and intestinal organoids. A genome-wide screen for mediators of RSPO3 signaling in cells lacking LGRs 4, 5 and 6 failed to reveal other receptors. We conclude that HSPGs are RSPO co-receptors that potentiate WNT signaling in the presence and absence of LGRs.

scholarly journals R-spondins can potentiate WNT signaling without LGRs

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Andres M Lebensohn ◽  
Rajat Rohatgi
Keyword(s):  
Wnt Signaling ◽  
Wnt Signaling Pathway ◽  
Heparan Sulfate Proteoglycans ◽  
G Protein Coupled Receptors ◽  
Leucine Rich Repeat ◽  
Biological Functions ◽  
High Affinity ◽  
Wnt Ligands ◽  
Necessary And Sufficient ◽  
G Protein Coupled

The WNT signaling pathway regulates patterning and morphogenesis during development and promotes tissue renewal and regeneration in adults. The R-spondin (RSPO) family of four secreted proteins, RSPO1-4, amplifies target cell sensitivity to WNT ligands by increasing WNT receptor levels. Leucine-rich repeat-containing G-protein coupled receptors (LGRs) 4-6 are considered obligate high-affinity receptors for RSPOs. We discovered that RSPO2 and RSPO3, but not RSPO1 or RSPO4, can potentiate WNT/β-catenin signaling in the absence of all three LGRs. By mapping the domains on RSPO3 that are necessary and sufficient for this activity, we show that the requirement for LGRs is dictated by the interaction between RSPOs and the ZNRF3/RNF43 E3 ubiquitin ligases and that LGR-independent signaling depends on heparan sulfate proteoglycans (HSPGs). We propose that RSPOs can potentiate WNT signals through distinct mechanisms that differ in their use of either LGRs or HSPGs, with implications for understanding their biological functions.

scholarly journals A Genome-wide RNAi Screen Reveals a Trio-Regulated Rho GTPase Circuitry Transducing Mitogenic Signals Initiated by G Protein-Coupled Receptors

2013 ◽  
Vol 49 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Jose P. Vaqué ◽  
Robert T. Dorsam ◽  
Xiaodong Feng ◽  
Ramiro Iglesias-Bartolome ◽  
David J. Forsthoefel ◽  
...  
Keyword(s):  
G Protein ◽  
Rho Gtpase ◽  
Rnai Screen ◽  
G Protein Coupled Receptors ◽  
Genome Wide ◽  
A Genome ◽  
G Protein Coupled ◽  
Mitogenic Signals

scholarly journals A Genome-Wide CRISPR/Cas9-Based Screen Identifies Heparan Sulfate Proteoglycans as Ligands of Killer-Cell Immunoglobulin-Like Receptors

2021 ◽  
Vol 12 ◽  
Author(s):  
Klara Klein ◽  
Angelique Hölzemer ◽  
Tim Wang ◽  
Tae-Eun Kim ◽  
Haley L. Dugan ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Cell Lines ◽  
Nk Cell ◽  
Killer Cell ◽  
Heparan Sulfate Proteoglycans ◽  
Knock Out ◽  
Cell Receptors ◽  
Nk Cell Receptors ◽  
Genome Wide ◽  
A Genome

While human leukocyte antigen (HLA) and HLA-like proteins comprise an overwhelming majority of known ligands for NK-cell receptors, the interactions of NK-cell receptors with non-conventional ligands, particularly carbohydrate antigens, is less well described. We previously found through a bead-based HLA screen that KIR3DS1, a formerly orphan member of the killer-cell immunoglobulin-like receptor (KIR) family, binds to HLA-F. In this study, we assessed the ligand binding profile of KIR3DS1 to cell lines using Fc fusion constructs, and discovered that KIR3DS1-Fc exhibited binding to several human cell lines including ones devoid of HLA. To identify these non-HLA ligands, we developed a magnetic enrichment-based genome-wide CRISPR/Cas9 knock-out screen approach, and identified enzymes involved in the biosynthesis of heparan sulfate as crucial for the binding of KIR3DS1-Fc to K562 cells. This interaction between KIR3DS1 and heparan sulfate was confirmed via surface plasmon resonance, and removal of heparan sulfate proteoglycans from cell surfaces abolished KIR3DS1-Fc binding. Testing of additional KIR-Fc constructs demonstrated that KIR family members containing a D0 domain (KIR3DS1, KIR3DL1, KIR3DL2, KIR2DL4, and KIR2DL5) bound to heparan sulfate, while those without a D0 domain (KIR2DL1, KIR2DL2, KIR2DL3, and KIR2DS4) did not. Overall, this study demonstrates the use of a genome-wide CRISPR/Cas9 knock-out strategy to unbiasedly identify unconventional ligands of NK-cell receptors. Furthermore, we uncover a previously underrecognized binding of various activating and inhibitory KIRs to heparan sulfate proteoglycans that may play a role in NK-cell receptor signaling and target-cell recognition.

scholarly journals Role of heparan sulfate proteoglycans in the binding and uptake of apolipoprotein E-enriched remnant lipoproteins by cultured cells

1993 ◽  
Vol 268 (14) ◽  
pp. 10160-10167
Author(s):  
Z.S. Ji ◽  
W.J. Brecht ◽  
R.D. Miranda ◽  
M.M. Hussain ◽  
T.L. Innerarity ◽  
...  
Keyword(s):  
Apolipoprotein E ◽  
Heparan Sulfate ◽  
Cultured Cells ◽  
Heparan Sulfate Proteoglycans ◽  
Remnant Lipoproteins

scholarly journals Heparan sulfate proteoglycans are critical for the organization of the extracellular distribution of Wingless

Development ◽  
2001 ◽  
Vol 128 (1) ◽  
pp. 87-94 ◽  
Author(s):  
G.H. Baeg ◽  
X. Lin ◽  
N. Khare ◽  
S. Baumgartner ◽  
N. Perrimon
Keyword(s):  
Heparan Sulfate ◽  
Wnt Signaling ◽  
Heparan Sulfate Proteoglycans ◽  
Gene Activity ◽  
Dramatic Decrease

Recent studies in Drosophila have shown that heparan sulfate proteoglycans (HSPGs) are required for Wingless (Wg/Wnt) signaling. In addition, genetic and phenotypic analyses have implicated the glypican gene dally in this process. Here, we report the identification of another Drosophila glypican gene, dally-like (dly) and show that it is also involved in Wg signaling. Inhibition of dly gene activity implicates a function for DLY in Wg reception and we show that overexpression of DLY leads to an accumulation of extracellular Wg. We propose that DLY plays a role in the extracellular distribution of Wg. Consistent with this model, a dramatic decrease of extracellular Wg was detected in clones of cells that are deficient in proper glycosaminoglycan biosynthesis. We conclude that HSPGs play an important role in organizing the extracellular distribution of Wg.

scholarly journals Perlecan regulates bidirectional Wnt signaling at the Drosophila neuromuscular junction

2013 ◽  
Vol 200 (2) ◽  
pp. 219-233 ◽  
Author(s):  
Keisuke Kamimura ◽  
Kohei Ueno ◽  
Jun Nakagawa ◽  
Rie Hamada ◽  
Minoru Saitoe ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Neuromuscular Junction ◽  
Heparan Sulfate ◽  
Wnt Signaling ◽  
Nuclear Import ◽  
Heparan Sulfate Proteoglycans ◽  
Down Regulation ◽  
Bidirectional Signaling ◽  
Synaptic Boutons ◽  
Signaling Activity

Heparan sulfate proteoglycans (HSPGs) play pivotal roles in the regulation of Wnt signaling activity in several tissues. At the Drosophila melanogaster neuromuscular junction (NMJ), Wnt/Wingless (Wg) regulates the formation of both pre- and postsynaptic structures; however, the mechanism balancing such bidirectional signaling remains elusive. In this paper, we demonstrate that mutations in the gene of a secreted HSPG, perlecan/trol, resulted in diverse postsynaptic defects and overproduction of synaptic boutons at NMJ. The postsynaptic defects, such as reduction in subsynaptic reticulum (SSR), were rescued by the postsynaptic activation of the Frizzled nuclear import Wg pathway. In contrast, overproduction of synaptic boutons was suppressed by the presynaptic down-regulation of the canonical Wg pathway. We also show that Trol was localized in the SSR and promoted postsynaptic accumulation of extracellular Wg proteins. These results suggest that Trol bidirectionally regulates both pre- and postsynaptic activities of Wg by precisely distributing Wg at the NMJ.

scholarly journals Identification of the C3a Receptor (C3AR1) as the Target of the VGF-derived Peptide TLQP-21 in Rodent Cells

2013 ◽  
Vol 288 (38) ◽  
pp. 27434-27443 ◽  
Author(s):  
Sebastien Hannedouche ◽  
Valerie Beck ◽  
Juliet Leighton-Davies ◽  
Martin Beibel ◽  
Guglielmo Roma ◽  
...  
Keyword(s):  
G Protein ◽  
Cellular Response ◽  
G Protein Coupled Receptors ◽  
Proteolytic Processing ◽  
Rodent Models ◽  
Cellular Functions ◽  
Genome Wide ◽  
Response To Stress ◽  
G Protein Coupled ◽  
Human Receptor

TLQP-21, a peptide derived from VGF (non-acronymic) by proteolytic processing, has been shown to modulate energy metabolism, differentiation, and cellular response to stress. Although extensively investigated, the receptor for this endogenous peptide has not previously been described. This study describes the use of a series of studies that show G protein-coupled receptor-mediated biological activity of TLQP-21 signaling in CHO-K1 cells. Unbiased genome-wide sequencing of the transcriptome from responsive CHO-K1 cells identified a prioritized list of possible G protein-coupled receptors bringing about this activity. Further experiments using a series of defined receptor antagonists and siRNAs led to the identification of complement C3a receptor-1 (C3AR1) as a target for TLQP-21 in rodents. We have not been able to demonstrate so far that this finding is translatable to the human receptor. Our results are in line with a large number of physiological observations in rodent models of food intake and metabolic control, where TLQP-21 shows activity. In addition, the sensitivity of TLQP-21 signaling to pertussis toxin is consistent with the known signaling pathway of C3AR1. The binding of TLQP-21 to C3AR1 not only has effects on signaling but also modulates cellular functions, as TLQP-21 was shown to have a role in directing migration of mouse RAW264.7 cells.

scholarly journals Genome-Wide Analysis of Chromosomal Features Repressing Human Immunodeficiency Virus Transcription

2005 ◽  
Vol 79 (11) ◽  
pp. 6610-6619 ◽  
Author(s):  
M. K. Lewinski ◽  
D. Bisgrove ◽  
P. Shinn ◽  
H. Chen ◽  
C. Hoffmann ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Fluorescent Protein ◽  
Centromeric Heterochromatin ◽  
Regulatory Sequences ◽  
Hiv Transcription ◽  
Genome Wide ◽  
A Genome ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
In Cells

ABSTRACT We have investigated regulatory sequences in noncoding human DNA that are associated with repression of an integrated human immunodeficiency virus type 1 (HIV-1) promoter. HIV-1 integration results in the formation of precise and homogeneous junctions between viral and host DNA, but integration takes place at many locations. Thus, the variation in HIV-1 gene expression at different integration sites reports the activity of regulatory sequences at nearby chromosomal positions. Negative regulation of HIV transcription is of particular interest because of its association with maintaining HIV in a latent state in cells from infected patients. To identify chromosomal regulators of HIV transcription, we infected Jurkat T cells with an HIV-based vector transducing green fluorescent protein (GFP) and separated cells into populations containing well-expressed (GFP-positive) or poorly expressed (GFP-negative) proviruses. We then determined the chromosomal locations of the two classes by sequencing 971 junctions between viral and cellular DNA. Possible effects of endogenous cellular transcription were characterized by transcriptional profiling. Low-level GFP expression correlated with integration in (i) gene deserts, (ii) centromeric heterochromatin, and (iii) very highly expressed cellular genes. These data provide a genome-wide picture of chromosomal features that repress transcription and suggest models for transcriptional latency in cells from HIV-infected patients.

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