How the LRC-TriCEPS technology works

Here, we report that A. muciniphila increases thermogenesis and glucagon-like peptide-1 (GLP-1) secretion in high-fat-diet (HFD)-induced C57BL/6J mice by induction of uncoupling protein 1 in brown adipose tissue and systemic GLP-1 secretion. We apply fast protein liquid chromatography and liquid chromatography coupled to mass spectrophotometry analysis to identify an 84 kDa protein, named P9, that is secreted by A. muciniphila. Using L cells and mice fed on an HFD, we show that purified P9 alone is sufficient to induce GLP-1 secretion and brown adipose tissue thermogenesis. Using ligand–receptor capture analysis, we find that P9 interacts with intercellular adhesion molecule 2 (ICAM-2). Interleukin-6 deficiency abrogates the effects of P9 in glucose homeostasis and downregulates ICAM-2 expression. Our results show that the interactions between P9 and ICAM-2 could be targeted by therapeutics for metabolic diseases.

Hyo Shin Yoon, Chung Hwan Cho, Myeong Sik Yun, Sung Jae Jang, Hyun Ju You, Jun-hyeong Kim, Dohyun Han, Kwang Hyun Cha, Sung Hyun Moon, Kiuk Lee, Yeon-Ji Kim, Sung-Joon Lee, Tae-Wook Nam & GwangPyo Ko

Identification of Neuroplastin (NPTN) as receptor of MANF polypeptide by LRC-TriCEPS. Endoplasmic reticulum (ER) stress is known to induce pro-inflammatory response and ultimately leads to cell death. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER-localized protein whose expression and secretion is induced by ER stress and a crucial survival factor. However, the underlying mechanism of how MANF exerts its cytoprotective activity remains unclear due to the lack of knowledge of its receptor. Here we show that Neuroplastin (NPTN) is such a receptor for MANF. Biochemical analysis shows the physiological interaction between MANF and NPTN on the cell surface. Binding of MANF to NPTN mitigates the inflammatory response and apoptosis via suppression of NF-kβ signaling. Our results demonstrate that NPTN is a cell surface receptor for MANF, which modulates inflammatory responses and cell death, and that the MANF-NPTN survival signaling described here provides potential therapeutic targets for the treatment of ER stress-related disorders, including diabetes mellitus, neurodegeneration, retinal degeneration, and Wolfram syndrome.

Takuya Yagi, Rie Asada, Kohsuke Kanekura, Ave Eesmaa, Maria Lindahl, Mart Saarma, Fumihiko Urano

The immune checkpoint molecule human leukocyte antigen (HLA)-G is upregulated on malignant cells but not on healthy surrounding cells, the requirement of understanding the basis of receptor mediated events at the HLA-G/NK cell interface becomes obvious. The NK cell receptors ILT2 and KIR2DL4 have been described to bind to HLA-G; however, their differential function and expression levels on NK cell subsets suggest the existence of an unreported receptor. Here, we performed a ligand-based receptor capture on living cells utilizing sHLA-G*01:01 molecules coupled to TriCEPS and bound to NK cells followed by mass spectrometric analyses. We could define NKG2A/CD94 as a cognate receptor of HLA-G.

Gia-Gia T. Hò, Alexander A. Celik, Trevor Huyton, Wiebke Hiemisch, Rainer Blasczyk, Gwendolin S. Simper, and Christina Bade-Doeding

• Using the LRC-TriCEPS platform  PSGL-1  was identified as the interaction partner of the co-inhibitor Vista on activated primary T-cells as at acidic pH mimicking the acidic tumour environment
• Now, Vista tumour immunotherapy can rationally move  forward
• The results also suggest to use also acidity as therapeutic target for tumour therapy
• Now also other interactions at acidic pH for drug candidates or co-inhibitor interactions should be tested on primary T-cells. It could explain why some drug candidates are not successful in later development.

Kathleen M. Mahoney and Gordon J. Freeman

Summary

We then performed ligand-based receptor capture with VISTA–Fc chimeric protein and human CD4 + Tcells at acidic pH 19 . PSGL-1 was one of few proteins that were enriched relative to controls (Fig.3a). In addition to its well-characterized role facilitating adhesion interactions between leukocytes, platelets and endothelial cells 20,21 , PSGL-1 has been identified as a negative regulator of T cell responses in contexts of chronic viral infection, cancer, and some autoimmune diseases 22–28 .

Robert J. Johnston, Linhui Julie Su, Jason Pinckney, David Critton, Eric Boyer, Arathi Krishnakumar, Martin Corbett, Andrew L. Rankin, Rose Dibella, Lynne Campbell, Gaelle H. Martin, Hadia Lemar, Thomas Cayton, Richard Y.-C. Huang, Xiaodi Deng, Akbar Nayeem, Haibin Chen, Burce Ergel, Joseph M. Rizzo, Aaron P. Yamniuk, Sanjib Dutta, Justine Ngo, Andrea Olga Shorts, Radha Ramakrishnan, Alexander Kozhich, Jim Holloway, Hua Fang, Ying-Kai Wang, Zheng Yang, Kader Thiam, Ginger Rakestraw, Arvind Rajpal, Paul Sheppard, Michael Quigley, Keith S. Bahjat & Alan J. Korman

Anti-VISTA antibody that inhibits Vista function and blocks interaction with PSGL-1 and VSIG3 proteins slows tumor growth.

Mehta, N., Maddineni, S., Kelly, R.L. et al.

L. monocytogenes is a Gram-positive, food-borne, intracellular pathogen that causes severe infection in susceptible individuals. Interestingly, almost all infections are caused by a subset of strains belonging to certain serovars featuring a complex glycosylation pattern on their cell surface. Using an engineered bacteriophage that specifically recognizes these modifications we selected for mutants that lost these sugars. We found that the resulting strains are severely deficient in invading host cells as we observed that a major virulence factor mediating host cell entry requires galactose decoration of the cell surface for its function. Without this galactose decoration, the strain represents a serovar not associated with disease. Altogether, we show a complex interplay between bacteriophages, bacteria, and the host, demonstrating that cellular invasiveness is dependent upon a serovar-defining structure, which also serves as a phage receptor.

Eric T. Sumrall, Yang Shen, Anja P. Keller, Jeanine Rismondo, Maria Pavlou, Marcel R. Eugster, Samy Boulos, Olivier Disson, Pierre Thouvenot, Samuel Kilcher, Bernd Wollscheid, Didier Cabanes, Marc Lecuit, Angelika Gründling, Martin J. Loessner

Intestinal epithelial cells (IEC) have important functions in nutrient absorption, barrier integrity, regeneration, pathogen-sensing, and mucus secretion. Goblet cells are a specialized cell type of IEC that secrete Trefoil factor 3 (TFF3) to regulate mucus viscosity and wound healing, but whether TFF3-responsiveness requires a receptor is unclear. We postulated that TFF3 interacted with its receptor through low-affinity interactions reliant upon carbohydrates because TFF3 glycosylation has been shown critical for biological activity34,35, therefore U937 cells were subjected to the TRICEPSTM protocol as a biochemical screening strategy to identify glycosylated transmembrane protein(s) on the cell surface32,36. As bait, rhTFF3 was covalently linked to the TRICEPS probe and incubated with PMA-treated U937 that had been treated with sodium periodate. Cell pellets were subjected to glycosidase digestion and peptides generated using mass spectrometry. As a positive control to account for enrichment efficiency, recombinant human>INS was used as bait for the>INS receptor. Whereas the TFF3-probe induced an 8-fold enrichment of LINGO2 (LIGO2) peptide, the>INS-probe induced a 7.76-fold-enrichment in INSR peptide (Fig. 1b). No other enriched peptides in this screen met this level of enrichment or were derived from proteins that satisfied our selection criterion (e.g., extracellular domain, transmembrane region, cytoplasmic tail).Here, we show that leucine rich repeat receptor and nogo-interacting protein 2 (LINGO2) is essential for TFF3-mediated functions. LINGO2 immunoprecipitates with TFF3, co-localizes with TFF3 on the cell membrane of IEC, and allows TFF3 to block apoptosis. We further show that TFF3-LINGO2 interactions disrupt EGFR-LINGO2 complexes resulting in enhanced EGFR signaling. Excessive basal EGFR activation in Lingo2 deficient mice increases disease severity during colitis and augments immunity against helminth infection. Conversely, TFF3 deficiency reduces helminth immunity. Thus, TFF3-LINGO2 interactions de-repress inhibitory LINGO2-EGFR complexes, allowing TFF3 to drive wound healing and immunity.

Nicole Maloney Belle1, Yingbiao Ji1,5, Karl Herbine1,5, Yun Wei2,3,5, JoonHyung Park1,5, Kelly Zullo1,

Li-Yin Hung1,2, Sriram Srivatsa1, Tanner Young1, Taylor Oniskey2, Christopher Pastore1, Wildaliz Nieves4,

Ma Somsouk4 & De’Broski R. Herbert1,2

1 Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19140, USA. 2 Division of Experimental Medicine,

University of California, San Francisco, San Francisco, CA 94110, USA. 3 Department of Inflammation and Oncology, Amgen Inc., 1120 Veterans Boulevard,

South San Francisco, CA 94080, USA. 4 Division of Gastroenterology at ZSFG, University of California, San Francisco, San Francisco, CA 94110, USA. 5These

authors contributed equally: Yingbiao Ji, Karl Herbine, Yun Wei, JoonHyung Park. *email: debroski@vet.upenn.edu

Comparison of different technologies to identify Ligand-Receptor interactions.

Maria P. Pavlou and Paul Helbling

The advent of ligand based receptor capture methodologies, allows the identification of unknown receptor candidates for orphan extracellular ligands. However, further target validation can be tedious, laborious and time consuming. Here, we present a methodology that provides a fast and costefficient alternative for candidate target verification on living cells for a peptide, a protein and an antibody.

Laura A. Lopez‑Garcia, Levent Demiray, Sandra Ruch‑Marder, Ann‑Katrin Hopp, Michael O. Hottiger, Paul M. Helbling and Maria P. Pavlou

Our previous work identified a 12-amino acid peptide that targets the heart, termed cardiac targeting peptide (CTP).We now quantitatively assess the bio-distribution of CTP, show a clinical application with the imaging of the murine heart, and study its mechanisms of  transduction. Bio-distribution studies of cyanine5.5-N-Hydroxysuccinimide (Cy5.5) labeled CTP were undertaken in wild-type mice. Cardiac targeting peptide was labeled with Tc. 99m (99mTc) using the chelator hydrazino-nicotinamide (HYNIC), and imaging performed using micro-single photon emission computerized tomography/computerized tomography (SPECT/CT). Human-induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMCs) were incubated with dual-labeled CTP, and imaged using confocal microscopy. TriCEPs technology was utilized to study the mechanism of transduction. Bio-distribution studies showed peak uptake of CTP at 15 min. 99mTc-HYNIC-CTP showed heart-specific uptake. Robust transduction of beating human iPSC-derived CMCs was seen. TriCEPs experiments revealed five candidate binding partners for CTP, with Kcnh5 being felt to be the most likely candidate as it showed a trend towards being competed out by siRNA knockdown. Transduction efficiency was enhanced by increasing extracellular potassium concentration, and with Quin., a Kcnh5 inhibitor, that blocks the channel in an open position. We demonstrate that CTP transduces the normal heart as early as 15 min. 99mTc-HYNIC-CTP targets the normal murine heart with substantially improved targeting compared with 99mTc Sestamibi. Cardiac targeting peptide’s transduction ability is not species limited and has human applicability. Cardiac targeting peptide appears to utilize Kcnh5 to gain cell entry, a phenomenon that is affected by pre-treatment with Quin. and changes in potassium levels.

Maliha Zahid 1,*, Kyle S. Feldman 1, Gabriel Garcia-Borrero 1, Timothy N. Feinstein 1, Nicholas Pogodzinski 1, Xinxiu Xu 1, Raymond Yurko 2, Michael Czachowski 3, Yijen L. Wu 1, Neale S. Mason 3 and CeciliaW. Lo 1

1 Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15201, USA; ksf23@pitt.edu (K.S.F.); gag44@pitt.edu (G.G.-B.); tnf8@pitt.edu (T.N.F.); nrp30@pitt.edu (N.P.);xux@pitt.edu (X.X.); yijenwu@pitt.edu (Y.L.W.); cel36@pitt.edu (C.W.L.)

2 Peptide Synthesis Facility, University of Pittsburgh, Pittsburgh, PA 15201, USA; yurko@pitt.edu

3 Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15201, USA; michael.czachowski@chp.edu (M.C.); masonns@upmc.edu (N.S.M.)

The plasma-protein histidine-rich glycoprotein (HRG) is implicated in phenotypic switching of tumor-associated macrophages, regulating cytokine production and phagocytotic activity, thereby promoting vessel normalization and anti-tumor immune responses. To assess the therapeutic effect of HRG gene delivery on CNS tumors, we used adenovirus-encoded HRG to treat mouse intracranial GL261 glioma. Delivery of Ad5-HRG to the tumor site resulted in a significant reduction in glioma growth, associated with increased vessel perfusion and increased CD45+ leukocyte and CD8+ T cell accumulation in the tumor. Antibody-mediated neutralization of colony-stimulating factor-1 suppressed the effects of HRG on CD45+ and CD8+ infiltration. Using a novel protein interaction-decoding technology, TRICEPS-based ligand receptor capture (LRC), we identified Stanniocalcin-2 (STC2) as an interacting partner of HRG on the surface of inflammatory cells in vitro and co-localization of HRG and STC2 in gliomas. HRG reduced the suppressive effects of STC2 on monocyte CD14+ differentiation and STC2-regulated immune response pathways. In consequence, Ad5-HRG treated gliomas displayed decreased numbers of Interleukin-35+ Treg cells, providing a mechanistic rationale for the reduction in GL261 growth in response to Ad5-HRG delivery. We conclude that HRG suppresses glioma growth by modulating tumor inflammation through monocyte infiltration and differentiation. Moreover, HRG acts to balance the regulatory effects of its partner, STC2, on inflammation and innate and/or acquired immunity. HRG gene delivery therefore offers a potential therapeutic strategy to control anti-tumor immunity.

Francis P Roche1, Ilkka Pietilä2, Hiroshi Kaito3, Elisabet O Sjöström1, Nadine Sobotzki4, Oriol Noguer1, Tor Persson Skare1, Magnus Essand1, Bernd Wollscheid5, Michael Welsh2, and Lena Claesson-Welsh1,*

1. 
   
   ¹Department of Immunology, Uppsala University
2. 
   
   ²Department of Medical Cell Biology, Uppsala University
3. 
   
   ³Department of Immunology, Uppsala university
4. 
   
   ⁴Department of Health Sciences, ETH Zurich
5. 
   
   ⁵Department of Health Sciences, ETH Zürich

1. ↵* Corresponding Author:

Adenoviruses as most viruses rely on glycan and protein interactions to attach to and enter susceptible host cells. The Adenoviridae family comprises more than 80 human types and they differ in their attachment factor and receptor usage, which likely contributes to the diverse tropism of the different types. In the past years, methods to systematically identify glycan and protein interactions have advanced. In particular sensitivity, speed and coverage of mass spectrometric analyses allow for high-throughput identification of glycans and peptides separated by liquid chromatography. Also, developments in glycan microarray technologies have led to targeted, high-throughput screening and identification of glycan-based receptors. The mapping of cell surface interactions of the diverse adenovirus types has implications for cell, tissue, and species tropism as well as drug development. Here we review known adenovirus interactions with glycan- and protein-based receptors, as well as glycomics and proteomics strategies to identify yet elusive virus receptors and attachment factors. We finally discuss challenges, bottlenecks, and future research directions in the field of non-enveloped virus entry into host cells.

Lisa Lasswitz¹Naresh Chandra^2,3Niklas Arnberg^2,3Gisa Gerold^1,2,4

¹ Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany

² Department of Clinical Microbiology, Virology, Umeå University, SE-90185 Umeå, Sweden

³ Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-90185 Umea, Sweden

⁴ Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, SE-90185 Umea, Sweden

Cellular responses depend on the interactions of extracellular ligands, such as nutrients, growth factors, or drugs, with specific cell-surface receptors. The sensitivity of these interactions to non-physiological conditions, however, makes them challenging to study using in vitro assays. Here we present HATRIC-based ligand receptor capture (HATRIC-LRC), a chemoproteomic technology that successfully identifies target receptors for orphan ligands on living cells ranging from small molecules to intact viruses. HATRIC-LRC combines a click chemistry-based, protein-centric workflow with a water-soluble catalyst to capture ligand-receptor interactions at physiological pH from as few as 1 million cells. We show HATRIC-LRC utility for general antibody target validation within the native nanoscale organization of the surfaceome, as well as receptor identification for a small molecule ligand. HATRIC-LRC further enables the identification of complex extracellular interactomes, such as the host receptor panel for influenza A virus (IAV), the causative agent of the common flu.

Nadine Sobotzki, Michael A. Schafroth, Alina Rudnicka, Anika Koetemann, Florian Marty, Sandra Goetze, Yohei Yamauchi, Erick M. Carreira and Bernd Wollscheid

Canonical Ag-dependent TCR signaling relies on activation of the src-family tyrosine kinase LCK. However, staphylococcal superantigens can trigger TCR signaling by activating an alternative pathway that is independent of LCK and utilizes a Gα11-containing G protein–coupled receptor (GPCR) leading to PLCβ activation. The molecules linking the superantigen to GPCR signaling are unknown. Using the ligand-receptor capture technology LRC-TriCEPS, we identified LAMA2, the α2 subunit of the extracellular matrix protein laminin, as the coreceptor for staphylococcal superantigens. Complementary binding assays (ELISA, pull-downs, and surface plasmon resonance) provided direct evidence of the interaction between staphylococcal enterotoxin E and LAMA2. Through its G4 domain, LAMA2 mediated the LCK-independent T cell activation by these toxins. Such a coreceptor role of LAMA2 involved a GPCR of the calcium-sensing receptor type because the selective antagonist NPS 2143 inhibited superantigen-induced T cell activation in vitro and delayed the effects of toxic shock syndrome in vivo. Collectively, our data identify LAMA2 as a target of antagonists of staphylococcal superantigens to treat toxic shock syndrome.

Zhigang Li, Joseph J. Zeppa, Mark A. Hancock, John K. McCormick, Terence M. Doherty, Geoffrey N. Hendy and Joaquín Madrenas

Metastatic chondrosarcoma is a bone malignancy not responsive to conventional therapies; new approaches and therapies are urgently needed. We have previously reported that mTORC1 inhibitor, antitumorigenic cytostatic proline rich polypeptide 1 (PRP-1), galarmin caused a significant upregulation of tumor suppressors including TET1/2 and SOCS3 (known to be involved in inflammatory processes), downregulation of oncoproteins and embryonic stem cell marker miR-302C and its targets Nanog, c-Myc and Bmi-1 in human chondrosarcoma. To understand better the mechanism of PRP-1 action it was very important to identify the receptor it binds to. Nuclear pathway receptor and GPCR assays indicated that PRP-1 receptors are not G protein coupled, neither do they belong to family of nuclear or orphan receptors. In the present study, we have demonstrated that PRP-1 binding interacting partners belong to innate immunity pattern recognition toll like receptors TLR1/2 and TLR6 and gel forming secreted mucin MUC5B. MUC5B was identified as PRP-1 receptor in human chondrosarcoma JJ012 cell line using Ligand-receptor capture technology. Toll like receptors TLR1/2 and TLR6 were identified as binding interaction partners with PRP-1 by western blot analysis in human chondrosarcoma JJ012 cell line lysates. Immunocytochemistry experiments confirmed the finding and indicated the localization of PRP-1 receptors in the tumor nucleus predominantly. TLR1/2, TLR6 and MUC5B were downregulated in human chondrosarcoma and upregulated in dose-response manner upon PRP-1 treatment. Experimental data indicated that in this cellular context the mentioned receptors had tumor suppressive function.

• Effect of cytostatic proline rich polypeptide-1 on tumor suppressors of inflammation pathway signaling in chondrosarcoma
• Epigenetic regulation of embryonic stem cell marker miR302C in human chondrosarcoma as determinant of antiproliferative activity of proline-rich polypeptide 1
• Restoration of desmosomal junction protein expression and inhibition of H3K9‑specific histone demethylase activity by cytostatic proline‑rich polypeptide‑1 leads to suppression of tumorigenic potential in human chondrosarcoma cells
• Analysis of IL6‑protein complexes in chondrosarcoma
• Epigenetic control of cancer by neuropeptides (Review)

Karina Galoian, Silva Abrahamyan, Gor Chailyan, Amir Qureshi, Parthik Patel, Gil Metser, Alexandra Moran, Inesa Sahakyan, Narine Tumasyan, Albert Lee, Tigran Davtyan, Samvel Chailyan and Armen Galoyan

The majority of antibody therapeutics have been isolated from target-led drug discovery, where many years of target research preceded drug program initiation. However, as the search for validated targets becomes more challenging and target space becomes increasingly competitive, alternative strategies, such as phenotypic drug discovery, are gaining favour. This review highlights successful examples of antibody phenotypic screens that have led to clinical drug candidates. We also review the requirements for performing an effective antibody phenotypic screen, including antibody enrichment and target identification strategies. Finally, the future impact of phenotypic drug discovery on antibody drug pipelines will be discussed.

Section editors: Neil O Carragher – Institute of Genetics and Molecular Medicine, Cancer Research UK Edinburgh Centre, University of Edinburgh, Edinburgh, United Kingdom. Jonathan A. Lee – Quantitative Biology, Eli Lilly and Company, Indianapolis, Indiana. Ellen L. Berg – BioMAP Systems Division of DiscoverX, DiscoverX Corporation.

Initial analysis demonstrated efficient coupling of TriCEPS to CTRP3. Further, flow cytometry analysis (FACS) demonstrated successful oxidation and crosslinking of CTRP3-TriCEPS and INS-TriCEPS complexes to cell surface glycans. Demonstrating the utility of TriCEPS under these conditions, the>INS receptor was identified in the control dataset. In the CTRP3 treated cells a total enrichment of 261 peptides was observed. From these experiments 5 putative receptors for CTRP3 were identified with two reaching statistically significance: Lysosomal-associated membrane protein 1 (LAMP-1) and Lysosome membrane protein 2 (LIMP II). Follow-up Co-immunoprecipitation analysis confirmed the association between LAMP1 and CTRP3 and further testing using a polyclonal antibody to block potential binding sites of LAMP1 prevented CTRP3 binding to the cells.

Conclusion

The LRC-TriCEPS methodology was successful in identifying potential novel receptors for CTRP3.

Relevance

The identification of the receptors for CTRP3 are important prerequisites for the development of small molecule drug candidates, of which none currently exist, for the treatment NAFLD.

Li Y¹, Ozment T², Wright GL¹, Peterson JM^1,3.

MChemokines and their receptors play a critical role in immune function by directing cell-specific movement. C-C chemokine receptor 7 (CCR7) facilitates entry of T cells into lymph nodes. CCR7-dependent chemotaxis requires either of the cognate ligands C-C chemokine ligand 19 (CCL19) or CCL21. Although CCR7-dependent chemotaxis can be augmented through receptor up-regulation or by increased chemokine concentrations, we found that chemotaxis is also markedly enhanced by serum in vitro. Upon purification, the serum cofactor activity was ascribed to domain 5 of high-molecular-weight kininogen. This peptide was necessary and sufficient for accelerated chemotaxis. The cofactor activity in serum was dependent on coagulation factor XIIa, a serine protease known to induce cleavage of high-molecular-weight kininogen (HK) at sites of inflammation. Within domain 5, we synthesized a 24-amino acid peptide that could recapitulate the activity of intact serum through a mechanism distinct from up-regulating CCR7 expression or promoting chemokine binding to CCR7. This peptide interacts with the extracellular matrix protein thrombospondin 4 (TSP4), and antibodies to TSP4 neutralize its activity. In vivo, an HK domain 5 peptide stimulated homing of both T and B cells to lymph nodes. A circulating cofactor that is activated at inflammatory foci to enhance lymphocyte chemotaxis represents a powerful mechanism coupling inflammation to adaptive immunity.

Manish P. Ponda^a and Jan L. Breslow^a,¹

a Laboratory of Biochemical Genetics and Metabolism, The Rockefeller University, New York, NY 10065

Contributed by Jan L. Breslow, September 23, 2016 (sent for review August 1, 2016; reviewed by Myron Cybulsky and Carl F. Nathan)

Target-blind activity-based screening of molecular libraries is often used to develop first-generation compounds, but subsequent target identification is rate-limiting to developing improved agents with higher specific affinity and lower off-target binding. A fluorescently labeled nerve-binding peptide, NP41, selected by phage display, highlights peripheral nerves in vivo. Nerve highlighting has the potential to improve surgical outcomes by facilitating intraoperative nerve identification, reducing accidental nerve transection, and facilitating repair of damaged nerves. To enable screening of molecular target-specific molecules for higher nerve contrast and to identify potential toxicities, NP41’s binding target was sought. Laminin-421 and -211 were identified by proximity-based labeling using singlet oxygen and by an adapted version of TRICEPS-based ligand-receptor capture to identify glycoprotein receptors via ligand cross-linking. In proximity labeling, photooxidation of a ligand-conjugated singlet oxygen generator is coupled to chemical labeling of locally oxidized residues. Photooxidation of methylene blue–NP41-bound nerves, followed by hydrazide labeling and purification, resulted in light-induced enrichment of laminin subunits α4 and α2, nidogen 1, and decorin (FDR-adjusted P value < 10⁻⁷) and minor enrichment of laminin-γ1 and collagens I and VI. Glycoprotein receptor capture also identified laminin-α4 and -γ1. Laminins colocalized with NP41 within nerve sheath, particularly perineurium, where laminin-421 is predominant. Binding assays with phage expressing NP41 confirmed binding to purified laminin-421, laminin-211, and laminin-α4. Affinity for these extracellular matrix proteins explains the striking ability of NP41 to highlight degenerated nerve “ghosts” months posttransection that are invisible to the unaided eye but retain hollow laminin-rich tubular structures.

Heather L. Glasgow

^aDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92093;

Michael A. Whitney

^aDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92093;

Larry A. Gross

^bHoward Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093;

Beth Friedman

^aDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92093;

Stephen R. Adams

^aDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92093;

Jessica L. Crisp

^bHoward Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093;

Timon Hussain

^cDivision of Otolaryngology–Head and Neck Surgery, University of California, San Diego, La Jolla, CA 92093;

Andreas P. Frei

^dInstitute of Molecular Systems Biology at the Department of Health Sciences and Technology, CH-8093 Zurich, Switzerland;

Karel Novy

^dInstitute of Molecular Systems Biology at the Department of Health Sciences and Technology, CH-8093 Zurich, Switzerland;

Bernd Wollscheid

^dInstitute of Molecular Systems Biology at the Department of Health Sciences and Technology, CH-8093 Zurich, Switzerland;

Quyen T. Nguyen

^cDivision of Otolaryngology–Head and Neck Surgery, University of California, San Diego, La Jolla, CA 92093;

Roger Y. Tsien

^aDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92093;

^bHoward Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093;

^eDepartment of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093

C1q TNF Related Protein 3 (CTRP3) is a member of a family of secreted proteins that exert a multitude of biological effects throughout the body. Our initial work shows promise in the development of CTRP3-induced cellular processes as a means to combat nonalcoholic fatty liver disease (NAFLD). Clinically, NAFLD is defined as the excessive accumulation of fat in the liver, usually due to obesity, and NAFLD effects 1 in 10 Americans. Our previous data show that when high fat fed mice are treated with CTRP3 they are protected from developing NAFLD. However, the mechanism for this effect remains unclear. The purpose of this project was to identify the unknown receptor that mediates the hepatic actions of CTRP3.

Jonathan M Peterson, Health Sciences, East Tennessee State University, Johnson City, TN

This abstract is from the Experimental Biology 2016 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

How different organs in the body sense growth perturbations in distant tissues to coordinate their size during development is poorly understood. Here we mutate an invertebrate orphan relaxin receptor gene, the Drosophila Leucine-rich repeat-containing G protein-coupled receptor 3 (Lgr3), and find body asymmetries similar to those found in INS-like peptide 8 (dilp8) mutants, which fail to coordinate growth with developmental timing. Indeed, mutation or RNA intereference (RNAi) against Lgr3 suppresses the delay in pupariation induced by imaginal disc growth perturbation or ectopic Dilp8 expression. By tagging endogenous Lgr3 and performing cell type-specific RNAi, we map this Lgr3 activity to a new subset of CNS neurons, four of which are a pair of bilateral pars intercerebralis Lgr3-positive (PIL) neurons that respond specifically to ectopic Dilp8 by increasing cAMP-dependent signalling. Our work sheds new light on the function and evolution of relaxin receptors and reveals a novel neuroendocrine circuit responsive to growth aberrations.

Andres Garelli, Fabiana Heredia, Andreia P. Casimiro, Andre Macedo, Catarina Nunes, Marcia Garcez, Angela R. Mantas Dias, Yanel A. Volonte, Thomas Uhlmann, Esther Caparros, Takashi Koyama & Alisson M. Gontijo