TFF3 is a ligand for LINGO2 that de-represses EGFR to control disease outcome during colitis and gastrointestinal nematode infection

Abstract

Intestinal epithelial cells (IEC) comprise diverse lineages that serve distinct roles necessary for regulation of nutrient absorption, regeneration, immunity, and homeostasis 1,2 . Goblet cells secrete Trefoil factor 3 (TFF3) to maintain mucus viscosity and drive mucosal healing by inhibiting cell death and influencing tight junction protein expression 3 . However, whether TFF3 signaling relies upon conventional ligand-receptor interactions has been unclear for decades. This study demonstrates that the orphan transmembrane protein leucine rich repeat receptor and nogo-interacting protein 2 (LINGO2) immunoprecipitates with TFF3, that LINGO2 and TFF3 co-localize at the IEC cell surface, and that TFF3/LINGO2 interactions block IEC apoptosis. Loss of function studies show that TFF3-driven STAT3 and EGFR activation are both LINGO2 dependent. Importantly, we demonstrate that TFF3 disrupts LINGO2/EGFR interactions that normally restrict EGFR activity, resulting in enhanced EGFR signaling. Excessive EGFR activation in Lingo2 gene deficient mice exacerbates colitic disease and accelerates host resistance to parasitic nematodes, whereas TFF3 deficiency results in host susceptibility. Thus, our data demonstrating that TFF3 functions through a previously unrecognized ligandreceptor interaction with LINGO2 to de-repress LINGO2-dependent inhibition of EGFR activation provides a novel conceptual framework explaining how TFF3-mediates mucosal wound healing through enhanced activation of the EGFR pathway.3 Although Trefoil factor 3 (TFF3) is well known to drive reparative pathways at respiratory, ocular, genitourinary and gastrointestinal mucosa, the identity of a potential TFF3 receptor has remained elusive for several decades 4-8 . In addition to enhancing mucous viscosity 9 , TFF3 induces epithelial cell survival and proliferation, activates EGFR, β-catenin, and STAT3 signaling pathways, and controls tight junction protein expression through ill-defined mechanisms to protect against gastrointestinal (GI) tissue injury and inflammation 3,10 . Since the anti-inflammatory activity of TFF3 suggested that leukocytes may be directly responsive to TFF3, we utilized a human macrophage/monocyte cell line (U937) to first ask whether cytokine release could be regulated in response to rTFF3 exposure in order to isolate the TFF3 receptor. We found that rhTFF3 caused a dose-dependent reduction in endotoxin-mediated TNF release over a range of 1-100 ng/ml and that TFF3 suppression was lost at a higher range of rhTFF3 (100-1000 ng/ml) ( Figure S1A). TFF3-induced interleukin 10 (IL-10) production was found over several orders of magnitude, but was lost at higher doses of rhTFF3 ( Figure 1A). As the dose response is similar to the established range of activity for most cytokine and growth factor receptors 11 , these observations suggested that TFF3 was interacting with a receptor in a conventional manner.TFF3 was likely to interact with its receptor through low-affinity interactions because glycosylation has been shown critical for biological...

Inhibition of TFF3 Enhances Sensitivity—and Overcomes Acquired Resistance—to Doxorubicin in Estrogen Receptor-Positive Mammary Carcinoma

“…TFF3 has been reported to bind LINGO2 [34], CXCR4/7 and other as yet unidentified receptors [35]. In addition, TFF3 indirectly activates other receptors including the HER family of tyrosine kinases and insulin-like growth factor receptor 1 (IGFR1) [32], triggering a multitude of downstream pathways, namely the mitogen-activated protein kinase (MAPK) [36,37], Janus kinase/signal transducers and activators of transcription (JAK/STAT3) [37,38], and phosphatidylinositol-3-Kinase (PI3K)/AKT [39,40].…”