The relaxin receptor RXFP1 signals through a mechanism of autoinhibition

Erlandson, S. C.; Rawson, S.; Brock, K. P.; Liu, X.; Paulo, J. A.; Mintseris, J.; Gygi, S. P.; Marks, D. S.; Cong, X.; Kruse, A. C.

doi:10.1101/2022.01.22.477343

bioRxiv · 10.1101/2022.01.22.477343

The relaxin receptor RXFP1 signals through a mechanism of autoinhibition

Erlandson, S. C.·Rawson, S.·Brock, K. P.·Liu, X.·Paulo, J. A.·Mintseris, J.·Gygi, S. P.·Marks, D. S.·Cong, X.·Kruse, A. C.

View original source ↗Export metadata ↓

Abstract

The relaxin family peptide receptor 1 (RXFP1) is the receptor for relaxin-2, an important regulator of reproductive and cardiovascular physiology. RXFP1 is a multi-domain G protein-coupled receptor (GPCR) with an ectodomain consisting of an LDLa module and leucine-rich repeats. The mechanism of RXFP1 signal transduction is clearly distinct from that of other GPCRs, but remains very poorly understood. Here, we present the cryo-electron microscopy structure of active-state human RXFP1, bound to a single-chain version of the endogenous agonist relaxin-2 and to the heterotrimeric Gs protein. Evolutionary coupling analysis and structure-guided functional experiments reveal that RXFP1 signals through a mechanism of autoinhibition, wherein the receptors extracellular loop 2 occupies the orthosteric site in the active state but is inhibited by the ectodomain in the absence of relaxin-2. Our results explain how an unusual GPCR family functions, providing a path to rational drug development targeting the relaxin receptors.

Explore related subjects

pharmacology and toxicology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Erlandson, S. C., Rawson, S., Brock, K. P., Liu, X., Paulo, J. A., Mintseris, J., Gygi, S. P., Marks, D. S., Cong, X., Kruse, A. C.. 2022-01-23. The relaxin receptor RXFP1 signals through a mechanism of autoinhibition. https://doi.org/10.1101/2022.01.22.477343

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Lipid-ASO therapeutics exhibit differential tissue targeted delivery upon systemic or local CNS administration

Antisense oligonucleotides (ASOs) are a powerful therapeutic modality, but their full potential is hindered by pharmacokinetic properties that affect tissue and cellular delivery. Lipid conjugation is increasingly used to modulate ASO's biodistribution and promote extrahepatic activity, yet lipid dependent effects on in vivo functional delivery, particularly in the central nervous system (CNS), remain less explored. Here, we performed a side by side in vivo comparison of cholesterol, palmitic acid (C16:0), docosanoic acid (C22:0), and eicosapentaenoic acid (C20:5) conjugated to a fully phosphorothioated 3 10 3 LNA gapmer ASO targeting the Malat1 long non coding RNA. Lipid-ASO conjugates were administered systemically or locally in the brain of mice and evaluated for tissue level and cellular level distribution by imaging, qPCR and single-cell RNA sequencing, simultaneously annotating cell origin and global transcriptional changes within the cell. Following systemic administration in mice, lipid conjugation improved overall multi organ efficacy compared to unconjugated ASO, but with pronounced tissue specific differences. Single cell sequencing of liver and heart transcriptomes revealed lipid dependent cellular uptake patterns and transcriptional responses distinct from administration of unconjugated ASO. After intracerebroventricular administration, selected fatty acid conjugates enhanced silencing in deep brain regions such as the striatum, whereas cholesterol conjugation impaired functional delivery despite increased CNS retention. Light-sheet microscopy showed restricted parenchymal penetration of cholesterol ASOs compared with broader but heterogeneous distribution of palmitic acid conjugate. Together, these findings demonstrate that lipid identity critically determines ASO efficacy, productive cellular uptake, and regional CNS engagement, emphasizing the need for context specific lipid design in ASO therapeutic development.

pharmacology and toxicology↗

bioRxiv2026

Novel Dissymmetric Ionizable Lipid-Assembled Lipid Nanoparticles for Delivery of Ferroptosis-Related siRNA in Diabetic Treatment

Small interfering RNA (siRNA) enables precise post-transcriptional gene silencing for refractory diseases, yet its clinical translation remains limited by the lack of safe and efficient delivery vectors. Inspired by the dissymmetric alkyl chain architecture of natural membrane phospholipids, we designed and synthesized 34 novel ionizable lipids with dissymmetric hydrophobic tails and formulated them into lipid nanoparticles (LNPs). Through systematic physicochemical and biological assessments, we established clear structure-activity relationships and identified two lead LNPs (O14-LNP, H18a-LNP) with superior endosomal escape capacity, enhanced in vivo gene silencing potency, and favorable biosafety relative to the clinical benchmark MC3-LNP. In both streptozotocin-induced and spontaneous db/db type 2 diabetes (T2D) mouse models, lead LNPs delivering ferroptosis-related siRNAs effectively ameliorated glucose and lipid metabolic disorders, restored islet function, and alleviated hepatic steatosis. This study not only lays a theoretical foundation for the rational design of novel ionizable lipids, but also validates the therapeutic potential of siRNA therapy targeting ferroptosis, providing a versatile delivery platform and targeted therapeutic strategy for the treatment of T2D.

pharmacology and toxicology↗

bioRxiv2022

Analysing the role of SERPINE1 network in the pathogenesis of human glioblastoma

BackgroundGlioblastoma multiforme (GBM) is one of the most aggressive and difficult to treat brain tumour in humans with a 5 year survival rate of less than 6%. SERPINE1 is a novel tumour receptor found on GBM that modulates the progression of this cancer through growth signals and remodelling of the extracellular matrix. Hence, we investigated the role of SERPINE1 and its network proteins in pathogenesis of GBM and assessed its targetability. Material and methodsNetwork proteins of SERPINE1 in homo sapiens was identified using the String database, and the affinity of the protein-protein interaction of this network was analysed using Chimera software. The expression profile of SERPINE1 in the different brain regions was evaluated to correlate its relevance to GBM pathology. Selected small molecules from Calotropis gigantea were screened using AutoDock vina to assess targetability of human SERPINE1. ResultsVTN, PLG, TGFB1, VWF, FGF2 and CXCR1 were identified as the major network proteins of SERPINE1. The strongest interaction was observed between SERPINE1 and FGF2 (42884 H-bonds) followed by CXCR1 (20279 H-bonds). Our results suggest that SERPINE1 and its network proteins identified here play a vital role in GBM development and progression through brain parenchyma by creating the prime microenvironment for carcinogenesis, tumour invasion and migration. The highest expression of SERPINE1 was observed in the pons, medulla, midbrain, corpus callosum and spinal cord. Expression of SERPINE1 was consistent with high grade lesions of GBM, suggesting association of SERPINE1 with advanced stages of GBM. The selected small molecules from Calotropis gigantea were observed to have therapeutically feasible binding affinity (140 - 550 M) and predicted efficacy (290 - 1115 M) against human SERPINE1. ConclusionSERPINE1 plays a vital role in the progression of GBM through its critical network proteins identified in this study. The expression of SERPINE1 aligns with the advanced stages of GBM. Small molecules from Calotropis gigantea tested in this study can serve as lead compounds for developing novel anti-SERPINE1 therapeutics for advanced stages of GBM.

pharmacology and toxicology↗