Poster Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Angiotensin II receptor type 1 (AT1) and the lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) form a heteromer with altered downstream pharmacology   (128666)

Julyan Tan 1 2 , Elizabeth Johnstone 1 2 , Kevin Pfleger 2 3
  1. University of Western Australia, Perth, WA, Australia
  2. Harry Perkins Institute of Medical Research, Perth, WA, Australia
  3. Dimerix Limited, Melbourne, VIC, Australia

Angiotensin II (Ang II) is a regulatory hormone that acts upon its type 1 and 2 receptors (AT1;AT2) in the renin-angiotensin system (RAS). The Ang II-AT1 axis is directly linked to the development of atherosclerosis – the formation of plaques in the arteries – which underpins many cardiovascular diseases.[1] The lectin-like oxidized low-density lipoprotein (OxLDL) receptor-1 (LOX-1) is a key receptor that mediates the uptake of modified lipoproteins leading to plaque formation.[2] The AT1 receptor is a G protein-coupled receptor (GPCR), while LOX-1 is a scavenger receptor; despite this difference, the receptors share significant signalling interplay. Interestingly, GPCRs may form heteromers with non-GPCR partner receptors to induce changes to their pharmacology, signalling and intracellular trafficking.[3,4]. Studies suggest the AT1 receptor heteromerises with LOX-1, leading to changes in their receptor biology with implications for atherosclerosis, including the action of Ang II.[4]

The present study aimed to demonstrate evidence of heteromerisation between the AT1 receptor and LOX-1, and investigate novel signalling using the Receptor-Heteromer Investigation Technology (Receptor-HIT) assay.[5] Receptor-HIT detects heteromers through ligand-induced recruitment of interacting proteins to the heteromer complex. In the present study, bioluminescence resonance energy transfer (BRET) techniques were employed to measure such recruitment.[6] By co-expressing one luciferase-labelled receptor and one unlabelled receptor, in addition to a fluorophore-labelled interacting protein, Receptor-HIT detects a BRET signal upon treatment with a ligand specific for the unlabelled receptor. This indicates recruitment of the interacting protein to the receptor heteromer, providing insights into pharmacological changes such as altered G protein signalling.

It was found that AT1 produced Receptor-HIT signals indicative of heteromerisation when co-transfected with LOX-1, and various signalling proteins. Additionally, AT1 and LOX-1 co-transfection selectively altered some of the downstream signalling properties of the receptors. These findings demonstrate the existence of the AT1-LOX-1 heteromer, and support novel signalling changes related to atherogenesis.

  1. Pacurari, Maricica et al. (2014). The Renin-Angiotensin-aldosterone system in vascular inflammation and remodeling. International journal of inflammation.
  2. Kattoor, Ajoe John et al. (2019). LOX-1: Regulation, Signaling and Its Role in Atherosclerosis. Antioxidants.
  3. Pickering, Raelene J et al. (2019). Transactivation of RAGE mediates angiotensin-induced inflammation and atherogenesis. The Journal of clinical investigation
  4. Takahashi, Toshimasa et al. (2021). The endocytosis of oxidized LDL via the activation of the angiotensin II type 1 receptor. iScience.
  5. Johnstone, Elizabeth K M, and Kevin D G Pfleger. (2012). Receptor-Heteromer Investigation Technology and its application using BRET. Frontiers in endocrinology
  6. Pfleger, Kevin D G, and Karin A Eidne. (2006). Illuminating insights into protein-protein interactions using bioluminescence resonance energy transfer (BRET). Nature methods.