An intracellular VHH targeting the Luteinizing Hormone receptor modulates G protein-dependent signaling and steroidogenesis

• Published in: Molecular and cellular endocrinology 2024-08, Vol.589, p.112235, Article 112235
• Main Authors: Gauthier, Camille, Raynaud, Pauline, Jean-Alphonse, Frédéric, Vallet, Amandine, Vaugrente, Océane, Jugnarain, Vinesh, Boulo, Thomas, Gauthier, Christophe, Reiter, Eric, Bruneau, Gilles, Crépieux, Pascale
• Format: Article
• Language: English
• Subjects: Animals; Cell signaling; Cyclic AMP - metabolism; G protein-coupled receptor; GTP-Binding Proteins - metabolism; HEK293 Cells; Humans; Intracellular VHH; LHR; Life Sciences; Luteinizing Hormone - metabolism; Progesterone - metabolism; Protein Binding; Receptors, FSH - genetics; Receptors, FSH - metabolism; Receptors, LH - genetics; Receptors, LH - metabolism; Reproduction; Signal Transduction - drug effects; Steroidogenesis; Steroids - biosynthesis; Steroids - metabolism; Testosterone - biosynthesis; Testosterone - metabolism
• ISSN: 0303-7207; 1872-8057; 1872-8057; 0303-7207
• DOI: 10.1016/j.mce.2024.112235

Luteinizing hormone (LH) is essential for reproduction, controlling ovulation and steroidogenesis. Its receptor (LHR) recruits various transducers leading to the activation of a complex signaling network. We recently identified iPRC1, the first variable fragment from heavy-chain-only antibody (VHH) interacting with intracellular loop 3 (ICL3) of the follicle-stimulating hormone receptor (FSHR). Because of the high sequence similarity of the human FSHR and LHR (LHCGR), here we examined the ability of the iPRC1 intra-VHH to modulate LHCGR activity. In this study, we demonstrated that iPRC1 binds LHCGR, to a greater extent when the receptor was stimulated by the hormone. In addition, it decreased LH-induced cAMP production, cAMP-responsive element-dependent transcription, progesterone and testosterone production. These impairments are not due to Gs nor β-arrestin recruitment to the LHCGR. Consequently, iPRC1 is the first intra-VHH to bind and modulate LHCGR biological activity, including steroidogenesis. It should help further understand signaling mechanisms elicited at this receptor and their outcomes on reproduction. [Display omitted] •°Functional characterization of a VHH targeting the LHR 3rd intracellular loop.•°Involvement of ICL3 in the cAMP response.•°Involvement of ICL3 in steroidogenesis in Leydig cells.