Relaxin 1 (RLN1)

Relaxin 1 (RLN1) is an endocrine hormone of the insulin superfamily synthesized as a preprohormone that is processed to a 6 kDa dimer comprised of an A and a B chain linked by disulfide bonds[2][5]. Its canonical action is via activation of the relaxin family peptide receptor 1 (RXFP1), a G protein-coupled receptor[1][2]. RLN1 is predominantly expressed in reproductive tissues such as the prostate, decidua, placenta, and endometrium, with lower levels in the myocardium[2][5]. It plays a key role in reproductive biology, including preparing the birth canal (cervical ripening, pubic symphysis elongation), suppressing uterine contractions, and modulating sperm motility[5][6]. It is also implicated in connective tissue remodeling, blood pressure regulation, heart rate control, and neuroendocrine hormone release[3][5]. In pathology, RLN1 is associated with reproductive disorders, prostate and thyroid neoplasia, germ cell tumors, spermatogenic failure, and may contribute to changes in lung tissue function[3][5]. Therapeutically, RLN1 and its pathway have drawn interest for potential application in heart failure and tissue remodeling, though clinical development is currently experimental with few direct drugs[1][2][4]. The safety profile for interventions targeting RLN1 remains to be fully elucidated, though risks may include effects on connective tissue and hormone-sensitive cancers[3][5].

Other names

Prorelaxin H1Relaxin B chainRelaxin A chainH1 relaxinH1H1RLXRLXH1bA12D24.3.1bA12D24.3.2preprorelaxin H1prorelaxin H1

Activates relaxin family peptide receptor 1 (RXFP1), a G protein-coupled receptor, increases cAMP signaling, activates ERK1/2, MAPK, tyrosine kinases, and nitric oxide pathways, drives tissue remodeling and relaxation responses[1][2][4]