Bioengineered recombinant kisspeptins with extended half-life exhibit novel peripheral function in a large-animal model

Kisspeptins are the small peptide products encoded by the KISS1 gene and physiologically exist in various isoforms of variable length. They are the central regulators of reproduction, being a prominent driver of GnRH hormone secretion. Additionally, they have emerged as an important peripheral therapeutic target for many metabolic diseases like diabetes, obesity, and polycystic ovary syndrome (PCOS). Despite their therapeutic potential, their utility is severely limited by their short half-life. We have rationally bioengineered two versions of native kisspeptins, which we named HSK-1 and HSK-2. HSK-1 (8kDa) and HSK-2 (13kDa) are derived from the fusion of the albumin-binding ZAG domain from Streptococcus zooepidemicus with KP-10 and KP-52 versions of kisspeptins (KPs), respectively. In vitro assays confirmed that the proteins were functionally active and triggered downstream signalling. Molecular dynamics simulations of the proteins revealed their structural features relative to the native kisspeptin isoforms. Both molecules demonstrated stable receptor engagement, and ligand-induced conformational changes were observed, suggesting receptor activation. HSK proteins demonstrated an extended half-life and mostly acted peripherally in young animals. They reduced peripheral luteinizing hormone levels in young animals, likely representing a previously unrecognized mode of peripheral kisspeptin action. Graphical Abstract