KLK1

Tissue kallikrein 1 (KLK1) is a serine protease primarily involved in the proteolytic release of vasoactive kinins, such as bradykinin, from precursor proteins in endothelial cells^[1]. Mechanistically, KLK1 mediates vascular relaxation through the activation of bradykinin-dependent pathways, contributing to local cardiovascular regulation^[1]. KLK1 expression is inducible in endothelial cells by angiotensin II, demonstrating its role in adaptive vascular responses^[1]. In disease contexts, KLK1 administration enhances spermatogenesis recovery in busulfan-induced azoospermic mice, promoting proliferation of spermatogonial stem cells via ERK1/2 and cell cycle protein activation^[2]. Transcriptomic analyses indicate that KLK1 is upregulated in high-altitude polycythemia, implicating it in hypertension and inflammatory responses through interactions with cholesterol^[3]. Compared with other kallikrein family members, KLK1 possesses a distinctive endothelial and renal expression profile, with unique local effects on vasodilation and reproductive tissue regeneration^[4][1][2]. Functionally, KLK1 serves as both a physiological regulator of vascular tone and a potential experimental target for reproductive and cardiovascular disease models^[1][2][3]. Pharmacologically, KLK1 activity can be modulated using specific inhibitors or recombinant protein administration, facilitating experimental investigation of its role in vivo^[1][2].