Cathepsin L and Cathepsin V (CTSL/CTSV)

Cathepsin L and Cathepsin V (also known as Cathepsin L2) are closely related lysosomal cysteine proteases belonging to the papain family [1, 12]. They play critical roles in intracellular protein degradation, extracellular matrix (ECM) remodeling, and the processing of prohormones and antigens [2, 6]. While Cathepsin L is ubiquitously expressed, Cathepsin V shows more tissue-specific expression in humans, particularly in the thymus, testis, and cornea [1, 2]. These enzymes are significant therapeutic targets due to their involvement in cancer progression, where they facilitate tumor invasion and metastasis by degrading the ECM [11, 18]. Additionally, they are essential for the entry of several viruses, including SARS-CoV-2 and Ebola, by cleaving viral glycoproteins to enable membrane fusion [3, 13]. In cardiovascular health, their dysregulation is linked to hypertension and atherosclerosis, making them targets for protease inhibitors like Relacatib [7, 9, 10].

Other names

Cathepsin L1Cathepsin L2CTSLCTSVMajor Excreted ProteinMEP

Inhibition of cysteine protease activity to prevent the cleavage of physiological and pathological substrates, such as viral glycoproteins, extracellular matrix proteins, and prohormones [3, 4, 13].