Catipepsinas

Catipepsinas, commonly referred to as cathepsins in English, are a family of proteolytic enzymes, primarily lysosomal cysteine proteases belonging to the C1 family. They are widely distributed in animal tissues and participate in the degradation of proteins delivered to lysosomes, helping to recycle amino acids and maintain cellular homeostasis. Most cathepsins operate best in the acidic environment of lysosomes, although some can be secreted or function in endosomes and, under certain conditions, in the extracellular space.

Physiological roles of cathepsins include intracellular protein turnover, remodeling of proteins within the endolysosomal system, and involvement in antigen processing for immune presentation. For example, cathepsins such as S and L contribute to the processing of antigens for MHC class II molecules, while others like B and L participate in general protein turnover and cellular remodeling. Cathepsin K is notable for its high expression in osteoclasts, where it drives bone and dentin resorption.

Dysregulation or mislocalization of cathepsins is associated with various diseases. Elevated cathepsin activity has been linked to cancer invasion and metastasis, inflammatory tissue destruction, osteolysis, and neurodegenerative processes. Cathepsins may be secreted by tumor or stromal cells and can promote extracellular matrix degradation, angiogenesis, and release of growth factors. Their activity is tightly regulated by endogenous inhibitors, notably cystatins, and by cellular localization and maturation pathways.

In research and clinical contexts, cathepsin activity and expression are explored as biomarkers and as potential therapeutic targets. Pharmacological inhibitors and modulators of cathepsins are studied for their potential to treat cancer, osteoporosis, and inflammatory diseases, reflecting the broad relevance of this enzyme family.