Glandular kallikrein

Glandular kallikrein is a group of enzymes belonging to the serine protease family, specifically within the S1 family of peptidases (clan PA(S)). These enzymes are known for their role in the processing of various proteins and peptides, including the activation of hormones and other bioactive peptides. Glandular kallikreins are encoded by the KLK genes in humans and are expressed in a wide range of tissues, including the salivary glands, pancreas, and kidneys.

Function

Glandular kallikreins play a crucial role in physiological processes such as blood pressure regulation, inflammation, and wound healing. They achieve this by cleaving kininogen to release kinins, peptides that are involved in vasodilation and increased vascular permeability. Additionally, these enzymes are implicated in the processing of prohormones, thereby influencing various hormonal pathways.

Classification

The human kallikrein-related peptidase (KLK) family consists of 15 members, ranging from KLK1 to KLK15. Each member exhibits unique expression patterns and substrate specificities, contributing to diverse physiological functions. The most well-known member, KLK3, also known as prostate-specific antigen (PSA), is used clinically as a biomarker for prostate cancer screening and monitoring.

Clinical Significance

Beyond their physiological roles, alterations in glandular kallikrein expression and activity have been associated with various diseases. Overexpression or dysregulation of certain KLKs has been linked to cancer progression, particularly in prostate, ovarian, and breast cancers. Consequently, some KLKs are being investigated as potential biomarkers for cancer diagnosis and prognosis, as well as targets for therapeutic intervention.

Research Directions

Current research on glandular kallikreins focuses on elucidating their precise roles in health and disease, improving the sensitivity and specificity of KLK-based diagnostic tests, and developing inhibitors that can modulate their activity for therapeutic purposes. Understanding the complex interplay between different KLKs and their substrates is crucial for unlocking their potential in clinical applications.