Polycystin 2

Polycystin 2, also known as PC2, is a protein that in humans is encoded by the PKD2 gene. It plays a crucial role in the function of cellular structures called cilia, which are hair-like projections on the surface of cells. Polycystin 2 is particularly significant in the context of polycystic kidney disease (PKD), a genetic disorder characterized by the growth of numerous cysts in the kidneys.

Function

Polycystin 2 functions as a calcium-permeable ion channel on the membrane of cellular organelles and the plasma membrane. It is involved in the regulation of intracellular calcium concentration, which is essential for various cellular processes including cell division, cell differentiation, and apoptosis (programmed cell death). Polycystin 2, together with polycystin 1, is thought to play a role in the mechanosensation process of the primary cilia, sensing fluid flow within the kidney nephron.

Genetic Association

Mutations in the PKD2 gene are responsible for approximately 15% of cases of autosomal dominant polycystic kidney disease (ADPKD), making it the second most common gene associated with this condition after PKD1. ADPKD is characterized by the development of numerous fluid-filled cysts in the kidneys, leading to enlarged kidneys and kidney failure in many cases. The PKD2 mutations are generally associated with a milder disease progression compared to PKD1 mutations.

Clinical Significance

Understanding the function of polycystin 2 and its role in ADPKD has been crucial for the development of potential therapeutic strategies. Research into polycystin 2 has also shed light on the broader significance of cilia in human health and disease, contributing to the emerging field of ciliopathies, a group of disorders caused by dysfunction of cilia.

Research Directions

Current research on polycystin 2 includes studies aimed at understanding its precise mechanism of action, its interaction with polycystin 1, and the pathways leading from gene mutation to the development of kidney cysts. There is also ongoing research into developing targeted therapies that can modulate the function of polycystin 2 or its pathways to treat or prevent the progression of ADPKD.

See Also

• Polycystic kidney disease
• Cilia
• Ion channel
• Calcium in biology