About BGN / Biglycan:
Biglycan is an SLRP or small leucine-rich repeat proteoglycan. It is found in various tissues, including cartilage, tendon, and bone. Due to its impact, Biglycan (BGN) is of particular relevance to conditions affecting humans, notably osteoporosis and atherosclerosis.
BGN Function
It is believed that Biglycan plays a significant role in bone mineralization. Studies have shown that when BGN is suppressed in mice, osteoporosis-like results occur, including lower bone mass and reduced growth rate.
Biglycan Mechanism
Biglycan core proteins impact mineralization by binding to growth factors BMP-4. Following this, Biglycan affects the bioactivity of BMP-4. It has been suggested that Biglycan must be present in order for growth factors BMP-4 to affect osteoblasts. Additionally, some evidence suggests that BGN also binds to Transforming growth factor beta 1 (TGF Beta 1).
Biglycan also binds with lipoproteins in human blood vessels and can, therefore, play a significant role in the development of atherosclerosis.
BGN Interactions
Both the core proteins and GAG chains of Biglycan interact with collagen. It is believed that Biglycan interacts less strongly with collagen type 1 than collagen type 2, and also that the small leucine-rich repeat proteoglycan will compete with decorin in order to bind with collagen. Studies have also shown that Biglycan interacts with Alpha-sarcoglycan (SGCA).
Biglycan Structure
Biglycan consists of two glycosaminoglycan (GAG) chains and a protein core, which contains leucine-rich repeat regions. The GAG chains are comprised of either dermatan sulfate (DS) or chondroitin sulfate (CS), although DS is more common when BGN is present in connective tissues. In human Biglycan, GAG chains are connected at amino acids 5 and 10.