Review Question - QID 214035

Decorin is the most predominant proteoglycan found in tendons. It is important in the regulation of collagen fiber diameter and provides cross-links between collagen fibers.

Decorin is a small leucine-rich proteoglycans (SLRPs) found within tendons. It serves as a key regulator of collagen fibril and matrix assembly, is a component of connective tissue, and binds type I collagen fibrils. The collagen within tendons are held together with decorin; in compressed regions of the tendon, aggrecan serves an important role.

Zang et al. reviewed tendon function development of collagen fibrils. They report that in decorin-deficient mice, altered fibril structure and mechanical function significantly reduced strength and stiffness. They also noted that biglycan expression increased substantially in decorin-deficient tendons suggesting a potential functional compensation. They conclude that the accumulation of structural defects during fibril growth may be the cause of compromised mechanical function in the absence of decorin.

Robinson et al. measured the mechanical properties of multiple tendon tissues from normal mice and from mice with knock-outs of the proteoglycans decorin or biglycan. They found that the loss of decorin caused an increase in modulus and stress relaxation in patellar tendons, however, this was not seen in other tendons. They concluded that tendons likely are uniquely tailored to their specific location and function.

Incorrect Answers:
Answer 1: Elastin is a key protein of the extracellular matrix that is highly elastic and present in connective tissue allowing tissues resume their shape after stretching or contracting
Answer 2: Fibronectin is a high-molecular weight glycoprotein that binds to extracellular matrix proteins such as collagen and fibrin and plays a major role in cell adhesion, growth, migration, and differentiation
Answer 3: Fibrillin is a glycoprotein, which is essential for the formation of elastic fibers found in connective tissue
Answer 4: Aggregan is a proteoglycan found in areas of tendon compression