IGF-I

Insulin-like growth factor 1 (IGF-1), also known as somatomedin C, is a protein that in humans is encoded by the IGF1 gene. IGF-1 has a similar molecular structure to insulin. It plays an important role in childhood growth and continues to have anabolic effects in adults.

Structure

IGF-1 is a small protein with a molecular weight of approximately 7.6 kDa. It consists of 70 amino acids in a single chain with three intramolecular disulfide bridges. The structure of IGF-1 is similar to that of proinsulin, and it shares a high degree of sequence homology with IGF-2.

Function

IGF-1 is primarily produced in the liver as an endocrine hormone and in target tissues in a paracrine/autocrine fashion. Its production is stimulated by growth hormone (GH), and it mediates many of the growth-promoting effects of GH. IGF-1 binds to the IGF-1 receptor (IGF1R), which is a receptor tyrosine kinase, and initiates a signaling cascade that promotes cell growth, differentiation, and survival.

Role in Growth and Development

IGF-1 is crucial for normal growth and development. It stimulates the proliferation of chondrocytes (cartilage cells), resulting in bone growth. It also plays a role in muscle growth by promoting the differentiation and proliferation of myoblasts. In addition, IGF-1 has neuroprotective effects and is involved in brain development.

Clinical Significance

Abnormal levels of IGF-1 are associated with various medical conditions. Elevated levels of IGF-1 are linked to acromegaly, a condition characterized by excessive growth of bones and tissues. Conversely, low levels of IGF-1 can result in growth failure and short stature, often seen in growth hormone deficiency.

IGF-1 has also been studied for its potential role in aging and longevity. Some studies suggest that lower levels of IGF-1 may be associated with increased lifespan, although the relationship is complex and not fully understood.

Therapeutic Uses

Recombinant IGF-1 is used in the treatment of growth failure in children with severe primary IGF-1 deficiency. It is also being investigated for its potential benefits in muscle wasting diseases, diabetes, and neurodegenerative disorders.

Research

Ongoing research is exploring the role of IGF-1 in cancer, as it can promote cell proliferation and inhibit apoptosis, potentially contributing to tumor growth. The IGF-1 signaling pathway is a target for cancer therapeutics.

Also see

• Insulin-like growth factor 2
• Growth hormone
• Insulin-like growth factor 1 receptor
• Acromegaly
• Growth hormone deficiency

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