Structural and Regulatory Aspects of the Human Genes Encoding IGF-I and -II
Insulin-like growth factors (IGFs) play an important role in regulation of growth. Of the two major forms of IGFs, IGF-I is important for postnatal growth, whereas IGF-II is involved in fetal growth and development. These factors are synthesized in many different tissues and exert their physiological functions probably through an endocrine as well as an autocrine/paracrine mechanism of action. During the last years it has become clear that the autocrine/paracrine mechanism of action is probably more important than originally foreseen. Elegant studies of Han and others have revealed that connective tissues play an important role in production of IGF-I, but that the peptide subsequently accumulates in the adjacent tissues1,2. The hypothesis has been formulated that IGF levels in plasma regulate the overall growth status, while locally produced IGFs are important for cell proliferation in specific tissues (for reviews see 3,4). If this assumption is correct, balanced growth requires that the local production of IGFs is delicately controlled in a tissue-specific manner. We have established the gene structure for human IGF-I and -II and investigated the mechanisms involved in the expression of these genes.
KeywordsChloramphenicol Acetyl Transferase Smooth Muscle Tissue Normal Myometrium Maximal Promoter Activity Malignant Smooth Muscle Tumor
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