elastin and Bone-Diseases

The elastic properties of many tissues such as the lung, dermis, and large blood vessels are due to the presence of elastic fibers in the extracellular space. These fibers have been shown by biochemical and ultrastructural analysis to be comprised of two distinct components, a more abundant amorphous component and the microfibrillar component. The microfibrillar component is found in 10- to 12-nm fibrils which are located primarily around the periphery of the amorphous component but, to some extent, interspersed within it. The protein, elastin, makes up the highly insoluble amorphous component and is responsible for the elastic properties. Elastin is found throughout the vertebrate kingdom except for very primitive fish and possesses an unusual chemical composition consonant with its characteristic physical properties. Elastin is composed largely of glycine, proline, and other hydrophobic residues and contains multiple lysine-derived cross-links, such as the desmosines, which link the individual polypeptide chains into a rubber-like network. The intervening, hydrophobic regions of the polypeptide chains between the cross-links are highly mobile, and the elastic properties of the fibers can be described in terms of the theory of rubber elasticity. Recent application of recombinant DNA techniques has led to further understanding of the structure of elastin. Analyses of the bovine and human elastin genes have demonstrated that the hydrophobic and cross-linking domains are encoded in separate exons. These exons tend to be small, varying from 27 to 114 base pairs, and are separated by large intervening sequences. Furthermore, DNA sequence analysis has demonstrated that the elastin molecule contains two cysteine residues which were not previously identified near the carboxy terminus and which may be important in the interaction of elastin with other extracellular matrix proteins. Further DNA sequencing should determine the complete amino acid sequence of elastin. Biosynthetic studies and in vitro translation of elastin mRNA have demonstrated that a 72,000-dalton polypeptide, designated tropoelastin, is the initial translation product. Analysis of several developing systems has demonstrated that elastin synthesis is controlled by the level of elastin mRNA. After packaging into membrane-bound vesicles in the Golgi apparatus, tropoelastin is secreted by exocytosis into the extracellular space where it is cross-linked by a copper-requiring extracellular enzyme, lys

Topics: Amino Acid Sequence; Amino Acids; Animals; Aorta; Base Sequence; Biological Evolution; Bone Diseases; Chemical Phenomena; Chemistry; Cutis Laxa; DNA; Elastin; Genes; Genetic Diseases, Inborn; Humans; Lung Diseases, Obstructive; Macromolecular Substances; Marfan Syndrome; Microscopy, Electron; Protein-Lysine 6-Oxidase; Pseudoxanthoma Elasticum; RNA, Messenger; Species Specificity; Syndrome; Tropoelastin; Vascular Diseases

Copper, as a component of numerous cuproenzymes, plays a vital role in many physiologic functions in man and animals. From the stand-point of human health there are at least three functional areas of prime importance. Copper is involved in the development and maintenance of cardiovascular and skeletal integrity, central nervous system structure and function, and erythropoietic function including iron metabolism. Although there is no evidence for widespread copper deficiency in the human population, it does occur, owing to genetic defects and other precipitating factors. A clear understanding of the functions of copper and its mechanisms of action could prove highly beneficial in the solution of present and unforeseen problems in medicine.

Topics: Anemia; Animals; Bone Diseases; Brain Diseases; Cardiovascular Diseases; Central Nervous System Diseases; Collagen; Copper; Deficiency Diseases; Elastin; Enzymes; Female; Growth Disorders; Hair; Humans; Infant; Infant, Newborn; Metalloproteins; Pigmentation Disorders; Pregnancy; Pregnancy Complications; Protein-Lysine 6-Oxidase

Topics: Abnormalities, Drug-Induced; Amino Acid Oxidoreductases; Aminopropionitrile; Aneurysm; Animals; Aortic Aneurysm; Blood Vessels; Bone and Bones; Bone Diseases; Cleft Palate; Collagen; Connective Tissue; Elastin; Fetus; Heart Defects, Congenital; Humans; Kyphosis; Lathyrism; Lysine; Neurologic Manifestations; Nitriles; Poultry Diseases; Rodent Diseases; Spinal Cord; Spinal Cord Diseases; Stomach; Turkeys

Topics: Aging; Aldehydes; Animals; Bone Diseases; Collagen; Connective Tissue; Elastin; Lathyrism; Lysine; Peptide Biosynthesis; Pyridinium Compounds

Topics: Animals; Bone Diseases; Cardiovascular Diseases; Catalysis; Collagen; Connective Tissue; Copper; Deficiency Diseases; Elastic Tissue; Elastin; Female; Fibroblasts; Glycosaminoglycans; Growth; Humans; Nutritional Physiological Phenomena; Osteogenesis; Pregnancy

Topics: Abnormalities, Drug-Induced; Aminopropionitrile; Aneurysm; Animals; Arteriosclerosis; Bone Diseases; Collagen; Elastin; Female; Humans; Joint Diseases; Lathyrism; Paralysis; Pregnancy; Wound Healing