Copper Deficiency and Elastin Metabolism in Avian Lung

Abstract

Copper deficiency in the chick causes anatomical changes in lung that are characterized by an apparent thinning of the air-blood capillary network of tertiary bronchi. Although the net content of the elastin in lung was not changed significantly by nutritional copper deficiency, it was possible to demonstrate an increase in the lysine content and a decrease in the desmosine content of lung elastin from copper-deficient chicks compared to that from controls. Further, the content of soluble elastin was also increased two-to fourfold in lung from copper-deficient chicks. Subsequently, nutritional copper deficiency was used to facilitate the isolation of chick lung tropoelastin. This lung protein appeared to be similar in selected properties to tropoelastin isolated from aorta of copper-deficient chicks. In addition, data are presented that indicate elastin in avian lung is possibly subject to only limited turnover.

IS MATERNAL COPPER SUPPLEMENTATION DURING ALVEOLARIZATION PROTECTING THE DEVELOPING RAT LUNG AGAINST THE ADVERSE EFFECTS OF MATERNAL NICOTINE EXPOSURE? A Morphometric Study

“…Lysyl oxidase, a copper-dependent enzyme, plays a central role in the formation of secondary septa and thus lung maturation [14][15][16][17][18]. It can therefore be expected that a decrease in the copper content of the developing lung will result in a slower lung development or that copper supplementation may enhance lung maturation.…”

“…Lysyl oxidase plays a key role in the cross-linking of elastin and the conversion of soluble elastin into insoluble elastin. Copper is an essential component of lysyl oxidase [14,15], and, thus, a deficiency of copper could then be expected to result in a metabolic defect, such as an increase in the soluble component of the protein and a decrease in the insoluble component [16]. Cross-linking of elastin may be crucial in further partitioning of the primitive alveolar sacs during alveolarization, and it has been shown that for some organs, particularly at specific periods of organogenesis (e.g., formation of the aorta or transition from a saccular to an alveolar lung), any impairment of the lysyl oxidase activity is critical [17,18].…”

Elastin metabolism and chemistry: potential roles in lung development and structure.

“…More information is needed to demonstrate that the proposed elastin types do not arise from genetic polymorphisms. With respect to lung, the observations to date (11,33,42) suggest that chick aorta and lung tropoelastin are nearly identical in size and have similar chemical properties and composition (Table 1). There also appear to be close similarities between sheep nuchal ligament and sheep lung elastin (15,41).…”

“…First, it is clear from examination of composition data that 3 to 8% of the total prolyl residues in elastin are hydroxylated (5,33,56). However, unlike collagen the lysyl residues in elastin are not hydroxylated and the hydroxylation of proline does not Figure 2 are indicated.…”

“…Tropoelastin appears to be secreted from cells in the form of a 72,000 molecular weight protein (5,10,11,15,41). This protein has now been isolated from the aorta and ligamentum of various species (1,5,10), and chick lung (33,42). As an example, the composition of tropoelastin isolated from copper-deficient chick lung is given in Table 1.…”