The characteristics of elastic fiber assembled with recombinant tropoelastin isoform

Objective: It is known that elastin mRNA is transcribed from a single gene. The variety of tropoelastin isoforms results from multiple alternative splicing of the primary transcript. The purpose of this study was to investigate the characteristics of elastic fiber assembled with tropoelastin isoform, which is full-length human tropoelastin (HTE), exon 26A missing tropoelastin (Δ26A), and exon 32 missing tropoelastin (Δ32). Design and methods: We demonstrated the process of elastic fiber assembly and the existence of elastic fiber resistant to pancreatic elastase with HTE, Δ26A, or Δ32 fiber using an in vitro model of elastic fiber assembly. These elastic fibers were evaluated by immunofluorescent staining, the quantitative analysis of cross-linked amino acids, and semi-quantitative analysis of matrix-associated tropoelastin. Results: There were no big differences getting into the matrix among these tropoelastins in immunofluorescence microscopy and semi-quantitative analysis. In the comparison with the HTE, the Δ26A and the Δ32 significantly increased and decreased, respectively, the formation of cross-linking amino acids and the binding to scaffold proteins. Furthermore, it was found that it is difficult to degrade the Δ26A assembly with pancreatic elastase as compared with HTE or Δ32 assembly. Conclusion: The elastic fiber assembled with the tropoelastin isoforms was characterized using an in vitro model. The present study provides important information regarding the pathology of human diseases including emphysema and atherosclerosis.