Elastic fibres are essential for normal physiology in numerous tissues, including arteries, lungs and skin. Fibulin-4 is an elastic-fibre-associated glycoprotein that is indispensable for elastic-fibre formation in mice. However, the mechanism by which fibulin-4 executes this function remains to be determined. Here, we established an in vitro functional assay system in which fibulin-4 was knocked down in human foreskin fibroblasts using siRNA (small interfering RNA) technology. With two different siRNAs, substantial knockdown of fibulin-4 was achieved, and this suppression was associated with impaired elastic-fibre formation by the fibroblasts. Real-time reverse transcription-PCR analysis showed that knockdown of fibulin-4 expression was accompanied by reduced expression of tropoelastin mRNA. Further analysis showed that this decrease was caused by transcriptional down-regulation of tropoelastin. This effect was selective, since the mRNA level of other elastic-fibre-associated proteins, including fibrillin-1, lysyl oxidase and lysyl oxidase-like-1, was not affected.Moreover, addition of conditionedmedium from cultures of CHO (Chinese-hamster ovary) cells overexpressing fibulin-4 stimulated tropoelastin expression and elastic-fibre formation in cultures of Williams-Beuren-syndrome fibroblasts. Knocking down or knocking out fibulin-4 in mice led to a decrease in tropoelastin expression in the aorta. These results indicate that fibulin-4, considered as a structural protein, may also participate in regulating elastic-fibre formation in human cells through an unanticipated mechanism, namely the regulation of tropoelastin expression.

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Keywords CHO cell, Cell culture, Cricetinae, Cricetulus, Elastic-fibre formation, Elastin, Extracellular-matrix protein, Fibers, Fibroblasts, Fibulin-4, Glycoproteins, Human foreskin fibroblast, Mus, Nucleic acids, RNA, Tissue, Transcription, Tropoelastin gene, Williams Beuren syndrome, amino acid sequence, animal, animal cell, animal embryo, animal tissue, aorta, article, cell culture, child, controlled study, culture medium, down regulation, elastic fiber, elastic tissue, embryo, female, fibrillin 1, fibroblast, fibroblast culture, fibulin, gene expression regulation, gene function, gene interaction, gene overexpression, genetics, hamster, human, human cell, human tissue, in vitro study, male, messenger RNA, metabolism, molecular genetics, mouse, mouse mutant, nonhuman, nucleotide sequence, physiology, prepuce, preschool child, priority journal, protein lysine 6 oxidase;, real time polymerase chain reaction, scleroprotein, small interfering RNA, tissue distribution, transcription regulation, tropoelastin, unclassified drug
Persistent URL dx.doi.org/10.1042/BJ20090993, hdl.handle.net/1765/17821
Journal Biochemical Journal
Chen, Q, Zhang, T, Roshetsky, J.F, Ouyang, Z, Essers, J, Fan, C, … Dicorleto, P.E. (2009). Fibulin-4 regulates expression of the tropoelastin gene and consequent elastic-fibre formation by human fibroblasts. Biochemical Journal, 423(1), 79–89. doi:10.1042/BJ20090993