elastin and Gangliosidosis--GM1

In this report we demonstrate that soluble peptides, elastin degradation products stimulate proliferation of arterial smooth muscle cells. We show that these effects are due to generation of intracellular signals transduced through the cell surface elastin receptor, which consists of peripheral 67-kDa elastin-binding protein (EBP) (spliced variant of beta-galactosidase), immobilized to the transmembrane sialidase and the protective protein. We found that elastin receptor-transduced signaling triggers activation of G proteins, opening of l-type calcium channels, and a sequential activation of tyrosine kinases: FAK, c-Src, platelet-derived growth factor-receptor kinase and then Ras-Raf-MEK1/2-ERK1/2 phosphorylation cascade. This, in turn, causes an increase in expression of cyclins and cyclin-dependent kinases, and a consequent increase in cellular proliferation. The EBP-transduced signals also induce tyrosine kinase-dependent phosphorylation of beta-tubulin, LC3, microtubule-associated protein 1, and alpha-actin and troponin-T, which could be linked to reorganization of cytoskeleton. We have also disclosed that induction of these signals can be abolished by anti-EBP antibody or by galactosugars, which cause shedding of EBP from the cell surface. Moreover, elastin-derived peptides did not induce proliferation of EBP-deficient cells derived from patients bearing a nonsense mutation of the beta-galactosidase gene or sialidase-deficient cells from patients with congenital sialidosis.

Topics: Animals; Arteries; Calcium; Calcium Channel Blockers; Cell Division; Cells, Cultured; CSK Tyrosine-Protein Kinase; Culture Media, Serum-Free; Cyclin-Dependent Kinases; Cyclins; Elastin; Enzyme Inhibitors; Fibroblasts; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; Gangliosidosis, GM1; Humans; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Models, Biological; Mucolipidoses; Muscle, Smooth, Vascular; Nisoldipine; Peptides; Pertussis Toxin; Phosphorylation; Protein-Tyrosine Kinases; Receptors, Cell Surface; Signal Transduction; src-Family Kinases; Swine; Tyrosine

We have previously shown that intracellular trafficking and extracellular assembly of tropoelastin into elastic fibers is facilitated by the 67-kD elastin-binding protein identical to an enzymatically inactive, alternatively spliced variant of beta-galactosidase (S-Gal). In the present study, we investigated elastic-fiber assembly in cultures of dermal fibroblasts from patients with either Morquio B disease or GM1-gangliosidosis who bore different mutations of the beta-galactosidase gene. We found that fibroblasts taken from patients with an adult form of GM1-gangliosidosis and from patients with an infantile form, carrying a missense mutations in the beta-galactosidase gene-mutations that caused deficiency in lysosomal beta-galactosidase but not in S-Gal-assembled normal elastic fibers. In contrast, fibroblasts from two cases of infantile GM1-gangliosidosis that bear nonsense mutations of the beta-galactosidase gene, as well as fibroblasts from four patients with Morquio B who had mutations causing deficiency in both forms of beta-galactosidase, did not assemble elastic fibers. We also demonstrated that S-Gal-deficient fibroblasts from patients with either GM1-gangliosidosis or Morquio B can acquire the S-Gal protein, produced by coculturing of Chinese hamster ovary cells permanently transected with S-Gal cDNA, resulting in improved deposition of elastic fibers. The present study provides a novel and natural model validating functional roles of S-Gal in elastogenesis and elucidates an association between impaired elastogenesis and the development of connective-tissue disorders in patients with Morquio B disease and in patients with an infantile form of GM1-gangliosidosis.

Topics: Alternative Splicing; Animals; beta-Galactosidase; Biopolymers; Cells, Cultured; CHO Cells; Codon, Nonsense; Cricetinae; Dermis; Elastic Tissue; Elastin; Exons; Fibroblasts; Gangliosidosis, GM1; Humans; Infant; Molecular Weight; Mucopolysaccharidosis IV; Mutation; Protein Binding; Solubility; Tropoelastin