Zebrafish to humans: Evolution of the α3-chain of type IV collagen and emergence of the autoimmune epitopes associated with Goodpasture syndrome

Goodpasture syndrome is an autoimmune vascular disease associated with kidney and lung failure, with pathogenic circulating autoantibodies targeted to a set of discontinuous epitope sequences within the noncollagenous domain-1 (NC1) of the α3 chain of type IV collagen (α3(IV)NC1), the Goodpasture autoantigen. We demonstrate that basement membrane extracted NC1 domain preparations from Caenorhabditis elegans, Drosophila melanogaster, and Danio rerio do not bind Goodpasture autoantibodies, while Xenopus laevis, chicken, mouse and human α3(IV)NC1 domains bind autoantibodies. The α3(IV) chain is not present in C elegans and Drosophila melanogaster, but is first detected in the Danio rerio. Interestingly, native Danio rerio α3(IV)NC1 does not bind Goodpasture autoantibodies. Next, we cloned, sequenced, and generated recombinant Danio rerio α3(IV)NC1 domain. In contrast to recombinant human α3(IV)NC1 domain, there was complete absence of autoantibody binding to recombinant Danio rerio α3(IV)NC1. Three-dimensional molecular modeling from existing x-ray coordinates of human NC1 domain suggest that evolutionary alteration of electrostatic charge and polarity due to the emergence of critical serine, aspartic acid, and lysine residues, accompanied by the loss of asparagine and glutamine, contributes to the emergence of the 2 major Goodpasture epitopes on the human α3(IV)NC1 domain, as it evolved from the Danio rerio over 450 million years.