Ian Hornstra, M.D., Ph.D.

Assistant Professor of Dermatology



The research focuses of my laboratory are lysyl oxidases. Lysyl oxidases are copper containing monoamine oxidase enzymes, which catalyzes the conversion of lysine residues in collagen and elastin to allysine. Allysine residues in collagen and elastin spontaneously condense to form highly stable cross-links that impart great mechanical strength in collagen and elastin.


Currently, five different lysyl oxidases exist in both humans and mice. These five forms of lysyl oxidases reside on five different chromosomes. To study the role of lysyl oxidases in growth and development, and maintenance of the extracellular matrix, the lysyl oxidase genes are being cloned, characterized, and individual gene “knockout vectors” constructed. Genetically deficient mice in lysyl oxidases-1 and-2 have been constructed and are being analyzed. Lysyl oxidase-1 deficiency appears lethal at parturition in mice, whereas, lysyl oxidase-2 deficiency causes no severe developmental phenotype.


In addition to the knockout models, the various forms of lysyl oxidases are being expressed in vitro to attempt to elucidate substrate specificities. The various tissue specificities and expression patterns of the lysyl oxidases are being investigated by analysis of individual promoter sequences in transfection assays and by in vivo footprinting.