Peroxidasin-mediated bromine enrichment of basement membranes

Abstract

<jats:p>Bromine and peroxidasin (an extracellular peroxidase) are essential for generating sulfilimine cross-links between a methionine and a hydroxylysine within collagen IV, a basement membrane protein. The sulfilimine cross-links increase the structural integrity of basement membranes. The formation of sulfilimine cross-links depends on the ability of peroxidasin to use bromide and hydrogen peroxide substrates to produce hypobromous acid (HOBr). Once a sulfilimine cross-link is created, bromide is released into the extracellular space and becomes available for reutilization. Whether the HOBr generated by peroxidasin is used very selectively for creating sulfilimine cross-links or whether it also causes oxidative damage to bystander molecules (e.g., generating bromotyrosine residues in basement membrane proteins) is unclear. To examine this issue, we used nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to define the distribution of bromine in mammalian tissues. We observed striking enrichment of bromine (<jats:sup>79</jats:sup>Br,<jats:sup>81</jats:sup>Br) in basement membranes of normal human and mouse kidneys. In peroxidasin knockout mice, bromine enrichment of basement membranes of kidneys was reduced by ∼85%. Proteomic studies revealed bromination of tyrosine-1485 in the NC1 domain of α2 collagen IV from kidneys of wild-type mice; the same tyrosine was brominated in collagen IV from human kidney. Bromination of tyrosine-1485 was reduced by &gt;90% in kidneys of peroxidasin knockout mice. Thus, in addition to promoting sulfilimine cross-links in collagen IV, peroxidasin can also brominate a bystander tyrosine. Also, the fact that bromine enrichment is largely confined to basement membranes implies that peroxidasin activity is largely restricted to basement membranes in mammalian tissues.</jats:p>

High-resolution visualization and quantification of nucleic acid–based therapeutics in cells and tissues using Nanoscale secondary ion mass spectrometry (NanoSIMS)

“…Br-ASO accumulation was observed in endolysosomes of renal tubule cells. When the bromine scale was altered, it was possible to visualize bromine enrichment in the basement membranes of the kidney ( Supplementary Figure S13 ) ( 45 ). Basement membrane proteins are normally brominated by the HOBr generated by peroxidasin, a peroxidase within the extracellular matrix ( 45 ).…”

“…When the bromine scale was altered, it was possible to visualize bromine enrichment in the basement membranes of the kidney ( Supplementary Figure S13 ) ( 45 ). Basement membrane proteins are normally brominated by the HOBr generated by peroxidasin, a peroxidase within the extracellular matrix ( 45 ). Bromine enrichment in endolysosomes of renal tubule cells in Br-ASO–treated mice was ∼70-fold higher than in the basement membranes and ∼178-fold higher than bromine enrichment in endolysosomes of renal tubule cells from control mice that had not been treated with Br-ASO ( Supplementary Figure S13 ).…”

“…NanoSIMS images of Br-ASO were superior. Bromine can be detected in mammalian cells and tissues and is enriched in basement membranes ( 45 ), but the background of bromine NanoSIMS analyses is far lower than with 34 S. 34 S levels in the endosomes of 34 S-ASO–treated cells were only ∼40% higher than the natural abundance of 34 S, whereas bromine levels in endosomes of Br-ASO–treated cells and tissues were as much as 170-fold higher than in endosomes of untreated control mice. Also, Br-ASO contained both 79 Br and 81 Br, and the ability to detect and quantify both isotopes improved image quality.…”

Characterization of the Proprotein Convertase-Mediated Processing of Peroxidasin and Peroxidasin-like Protein

“…Two groups, including ours, have demonstrated that the mammalian enzyme functions in trimers as it was initially suggested for the Drosophila homolog [9,10]. It was also recently described that the enzyme mediates the bromination of tyrosine residues but the physiological significance of this activity remains to be clarified [11,12].…”

A Biomimetic In Vitro Model of the Kidney Filtration Barrier Using Tissue‐Derived Glomerular Basement Membrane

“…[ 64,65 ] Under normal physiological conditions, these reactions seem to be benign and peroxidasin activity is required for crosslinking of collagen IV. [ 65–67 ] However, under pathological conditions, including diabetes, myeloperoxidase enzyme activity is upregulated. [ 68 ] Studies have demonstrated that hypohalous acids damage the ECM both in vitro and in animal models of diabetes.…”