Biallelic Expression of Mucin-1 in Autosomal Dominant Tubulointerstitial Kidney Disease: Implications for Nongenetic Disease Recognition.

Abstract

BACKGROUND:

Providing the correct diagnosis for patients with tubulointerstitial kidney disease and secondary degenerative disorders, such as hypertension, remains a challenge. The autosomal dominant tubulointerstitial kidney disease (ADTKD) subtype caused by MUC1 mutations (ADTKD-MUC1) is particularly difficult to diagnose, because the mutational hotspot is a complex repeat domain, inaccessible with routine sequencing techniques. Here, we further evaluated SNaPshot minisequencing as a technique for diagnosing ADTKD-MUC1 and assessed immunodetection of the disease-associated mucin 1 frameshift protein (MUC1-fs) as a nongenetic technique.

METHODS:

We re-evaluated detection of MUC1 mutations by targeted repeat enrichment and SNaPshot minisequencing by haplotype reconstruction via microsatellite analysis in three independent ADTKD-MUC1 families. Additionally, we generated rabbit polyclonal antibodies against MUC1-fs and evaluated immunodetection of wild-type and mutated allele products in human kidney biopsy specimens.

RESULTS:

The detection of MUC1 mutations by SNaPshot minisequencing was robust. Immunostaining with our MUC1-fs antibodies and an MUC1 antibody showed that both proteins are readily detectable in human ADTKD-MUC1 kidneys, with mucin 1 localized to the apical membrane and MUC1-fs abundantly distributed throughout the cytoplasm. Notably, immunohistochemical analysis of MUC1-fs expression in clinical kidney samples facilitated reliable prediction of the disease status of individual patients.

CONCLUSIONS:

Diagnosing ADTKD-MUC1 by molecular genetics is possible, but it is technically demanding and labor intensive. However, immunohistochemistry on kidney biopsy specimens is feasible for nongenetic diagnosis of ADTKD-MUC1 and therefore, a valid method to select families for further diagnostics. Our data are compatible with the hypothesis that specific molecular effects of MUC1-fs underlie the pathogenesis of this disease.

• Authors: Karl X Knaup, Thomas Hackenbeck, Bernt Popp, Johanna Stoeckert, Andrea Wenzel, Maike Büttner-Herold, Frederick Pfister, Markus Schueler, Didem Seven, Annette M May, Jan Halbritter, Hermann-Josef Gröne, André Reis, Bodo B Beck, Kerstin Amann, Arif B Ekici, Michael S Wiesener
• Journal: Journal of the American Society of Nephrology : JASN (J Am Soc Nephrol) Vol. 29 Issue 9 Pg. 2298-2309 (09 2018) ISSN: 1533-3450 [Electronic] United States
• PMID: 30049680 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2018 by the American Society of Nephrology.

Chemical References

• MUC1 protein, human
• Mucin-1

Topics

• Adult
• Alleles
• Animals
• Biopsy, Needle
• Cohort Studies
• Female
• Gene Expression Regulation, Developmental
• Genetic Predisposition to Disease (epidemiology)
• Haplotypes
• Humans
• Immunohistochemistry
• Male
• Middle Aged
• Mucin-1 (genetics)
• Mutation (genetics)
• Nephritis, Interstitial (genetics, pathology)
• Pedigree
• Polycystic Kidney, Autosomal Dominant (genetics, pathology)
• Rabbits
• Retrospective Studies
• Risk Assessment
• Sensitivity and Specificity