Single-nephron proteomes connect morphology and function in proteinuric kidney disease

Kidney Int. 2018 Jun;93(6):1308-1319. doi: 10.1016/j.kint.2017.12.012. Epub 2018 Mar 9.

Abstract

In diseases of many parenchymatous organs, heterogeneous deterioration of individual functional units determines the clinical prognosis. However, the molecular characterization at the level of such individual subunits remains a technological challenge that needs to be addressed in order to better understand pathological mechanisms. Proteinuric glomerular kidney diseases are frequent and assorted diseases affecting a fraction of glomeruli and their draining tubules to variable extents, and for which no specific treatment exists. Here, we developed and applied a mass spectrometry-based methodology to investigate heterogeneity of proteomes from individually isolated nephron segments from mice with proteinuric kidney disease. In single glomeruli from two different mouse models of sclerotic glomerular disease, we identified a coherent protein expression module consisting of extracellular matrix protein deposition (reflecting glomerular sclerosis), glomerular albumin (reflecting proteinuria) and LAMP1, a lysosomal protein. This module was associated with a loss of podocyte marker proteins while genetic ablation of LAMP1-correlated lysosomal proteases could ameliorate glomerular damage in vivo. Furthermore, proteomic analyses of individual glomeruli from patients with genetic sclerotic and non-sclerotic proteinuric diseases revealed increased abundance of lysosomal proteins, in combination with a decreased abundance of mutated gene products. Thus, altered protein homeostasis (proteostasis) is a conserved key mechanism in proteinuric kidney diseases. Moreover, our technology can capture intra-individual variability in diseases of the kidney and other tissues at a sub-biopsy scale.

Keywords: albuminuria; focal segmental glomerulosclerosis; glomerulus proteomic analysis; podocyte; proximal tubule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Variation, Individual
  • Biomarkers / metabolism
  • Disease Models, Animal
  • Extracellular Matrix Proteins / metabolism
  • Glomerulonephritis / genetics
  • Glomerulonephritis / metabolism*
  • Glomerulonephritis / pathology
  • Glomerulonephritis / physiopathology
  • Humans
  • Lysosome-Associated Membrane Glycoproteins / genetics
  • Lysosome-Associated Membrane Glycoproteins / metabolism
  • Male
  • Mice
  • Mice, Knockout
  • Nephrons / metabolism*
  • Nephrons / pathology
  • Nephrons / physiopathology
  • Nephrotic Syndrome / genetics
  • Nephrotic Syndrome / metabolism
  • Nephrotic Syndrome / pathology
  • Nephrotic Syndrome / physiopathology
  • Podocytes / metabolism
  • Podocytes / pathology
  • Proteinuria / genetics
  • Proteinuria / metabolism*
  • Proteinuria / pathology
  • Proteinuria / physiopathology
  • Proteome*
  • Proteomics / methods*
  • Proteostasis
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Reproducibility of Results
  • Serum Albumin / metabolism
  • Tandem Mass Spectrometry*

Substances

  • Biomarkers
  • Extracellular Matrix Proteins
  • Lamp1 protein, mouse
  • Lysosome-Associated Membrane Glycoproteins
  • Proteome
  • Repressor Proteins
  • Serum Albumin
  • WT1 protein, mouse

Supplementary concepts

  • Nephrosis, congenital