Cited by 290Extracellular vesicles in diseaseRenal Diseases and GlomerulopathiesKidney Stones and Urolithiasis Treatments

Tamm-Horsfall protein and urinary exosome isolation

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Fernández-Llama, Patricia, Khositseth, Sookkasem, Gonzales, Patricia A., Star, Robert A., Pisitkun, Trairak, Knepper, Mark A.·2010·Kidney International

Abstract

Urinary exosomes have been proposed as starting material for discovery of protein biomarkers of kidney disease. Current protocols for their isolation use a two-step differential centrifugation process. Due to their low density, exosomes are expected to remain in the low-speed (17,000 x g) supernatant and to sediment only when the sample is spun at high speed (200,000 x g). Analysis using western blot and electron microscopy found that urinary exosomes are also present in the low-speed pellet entrapped by polymeric Tamm-Horsfall protein, thus diminishing the procedure's reproducibility. Here we show that addition of dithiothreitol to the low-speed pellet disrupted the polymeric network, presumably by reduction of disulfide bonds linking the monomers. This modification shifted the exosomal proteins from the low- to the high-speed pellet. Also, by shifting the Tamm-Horsfall protein to the high-speed pellet, the use of dithiothreitol makes it feasible to use Tamm-Horsfall protein to normalize excretion rates of exosomal proteins in spot urines. We tested this by western blot, and found that there was a high degree of correlation between exosomal proteins and Tamm-Horsfall protein in the high-speed pellet. Since the yield of exosomes by differential centrifugation can be increased by chemical reduction, Tamm-Horsfall protein may be a suitable normalizing variable for urinary exosome studies when quantitative urine collections are not practical.

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Authors
Fernández-Llama, P., Khositseth, S., Gonzales, P. A., Star, R. A., Pisitkun, T., & Knepper, M. A.
Affiliations
National Institutes of Health (US)
Corresponding author
Knepper, Mark A.
Venue
Kidney International
Publisher
Elsevier BV
Published
2010-04
Volume
77
Issue
8
Pages
736-742
ISSN
0085-2538 (ISSN-L)
OpenAlex
W2038509755
Cited by
290
References
17
Citations by year
2026: 7 · 2025: 10 · 2024: 12 · 2023: 12 · 2022: 23 · 2021: 27 · 2020: 37 · 2019: 18 · 2018: 22 · 2017: 20 · 2016: 18 · 2015: 18 · 2014: 22 · 2013: 18 · 2012: 13
FWCI
5.74
Type
journal article
Language
en
Open access
Locations
  • Kidney International (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Sociedad Española de Nefrología
  • National Institutes of Health (Z99 HL999999)
  • National Heart, Lung, and Blood Institute (Z01HL001285, ZIAHL001285, Z01-HL001285)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Extracellular vesicles in disease
  • Health Sciences › Medicine › Nephrology › Renal Diseases and Glomerulopathies
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Kidney Stones and Urolithiasis Treatments
Keywords
uromodulin, urinary exosomes, exosome isolation, differential centrifugation, dithiothreitol, disulfide bond reduction, kidney disease biomarkers, spot urine, urinary protein excretion
MeSH terms
Adult, Humans, Male, Microscopy, Electron, Mucoproteins, Urinary Tract, Blotting, Western, Biomarkers, Exosomes, Uromodulin

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