Molecular and cellular effects of Tamm-Horsfall protein mutations and their rescue by chemical chaperones

Lijie Ma, Yan Liu, Tarek Ashkar (El-Achkar), Xue Ru Wu

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Correct folding of a nascent polypeptide in the lumen of the endoplasmic reticulum (ER) into a three-dimensional conformation is a crucial step in the stability, intracellular trafficking, and targeting to the final destination of a protein. By transiently and stably expressing human-relevant mutants of Tamm-Horsfall protein in polarized Madin-Darby canine kidney cells, we show here that a cysteine-altering mutation in the evolutionally conserved cysteine-rich domain had more severe defects in ER exit and surface translocation and triggered more apoptosis than a cysteine-altering mutation outside the domain. Both mutants were able to specifically bind and trap the wild-type Tamm-Horsfall protein (THP) and prevent it from exiting the ER and translocating to the cell surface. This explains at least partly why in patients with THP-associated diseases there is a marked urinary reduction of both the mutant and the wild-type THP. Exposure of mutant-expressing cells to low temperature (30°C), osmolytes (glycerol, trimethylamine N-oxide, and dimethyl sulfoxide), and the Ca 2+-ATP inhibitor thapsigargin only slightly relieved ER retention and increased surface targeting of the mutants. In contrast, sodium 4-phenylbutyrate and probenecid, the latter a uricosuric drug used clinically to treat gout, markedly reduced ER retention of the mutants and increased their surface translocation and secretion into the culture media. The rescue of the THP mutants was associated with the restoration of the level and subcellular localization of cytosolic chaperone HSP70. Our results reveal intricate mechanistic details that may underlie THP-associated diseases and suggest that novel therapeutics enhancing the refolding of THP mutants may be of important value in therapy.

Original languageEnglish (US)
Pages (from-to)1290-1305
Number of pages16
JournalJournal of Biological Chemistry
Volume287
Issue number2
DOIs
StatePublished - Jan 6 2012
Externally publishedYes

Fingerprint

Uromodulin
Endoplasmic Reticulum
Mutation
Cysteine
Probenecid
Madin Darby Canine Kidney Cells
Thapsigargin
Gout
Dimethyl Sulfoxide
Glycerol
Restoration
Culture Media
Conformations
Adenosine Triphosphate
Apoptosis
Defects
Peptides
Temperature
Therapeutics

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Molecular and cellular effects of Tamm-Horsfall protein mutations and their rescue by chemical chaperones. / Ma, Lijie; Liu, Yan; Ashkar (El-Achkar), Tarek; Wu, Xue Ru.

In: Journal of Biological Chemistry, Vol. 287, No. 2, 06.01.2012, p. 1290-1305.

Research output: Contribution to journalArticle

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