A transgenic mouse model for uromodulin-associated kidney diseases shows specific tubulo-interstitial damage, urinary concentrating defect and renal failure.
Uromodulin-associated kidney diseases (UAKD) are autosomal-dominant disorders characterized by alteration of urinary concentrating ability, tubulo-interstitial fibrosis, hyperuricaemia and renal cysts at the cortico-medullary junction. UAKD are caused by mutations in UMOD, the gene encoding uromodulin. Although uromodulin is the most abundant protein secreted in urine, its physiological role remains elusive. Several in vitro studies demonstrated that mutations in uromodulin lead to endoplasmic reticulum (ER) retention of mutant protein, but their relevance in vivo has not been studied. We here report on the generation and characterization of the first transgenic mouse model for UAKD. Transgenic mice that express the C147W mutant uromodulin (Tg(Umod)(C147W)), corresponding to the well-established patient mutation C148W, were compared with expression-matched transgenic mice expressing the wild-type protein (Tg(Umod)(wt)). Tg(Umod)(C147W) mice recapitulate most of the UAKD features, with urinary concentrating defect of renal origin and progressive renal injury, i.e. tubulo-interstitial fibrosis with inflammatory cell infiltration, tubule dilation and specific damage of the thick ascending limb of Henle's loop, leading to mild renal failure. As observed in patients, Tg(Umod)(C147W) mice show a marked reduction of urinary uromodulin excretion. Mutant uromodulin trafficking to the plasma membrane is indeed impaired as it is retained in the ER of expressing cells leading to ER hyperplasia. The Tg(Umod)(C147W) mice represent a unique model that recapitulates most of the features associated with UAKD. Our data clearly demonstrate a gain-of-toxic function of uromodulin mutations providing insights into the pathogenetic mechanism of the disease. These findings may also be relevant for other tubulo-interstitial or ER-storage disorders.
Bernascone
Ilenia
I
Division of Genetics and Cell Biology, Dulbecco Telethon Institute, Milan, Italy.
Janas
Sylvie
S
Ikehata
Masami
M
Trudu
Matteo
M
Corbelli
Alessandro
A
Schaeffer
Céline
C
Rastaldi
Maria Pia
MP
Devuyst
Olivier
O
Rampoldi
Luca
L
D000595:Amino Acid Sequence; D000818:Animals; D004195:Disease Models, Animal; D018450:Disease Progression; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D007249:Inflammation / Q000473:pathology; D042541:Intracellular Space / Q000378:metabolism; D007684:Kidney Tubules / Q000473:pathology* / Q000648:ultrastructure; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000737:chemistry / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D021381:Protein Transport; D051437:Renal Insufficiency / Q000150:complications* / Q000473:pathology / Q000652:urine*; D058949:Uromodulin; D014868:Water Deprivation
D009088:Mucoproteins; D050505:Mutant Proteins; C548613:Umod protein, mouse; D058949:Uromodulin