The mTOR pathway is activated in human autosomal-recessive polycystic kidney disease.
BACKGROUND
An inappropriate activation of the mTOR pathway was demonstrated in the autosomal dominant (AD) form of polycystic kidney disease (PKD). To date it is unclear whether the mTOR pathway is activated in autosomal-recessive (AR) PKD, a cystic disease which occurs in childhood. The purpose of the present study was to evaluate the mTOR pathway in AR PKD.


METHODS
We evaluated the expression of mTOR pathway molecules in paraffin-embedded liver and kidney samples from patients with AR PKD and control specimens from animals as well as humans. Monoclonal antibodies, the phosphorylated proteins pmTOR, pS6-ribosomal-protein (pS6K), p4E-BP1, peIF4G, and phospho-tuberin/TSC2 were used.


RESULTS
mTOR was strongly expressed in renal cyst-lining cells and bile ducts from AR PKD specimen. S6K immunostaining was strong in smaller tubules and weak both in larger renal cysts and in the bile duct epithelium. In controls, mTOR and S6K were expressed in distal tubule segments. 4E-BP1-immunostaining was restricted to noncystic tubules in AR PKD. eIFG4-immunostaining was observed in bile duct epithelium in AR PKD, but not in control tissue. Tuberin/TSC2 immunostaining was negative in all specimens.


CONCLUSIONS
Our data suggest that the mTOR pathway may be activated in AR PKD, and mTOR molecules may represent a potential target to slow down cyst development in this disease.
Becker
Jan Ulrich
JU
Institute of Pathology and Neuropathology, University Hospital of Essen, University Duisburg-Essen, Essen, Germany.
Opazo Saez
Anabelle
A
Zerres
Klaus
K
Witzke
Oliver
O
Hoyer
Peter Friedrich
PF
Schmid
Kurt Werner
KW
Kribben
Andreas
A
Bergmann
Carsten
C
Nürnberger
Jens
J
D000293:Adolescent; D000818:Animals; D001652:Bile Ducts / Q000737:chemistry / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000378:metabolism*; D007668:Kidney / Q000737:chemistry / Q000473:pathology; D016030:Kidney Transplantation; D008099:Liver / Q000737:chemistry / Q000473:pathology; D016031:Liver Transplantation; D008297:Male; D017044:Polycystic Kidney, Autosomal Recessive / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases
D047908:Intracellular Signaling Peptides and Proteins; C546842:MTOR protein, human; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases