Mutations in autosomal dominant polycystic kidney disease 2 gene: Reduced expression of PKD2 protein in lymphoblastoid cells

• Published in: American journal of kidney diseases Vol. 33; no. 5; pp. 880 - 885
• Main Authors: Aguiari, Gianluca, Manzati, Elisa, Penolazzi, Letizia, Micheletti, Fabiola, Augello, Giuseppina, De Vitali, Ermanno, Cappelli, Gianni, Cai, Yiqiang, Reynolds, David, Somlo, Stefan, Piva, Roberta, del Senno, Laura
• Format: Journal Article
• Language: English
• Published: Orlando, FL Elsevier Inc 01-05-1999; Elsevier
• Subjects: ADPKD; Aged; Alleles; Biological and medical sciences; Female; Humans; Kidneys; Male; Medical sciences; Membrane Proteins - analysis; Membrane Proteins - genetics; Middle Aged; Mutation; Nephrology. Urinary tract diseases; Pedigree; PKD2 mutations; Polycystic Kidney, Autosomal Dominant - blood; Polycystic Kidney, Autosomal Dominant - genetics; polycystin-2 expression; Restriction Mapping; Reverse Transcriptase Polymerase Chain Reaction; TRPP Cation Channels; Tumors of the urinary system; polycystin-2 expression; ADPKD; PKD2 mutations; Kidney disease; Human; Membrane protein; Urinary system disease; Polycystic kidney; Gene expression; Genetic determinism; Genetic disease; Polymerase chain reaction; Phenotype; Autosomal character; Cyst; Dominant character; Benign neoplasm; Mutation; Lymphoblastoid cell; Polymorphism
• ISSN: 0272-6386; 1523-6838
• DOI: 10.1016/S0272-6386(99)70420-8

The polycystic kidney disease 2 (PKD2) gene, encoding a 968-amino acid integral membrane protein with six predicted membrane-spanning domains and intracellular NH2 and COOH termini, is mutated in approximately 15% of the cases of autosomal dominant polycystic kidney disease (ADPKD), a common genetic disease frequently resulting in renal failure. For a better understanding of the cause of this disorder, we searched for mutations in the PKD2 gene in two PKD2-linked families characterized by different clinical phenotypes. A common polymorphism, a nonsense mutation, and a frameshift mutation were found. Both mutations are predicted to produce truncated proteins of 314 and 386 amino acids, arrested at the first extracellular loop of the protein. Restriction enzyme analysis of polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR products, respectively, showed that mutations cosegregated with the disease and mutated alleles were expressed at the messenger RNA level in lymphoblastoid cell lines. However, in these cells, Western blot analysis showed only PKD2 normal protein, and it was expressed at a lower level than that found in cells without the PKD2 mutation. These findings suggest that in lymphoblastoid cells, the truncated protein product of the mutant allele may not be stable.