[Expression of PKD1 and PKD2 transcripts and proteins and its significance in different types of kidney tissues and kidney lines].

OBJECTIVE: To investigate the expression and function of PKD1 and PKD2 in different kidney tissues and cell lines. METHODS: Immunoprecipitation, Western blotting, In situ hybridization and immunohistochemical staining methods were used to observe the expression of PKD1 mRNA and PKD2 mRNA and their protein abundance in different kidney tissues and cell lines. RESULTS: Coordinate expressions of PKD1 and PKD2 were found in all kidney tissues and cell lines. Distribution of PKD1 mRNA and PKD2 mRNA and their protein polycystin-1 and polycystin-2 in normal human adult kidney tissue were mainly expressed in the medullary collecting ducts and distal tubules. Positive staining was also found in the majority of cyst-lining epithelial cells of PKD1 cystic kidney tissue, PKD1 cyst-lining epithelia cell line and LLC-PK1. The expression level of them in cystic epithelia of ADPKD kidney tissue was much higher than that in adult renal tubules (P < 0.01). CONCLUSIONS: Similar expression pattern of PKD1 and PKD2 and their different tissue distribution in different kidney tissues show that the molecular mutuality of PC-1 and PC-2 might be the base of their functional correlation. Polycystins might play an important role in the maintenance of tubular architecture.

[Gene diagnosis of autosomal dominant polycystic kidney disease type 2 using microsatellite DNA tightly linked to polycystic kidney disease gene 2].

OBJECTIVE: To use microsatellite DNA tightly linked to polycystic kidney disease gene 2 in the gene diagnosis of autosomal dominant polycystic kidney disease type 2. METHODS: Microsatellite DNA of D4S1534, D4S1542, D4S1563,D4S2460 and D4S423 were amplified with PCR and the fragments of products were analyzed by capillary electrophoresis and Genescan and Genotyper software, and then gene diagnosis of the pedigrees was made by linkage analysis. RESULTS: Three families were found to be linked to PKD2 in 20 families. Two carriers of PKD2 mutation were revealed by linkage analysis. CONCLUSION: Gene diagnosis can be done for PKD2 mutation carriers prior to cytogenesis. Linkage analysis is a rapid, simple method for studying the heterogeneity of polycystic kidney disease and for diagnosing the disease at the molecular level.

[Mutation detection of PKD2 gene in Chinese by denaturing high-performance liquid chromatograph].

OBJECTIVE: To detect the mutations of autosomal dominant polycystic kidney disease gene 2(PKD2)in Chinese. METHODS: The white blood cell genomic DNA from patients of 94 Chinese autosomal dominant polycystic kidney disease(ADPKD) pedigrees was isolated and amplified by polymerase chain reaction(PCR). The PCR products were analyzed by denaturing high-performance liquid chromatography(DHPLC). The samples with abnormal profiles were sequenced. RESULTS: Eight mutations were identified, including 2 nonsense mutations, 2 deletion mutations,1 insertion mutation and 3 missense mutations. Two nonsense mutations occurred in exon 5(1249C-->T) and exon 13(2407C-->T),both resulted in a stop codon. The insertion was in exon 2(636-637 ins T),and the deletion mutations were in exons 12(2348-2351 del AGAA) and 13(2401 delete A),resulting in the reading frame shift. Three missense mutations were in exons 1(G568-->A),4(C964-->T),and 5(G1168-->A), which caused amino acid changes (190Ala-->Thr,322Arg-->Trp,390Gly-->Ser). CONCLUSION: The method of DHPLC was used in detecting mutations successfully and 8 mutations in PKD2 were identified. It will be useful in the molecular diagnosis of ADPKD in advance of the cysts formation and birth.

[Preparation and characterization of monoclonal antibody against N-terminal domain of polycystin 1].

AIM: To prepare and identify monoclonal antibody (mAb) against N-terminal domain of polycystin 1. METHODS: Total RNA was extracted from kidney tissue of a healthy man. Gene sequence encoding polycystin 1 N-terminal domain was amplified by one-step RT-PCR. The target gene was inserted into prokaryotic expression vector pQE30 and transformed into competent cells E. coli M15. The fusion protein was expressed under IPTG induction and purified by affinity chromatography. The purified fusion protein was then used to immunize BALB/c mice. The splenocytes from immunized mice were fused with myeloma cells Sp2/0 by PEG 4000 mediator method and the hybridomas were selected in HAT medium. The hybridoma clones secreting mAb against polycystin 1 amino-terminal domain were detected by ELISA and cloned by limiting dilution. The specificity of mAb against polycystin 1 N-terminal domain was verified by ELISA and Western blot. RESULTS: cDNA encoding polycystin 1 extracellular region was obtained. Fusion protein of polycystin 1 N-terminal domain were expressed in pQE30 expression system. The relative molecular masses (Mr) of the two fusion proteins were 19,800 and 18,900, respectively. One hybridoma cell 7B1 secreting specific mAb was obtained. Western blot analysis showed that the mAb reacted strongly and specifically to polycystin 1 N-terminal domain. CONCLUSION: polycystin 1 N-terminal fusion proteins have been expressed in E.coli M15. Anti-fusion protein mAb with antigen-binding activity has been prepared successfully.