Polycystic kidney disease 1 gene and uses thereof

Details Polycystic kidney disease 1 gene and uses thereof Polycystic kidney disease 1 gene and uses thereof

1995-04-14

2002-11-26

Low, Christopher S. F. (Department: 1653)

Chemistry: molecular biology and microbiology

Micro-organism, per se ; compositions thereof; proces of...

Bacteria or actinomycetales; media therefor

C435S320100, C536S023500, C536S024310, C536S023100

Reexamination Certificate

active

06485960

ABSTRACT:

BACKGROUND TO THE INVENTION
In humans, one of the commonest of all genetic disorders is autosomal polycystic kidney disease (ADPKD) also termed adult polycystic kidney disease (APKD), affecting approximately 1/1000 individuals (Dalgaard, 1957). ADPKD is a progressive disease of cyst formation and enlargement typically leading to end stage renal disease (ESRD) in late middle age. The major cause of morbidity in ADPKD is progressive renal disease characterized by the formation and enlargement of fluid filled cysts, resulting in grossly enlarged kidneys. Renal function deteriorates as normal tissue is compromised by cystic growth, resulting in end stage renal disease (ESRD) in more than 50% of patients by the age of 60 years (Gabow, et al., 1992). ADPKD accounts for 8-10% of all renal transplantation and dialysis patients in Europe and the USA (Gabow, 1993).
ADPKD also causes cystic growth in other organs (reviewed in Gabow, 1990) and occasionally presents in childhood (Fink, et al., 1993; Zerres, et al., 1993). Extrarenal manifestations include liver cysts (Milutinovic, et al., 1980), and more rarely cysts of the pancreas (Gabow, 1993) and other organs. Intracranial aneurysms occur in approximately 5% of patients and are a significant cause of morbidity and mortality due to subarachnoid haemorrhage (Chapman, et al., 1992). ADPKD is associated with a higher prevalence of various connective tissue disorders. An increased prevalence of heart valve defects (Hossack, et al., 1988), hernia (Gabow, 1990) and colonic diverticulae (Scheff, et al., 1980) have been reported.
Considerable progress has been made in the last few years in understanding the pathophysiology of ADPKD (and other animal models of cystic disease). Cysts in ADPKD are known to develop from outpouchings of descending or ascending kidney tubules and the early stages are characterized by a thickening and disorganization of the basement membrane, accompanied by a de-differentiation of tubular epithelial cells. Several of the characteristics of ADPKD epithelia: altered growth responses, abnormal expression of various proteins and reversal of polarity, may be a sign of this de-differentiation and important in cyst expansion. The nature of the primary defect which triggers these changes is, however, unknown and consequently much effort has been devoted to identifying the causative agent by genetic means.
The first step towards positional cloning of an ADPKD gene was the demonstration of linkage of one locus now designated the polycystic kidney disease 1 (PKD1) locus to the &agr; globin cluster on the short arm of chromosome 16 (Reeders, et al., 1985). Subsequently, families with ADPKD unlinked to markers one of 16p were described (Kimberling, et al., 1988; Romeo, et al., 1988) and a second ADPKD locus (PKD2) has recently been assigned to chromosome region 4q13-q23 (Kimberling, et al., 1993; Peter, et al., 1993). It is estimated that approximately 85% of ADPKD is due to PKD1 (Peters and Sankuijl, 1992) with PKD2 accounting for most of the remainder. PKD2 appears to be milder condition with a later age of onset and ESRD (Parfrey, et al., 1990; Gabow, et al., 1992; Ravine, et al., 1992).
The position of the PKD1 locus was refined to chromosome band 16p13.3 and many markers were isolated from that region (Breuning, et al., 1987; Reeders, et al., 1988; Breuning, et al., 1990; Germino, et al., 1990; Hyland, et al., 1990; Himmelbauer, et al., 1991). Their order, and the position of the PKD1 locus, has been determined by extensive linkage analysis in normal and PKD1 families and by the use of a panel of somatic cell hybrids (Reeders et al., 1988; Breuning, et al., 1990; Germino, et al., 1990). ADPKD is genetically heterogenous with loci mapped not only to 16p13.3 (PKD1), but also to chromosome 4 (PKD2). Although the phenotype of PKD1 and PKD2 are clearly similar, it is now well documented that PKD1 (which accounts for about 85% of ADPKD; (Peters, 1992) is a more severe disease with an average age at ESRD of about 56 years compared to about 71.5 years for PKD2 (Ravine, 1992). An accurate long range restriction map of the 16p13.3 region (Harris, et al., 1990; Germino, et al., 1992) has located the PKD1 locus in an interval of approximately 600 kb between the markers GGG1 and SM7 (Harris, et al., 1991; Somlo, et al., 1992) (see
FIG. 1
a
). The density of CpG islands and identification of many mRNA transcripts indicated that this area is rich in gene sequences. Germino et al. (1992) estimated that the candidate region contains approximately 20 genes.
Identification of the PKD1 gene from within this area has thus proved difficult and other means to pinpoint the disease gene have been sought. Linkage disequilibrium has been demonstrated between PKD1 and the proximal marker VK5, in a Scottish population (Pound, et al., 1992) and between PKD1 and BLu24 (see
FIG. 1
a
), in a Spanish population (Peral, et al., 1994). Studies with additional markers have shown evidence of a common ancestor in a proportion of each population (Peral, et al., 1994; Snarey, et al., 1994), but the association has not precisely positioned the PKD1 locus.
Disease associated genomic rearrangements, detected by cytogenetics or pulsed field gel electrophoresis (PFGE) have been instrumental in the identification of various genes associated with various genetic disorders. Hitherto, no such abnormalities related to PKD1 have been described. This situation contrasts with that for the tuberous sclerosis locus, which lies within 16p13.3 (TSC2). In that case, TSC associated deletions were detected by PFGE within the interval thought to contain the PKD1 gene and their characterisation was a significant step toward the rapid identification of the TSC2 gene (European Chromosome 16 Tuberous Sclerosis Consortium, 1993). The TSC2 gene therefore maps within the candidate region for the hitherto unidentified PKD1 gene; as polycystic kidneys are a feature common to TSC and ADPKD1 (Bernstein and Robbins, 1991) the possibility of an etiological link, as proposed by Kandt et al. (1992), was considered. A contiguous gene syndrome resulting from the disruption of PKD1 and the adjacent tuberous sclerosis 2 (TSC2) gene, which is associated with TSC and severe childhood onset polycystic kidney disease, has also been defined (Brook-Carter et al, 1994).
We have now identified a pedigree in which the two distinct phenotypes, typical ADPKD or TSC, are seen in different members. In this family, the two individuals with ADPKD are carriers of a balanced chromosome translocation with a breakpoint within 16p13.3. We have located the chromosome 16 translocation breakpoint and a gene disrupted by this rearrangement has been defined; the discovery of additional mutations of that gene in other PKD1 patients shows that we have identified the PKD1 gene. Full characterisation of the PKD1 transcript has been significantly complicated because of the unusual genomic region containing most of the gene. All but 3.5 kb at the 3′ end of the transcript (which is about 14 kb in total) is encoded by a region which is reiterated several times elsewhere on the same chromosome (in 16p13.1 and termed the HG area). The structure of the duplication is complex, with some regions copied more times than others, and the HG region encoding three large transcripts. The transcripts from the HG area are: HG-A (21 kb), HG-B (17 kb) and HG-C (8.5 kb) and although these have 3′ ends which differ from PKD1, over most of their length they share substantial homology to the PKD1 transcript. Consequently, cloning and characterizing a bona fide PKD1 cDNA has proven difficult. To overcome the problem caused by duplication we have cloned cDNAs covering the entire transcript from a cell line which contains the PKD1 but not the HG loci. Characterisation of these cDNAs has enabled the PKD1 protein sequence to be predicted and led to the identification of several homologies with described motifs.
SUMMARY OF THE INVENTION
Accordingly, in one aspect, this invention provides an isolated, purified or recombinant nucleic acid sequence co

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