Mutational analysis of the GDNF/RET-GDNFRα signaling complex in a kindred with vesicoureteral reflux

Abstract

Glial cell line-derived neurotrophic factor (GDNF) mediates signaling across the cell membrane by interaction with the RET-GDNFR alpha receptor complex. We identified a family in which one member had medullary thyroid carcinoma (MTC) and four members had vesicoureteral reflux (VUR). Knowledge that mutations in the RET proto-oncogene cause MTC and studies documenting genitourinary abnormalities in RET or GDNF knockout mice led us to examine the GDNF/RET-GDNFR alpha signaling complex in this family. RET and GDNF were excluded as the causative VUR gene by haplotype and sequence analysis. The GDNFR alpha gene was mapped to chromosome 10q25-26 by radiation hybrid techniques and was eliminated as the causative gene by haplotype analysis and sequencing of cDNA from an obligate carrier. Sequencing identified a 15-nucleotide deletion in GDNFR alpha mRNA, which was found to code for a single exon; analysis of several cell types revealed an identical mRNA form, indicating that this variant is a product of alternative RNA processing. We conclude that GDNFR alpha maps to 10q25-26 and that its RNA transcript is alternatively processed. Mutation abnormalities in the GDNF/RET-GDNFR alpha signaling system do not cause VUR in this family.

Genetic analysis of RET, GFRα1 and GDNF genes in Spanish families with multiple endocrine neoplasia type 2A

“…28,38 In our study, we detected 4 different polymorphisms of GFR␣1 gene. Three of them were previously reported, 28 Y85N (exon 3), N184N (AAC-AAT, exon 6) and T366A (exon 9) and the frequencies of these alleles were similar in MEN 2A patients and healthy relatives.…”

RET Gly691Ser mutation is associated with primary vesicoureteral reflux in the French-Canadian population from Quebec

“…Our results of cellular protein phosphorylation profiles show that this mutation does not abolish the Ret kinase activity, which is critical during kidney and ureter development [Shefelbine et al, 1998;Costantini and Shakya, 2006]. Since Gly691Ser is in the cytoplasmic juxtamembrane region, away from the Ret kinase domain, this was not unexpected.…”

“…A total of 70 index pVUR patients (probands), randomly drawn from the 125 pVUR families and 90 French-Canadian controls were used for the analysis. The SNPs tested are within 20 kb of rs1799939, have published allele frequencies in the Caucasian population, are amenable to RFLP-PCR screening, and have been used in similar studies [Shefelbine et al, 1998]. …”

“…Although there is only limited evidence that links mutations in Ret to kidney and urinary tract malformations in humans [Loré et al, 2000[Loré et al, , 2001 and Ret mutations have not been identified in the only VUR family studied [Shefelbine et al, 1998], several investigations with animal models suggested that Ret dysfunction may be responsible for UB branching, distal ureter abnormalities, and VUR [Shakya et al, 2005;Yu et al, 2004, Batourina et al, 2002Schuchardt et al, 1996]. UB outgrowth is inhibited in ret-null mice; however, their metanephric mesenchyme is still responsive to inductive signals [Murawski and Gupta, 2006;Costantini and Shakya, 2006;Pachnis et al, 1993].…”

Glial Cell Line-Derived Neurotrophic Factor and Neurturin Inhibit Neurite Outgrowth and Activate RhoA through GFRα2b, an Alternatively Spliced Isoform of GFRα2

“…It has been estimated that Ͼ50% of human multi-exon genes are alternatively spliced (Modrek and Lee, 2002). Multiple alternatively spliced variants of GFR␣1 (Sanicola et al, 1997;Dey et al, 1998;Shefelbine et al, 1998), GFR␣2 Dolatshad et al, 2002), and GFR␣4 (Lindahl et al, 2000(Lindahl et al, , 2001Masure et al, 2000) have been reported. Similarly, alternative spliced isoforms of the coreceptors RET (Lorenzo et al, 1997;de Graaff et al, 2001;Lee et al, 2002) and NCAM (Povlsen et al, 2003;Buttner et al, 2004) have been reported.…”