In congenital bilateral absence of the vas deferens patients, the T5 allele at the polymorphic Tn locus in the CFTR (cystic fibrosis transmembrane conductance regulator) gene is a frequent disease mutation with incomplete penetrance. This T5 allele will result in a high proportion of CFTR transcripts that lack exon 9, whose translation products will not contribute to apical chloride channel activity. Besides the polymorphic Tn locus, more than 120 polymorphisms have been described in the CFTR gene. We hypothesized that the combination of particular alleles at several polymorphic loci might result in less functional or even insufficient CFTR protein. Analysis of three polymorphic loci with frequent alleles in the general population showed that, in addition to the known effect of the Tn locus, the quantity and quality of CFTR transcripts and/or proteins was affected by two other polymorphic loci: (TG)m and M470V. On a T7 background, the (TG)11 allele gave a 2.8-fold increase in the proportion of CFTR transcripts that lacked exon 9, and (TG)12 gave a sixfold increase, compared with the (TG)10 allele. T5 CFTR genes derived from patients were found to carry a high number of TG repeats, while T5 CFTR genes derived from healthy CF fathers harbored a low number of TG repeats. Moreover, it was found that M470 CFTR proteins matured more slowly, and that they had a 1.7-fold increased intrinsic chloride channel activity compared with V470 CFTR proteins, suggesting that the M470V locus might also play a role in the partial penetrance of T5 as a disease mutation. Such polyvariant mutant genes could explain why apparently normal CFTR genes cause disease. Moreover, they might be responsible for variation in the phenotypic expression of CFTR mutations, and be of relevance in other genetic diseases.

Ten polymorphic loci, located in a 1 Mb interval across the cystic fibrosis locus, were analyzed on normal and mutant CFTR genes. A different distribution of haplotype backgrounds among normal and mutant CFTR genes was observed. With exception of the D7S8 locus, the three most common mutations, delta F508, G542X and N1303K, were found on an identical haplotype background. In agreement with the observed linkage equilibrium between the Q1463Q and D7S8 loci, both alleles at the D7S8 locus were found on delta F508 CFTR genes. However, the G542X and N1303K mutations, which have been estimated to be at least 35000 years old, were found to be associated with a single allele at the D7S8 locus. Absence of recombination between the D7S8 and Q1463Q loci was also observed on normal CFTR genes with this haplotype background. At the Tn locus in intron 8, allele 9 known to result in very efficient splicing was associated with the most frequent mutations. At the M470V locus, located in a conserved region of the first nucleotide binding fold, the amino acid methionine was found to be associated with the frequent mutations, in particular with mutations located in one of the two nucleotide binding folds which are generally known as severe mutations with regard to exocrine pancreatic function. On mutant CFTR gene, this locus was in complete association with the centromeric D9 locus, in the absence of a complete association with the intervening loci.(ABSTRACT TRUNCATED AT 250 WORDS)

In order to get a better insight into the function of amino acid residues located in the second transmembrane domain of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, all exon 18 mutations found in cystic fibrosis (CF) patients were characterized at the protein and at the electrophysiological level. Of the different mutations present in transmembrane helix 12 (M1137V, M1137R, I1139V and v vM1140), and the intracytoplasmic loop connecting TM12 and NBD2 (D1152H and D1154G), only M1137R interfered with the proper maturation of the protein. Permeability studies performed after injection of the different wild-type and mutant cRNAs in Xenopus laevis oocytes indicated that the mutations did not alter the permeability sequence of the CFTR channels. The whole cell cAMP activated chloride currents, however, were significantly reduced for M1137V, I1139V, D1152H and D1154G and close to zero for v vM1140, indicating that these mutations interfere with the proper gating of the chloride channels.z 1998 Federation of European Biochemical Societies.

CFTR transcripts have been qualitatively and quantitatively analysed in nasal epithelial and vas deferens cells by means of reverse transcription PCR. Alternative splicing of exon 9, which is known to occur in nasal epithelial cells, also occurred in vas deferens cells. The extent of this alternative splicing was determined by the allele present at the Tn locus at the end of intron 8 of the CFTR gene. However, the proportion of transcripts lacking exon 9 sequences was increased in vas deferens cells compared with nasal epithelial cells, independent of the Tn genotype. We postulate that this tissue specific difference in the proportion of CFTR transcripts lacking exon 9 sequences could contribute to the tissue specific disease phenotype observed in individuals with congenital bilateral absence of the vas deferens.

Ovarian physiology and pathology are important areas of scientific research. Efforts have been made to identify the ovary-related transcriptomes in different species. However, the proteomic studies are limited. The rhesus monkey is very similar to humans, and it is widely used in the study of reproductive biology and medicine. In this study, using an optimized proteomics platform, we successfully identified 5723 rhesus ovarian proteins, of which 4325 proteins were consistently identified in all three replicates and with at least 2 unique peptides. The 4325 proteins were chosen for further analysis. Through gene ontology and pathway analyses, we obtained a preliminary understanding of the function of these proteins. A random immunohistochemistry analysis was used to determine the expression of proteins in various cell types. By comparing the genes identified in this study with genes that were reported to have relatively high levels of expression in human oocytes, we obtained genes that were predicted to play roles in maintenance of normal ovarian physiology. Searching the identified genes from this study against the MGI database gave us a list of proteins those exist in the rhesus monkey ovary and are important for female mouse reproduction as well. The overlap of genes in this study and the genes whose abnormal expression or dysfunction were reported to be associated with human polycystic ovary syndrome (PCOS) and premature ovarian failure (POF) prompted us to use the rhesus monkey to study these two common causes of female infertility. This study may provide a basis for future studies of human reproductive disorders using the rhesus monkey as a model.