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PubMed1981

Anti-H-2 hybridoma antibodies as immunoselective agents. I. Isolation of forward and reverse mutations for reactivity with a monoclonal antibody.

Using immunoselection with an H-2Kk-specific monoclonal antibody following mutagenesis on an (H-2k/H-2d) F1 cell line we have obtained variants that do not react with the selecting monoclonal antibody but continue to react with other monoclonal antibodies directed against the same gene product. The mutants fall into two classes based on their serological profile. This phenotype is suggestive of a structural mutation in the selected gene. If the genetic change involved is a point mutation (as opposed to a deletion), one should be able to obtain revertants. Using the fluorescence-activated cell sorter, we have been able to obtain from one of the monoclonal-antibody-nonreactive mutants cells that do bind the selecting antibody. In order to prove that the presumptive revertant is not a contaminant wild-type cell that inadvertently got mixed into the resistance mutant, we first introduced an outside marker, resistance to the purine analogue 2-amino-6-mercaptopurine (6-thioguanine), into the monoclonal-antibody-resistant mutant. The revertants obtained using the cell sorter continue to express the nonselective phenotype of resistance to 6-thioguanine, showing that they are not wild-type cells. In addition, their serological characteristics are different from those of either the wild-type cells or the hybridoma-resistant mutants from which they were derived. Based on the serological analyses, it would seem that we have isolated at least three variant forms of the H-2Kk gene product.

Animals↗
PubMed2006

Differences in the carotenoid content of ordinary citrus and lycopene-accumulating mutants.

High-performance liquid chromatography, coupled with photodiode array detection, was used to analyze the carotenoid composition of peel and juice vesicle tissues of ordinary and lycopene-accumulating mutants (referred to as red mutants in this article) of orange, pummelo, and grapefruit. Thirty-six major carotenoids, including some cis-trans isomers, were separated on a C30 reversed phase column, and 23 of them were identified on the basis of retention times and spectral characteristics with authentic standards. Carotenoid profiles varied with tissue types, citrus species, and mutations. beta-Citraurin occurred in the peel of oranges but not in juice vesicles, whereas the reverse was found for violaxanthin, 9-cis-violaxanthin, and luteoxanthin. The diversity of carotenoids in peel and juice vesicle tissues and the fact that there was over 250 times higher content of total carotenoids in peels of Yuhuan pummelo than juice vesicles suggested that the biosynthesis of carotenoids in these two tissues was independent and exchange of carotenoids between the tissues was not likely. Lutein was observed in peels of pummelos and grapefruits and juice vesicles of ordinary pummelo but not in orange tissues. Accumulation of lycopene and beta-carotene was observed in red mutant citrus, except for the peel of Cara Cara red orange. Additionally, phytoene accumulated in all tissues except for the peel of Chuzhou Early Red pummelo. No obvious change in the total content of xanthophylls was observed in the Cara Cara red orange. Ordinary grapefruit (Marsh) tissues and pummelo (Yuhuan) juice vesicles were almost devoid of carotenoids, and in red mutants, the content of total carotenoids increased dramatically up to 790-fold. The different changes in carotenoid content and profiles in mutant(s) of different citrus species suggest that the underlying mechanisms for the mutations might be different.

Carotenoids↗
PubMed1991

The action of 1-nitroso-8-nitropyrene in Escherichia coli: DNA adduct formation and mutational consequences in the absence of nucleotide excision-repair.

To study the mechanisms of mutagenesis by the carcinogen 1,8-dinitropyrene we have determined the DNA adducts formed and mutations induced by its partially activated metabolite 1-nitroso-8-nitropyrene (1,8-NONP) in an Escherichia coli strain deficient in nucleotide excision-repair. Using DNA sequence analysis we have characterized a collection of 159 lacI- mutations recovered following treatment with 1,8-NONP. The mutational spectrum was dominated by -1 frameshifts (110 events) in runs of contiguous G or C residues. Frameshift frequency was observed to increase with the length of the reiterated sequence. Two mutations involved the loss of GpC from alternating (GpC)n sequences. The ratio of -1:-2 events observed following 1,8-NONP treatment was markedly different from that induced by N-acetoxy-N-acetyl-2-aminofluorene in the same genetic target. Other mutational classes recovered included 'spontaneous' hotspot mutations (19 events), base substitutions (12 events), deletions (7 events), one duplication, one + (A:T) frameshift and one mutation containing closely juxtaposed -(G:C) events. Of the 125 point mutations characterized, 124 occurred at G:C sites. The site specificity of mutation was consistent with the 32P-postlabeling profile of 1,8-NONP-DNA adducts which showed that 95% of the adducts migrated to the same position on the TLC plates as the guanine C(8) adduct 1-N-(2'-deoxyguanosin-8-yl)-amino-8-nitropyrene. Two minor 1,8-NONP-DNA mutations were also detected, one at dG/dC sites, and the other at dA/dT sites.

Animals↗
PubMed2007

Ba/F3 cells and their use in kinase drug discovery.

PURPOSE OF REVIEW: Due to their ability to function as dominant oncogenes, protein kinases have become favored targets in the quest for 'molecularly-targeted' cancer chemotherapeutics. The discovery of a large number of cancer-associated mutations in the kinome, and the progress in developing specific small-molecule kinase inhibitors has increased the need for accurate, reproducible, and efficient kinase activity-dependent cellular assay systems. RECENT FINDINGS: Ba/F3, a murine interleukin-3 dependent pro-B cell line is increasingly popular as a model system for assessing both the potency and downstream signaling of kinase oncogenes, and the ability of small-molecule kinase inhibitors to block kinase activity. Facilitated by their growth properties, Ba/F3 cells have recently been adapted to high-throughput assay formats for compound profiling. Further, several published approaches show promise in predicting resistance to small-molecule kinase inhibitors elicited by point mutations interfering with inhibitor binding. SUMMARY: Ba/F3 cells are an increasingly popular tool in kinase drug discovery. The ability to test the transforming capacity of newly identified kinase mutations, and to profile drug candidates and compound libraries in high-throughput fashion, combined with the use of Ba/F3 cells to predict clinical resistance will greatly facilitate developments in this field.

Animals↗
PubMed2005

Detection of a new 3-base pair insertion mutation in the protease gene of human immunodeficiency virus type 1 during highly active antiretroviral therapy (HAART).

To investigate a new insertion mutation in the protease (PR) gene of human immunodeficiency virus type 1 (HIV-1) in a patient extensively pretreated with antiretroviral drugs, genotypic analyses of plasma-derived viruses were performed by sequencing segments of 1302 nucleotides in the pol gene of HIV-1. Despite optimal compliance to highly active antiretroviral therapy (HAART) the patient showed poor virological success. Nucleotide sequences of retrospective available plasma samples exhibited a previously unknown 3-bp insertion mutation, corresponding to a leucine, between codons 31 and 32 of the PR gene. This kind of mutation appears to be very rare and it does not seem to be associated with any phenotypic resistance profile known so far. It should be noted that the insert mutation, once it appeared, did not revert to the wild-type variant, suggesting that it seems to correspond to a better fitness of the variant viruses.

Adult↗
PubMed2006

Transcriptional profiling of the protein phosphatase 2C family in yeast provides insights into the unique functional roles of Ptc1.

Type 2C protein phosphatases are encoded in Saccharomyces cerevisiae by several related genes (PTC1-5 and PTC7). To gain insight into the functions attributable to specific members of this gene family, we have investigated the transcriptional profiles of ptc1-5 mutants. Two main patterns were obtained as follows: the one generated by the ptc1 mutation and the one resulting from the lack of Ptc2-5. ptc4 and ptc5 profiles were quite similar, whereas that of ptc2 was less related to this group. Mutation of PTC1 resulted in increased expression of numerous genes that are also induced by cell wall damage, such as YKL161c, SED1, or CRH1, as well as in higher amounts of active Slt2 mitogen-activated protein kinase, indicating that lack of the phosphatase activates the cell wall integrity pathway. ptc1 cells were even more sensitive than slt2 mutants to a number of cell wall-damaging agents, and both mutations had additive effects. The sensitivity of ptc1 cells was not dependent on Hog1. Besides these phenotypes, we observed that calcineurin was hyperactivated in ptc1 cells, which were also highly sensitive to calcium ions, heavy metals, and alkaline pH, and exhibited a random haploid budding pattern. Remarkably, many of these traits are found in certain mutants with impaired vacuolar function. As ptc1 cells also display fragmented vacuoles, we hypothesized that lack of Ptc1 would primarily cause vacuolar malfunction, from which other phenotypes would derive. In agreement with this scenario, overexpression of VPS73, a gene of unknown function involved in vacuolar protein sorting, largely rescues not only vacuolar fragmentation but also sensitivity to cell wall damage, high calcium, alkaline pH, as well as other ptc1-specific phenotypes.

Calcineurin↗
PubMed2002

Wnt-4 regulation by the Wilms' tumour suppressor gene, WT1.

The Wilms' tumour suppressor gene, WT1, encodes multiple nuclear protein isoforms, all containing four C-terminal zinc finger motifs. WT1 proteins can both activate and repress putative target genes in vitro, although the in vivo relevance of these putative target genes is often unverified. WT1 mutations can result in Wilms' tumour and the Denys-Drash Syndrome (DDS) of infantile nephropathy, XY pseudohermaphroditism and predisposition to Wilms' tumour. We have established stable transfectants of the mouse mesonephric cell line, M15, which express WT1 harbouring a common DDS point mutation (R394W). A comparison of the expression profiles of M15 and transfectant C2A was performed using Nylon-based arrays. Very few genes showed differential expression. However Wnt-4, a member of the Wnt gene family of secreted glycoproteins, was downregulated in C2A and other similar clones. Doxycycline induction of WT1-A or WT1-D expression in HEK293 stable transfectants also elicited an elevation in Wnt4 expression. Wnt4 is critical for the mesenchyme-to-epithelial transition during kidney development, making it an attractive putative WT1 target. We have mapped human Wnt-4 gene to chromosome 1p35-36, a region of frequent LOH in WT, have characterized the genomic structure of the human Wnt-4 gene and isolated 9 kb of immediate promoter. While several potential WT1 binding sites exist within this promoter, reporter analysis does not strongly support the direct regulation of Wnt4 by WT1. We propose that Wnt-4 regulation by WT1 occurs at a more distant promoter or enhancer site, or is indirect.

Amino Acid Substitution↗
PubMed2003

Mutation analysis in patients with N-acetylglutamate synthase deficiency.

N-acetylglutamate synthase (NAGS) is the key enzyme for the regulation of the hepatic urea cycle and is also highly expressed in kidney and gut. The reaction product, N-acetylglutamate, is an allosteric activator of carbamylphosphate synthetase 1 in the liver, catalyzing the initial step of ammonia detoxification. NAGS deficiency is a rare inborn error of metabolism inherited as an autosomal recessive trait leading to hyperammonemia. Using homology search based on genetic information of ascomycetes, we identified the human gene for NAGS on chromosome 17q21.31. There is a distinct pattern of organospecific expression of transcripts in liver, small intestine, and kidney similar to the other mitochondrially located enzymes of the urea cycle. The encoded 534 amino acid polypeptide has a consensus sequence for a 49 amino acid mitochondrial leader peptide. We identified private mutations of the NAGS gene in patients with severe early onset of clinical symptoms (IVS3-2A>T, c.1306_1307insT, c.971G>A/W324X, c.1289T>C/L430P, c.1299G>C/E433S, c.1450T>C/W484R), as well as in a case with late onset (c.835G>A/A279P). Four out of seven mutations were detected on exon 6. This is the first report of mutation analysis in a series of families affected with deficiency of NAGS. Molecular analysis of patients and reliable antenatal diagnostics for affected families are now feasible.

Acetyltransferases↗
PubMed1995

In vivo assessment of mutations in the phenylalanine hydroxylase gene by phenylalanine loading: characterization of seven common mutations.

UNLABELLED: Mutations in the gene encoding phenylalanine hydroxylase (PAH) cause persistent hyperphenylalaninaemia. To date, more than 200 point mutations and microdeletions have been characterized. Each mutation has a particular quantitative effect on enzyme activity and recessive expression of different mutant alleles results in a marked interindividual heterogeneity of metabolic and clinical phenotypes. In this paper we demonstrate how a simple clinical test can be used to evaluate the correlation between mutation genotype and phenylalanine metabolism. In hyperphenylalaninaemic patients with known PAH mutation genotype, we have investigated phenylalanine turnover in vivo by measuring the ability to eliminate a test dose of L-phenylalanine. All patients could be considered functionally hemizygous for one of their mutant alleles by carrying on the other allele a mutation that is known to completely abolish PAH activity and encode a peptide with no immunoreactivity. Seven mutations (R408W, IVS-12nt1, R261Q, G46S, Y414C, A104D, and D415N) were characterized by oral phenylalanine loading, each mutation being represented by at least three patients. The elimination profile determined for a 3-day period provides a measure to compare residual activity of the mutant proteins and to assign each mutation to a particular metabolic phenotype. The established relation between genotype and phenotype may enable prediction of the severity of the disease by genotype determination in the newborn period. This will aid in the management of hyperphenylalaninaemia and may improve prognosis. CONCLUSION: The possibility of predicting the residual enzyme activity by DNA analysis performed already in the newborn period allows the prompt implementation of a diet that is adjusted to the degree of PAH deficiency. This may improve management and prognosis of hyperphenylalaninaemia.

Alleles↗
PubMed2006

Mutational analysis of polar amino acid residues within predicted transmembrane helices 10 and 16 of multidrug resistance protein 1 (ABCC1): effect on substrate specificity.

Human multidrug resistance protein 1 (MRP1) has a total of 17 transmembrane (TM) helices arranged in three membrane-spanning domains, MSD0, MSD1, and MSD2, with a 5 + 6 + 6 TM configuration. Photolabeling studies indicate that TMs 10 and 11 in MSD1 and 16 and 17 in MSD2 contribute to the substrate binding pocket of the protein. Previous mutational analyses of charged and polar amino acids in predicted TM helices 11, 16, and 17 support this suggestion. Mutation of Trp(553) in TM10 also affects substrate specificity. To extend this analysis, we mutated six additional polar residues within TM10 and the remaining uncharacterized polar residue in TM16, Asn(1208). Although mutation of Asn(1208) was without effect, two of six mutations in TM10, T550A and T556A, modulated the drug resistance profile of MRP1 without affecting transport of leukotriene C4, 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG), and glutathione. Mutation T550A increased vincristine resistance but decreased doxorubicin resistance, whereas mutation T556A decreased resistance to etoposide (VP-16) and doxorubicin. Although conservative mutation of Tyr(568) in TM10 to Phe or Trp had no apparent effect on substrate specificity, substitution with Ala decreased the affinity of MRP1 for E(2)17betaG without affecting drug resistance or the transport of other substrates tested. These analyses confirm that several amino acids in TM10 selectively alter the substrate specificity of MRP1, suggesting that they interact directly with certain substrates. The location of these and other functionally important residues in TM helices 11, 16, and 17 is discussed in the context of an energy-minimized model of the membrane-spanning domains of MRP1.

Antineoplastic Agents↗
PubMed1993

Polioviruses with natural recombinant genomes isolated from vaccine-associated paralytic poliomyelitis.

To determine how oral poliovirus vaccine (Sabin) strains evolve during replication in humans and to confirm the etiology of vaccine-associated paralytic poliomyelitis (VAPP), we examined 70 vaccine-derived strains isolated from VAPP cases. Two distant sequences of the poliovirus genome were targeted for a double restriction fragment length polymorphism assay (RFLP) of reverse-transcribed genomic segments amplified by PCR, an extension of the method that we described previously (Balanant et al., 1991). One (RFLP-1) was a 480-long nucleotide sequence coding for the N-terminal part of the VP1 capsid polypeptide, situated in the 5' third of the viral genome (nucleotides 2401-2880). The other (RFLP-3D1) was a 291-long nucleotide sequence coding for a part of the viral polymerase, situated near the 3' end of the genome (nucleotides 6086-6376). Strain-specific restriction profiles could be generated for different field isolates by using three restriction enzymes in each case: HaeIII, DdeI, and HpaII for RFLP-1 and HaeIII, DdeI and RsaI for RFLP-3D1. With few exceptions, the vaccine-specific RFLP profiles were found to be conserved in both regions during replication of these viruses in humans. Thus, RFLP could be used as a marker so as to identify the origin of viral isolates at both ends of their genome. Whether viral isolates were vaccine-derived was determined by using strain-specific monoclonal antibodies and RFLP-1. Among the 70 isolates, 21 of the 43 type 2 strains and 15 of the 22 type 3 strains had a recombinant genome. None of the 5 type 1 Sabin-derived isolates was found to be recombinant. Both intertypic vaccine/vaccine and vaccine/non-vaccine recombinants were detected. Partial nucleotide sequencing confirmed the RFLP results in all cases that were investigated. In one case, it was possible to predict the recombination junction site from the restriction profiles. This site was more precisely localized by sequencing. The C6203 > U nucleotide substitution, which is suspected to contribute to the reversion toward neurovirulence of the attenuated Sabin 1 strain, was detected in almost all the recombinant genomes containing Sabin 1-specific sequences at the 3' extremity. This mutation was detected by identification of the modified RsaI profile in the RFLP-3D1. The results presented in this paper suggest that recombination, alone or together with mutation, might be one of the mechanisms of the reversion toward neurovirulence of attenuated vaccine strains and of the natural evolution of poliovirus.

Base Sequence↗
PubMed2004

Neuropsychiatric symptoms of fragile X syndrome: pathophysiology and pharmacotherapy.

Fragile X syndrome is the leading inherited form of mental retardation, and second only to Down's syndrome as a cause of mental retardation attributable to an identifiable genetic abnormality. Fragile X syndrome is caused by a defect in the fragile X mental retardation 1 gene (FMR1), located near the end of the long arm of the X chromosome. FMR1 normally synthesises the fragile X protein (FMRP), but mutations in FMR1 lead to a lack of FMRP synthesis, resulting in fragile X syndrome. While the specific function of FMRP is not yet fully understood, the protein is known to be important for normal brain development. The physical, cognitive and behavioural features of individuals with fragile X syndrome depend on gender (females have two X chromosomes, one active and one inactive) and the molecular status of the mutation (premutation, full mutation or mosaic). Features of the behavioural profile of individuals with fragile X syndrome include hypersensitivity to stimuli, overarousability, inattention, hyperactivity and (mostly in men) explosive and aggressive behaviour to others or self. Social anxiety, other anxiety disorders, depression, impulse control disorder and mood disorders are the most common psychiatric disorders diagnosed in individuals with fragile X syndrome, although no formal studies have been undertaken. There have been very few psychopharmacological studies of the treatment of behaviours associated with fragile X syndrome. These limited studies and surveys of psychotropic drugs used in individuals with fragile X syndrome suggest that stimulants are helpful for hyperactivity, that alpha(2)-adrenoceptor agonists and beta-adrenoceptor antagonists help to control overarousability, impulsivity and aggressiveness, and that SSRIs can control anxiety, impulsivity and irritability, alleviate depressive symptoms and decrease aggressive and self-injurious behaviour. Typical and atypical antipsychotics in combination with other psychotropics have been used for control of psychotic disorders and severe aggressive behaviours. Mood stabilisers have been found to be useful when mood dysregulation or mood disorders are present with or without aggressive behaviour. Folic acid and L-acetylcarnitine (levacecarnine) have not been found to improve deficits or behaviours. As there is no specific psychotropic drug for any of the deficits or behaviours associated with fragile X syndrome, clinicians are advised to diagnose any psychiatric syndromes or disorders present and treat them with the appropriate psychotropic drug. If no psychiatric disorder can be diagnosed and the patient's challenging behaviours cannot be controlled with environmental manipulation or behaviour modification techniques, the most benign psychotropic drug should be used. Antipsychotics should be reserved for psychotic disorders, for impulse control disorders (used in combination with other psychotropics), or when challenging behaviours constitute an emergency. In the future, new medications targeting molecules implicated in the modulation of anxiety, fear and fear responding will be useful for treating the social anxiety and overarousability exhibited by individuals with fragile X syndrome.

Animals↗
PubMed2004

The decision to test in women receiving genetic counseling for BRCA1 and BRCA2 mutations.

Functions of genetic counseling include provision of risk information and provision of support in an effort to assist with decision making. This study examines (1) the relationship among intentions to test, self-reported provision of blood sample, and receipt of test results; (2) the impact of genetic counseling on distress specific to gene status, perceived risk of developing breast and ovarian cancer in the context having BRCA1/2 mutations (mutations predisposing to increased risk of breast-ovarian cancer), and perceived risk factors for breast cancer; and (3) the clinical profile of those receiving/not receiving results. Intentions to test for BRCA1/2 mutations, self-reported provision of blood sample immediately after counseling, and receipt of test results were statistically different but highly correlated, and intentions to test increased from pre- to postcounseling. A repeated measures ANOVA found distress specific to gene status and perceived risk factors decreased from pre- to postcounseling. Further, two clinical profiles of consultands emerged: (1) those receiving results with change in intentions to test having lower levels of distress and (2) those not receiving results and those receiving results with no change in intentions to test with higher levels of distress. Our findings are consistent with the function of genetic counseling-to provide information and support to those with familial cancer, as well as to assist in decision making. The provision of support is important as distress specific to gene status may impede flexible decision making about genetic testing.

Adaptation, Psychological↗
PubMed2002

DHPLC screening of cystic fibrosis gene mutations.

Denaturing high performance liquid chromatography (DHPLC) using ion-pairing reverse phase chromatography (IPRPC) columns is a technique for the screening of gene mutations. In order to evaluate the potential utility of this assay method in a clinical laboratory setting, we subjected the PCR products of 73 CF patients known to bear CFTR mutations to this analytic technique. We used thermal denaturation profile parameters specified by the MELT program tool, made available by Stanford University. Using this strategy, we determined an initial analytic sensitivity of 90.4% for any of 73 known CFTR mutations. Most of the mutations not detected by DHPLC under these conditions are alpha-substitutions. This information may eventually help to improve the MELT algorithm. Increasing column denaturation temperatures for one or two degrees above those recommended by the MELT program allowed 100% detection of CFTR mutations tested. By comparing DHPLC methodology used in this study with the recently reported study based on Wavemaker 3.4.4 software (Transgenomic, Omaha, NE) [Le Marechal et al., 2001) and with previous SSCP analysis of CFTR mutations [Ravnik-Glavac et al., 1994] we emphasized differences and similarities in order to refine the DHPLC system and discuss the relationship to the alternative approaches. We conclude that the DHPLC method, under optimized conditions, is highly accurate, rapid, and efficient in detecting mutations in the CFTR gene and may find high utility in screening individuals for CFTR mutations. Hum Mutat 19:374-383, 2002. Published 2002 Wiley-Liss, Inc.

Algorithms↗
PubMed2006

The 471delAAAG mutation and C353T polymorphism in the RNASEL gene in sporadic and inherited cancer in Israel.

The rate of RNASEL 471delAAAG mutation was previously reported to be less than 7% in Ashkenazi prostate cancer patients. It seems plausible that the same mutation may also be involved in breast/ovarian cancer predisposition in Jewish individuals. To evaluate the role of this mutation in cancer predisposition, a total of 1011 individuals including 294 Jewish men with prostate cancer, 61 Ashkenazi women with ovarian cancer and 50 unaffected women, matched for age and ethnicity, were genotyped for sequence anomalies in a single RNASEL gene amplicon using DGGE and sequencing. Additionally, 209 Ashkenazi BRCA1/2 mutation carriers, 205 high-risk non-carriers matched for cancer type and age at diagnosis, and 192 healthy Ashkenazi women were screened, using DHPLC and restriction methods. The 471delAAAG mutation was detected in a single male with prostate cancer (1/294, 0.3%), in two ovarian cancer patients (2/141, 1.4%) and in one of 242 healthy controls (0.41%). An abnormal DHPLC profile identical to the one produced by the 471delAAAG mutation was noted in 23 additional women. The rate of this polymorphism was significantly elevated in high-risk non-carrier women (16/205; 7.8%) than in BRCA1/2 carriers (2/209; 1.0%) and controls (5/192; 2.6%) (chi = 11.670; P < 0.001). Sequence analysis disclosed a silent polymorphism in Valine at codon 118: c.353 C- > T.The 471delAAAG mutation occurs rarely in Israeli prostate and breast/ovarian cancer patients. A silent polymorphism in the RNASEL gene occurs more prevalently in high-risk Ashkenazi breast/ovarian cancer patients without a BRCA1/2 mutation.

Breast Neoplasms↗
PubMed2026

Identification of a Novel Splice-Site variant in TACR3 (c.888&#x2009;+&#x2009;1G&#x2009;>&#x2009;A) Associated with Asthenozoospermia and Hypogonadotropic Hypogonadism in an Iranian Family.

BACKGROUND: TACR3 encodes the receptor for neurokinin B, a key regulator of the hypothalamic-pituitary-gonadal axis. Disruption of this pathway can impair gonadotropin release and male reproductive function. Given the genetic heterogeneity of male infertility, this study aimed to identify novel variants in TACR3 that may underlie asthenozoospermia and related hormonal abnormalities. METHODS: Fifteen infertile men with confirmed asthenozoospermia were enrolled. Whole-exome sequencing (WES) was performed on genomic DNA from peripheral blood, and the candidate variant was validated by Sanger sequencing. Functional predictions were made using PolyPhen-2, SIFT, MutationTaster, and REVEL. TACR3 mRNA expression levels were assessed by real-time PCR in available samples. RESULTS: A novel splice-site variant, TACR3 (NM_001059.3:c.888&#x2009;+&#x2009;1G&#x2009;>&#x2009;A), was detected and found to segregate with infertility in one family, appearing homozygously in two infertile brothers and heterozygously in the proband with severe asthenozoospermia. The variant was absent in public and local genomic databases, suggesting its extremely rare frequency. Furthermore, RT-PCR showed a dramatic reduction or complete loss of TACR3 expression in affected individuals, confirming its deleterious effect on splicing and mRNA stability. CONCLUSION: We identified a previously unreported splice-site mutation in TACR3 (c.888&#x2009;+&#x2009;1G&#x2009;>&#x2009;A) that likely causes familial infertility by disrupting the neurokinin B/NK3R signaling pathway. While the heterozygous proband exhibited severe asthenozoospermia, the homozygous brothers displayed hormonal profiles typical of hypogonadotropic hypogonadism. These findings extend the mutational landscape of TACR3 and highlight its essential contribution to male reproductive endocrinology.

Humans↗
PubMed2006

Expression profiling of clonal lymphocyte cell cultures from Rett syndrome patients.

BACKGROUND: More than 85% of Rett syndrome (RTT) patients have heterozygous mutations in the X-linked MECP2 gene which encodes methyl-CpG-binding protein 2, a transcriptional repressor that binds methylated CpG sites. Because MECP2 is subject to X chromosome inactivation (XCI), girls with RTT express either the wild type or mutant MECP2 in each of their cells. To test the hypothesis that MECP2 mutations result in genome-wide transcriptional deregulation and identify its target genes in a system that circumvents the functional mosaicism resulting from XCI, we performed gene expression profiling of pure populations of untransformed T-lymphocytes that express either a mutant or a wild-type allele. METHODS: Single T lymphocytes from a patient with a c.473C>T (p.T158M) mutation and one with a c.1308-1309delTC mutation were subcloned and subjected to short term culture. Gene expression profiles of wild-type and mutant clones were compared by oligonucleotide expression microarray analysis. RESULTS: Expression profiling yielded 44 upregulated genes and 77 downregulated genes. We compared this gene list with expression profiles of independent microarray experiments in cells and tissues of RTT patients and mouse models with Mecp2 mutations. These comparisons identified a candidate MeCP2 target gene, SPOCK1, downregulated in two independent microarray experiments, but its expression was not altered by quantitative RT-PCR analysis on brain tissues from a RTT mouse model. CONCLUSION: Initial expression profiling from T-cell clones of RTT patients identified a list of potential MeCP2 target genes. Further detailed analysis and comparison to independent microarray experiments did not confirm significantly altered expression of most candidate genes. These results are consistent with other reported data.

Animals↗