Influence of Nucleoshuttling of the ATM Protein in the Healthy Tissues Response to Radiation Therapy: Toward a Molecular Classification of Human Radiosensitivity.

PURPOSE: Whereas post-radiation therapy overreactions (OR) represent a clinical and societal issue, there is still no consensual radiobiological endpoint to predict clinical radiosensitivity. Since 2003, skin biopsy specimens have been collected from patients treated by radiation therapy against different tumor localizations and showing a wide range of OR. Here, we aimed to establish quantitative links between radiobiological factors and OR severity grades that would be relevant to radioresistant and genetic hyperradiosensitive cases. METHODS AND MATERIALS: Immunofluorescence experiments were performed on a collection of skin fibroblasts from 12 radioresistant, 5 hyperradiosensitive, and 100 OR patients irradiated at 2 Gy. The numbers of micronuclei, γH2AX, and pATM foci that reflect different steps of DNA double-strand breaks (DSB) recognition and repair were assessed from 10 minutes to 24 hours after irradiation and plotted against the severity grades established by the Common Terminology Criteria for Adverse Events and the Radiation Therapy Oncology Group. RESULTS: OR patients did not necessarily show a gross DSB repair defect but a systematic delay in the nucleoshuttling of the ATM protein required for complete DSB recognition. Among the radiobiological factors, the maximal number of pATM foci provided the best discrimination among OR patients and a significant correlation with each OR severity grade, independently of tumor localization and of the early or late nature of reactions. CONCLUSIONS: Our results are consistent with a general classification of human radiosensitivity based on 3 groups: radioresistance (group I); moderate radiosensitivity caused by delay of nucleoshuttling of ATM, which includes OR patients (group II); and hyperradiosensitivity caused by a gross DSB repair defect, which includes fatal cases (group III).

PRKDC mutations associated with immunodeficiency, granuloma, and autoimmune regulator-dependent autoimmunity.

BACKGROUND: PRKDC encodes for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a kinase that forms part of a complex (DNA-dependent protein kinase [DNA-PK]) crucial for DNA double-strand break repair and V(D)J recombination. In mice DNA-PK also interacts with the transcription factor autoimmune regulator (AIRE) to promote central T-cell tolerance. OBJECTIVE: We sought to understand the causes of an inflammatory disease with granuloma and autoimmunity associated with decreasing T- and B-cell counts over time that had been diagnosed in 2 unrelated patients. METHODS: Genetic, molecular, and functional analyses were performed to characterize an inflammatory disease evocative of a combined immunodeficiency. RESULTS: We identified PRKDC mutations in both patients. These patients exhibited a defect in DNA double-strand break repair and V(D)J recombination. Whole-blood mRNA analysis revealed a strong interferon signature. On activation, memory T cells displayed a skewed cytokine response typical of TH2 and TH1 but not TH17. Moreover, mutated DNA-PKcs did not promote AIRE-dependent transcription of peripheral tissue antigens in vitro. The latter defect correlated in vivo with production of anti-calcium-sensing receptor autoantibodies, which are typically found in AIRE-deficient patients. In addition, 9 months after bone marrow transplantation, patient 1 had Hashimoto thyroiditis, suggesting that organ-specific autoimmunity might be linked to nonhematopoietic cells, such as AIRE-expressing thymic epithelial cells. CONCLUSION: Deficiency of DNA-PKcs, a key AIRE partner, can present as an inflammatory disease with organ-specific autoimmunity, suggesting a role for DNA-PKcs in regulating autoimmune responses and maintaining AIRE-dependent tolerance in human subjects.

The clinical presentation of Marfan syndrome is modulated by expression of wild-type FBN1 allele.

Marfan syndrome is an autosomal dominant disorder mainly caused by mutations within FBN1 gene. The disease displays large variability in age of onset or severity and very poor phenotype/genotype correlations have been demonstrated. We investigated the hypothesis that phenotype severity could be related to the variable expression level of fibrillin-1 (FBN1) synthesized from the wild-type (WT) allele. Quantitative reverse-transcription and polymerase chain reaction was used to evaluate FBN1 levels in skin fibroblasts from 80 Marfan patients with premature termination codons and in skin fibroblasts from 80 controls. Results in controls showed a 3.9-fold variation in FBN1 mRNA synthesis level between subjects. A similar 4.4-fold variation was found in the Marfan population, but the mean level of FBN1 mRNA was a half of the control population. Differential allelic expression analysis in Marfan fibroblasts showed that over 90% of FBN1 mRNA was transcribed from the wild allele and the mutated allele was not detected. In the control population, independently of the expression level of FBN1, we observed steady-state equilibrium between the two allelic-mRNAs suggesting that FBN1 expression mainly depends on trans-acting regulators. Finally, we show that a low level of residual WT FBN1 mRNA accounts for a high risk of ectopia lentis and pectus abnormality and tends to increase the risk of aortic dilatation.

Protective effect of Basella alba and Carpolobia alba extracts against maneb-induced male infertility.

CONTEXT: Male infertility is one of the leading causes of social frustration and marginalization, mainly in the developing world. It is attributed to many factors including exposure to agropesticides such as manganese ethylenebis (dithiocarbamate) (maneb), which is one of the most frequently used fungicides in Cameroon. Previous reports support efficiency of some medicinal plants commonly used in Cameroonian folk medicine for the treatment of this disorder. OBJECTIVE: The present study was aimed at assessing the protective effect of extracts from selected plant species, namely Basella alba L. (Basellaceae) (MEBa) and Carpolobia alba G. Don (Polygalaceae) (AECa), in alleviating the maneb-induced impairment of male reproductive function in Wistar albino rats. MATERIALS AND METHODS: The rats were treated with vehicle, plant extract (MEBa or AECa), maneb and maneb plus plant extract, respectively, and their fertility was assessed. Animals were thereafter sacrificed and organs (liver, kidneys and reproductive organs) were dissected out and weighed. Serum androgens together with alanine aminotransferase, liver glutathione and thiobarbituric acid reactive species (TBARS) were also measured. RESULTS AND DISCUSSION: From this study, both plant extracts stimulated testosterone and improved fertility. Administration of MEBa plus maneb prevented fertility reduction by maneb and minimized the inhibitory effect of maneb on testosterone levels. AECa also improved fertility of the maneb-exposed rats, though without restoring testosterone levels, and other investigated parameters remained unaffected by different treatments. CONCLUSION: These findings emphasized the beneficial effects of B. alba and C. alba extracts on male fertility, and suggest their protective effect against maneb-induced toxicity in male reproductive function.

Protein kinase cδ deficiency causes mendelian systemic lupus erythematosus with B cell-defective apoptosis and hyperproliferation.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a prototype autoimmune disease that is assumed to occur via a complex interplay of environmental and genetic factors. Rare causes of monogenic SLE have been described, providing unique insights into fundamental mechanisms of immune tolerance. The aim of this study was to identify the cause of an autosomal-recessive form of SLE. METHODS: We studied 3 siblings with juvenile-onset SLE from 1 consanguineous kindred and used next-generation sequencing to identify mutations in the disease-associated gene. We performed extensive biochemical, immunologic, and functional assays to assess the impact of the identified mutations on B cell biology. RESULTS: We identified a homozygous missense mutation in PRKCD, encoding protein kinase δ (PKCδ), in all 3 affected siblings. Mutation of PRKCD resulted in reduced expression and activity of the encoded protein PKCδ (involved in the deletion of autoreactive B cells), leading to resistance to B cell receptor- and calcium-dependent apoptosis and increased B cell proliferation. Thus, as for mice deficient in PKCδ, which exhibit an SLE phenotype and B cell expansion, we observed an increased number of immature B cells in the affected family members and a developmental shift toward naive B cells with an immature phenotype. CONCLUSION: Our findings indicate that PKCδ is crucial in regulating B cell tolerance and preventing self-reactivity in humans, and that PKCδ deficiency represents a novel genetic defect of apoptosis leading to SLE.

Effect of agropesticides use on male reproductive function: a study on farmers in Djutitsa (Cameroon).

This study aimed at investigating the effect of agropesticides on male reproductive function in farmers in Djutitsa (West Cameroon). To this end, 47 farmers in Djutitsa were asked questions on their health status and pesticide use in agriculture. Thereafter, their blood samples were collected for assessment of sex hormones including serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), androstenedione, testosterone, as well as sex hormone binding globulin (SHBG). Their serum triiodothyronine (T3) and thyroxine (T4) levels were also measured. Thirty seven men not exposed to agropesticides were recruited as control group. Fifty six pesticides containing 25 active substances were currently used by farmers enrolled in our study, and most of their symptoms were related to spread/use of these chemicals. Compared to the control group, there was no significant difference in FSH, LH, SHBG, estradiol, and thyroid hormones (T3 and T4) levels. Farmers had significantly lower serum testosterone (20.93 ± 1.03 nM vs. 24.32 ± 1.32 nM; P < 0.05) and higher androstenedione level (3.83 ± 0.20 nM vs. 2.80 ± 0.15 nM; P < 0.001). Their serum free testosterone as well as bioavailable testosterone were unchanged, while estradiol/testosterone and androstenedione/testosterone ratios were significantly increased (0.45 ± 0.03% vs. 0.33 ± 0.02%; P < 0.01 and 12.26 ± 3.64 vs 19.31 ± 6.82; P < 0.001, respectively). Our results suggest that male farmers of Djutitsa (West Cameroon) are exposed to agropesticides due to improper protective tool, and this exposure may impair their reproductive function through inhibition of testosterone synthesis; probably by inhibition of testicular 17ß- hydroxysteroid dehydrogenase (17HSD3) and induction of aromatase (CYP19).

A pharmacodynamic model of ganciclovir antiviral effect and toxicity for lymphoblastoid cells suggests a new dosing regimen to treat cytomegalovirus infection.

In bone marrow transplantation, the efficacy of ganciclovir in cytomegalovirus (CMV) disease treatment or prophylaxis remains partial. Because its hematological toxicity is dose limiting, optimization of the dosing schedule is required to increase its therapeutic index. The goal of our study was to describe the influence of the ganciclovir concentration and duration of exposure on cell survival and antiviral efficacy. The study was carried out in vitro on cultures of lymphoblastoid cells infected or not with the CMV AD169 reference strain and exposed to ganciclovir at different concentrations for 1, 2, 7, or 14 days. The data were analyzed by a mathematical model that allowed a quantitative characterization of ganciclovir pharmacodynamics and its variability. Simulations of the model were undertaken to determine the optimal concentration profile for maximizing the ganciclovir therapeutic index. Ganciclovir had very little toxic and antiviral effect, even at 20 mg liter(-1), when the duration of exposure was ≤ 7 days. A biologically significant effect was observed only with a 14-day exposure. Complete inhibition of viral replication was obtained at 20 mg liter(-1). The utility function, assuming equal weights for antiviral effect and toxicity, showed that maximal utility was reached around 10 mg liter(-1). The optimal ganciclovir concentration profile consisted of maintaining the concentration at 20 mg liter(-1) at the intervals 0 to 2 days and 7.58 to 9.58 days and a null concentration at other times. This optimal profile could be obtained by intravenous (i.v.) ganciclovir at 10 mg/kg of body weight twice daily (b.i.d.) at days 1, 2, 8.5, and 9.5 in stem cell transplant patients with normal renal function.

Clinical expression of Menkes disease in females with normal karyotype.

BACKGROUND: Menkes Disease (MD) is a rare X-linked recessive fatal neurodegenerative disorder caused by mutations in the ATP7A gene, and most patients are males. Female carriers are mosaics of wild-type and mutant cells due to the random X inactivation, and they are rarely affected. In the largest cohort of MD patients reported so far which consists of 517 families we identified 9 neurologically affected carriers with normal karyotypes. METHODS: We investigated at-risk females for mutations in the ATP7A gene by sequencing or by multiplex ligation-dependent probe amplification (MLPA). We analyzed the X-inactivation pattern in affected female carriers, unaffected female carriers and non-carrier females as controls, using the human androgen-receptor gene methylation assay (HUMAR). RESULTS: The clinical symptoms of affected females are generally milder than those of affected boys with the same mutations. While a skewed inactivation of the X-chromosome which harbours the mutation was observed in 94% of 49 investigated unaffected carriers, a more varied pattern was observed in the affected carriers. Of 9 investigated affected females, preferential silencing of the normal X-chromosome was observed in 4, preferential X-inactivation of the mutant X chromosome in 2, an even X-inactivation pattern in 1, and an inconclusive pattern in 2. The X-inactivation pattern correlates with the degree of mental retardation in the affected females. Eighty-one percent of 32 investigated females in the control group had moderately skewed or an even X-inactivation pattern. CONCLUSION: The X- inactivation pattern alone cannot be used to predict the phenotypic outcome in female carriers, as even those with skewed X-inactivation of the X-chromosome harbouring the mutation might have neurological symptoms.

DNA double-strand breaks induced by mammographic screening procedures in human mammary epithelial cells.

PURPOSE: To assess in vitro mammographic radiation-induced DNA damage in mammary epithelial cells from 30 patients with low (LR) or high (HR) family risk of breast cancer. MATERIALS AND METHODS: Spontaneous and radiation-induced DNA double-strand breaks (DSB) were quantified by using immunofluorescence of the phosphorylated H2AX histone (γH2AX) in different conditions of mammography irradiation (2, 4, 2 + 2 mGy). RESULTS: HR patients showed significantly more spontaneous γH2AX foci than LR patients (p = 0.014). A significant dose-effect was observed, with an exacerbation in HR patients (p = 0.01). The dose repetition (2 + 2 mGy) provided more induced and more unrepaired DSB than 2 mGy and 4 mGy, and was exacerbated in HR (p = 0.006). CONCLUSIONS: This study highlights the existence of DSB induced by mammography and revealed by γH2AX assay with two major radiobiological effects occurring: A low-dose effect, and a LOw and Repeated Dose (LORD) effect. All these effects were exacerbated in HR patients. These findings may lead us to re-evaluate the number of views performed in screening using a single view (oblique) in women whose mammographic benefit has not properly been proved such as HR patients.

Using transcription modules to identify expression clusters perturbed in Williams-Beuren syndrome.

The genetic dissection of the phenotypes associated with Williams-Beuren Syndrome (WBS) is advancing thanks to the study of individuals carrying typical or atypical structural rearrangements, as well as in vitro and animal studies. However, little is known about the global dysregulations caused by the WBS deletion. We profiled the transcriptomes of skin fibroblasts from WBS patients and compared them to matched controls. We identified 868 differentially expressed genes that were significantly enriched in extracellular matrix genes, major histocompatibility complex (MHC) genes, as well as genes in which the products localize to the postsynaptic membrane. We then used public expression datasets from human fibroblasts to establish transcription modules, sets of genes coexpressed in this cell type. We identified those sets in which the average gene expression was altered in WBS samples. Dysregulated modules are often interconnected and share multiple common genes, suggesting that intricate regulatory networks connected by a few central genes are disturbed in WBS. This modular approach increases the power to identify pathways dysregulated in WBS patients, thus providing a testable set of additional candidates for genes and their interactions that modulate the WBS phenotypes.

Clinical and molecular characterization of five patients with succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency.

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency is an inborn error of ketone body metabolism and causes episodic ketoacidosis. We report clinical and molecular analyses of 5 patients with SCOT deficiency. Patients GS07, GS13, and GS14 are homozygotes of S405P, L327P, and R468C, respectively. GS17 and GS18 are compound heterozygotes for S226N and A215V, and V404F and E273X, respectively. These mutations have not been reported previously. Missense mutations were further characterized by transient expression analysis of mutant cDNAs. Among 6 missense mutations, mutants L327P, R468C, and A215V retained some residual activities and their mutant proteins were detected in immunoblot analysis following expression at 37°C. They were more stable at 30°C than 37°C, indicating their temperature sensitive character. The R468C mutant is a distinct temperature sensitive mutant which retained 12% and 51% of wild-type residual activities at 37 and 30°C, respectively. The S226N mutant protein was detected but retained no residual activity. Effects of missense mutations were predicted from the tertiary structure of the SCOT molecule. Main effects of these mutations were destabilization of SCOT molecules, and some of them also affected catalytic activity. Among 5 patients, GS07 and GS18 had null mutations in both alleles and the other three patients retained some residual SCOT activities. All 5 developed a first severe ketoacidotic crisis with blood gas pH <7.1, and experienced multiple ketoacidotic decompensations (two of them had seven such episodes). In general, the outcome was good even following multiple ketoacidotic events. Permanent ketosis or ketonuria is considered a pathognomonic feature of SCOT deficiency. However, this condition depends not only on residual activity but also on environmental factors.

POLG exon 22 skipping induced by different mechanisms in two unrelated cases of Alpers syndrome.

The POLG genes were sequenced in two unrelated patients presenting with Alpers syndrome. The novel c.3626_3629dupGATA and the c.3643+2T>C alleles were associated in trans with p.A467T and p.[W748S;E1143G], respectively. POLG transcripts from skin fibroblasts showed complete exon 22 skipping for patient 2, but surprisingly partial exon 22 skipping from the c.3626_3629dupGATA for patient 1. The creation of a putative exonic splicing silencer could be responsible for the splicing anomaly observed in patient 1. Both c.3643+2T>C and c.3626_3629dupGATA create a premature termination codon and a low polymerase γ activity in skin fibroblasts is responsible for the severe phenotype in these patients.

Effect of duration and intensity of ganciclovir exposure on lymphoblastoid cell toxicity.

INTRODUCTION: Human cytomegalovirus infection is still a major complication after pediatric bone marrow transplantation and could be fatal in some cases. The toxicity of the drug in dividing transplanted haematopoietic cells combined with the suppression of cell growth caused by the virus remains a major problem in managing human cytomegalovirus infection. METHODS: The aim of the current in vitro study was to evaluate the effect of the intensity (1-20 mg/l) and duration (1, 2, 7 or 14 days) of ganciclovir exposure on toxicity in B lymphoblastoid cells (using cell counting and viability measurements). RESULTS: A correlation was found between the dose of ganciclovir exposure and a decrease in total cell number when duration exceeded 2 days (r(2)=0.92 and 0.93 after 7 and 14 days, respectively). High levels (20 mg/l) of ganciclovir were not more toxic than lowest levels (1 mg/l) for the shortest durations of ganciclovir exposure (1 and 2 days). Moreover, 50% cytotoxic concentrations markedly decreased with the duration of ganciclovir exposure (374-3 mg/l from 1 to 14 days respectively) after 14 days of culture. CONCLUSIONS: This in vitro study demonstrated for the first time that ganciclovir exhibited an in vitro duration-dependent toxicity on haematopoietic-derived cells when in vivo doses of the drug were used.

Identification of an Alu-mediated tandem duplication of exons 8 and 9 in a patient with mitochondrial acetoacetyl-CoA thiolase (T2) deficiency.

A tandem repeat of exons 8 and 9 was identified in the cDNA for mitochondrial acetoacetyl-CoA thiolase (T2) in a typical T2 deficient patient. Routine mutation analysis using PCR at the genomic level had failed to identify any mutations. Alu element-mediated unequal homologous recombination between an Alu-Jo in intron 7 and another Alu-Jo in intron 9 appears to be responsible for this duplication.

Kinetic properties of mutant deoxyguanosine kinase in a case of reversible hepatic mtDNA depletion.

DGUOK [dG (deoxyguanosine) kinase] is one of the two mitochondrial deoxynucleoside salvage pathway enzymes involved in precursor synthesis for mtDNA (mitochondrial DNA) replication. DGUOK is responsible for the initial rate-limiting phosphorylation of the purine deoxynucleosides, using a nucleoside triphosphate as phosphate donor. Mutations in the DGUOK gene are associated with the hepato-specific and hepatocerebral forms of MDS (mtDNA depletion syndrome). We identified two missense mutations (N46S and L266R) in the DGUOK gene of a previously reported child, now 10 years old, who presented with an unusual revertant phenotype of liver MDS. The kinetic properties of normal and mutant DGUOK were studied in mitochondrial preparations from cultured skin fibroblasts, using an optimized methodology. The N46S/L266R DGUOK showed 14 and 10% residual activity as compared with controls with dG and deoxyadenosine as phosphate acceptors respectively. Similar apparent negative co-operativity in the binding of the phosphate acceptors to the wild-type enzyme was found for the mutant. In contrast, abnormal bimodal kinetics were shown with ATP as the phosphate donor, suggesting an impairment of the ATP binding mode at the phosphate donor site. No kinetic behaviours were found for two other patients with splicing defects or premature stop codon. The present study represents the first characterization of the enzymatic kinetic properties of normal and mutant DGUOK in organello and our optimized protocol allowed us to demonstrate a residual activity in skin fibroblast mitochondria from a patient with a revertant phenotype of MDS. The residual DGUOK activity may play a crucial role in the phenotype reversal.

Submicroscopic deletion in patients with Williams-Beuren syndrome influences expression levels of the nonhemizygous flanking genes.

Genomic imbalance is a common cause of phenotypic abnormalities. We measured the relative expression level of genes that map within the microdeletion that causes Williams-Beuren syndrome and within its flanking regions. We found, unexpectedly, that not only hemizygous genes but also normal-copy neighboring genes show decreased relative levels of expression. Our results suggest that not only the aneuploid genes but also the flanking genes that map several megabases away from a genomic rearrangement should be considered possible contributors to the phenotypic variation in genomic disorders.

A 6-bp deletion at the splice donor site of the first intron resulted in aberrant splicing using a cryptic splice site within exon 1 in a patient with succinyl-CoA: 3-Ketoacid CoA transferase (SCOT) deficiency.

Succinyl-CoA: 3-ketoacid-CoA transferase (SCOT; locus symbol OXCT, EC 2.8.3.5) deficiency is a rare genetic disorder affecting ketone body utilization in extra-hepatic tissues. A 6-bp deletion at the splice donor site of intron 1 resulted in the absence of a full-length mature SCOT mRNA with faint amounts of aberrantly spliced transcripts using a cryptic splice donor site within exon 1, which was located just 7 bases upstream from the authentic site in a SCOT deficient patient.