TFIIH stabilization recovers the DNA repair and transcription dysfunctions in thermo-sensitive trichothiodystrophy

Trichothiodystrophy (TTD) is a rare hereditary disease whose prominent feature is brittle hair. Additional clinical signs are physical and neurodevelopmental abnormalities and in about half of the cases hypersensitivity to UV radiation. The photosensitive form of TTD (PS-TTD) is most commonly caused by mutations in the ERCC2/XPD gene encoding a subunit of the transcription/DNA repair complex TFIIH. Here we report novel ERCC2/XPD mutations affecting proper protein folding, which generate thermo-labile forms of XPD associated with thermo-sensitive phenotypes characterized by reversible aggravation of TTD clinical signs during episodes of fever. In patient cells, the newly identified XPD variants result in thermo-instability of the whole TFIIH complex and consequent temperature-dependent defects in DNA repair and transcription. Improving the protein folding process by exposing patient cells to low temperature or to the chemical chaperone glycerol allowed rescue of TFIIH thermo-instability and a concomitant recovery of the complex activities. Besides providing a rationale for the peculiar thermo-sensitive clinical features of these new cases, the present findings demonstrate how variations in the cellular concentration of mutated TFIIH impact the cellular functions of the complex and underlie how both quantitative and qualitative TFIIH alterations contribute to TTD clinical features.

Cockayne syndrome group A and ferrochelatase finely tune ribosomal gene transcription and its response to UV irradiation

CSA and CSB proteins are key players in transcription-coupled nucleotide excision repair (TC-NER) pathway that removes UV-induced DNA lesions from the transcribed strands of expressed genes. Additionally, CS proteins play relevant but still elusive roles in other cellular pathways whose alteration may explain neurodegeneration and progeroid features in Cockayne syndrome (CS). Here we identify a CS-containing chromatin-associated protein complex that modulates rRNA transcription. Besides RNA polymerase I (RNAP1) and specific ribosomal proteins (RPs), the complex includes ferrochelatase (FECH), a well-known mitochondrial enzyme whose deficiency causes erythropoietic protoporphyria (EPP). Impairment of either CSA or FECH functionality leads to reduced RNAP1 occupancy on rDNA promoter that is associated to reduced 47S pre-rRNA transcription. In addition, reduced FECH expression leads to an abnormal accumulation of 18S rRNA that in primary dermal fibroblasts from CS and EPP patients results in opposed rRNA amounts. After cell irradiation with UV light, CSA triggers the dissociation of the CSA–FECH–CSB–RNAP1–RPs complex from the chromatin while it stabilizes its binding to FECH. Besides disclosing a function for FECH within nucleoli, this study sheds light on the still unknown mechanisms through which CSA modulates rRNA transcription.

Genetics-assisted breeding for downy/powdery mildew and phylloxera resistance at fem

The genetics-assisted program for resistance to biotic stresses began at the Edmund Mach Foundation in 2007 and has developed on two lines. The first line was based on obtaining resistant materials with parents the historical varieties of Trentino. During the three-year period 2015–2017, 3 Teroldego X Merzling genotypes, 3 Marzemino X Merzling genotypes, 1 Nosiola X Bianca genotype and 1 Nosiola X Kulneany genotype were collected the data related to resistance to various fungal diseases both on the leaf and on the bunch. At harvest the plant production data and the must characteristics were recorded; the grapes were vinified and for each year the wines were subjected to sensorial analysis. 5 resistant selections were considered interesting for all the characteristics found and therefore the data for the registration to the National Register of Grapevine Varieties will be collected. The second line of research was based on the retrieval and both genotypic and phenotypic characterization of potentially parental lines acquired from foreign breeding programs and of wild materials. Once the crossings have been planned and obtained, the evaluation of the progeny takes place following a process of Marker-Assisted Selection optimized in order to maintain a compromise between efficiency and cost containment.

Performance of resistant varieties (PIWI) at two different altitudes in Southern Brazil

In southern Brazil there is a predominance of labrusca and hybrid varieties for wine and juice production due to climatic conditions of high rainfall, temperature and relative humidity. Growing varieties that combine disease resistance and wine quality (PIWI) can be an alternative to improve wine quality. The objective of this work was to evaluate the performance of three PIWI varieties (Felicia, Calardis Blanc and Aromera) in two regions (Videira, 27∘01′S and 51∘08′W, altitude 830 m; and São Joaquim, 28∘13′S and 50∘04′W, altitude 1100 m) in the vintage 2018. The date of occurrence of main phenological stages, productiveindexes, clusters characteristics and grape qualitative indexes was evaluated. There was no difference for budbreak date, but flowering, veraison an maturity time varied between regions. The development of plants is slower when they are cultivated at a higher altitude. The number of clusters per plant and yield were higher at 830 m for all varieties. For productive indexes Felicia and Calardis Blanc varieties stood out in relation to Aromera in all parameters. Among the evaluated varieties, Felicia and Calardis Blanc were better adapted to the lower altitude region and had higher productivity and the same grape quality. On the other hand, Aromera presented higher productivity at 830 m but higher soluble solids content at 1100 m.

Cockayne Syndrome Type A Protein Protects Primary Human Keratinocytes from Senescence

Defects in Cockayne syndrome type A (CSA), a gene involved in nucleotide excision repair, cause an autosomal recessive syndrome characterized by growth failure, progressive neurological dysfunction, premature aging, and skin photosensitivity and atrophy. Beyond its role in DNA repair, the CSA protein has additional functions in transcription and oxidative stress response, which are not yet fully elucidated. Here, we investigated the role of CSA protein in primary human keratinocyte senescence. Primary keratinocytes from three patients with CS-A displayed premature aging features, namely premature clonal conversion, high steady-state levels of reactive oxygen species and 8-OH-hydroxyguanine, and senescence-associated secretory phenotype. Stable transduction of CS-A keratinocytes with the wild-type CSA gene restored the normal cellular sensitivity to UV irradiation and normal 8-OH-hydroxyguanine levels. Gene correction was also characterized by proper restoration of keratinocyte clonogenic capacity and expression of clonal conversion key regulators (p16 and p63), decreased NF-κB activity and, in turn, the expression of its targets (NOX1 and MnSOD), and the secretion of senescence-associated secretory phenotype mediators. Overall, the CSA protein plays an important role in protecting cells from senescence by facilitating DNA damage processing, maintaining physiological redox status and keratinocyte clonogenic ability, and reducing the senescence-associated secretory phenotype-mediated inflammatory phenotype.

Liability to Chromosome Damage in Lymphocytes of “Cancer Family” Subjects: A Study of Spontaneous and Induced Chromosomal Fragility

Spontaneous chromosomal fragility was detected in seven tumor patients and one healthy member from two families with a high recurrence of cancer. Major chromosome lesions, such as terminal deletions and rearranged chromosomes, were found at levels significantly higher than those reported for control individuals. The prevalence of these aberrations in comparison to minor ones (chromosome gaps and chromatid breaks) in this group ofpatients seems to indicate that the fragility observed is the end-point of a process of chromosomal instability, which may have already been brought to expression. Study of other parameters of genetic instability in the most unstable karyotypes showed that the chromosome damage observed was neither paralleled by abnormal SCE frequency nor sustained by defective DNA repair mechanisms or expression of inherited or constitutional fragile sites. As all the subjects investigated here had previously been shown to display intraindividual variations in the C-banded region of chromosome 1, it is possible that spontaneous fragility and acquired C-heterochromatin polymorphism may be markers that, combined with chromosomal instability, create genetic predisposition to cancer.

Functional and clinical relevance of novel mutations in a large cohort of patients with Cockayne syndrome

BACKGROUND

Cockayne syndrome (CS) is a rare, autosomal recessive multisystem disorder characterised by prenatal or postnatal growth failure, progressive neurological dysfunction, ocular and skeletal abnormalities and premature ageing. About half of the patients with symptoms diagnostic for CS show cutaneous photosensitivity and an abnormal cellular response to UV light due to mutations in either the ERCC8/CSA or ERCC6/CSB gene. Studies performed thus far have failed to delineate clear genotype-phenotype relationships. We have carried out a four-centre clinical, molecular and cellular analysis of 124 patients with CS.

METHODS AND RESULTS

We assigned 39 patients to the ERCC8/CSA and 85 to the ERCC6/CSB genes. Most of the genetic variants were truncations. The missense variants were distributed non-randomly with concentrations in relatively short regions of the respective proteins. Our analyses revealed several hotspots and founder mutations in ERCC6/CSB. Although no unequivocal genotype-phenotype relationships could be made, patients were more likely to have severe clinical features if the mutation was downstream of the PiggyBac insertion in intron 5 of ERCC6/CSB than if it was upstream. Also a higher proportion of severely affected patients was found with mutations in ERCC6/CSB than in ERCC8/CSA.

CONCLUSION

By identifying >70 novel homozygous or compound heterozygous genetic variants in 124 patients with CS with different disease severity and ethnic backgrounds, we considerably broaden the CSA and CSB mutation spectrum responsible for CS. Besides providing information relevant for diagnosis of and genetic counselling for this devastating disorder, this study improves the definition of the puzzling genotype-phenotype relationships in patients with CS.

Coronally Advanced Flap with Different Designs in the Treatment of Gingival Recession: A Comparative Controlled Randomized Clinical Trial

The aim of this parallel double-blind randomized controlled clinical trial was to describe a modified approach using the coronally advanced flap (CAF) with triangular design and to compare its efficacy, in terms of root coverage and esthetics, with a trapezoidal type of CAF. A sample of 50 isolated Miller Class I and II gingival recessions with at least 1 mm of keratinized tissue apical to the defects were treated with CAF. Of these recessions, 25 were randomly treated with trapezoidal CAF (control group) while the other 25 (test group) were treated with a modified triangular CAF. The clinical and esthetic evaluations, made by the patient and an independent periodontist, were performed 3 months, 6 months, and 1 year after the surgery. No statistically significant difference was demonstrated between the two CAF groups in terms of recession reduction, complete root coverage, or 6-month and 1-year patient esthetic scores. Better 3-month patient esthetic evaluations and better periodontist root coverage, color match, and contiguity assessments were reported after triangular CAF. Trapezoidal CAF was associated with greater incidence of keloid formation. Single-type gingival recessions can be successfully covered with both types of CAF. The triangular CAF should be preferred for esthetically demanding patients.

CT Angiography ASPECTS Predicts Outcome Much Better Than Noncontrast CT in Patients with Stroke Treated Endovascularly

BACKGROUND AND PURPOSE

Noncontrast CT ASPECTS has been investigated as a predictor of outcome in patients with acute ischemic stroke. Our purpose was to investigate whether CTA source images are a better predictor of clinical and radiologic outcomes than NCCT ASPECTS in candidates for endovascular stroke therapy.

MATERIALS AND METHODS

CT scans of patients (n = 124) were independently evaluated by 2 readers for baseline NCCT and CTA source image ASPECTS and for follow-up ASPECTS. An mRS of ≤2 at 3 months was considered a favorable outcome. Receiver operating characteristic curve analysis was used to assess the ability of NCCT and CTA source image ASPECTS to identify patients with favorable outcomes. A stepwise multiple regression analysis was performed to find independent predictors of outcome.

RESULTS

Baseline CTA source image ASPECTS correlated better than NCCT ASPECTS with follow-up ASPECTS (r = 0.76 versus r = 0.51; P for comparison of the 2 coefficients < .001). Receiver operating characteristic curve analysis showed that baseline CTA source image ASPECTS compared with NCCT ASPECTS can better identify patients with favorable outcome (CTA source image area under the curve = 0.83; 95% CI, 0.76-0.91; NCCT area under the curve = 0.67; 95% CI, 0.58-0.77; P < .001). Finally, the stepwise regression analysis showed that lower age, good recanalization, lower time to recanalization, and good baseline CTA source image ASPECTS, not NCCT ASPECTS, were independent predictors of favorable outcome.

CONCLUSIONS

CTA source image ASPECTS predicts outcome better than NCCT ASPECTS; this finding suggests CTA rather than NCCT as a main step in the decision-making process for patients with acute ischemic stroke.

PtI2(DACH), the iodido analogue of oxaliplatin as a candidate for colorectal cancer treatment: chemical and biological features

PtI₂(DACH) has been prepared and tested. PtI₂(DACH) shows different chemical and biological features than oxaliplatin, manifesting cellular effects nearly comparable to those of parent drug in three cellular lines of CRC.

Overexpression of parkin rescues the defective mitochondrial phenotype and the increased apoptosis of Cockayne Syndrome A cells

The ERCC8/CSA gene encodes a WD-40 repeat protein (CSA) that is part of a E3-ubiquitin ligase/COP9 signalosome complex. When mutated, CSA causes the Cockayne Syndrome group A (CS-A), a rare recessive progeroid disorder characterized by sun sensitivity and neurodevelopmental abnormalities. CS-A cells features include ROS hyperproduction, accumulation of oxidative genome damage, mitochondrial dysfunction and increased apoptosis that may contribute to the neurodegenerative process. In this study, we show that CSA localizes to mitochondria and specifically interacts with the mitochondrial fission protein dynamin-related protein (DRP1) that is hyperactivated when CSA is defective. Increased fission is not counterbalanced by increased mitophagy in CS-A cells thus leading to accumulation of fragmented mitochondria. However, when mitochondria are challenged with the mitochondrial toxin carbonyl cyanide m-chloro phenyl hydrazine, CS-A fibroblasts undergo mitophagy as efficiently as normal fibroblasts, suggesting that this process remains targetable to get rid of damaged mitochondria. Indeed, when basal mitophagy was potentiated by overexpressing Parkin in CSA deficient cells, a significant rescue of the dysfunctional mitochondrial phenotype was observed. Importantly, Parkin overexpression not only reactivates basal mitophagy, but plays also an anti-apoptotic role by significantly reducing the translocation of Bax at mitochondria in CS-A cells. These findings provide new mechanistic insights into the role of CSA in mitochondrial maintenance and might open new perspectives for therapeutic approaches.

GTF2E2 Mutations Destabilize the General Transcription Factor Complex TFIIE in Individuals with DNA Repair-Proficient Trichothiodystrophy

The general transcription factor IIE (TFIIE) is essential for transcription initiation by RNA polymerase II (RNA pol II) via direct interaction with the basal transcription/DNA repair factor IIH (TFIIH). TFIIH harbors mutations in two rare genetic disorders, the cancer-prone xeroderma pigmentosum (XP) and the cancer-free, multisystem developmental disorder trichothiodystrophy (TTD). The phenotypic complexity resulting from mutations affecting TFIIH has been attributed to the nucleotide excision repair (NER) defect as well as to impaired transcription. Here, we report two unrelated children showing clinical features typical of TTD who harbor different homozygous missense mutations in GTF2E2 (c.448G>C [p.Ala150Pro] and c.559G>T [p.Asp187Tyr]) encoding the beta subunit of transcription factor IIE (TFIIEβ). Repair of ultraviolet-induced DNA damage was normal in the GTF2E2 mutated cells, indicating that TFIIE was not involved in NER. We found decreased protein levels of the two TFIIE subunits (TFIIEα and TFIIEβ) as well as decreased phosphorylation of TFIIEα in cells from both children. Interestingly, decreased phosphorylation of TFIIEα was also seen in TTD cells with mutations in ERCC2, which encodes the XPD subunit of TFIIH, but not in XP cells with ERCC2 mutations. Our findings support the theory that TTD is caused by transcriptional impairments that are distinct from the NER disorder XP.

Iatrogenic anemia (can it be prevented?)

'Iatrogenic anemia' is a condition of lowered hematocrit and hemoglobin count resulting from large or frequent removal of blood samples, usually for laboratory testing. It is frequently seen in patients who are already suffering from bone marrow depression, and thus may become a comorbidity. Because several different types of chemical agents may be required for test procedures, a large volume of blood could be removed for each set of testing, perhaps 50-60 mL. Often local and reference laboratories request larger samples than are really necessary to perform a given test and still have some left to perform any required repeat testing. My experience shows that a volume of about 3 mL of each type of sample should be sufficient for this purpose.

Patients with xeroderma pigmentosum complementation groups C, E and V do not have abnormal sunburn reactions

BACKGROUND

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder of DNA repair. It is divided into eight complementation groups: XP-A to XP-G (classical XP) and XP variant (XP-V). Severe and prolonged sunburn reactions on minimal sun exposure have been considered a cardinal feature of classical XP. However, it has recently become clear that not all patients have abnormal sunburn reactions.

OBJECTIVES

To examine sunburn reactions in a cohort of patients with XP and correlate this to the complementation group.

METHODS

Sixty patients with XP attending the U.K. National XP Service from 2010 to 2012 were studied. Their history of burning after minimal sun exposure was assessed using a newly developed sunburn severity score. The age at which the first skin cancer was histologically diagnosed in each patient, and the presence of any neurological abnormality, was also recorded.

RESULTS

Sunburn severity scores were abnormally high in patients with XP-A, XP-D, XP-F and XP-G compared with non-XP controls. There was no significant difference in sunburn score of patients with XP-C, XP-E and XP-V compared with controls (P > 0·05). Patients with XP-C, XP-E and XP-V were more likely to have skin cancer diagnosed at an earlier age than those with severe sunburn on minimal sun exposure. In addition, patients with XP with severe sunburn had an increased frequency of neurological abnormalities.

CONCLUSIONS

Not all patients with XP have a history of severe and prolonged sunburn on minimal sun exposure. The normal sunburn response of patients with XP-C, XP-E and XP-V may relate to the preservation of transcription-coupled DNA repair in these groups. Those with a history of severe sunburn on minimal sun exposure developed their first skin cancer at an older age compared with patients with XP-C, XP-E and XP-V, but they had an increased frequency of neurological abnormalities. Physicians need to be aware that about half of all patients with XP will present without a history of abnormal sunburn.

Phlebographic study does not show differences between patients with MS and control subjects

BACKGROUND AND PURPOSE

Hypothetical correlation between chronic cerebrospinal venous insufficiency and MS has gained the attention of patients and the scientific community. Studies performed by echo-color Doppler ultrasonography have shown different results, and it is necessary to use more objective diagnostic techniques. The aim of our study was to evaluate the presence of stenoses affecting azygos veins and internal jugular veins by use of venography in patients with MS.

MATERIALS AND METHODS

We recruited 2 groups of subjects who underwent venography: the study group included 29 patients with MS and the control group included 15 healthy volunteers. The ileo-lumbar plexus, the azygos, and the internal jugular veins were selectively catheterized. We considered any cross-sectional area reduction of the venous lumen >50% to be a significant stenosis. Furthermore, blood pressure was measured in the studied vessels at the stenotic internal jugular veins.

RESULTS

Selective venography showed at least 1 significant venous stenosis in 84% of subjects examined, without significant difference between the study group and the control group. Positive venography chronic cerebrospinal venous insufficiency patterns were found in 50% of all subjects examined, without any significant difference between the 2 groups. The multivariate logistic regression analysis failed to assess any significant association between the presence of a positive venography and MS condition. The difference between the median blood pressure of stenotic and nonstenotic internal jugular veins was not statistically significant (P = .46).

CONCLUSIONS

Our data exclude any direct correlation between chronic cerebrospinal venous insufficiency and MS because venous abnormalities were equally present in both groups.

Decompressive craniectomy may cause diagnostic challenges to assess brain death by computed tomography angiography

According to Italian legislation to diagnose brain death (BD) after the initial documentation of the clinical signs, repetition of clinical testing and confirmation of the loss of bioelectrical activity of the brain (EEG) is required. However, when EEG is unreliable it is necessary to demonstrate cerebral circulatory arrest (CCA). Accepted imaging techniques to demonstrate CCA include: cerebral angiography, cerebral scintigraphy, transcranial Doppler (TCD) and computed tomography angiography (CTA). This latter technique, due to its large availability, low invasivity and easy and fast acquisition is widely used over the country. Nevertheless its diagnostic reliability is affected by some limitations in patients with decompressive craniectomy. Here we report two cases of brain injury with clinical signs of BD and at the same time, opacification of intracranial arteries on CTA and a pattern consistent with flow arrest on the corresponding insonable arteries on TCD. The discrepancy between CTA and TCD results points out a methodology limitation that could be overcome by updating Italian legislation according to other European Countries legislation.

Histone methyltransferase DOT1L drives recovery of gene expression after a genotoxic attack

UV-induced DNA damage causes repression of RNA synthesis. Following the removal of DNA lesions, transcription recovery operates through a process that is not understood yet. Here we show that knocking-out of the histone methyltransferase DOT1L in mouse embryonic fibroblasts (MEF^DOT1L) leads to a UV hypersensitivity coupled to a deficient recovery of transcription initiation after UV irradiation. However, DOT1L is not implicated in the removal of the UV-induced DNA damage by the nucleotide excision repair pathway. Using FRAP and ChIP experiments we established that DOT1L promotes the formation of the pre-initiation complex on the promoters of UV-repressed genes and the appearance of transcriptionally active chromatin marks. Treatment with Trichostatin A, relaxing chromatin, recovers both transcription initiation and UV-survival. Our data suggest that DOT1L secures an open chromatin structure in order to reactivate RNA Pol II transcription initiation after a genotoxic attack.

Through the deformation of the genomic DNA structure, UV-induced DNA lesions have repressive effect on various nuclear processes including replication and transcription. As a matter of fact, the removal of these lesions is a priority for the cell and takes place at the expense of fundamental cellular processes that are paused to circumvent the risks of mutations that may lead to cancer. The molecular mechanism underlying transcription inhibition and recovery is not clearly understood and appears more complicated than anticipated. Here we analyzed the process of transcription recovery after UV-irradiation and found that it depends on DOT1L, a histone methyltransferase that promotes the reformation of the transcription machinery at the promoters of UV-repressed genes. Our discovery shows that transcription recovery after a genotoxic attack is an active process under the control of chromatin remodelling enzymes.

Malfunction of nuclease ERCC1-XPF results in diverse clinical manifestations and causes Cockayne syndrome, xeroderma pigmentosum, and Fanconi anemia

Cockayne syndrome (CS) is a genetic disorder characterized by developmental abnormalities and photodermatosis resulting from the lack of transcription-coupled nucleotide excision repair, which is responsible for the removal of photodamage from actively transcribed genes. To date, all identified causative mutations for CS have been in the two known CS-associated genes, ERCC8 (CSA) and ERCC6 (CSB). For the rare combined xeroderma pigmentosum (XP) and CS phenotype, all identified mutations are in three of the XP-associated genes, ERCC3 (XPB), ERCC2 (XPD), and ERCC5 (XPG). In a previous report, we identified several CS cases who did not have mutations in any of these genes. In this paper, we describe three CS individuals deficient in ERCC1 or ERCC4 (XPF). Remarkably, one of these individuals with XP complementation group F (XP-F) had clinical features of three different DNA-repair disorders--CS, XP, and Fanconi anemia (FA). Our results, together with those from Bogliolo et al., who describe XPF alterations resulting in FA alone, indicate a multifunctional role for XPF.

From laboratory tests to functional characterisation of Cockayne syndrome

The significant progress made over the last few years on the pathogenesis of Cockayne syndrome (CS) greatly improved our knowledge on several aspects crucial for development and ageing, demonstrating that this disorder, even if rare, represents a valuable tool to clarify key aspects of human health. Primary cells from patients have been instrumental to elucidate the multiple roles of CS proteins and to approach the dissection of the complex interplay between repair and transcription that is central to the CS clinical phenotype. Here we discuss the results of the cellular assays applied for confirmation of the clinical diagnosis as well as the results of genetic and molecular studies in DNA repair defective patients. Furthermore, we provide a general overview of recent in vivo and in vitro studies indicating that both CSA and CSB proteins are involved in distinct aspects of the cellular responses to UV and oxidative stress, transcription and regulation of gene expression, chromatin remodelling, redox balance and cellular bioenergetics. In light of the literature data, we will finally discuss how inactivation of specific functional roles of CS proteins may differentially affect the phenotype, thus explaining the wide range in type and severity of symptoms reported in CS patients.

Endovascular management of acute stroke

Ischemic stroke is the third leading cause of death and most common cause of permanent disability in industrialized nations. Eighty-five percent of strokes are ischemic in nature, with an associated mortality between 53% and 92%. The focus of treatment for acute stroke starts with prompt and accurate diagnosis of ischemic brain tissue at risk, followed by time sensitive delivery of therapy that effectively and safely restores flow to that vascular territory. Time-dependent reperfusion therapy is the only proven treatment for Acute Ischemic Stroke. In this paper, we review the clinical and imaging factors that are relevant to guide endovascular treatment decisions; the different approaches of stroke therapy and the devices used with the goal of obtaining the most rapid and complete recanalization possible, while minimizing vascular damage and hemorrhagic complications. It is paid particular attention to indications and outcomes of the different endovascular stroke therapy devices use, as defined in major clinical trials or current clinical practice. Anterior circulation strokes represent the primary focus of this review.

XPD mutations in trichothiodystrophy hamper collagen VI expression and reveal a role of TFIIH in transcription derepression

Mutations in the XPD subunit of the transcription/DNA repair factor (TFIIH) give rise to trichothiodystrophy (TTD), a rare hereditary multisystem disorder with skin abnormalities. Here, we show that TTD primary dermal fibroblasts contain low amounts of collagen type VI alpha1 subunit (COL6A1), a fundamental component of soft connective tissues. We demonstrate that COL6A1 expression is downregulated by the sterol regulatory element-binding protein-1 (SREBP-1) whose removal from the promoter is a key step in COL6A1 transcription upregulation in response to cell confluence. We provide evidence for TFIIH being involved in transcription derepression, thus highlighting a new function of TFIIH in gene expression regulation. The lack of COL6A1 upregulation in TTD is caused by the inability of the mutated TFIIH complexes to remove SREBP-1 from COL6A1 promoter and to sustain the subsequent high rate of COL6A1 transcription. This defect might account for the pathologic features that TTD shares with hereditary disorders because of mutations in COL6A genes.

An altered redox balance mediates the hypersensitivity of Cockayne syndrome primary fibroblasts to oxidative stress

Cockayne syndrome (CS) is a rare hereditary multisystem disease characterized by neurological and development impairment, and premature aging. Cockayne syndrome cells are hypersensitive to oxidative stress, but the molecular mechanisms involved remain unresolved. Here we provide the first evidence that primary fibroblasts derived from patients with CS-A and CS-B present an altered redox balance with increased steady-state levels of intracellular reactive oxygen species (ROS) and basal and induced DNA oxidative damage, loss of the mitochondrial membrane potential, and a significant decrease in the rate of basal oxidative phosphorylation. The Na/K-ATPase, a relevant target of oxidative stress, is also affected with reduced transcription in CS fibroblasts and normal protein levels restored upon complementation with wild-type genes. High-resolution magnetic resonance spectroscopy revealed a significantly perturbed metabolic profile in CS-A and CS-B primary fibroblasts compared with normal cells in agreement with increased oxidative stress and alterations in cell bioenergetics. The affected processes include oxidative metabolism, glycolysis, choline phospholipid metabolism, and osmoregulation. The alterations in intracellular ROS content, oxidative DNA damage, and metabolic profile were partially rescued by the addition of an antioxidant in the culture medium suggesting that the continuous oxidative stress that characterizes CS cells plays a causative role in the underlying pathophysiology. The changes of oxidative and energy metabolism offer a clue for the clinical features of patients with CS and provide novel tools valuable for both diagnosis and therapy.

Mutations in UVSSA cause UV-sensitive syndrome and impair RNA polymerase IIo processing in transcription-coupled nucleotide-excision repair

UV-sensitive syndrome (UV(S)S) is a genodermatosis characterized by cutaneous photosensitivity without skin carcinoma. Despite mild clinical features, cells from individuals with UV(S)S, like Cockayne syndrome cells, are very UV sensitive and are deficient in transcription-coupled nucleotide-excision repair (TC-NER), which removes DNA damage in actively transcribed genes. Three of the seven known UV(S)S cases carry mutations in the Cockayne syndrome genes ERCC8 or ERCC6 (also known as CSA and CSB, respectively). The remaining four individuals with UVSS , one of whom is described for the first time here, formed a separate UV(S)S-A complementation group; however, the responsible gene was unknown. Using exome sequencing, we determine that mutations in the UVSSA gene (formerly known as KIAA1530) cause UV(S)S-A. The UVSSA protein interacts with TC-NER machinery and stabilizes the ERCC6 complex; it also facilitates ubiquitination of RNA polymerase IIo stalled at DNA damage sites. Our findings provide mechanistic insights into the processing of stalled RNA polymerase and explain the different clinical features across these TC-NER–deficient disorders.

Coronaric stent-graft deployment in the treatment of carotid blowout

"Carotid blowout syndrome" is defined as a hemorrhage caused by rupture of the carotid artery and its branches, and may be a severe complication of rhinopharyngeal carcinoma. This study aimed to highlight the usefulness and versatility of endovascular stent-graft placement as a rescue treatment in life-threatening carotid blowout syndrome. We describe the unconventional use of a 6 × 5 mm balloon-expandable coronaric covered stent in a patient with a diagnosis of spinocellular rhinopharyngeal carcinoma, followed by carotid blowout syndrome. Although long-term follow-up is needed to assess the eventuality of bleeding recurrence, the immediate clinical results were satisfactory.

CSA and CSB proteins interact with p53 and regulate its Mdm2-dependent ubiquitination

Mutations in Cockayne syndrome (CS) A and B genes (CSA and CSB) result in a rare genetic disease that affects the development and homeostasis of a wide range of tissues and organs. We previously correlated the degenerative phenotype of patients to the enhanced apoptotic response, exhibited by CS cells, which is associated with the exceptional induction of p53 protein, upon a variety of stress stimuli. Here we showed that the elevated and persistent levels of p53 displayed by CS cells are due to the insufficient ubiquitination of the p53 protein. We further demonstrated that CSA and CSB proteins associate in a unique complex with p53 and Mdm2; this interaction greatly stimulates the ubiquitination of p53 in an Mdm2-dependent manner. Tandem affinity purification and immunoprecipitations combined with mass spectrometry studies indicate that CSA and CSB associate within a Cullin Ring Ubiquitin Ligase complex responsible, under certain circumstances, for p53 ubiquitination. This study identifies CSA and CSB as the key elements of a regulatory mechanism that equilibrate beneficial and detrimental effects of p53 activity upon cellular stress. The deregulation of p53, in absence of either of the CS proteins, can potentially explain the early onset degeneration of tissues and organs observed in CS patients.

Xeroderma pigmentosum

Xeroderma pigmentosum (XP) is defined by extreme sensitivity to sunlight, resulting in sunburn, pigment changes in the skin and a greatly elevated incidence of skin cancers. It is a rare autosomal recessive disorder and has been found in all continents and racial groups. Estimated incidences vary from 1 in 20, 000 in Japan to 1 in 250, 000 in the USA, and approximately 2.3 per million live births in Western Europe.

The first features are either extreme sensitivity to sunlight, triggering severe sunburn, or, in patients who do not show this sun-sensitivity, abnormal lentiginosis (freckle-like pigmentation due to increased numbers of melanocytes) on sun-exposed areas. This is followed by areas of increased or decreased pigmentation, skin aging and multiple skin cancers, if the individuals are not protected from sunlight. A minority of patients show progressive neurological abnormalities. There are eight XP complementation groups, corresponding to eight genes, which, if defective, can result in XP. The products of these genes are involved in the repair of ultraviolet (UV)-induced damage in DNA. Seven of the gene products (XPA through G) are required to remove UV damage from the DNA. The eighth (XPV or DNA polymerase η) is required to replicate DNA containing unrepaired damage. There is wide variability in clinical features both between and within XP groups. Diagnosis is made clinically by the presence, from birth, of an acute and prolonged sunburn response at all exposed sites, unusually early lentiginosis in sun-exposed areas or onset of skin cancers at a young age. The clinical diagnosis is confirmed by cellular tests for defective DNA repair. These features distinguish XP from other photodermatoses such as solar urticaria and polymorphic light eruption, Cockayne Syndrome (no pigmentation changes, different repair defect) and other lentiginoses such as Peutz-Jeghers syndrome, Leopard syndrome and Carney complex (pigmentation not sun-associated), which are inherited in an autosomal dominant fashion. Antenatal diagnosis can be performed by measuring DNA repair or by mutation analysis in CVS cells or in amniocytes. Although there is no cure for XP, the skin effects can be minimised by rigorous protection from sunlight and early removal of pre-cancerous lesions. In the absence of neurological problems and with lifetime protection against sunlight, the prognosis is good. In patients with neurological problems, these are progressive, leading to disabilities and a shortened lifespan.

The effect of hepatocyte growth factor on the initial stages of mouse follicle development

Interactions between theca and granulosa cells of the follicle are critical for the coordination of ovarian follicle development. The cell-cell interactions are mediated through the local production and actions of a variety of factors. The current study is designed to investigate the expression of Hgf and its receptor, c-Met, in the mouse ovary during in vivo folliculogenesis. We found that Hgf and c-Met mRNAs were already expressed in 2-day-old ovaries, and that, while c-Met levels remained constant until 22-day-old, Hgf levels slightly but not significantly increased with age. The expression of Hgf mRNA in theca/interstitial cells was higher than in granulosa cells in 22-day-old ovaries. Immunohistochemistry analysis confirmed the expression pattern demonstrated by RT-PCR. We investigated the role of hepatocyte growth factor (HGF) at the beginning of mouse folliculogenesis and its possible interaction with kit ligand (KL). Interestingly, both KL and HGF were able to increase the expression of each other, creating a positive feedback loop. In the presence of HGF, we observed an increase of granulosa cell proliferation and an increase in the number of pre-antral and early antral follicles in ovary organ cultures. We also observed a significant increase in the diameters of follicles in individual follicle cultures. Moreover, HGF stimulated the expression of the FSH receptors, both in the whole ovary and in isolated pre-antral follicle cultures. Based on the data presented, we concluded that HGF exerts multiple levels of control over follicular cell functions, which collectively enable the progression of follicular development.

Trichothiodystrophy: from basic mechanisms to clinical implications

Trichothiodystrophy (TTD) is an autosomal recessive disorder with symptoms affecting several tissues and organs. The most relevant features are hair abnormalities, physical and mental retardation, ichthyosis, signs of premature aging and cutaneous photosensitivity. The clinical spectrum of TTD varies widely from patients with only brittle, fragile hair to patients with the most severe neuroectodermal symptoms. To date, four genes have been identified as responsible for TTD: XPD, XPB, p8/TTDA, and TTDN1. Whereas the function of TTDN1 is still unknown, the former three genes encode subunits of TFIIH, the multiprotein complex involved in basal and activated transcription and in nucleotide excision repair (NER). Ongoing investigations on TTD are elucidating not only the pathogenesis of the disease, which appears to be mainly related to transcriptional impairment, but also the modalities of NER and transcription in human cells and how TFIIH operates in these two fundamental cellular processes.

Bmi-1 reduction plays a key role in physiological and premature aging of primary human keratinocytes

Accumulation of senescent cells contributes to the reduced regenerative capacity in aged tissues. By evaluating the molecular pathways of senescence in relation to proliferative potential of primary keratinocyte cultures from young and old healthy donors, and from young patients with inherited defects leading to premature aging, we demonstrated that p16(INK4a) is a reliable marker of both physiological and premature epidermal aging. Analysis of the expression and activity of p16(INK4a) regulators showed that stem cell depletion, reduced proliferation, and p16(INK4a) upregulation in keratinocytes derived from the chronologically and prematurely aged epidermis strongly correlate with Bmi-1 downregulation. In highly proliferative tissues, replicative and premature senescence participate in determining senescent cell accumulation. Our findings demonstrated that Bmi-1 is downregulated in human keratinocytes during both in vitro processes, in parallel with p16(INK4a) upregulation and accomplishment of clonal conversion. When premature senescence was induced by specific exogenous stimuli, concomitant Ets-1 upregulation was also observed. Moreover, Bmi-1 inhibited Ets-1-mediated p16(INK4a) upregulation. Finally, Bmi-1 overexpression reduced p16(INK4a) promoter activity and decreased protein expression in aged and diseased keratinocytes, inducing a delay of clonal conversion and an increase of cell clonogenic ability. Altogether these findings underline a key role of Bmi-1 downregulation in enforcing aging in primary human keratinocytes.

Carotid artery stenting: findings based on 8 years' experience

PURPOSE

Carotid artery stenting (CAS) may be an alternative to surgical endarterectomy not only in high-risk patients. Few data are available regarding the long-term clinical efficacy of CAS with the use of cerebral protection devices and the incidence of restenosis. Our experience demonstrates that if certain requirements are fulfilled, CAS can be considered a safe and effective treatment with high short-and long-term success rates.

MATERIALS AND METHODS

In the past 8 years, we treated 1,003 patients (1,096 arteries) affected by internal carotid artery stenosis, 93 with bilateral stenosis. Of these, 567 (51.74%) were symptomatic and 529 (48.26%) asymptomatic lesions. The preprocedural evaluation was performed with Doppler ultrasound (US), magnetic resonance (MR) angiography/computed tomography (CT) angiography and a neurological evaluation. Antiplatelet therapy was administered before and after the procedure.

RESULTS

Technical success was achieved in 1,092 cases (99.6%), and a cerebral protection device was successfully used in 1,019 procedures (92.9%). The 30-day transient ischaemic attack (TIA)/stroke/death rate was 2.16%: death (0.18%) major stroke (0.45%) and minor stroke/TIA (1.53%). During a follow-up up to 8 years, restenoses occurred in 39 cases (3.57%), of which 28 were post-CAS (2.57%) and 11 post-CAS performed for restenosis after carotid endarterectomy (1%). Only five symptomatic restenoses>80% were treated with a repeated endovascular procedure.

CONCLUSIONS

A retrospective analysis of our experience suggests that CAS is a safe and effective procedure with better results than endarterectomy. In up to 8 years of follow-up, CAS seems to be effective in preventing stroke, with a low restenosis rate.

Incidence of DNA repair deficiency disorders in western Europe: Xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy

Laboratory diagnosis for DNA repair diseases has been performed in western Europe from the early seventies for xeroderma pigmentosum (XP) and from the mid-eighties for Cockayne syndrome (CS) and trichothiodystrophy (TTD). The combined data from the DNA repair diagnostic centres in France, (West) Germany, Italy, the Netherlands and the United Kingdom have been investigated for three groups of diseases: XP (including XP-variant), CS (including XP/CS complex) and TTD. Incidences in western Europe were for the first time established at 2.3 per million livebirths for XP, 2.7 per million for CS and 1.2 per million for TTD. As immigrant populations were disproportionately represented in the patients' groups, incidences were also established for the autochthonic western European population at: 0.9 per million for XP, 1.8 per million for CS and 1.1 per million for TTD. Perhaps contrary to general conceptions, compared to XP the incidence of CS appears to be somewhat higher and the incidence of TTD to be quite similar in the native West-European population.

HIV-1 viral DNA is present in ejaculated abnormal spermatozoa of seropositive subjects

BACKGROUND

Semen is the major vehicle for HIV-1 infection as it contains free and cell-associated virions and infected cells. However, the presence of HIV-1 in spermatozoa has been a matter of debate, since the sperm cell fraction may contain somatic infected cells that jeopardize the attribution of the detected virus to the spermatozoa.

METHODS

Spermatozoa from 12 HIV-1 seropositive subjects were purified by multilayered Percoll gradient followed by osmotic shock. Residual presence of non-seminal cells (NCS) in purified spermatozoa, was then evaluated by cytometric and molecular analysis. HIV-1 DNA was revealed by nested PCR and in situ PCR after sperm chromatin decondensation. DNA-fragmented ejaculated spermatozoa in semen of infected subjects were detected by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labeling (TUNEL) analysis.

RESULTS

Purification procedure adopted allowed complete removal of NCS. On purified sperm cells, HIV-1 DNA was detected in 5 out of 12 subjects by nested-PCR. On crude semen of 10 out of 12 subjects, HIV-1 DNA was in situ detected in a small percentage of abnormal spermatozoa with a wide range of structural alterations. TUNEL analysis revealed an increased percentage of DNA-fragmented ejaculated spermatozoa in semen of infected subjects.

CONCLUSIONS

We report molecular evidence demonstrating that HIV-1 infected subjects can ejaculate small amounts of HIV-1 DNA-positive abnormal spermatozoa. Their possible role in HIV-1 sexual transmission remains to be clarified.

In vivo destabilization and functional defects of the xeroderma pigmentosum C protein caused by a pathogenic missense mutation

Xeroderma pigmentosum group C (XPC) protein plays an essential role in DNA damage recognition in mammalian global genome nucleotide excision repair (NER). Here, we analyze the functional basis of NER inactivation caused by a single amino acid substitution (Trp to Ser at position 690) in XPC, previously identified in the XPC patient XP13PV. The Trp690Ser change dramatically affects the in vivo stability of the XPC protein, thereby causing a significant reduction of its steady-state level in XP13PV fibroblasts. Despite normal heterotrimeric complex formation and physical interactions with other NER factors, the mutant XPC protein lacks binding affinity for both undamaged and damaged DNA. Thus, this single amino acid substitution is sufficient to compromise XPC function through both quantitative and qualitative alterations of the protein. Although the mutant XPC fails to recognize damaged DNA, it is still capable of accumulating in a UV-damaged DNA-binding protein (UV-DDB)-dependent manner to UV-damaged subnuclear domains. However, the NER factors transcription factor IIH and XPA failed to colocalize stably with the mutant XPC. As well as highlighting the importance of UV-DDB in recruiting XPC to UV-damaged sites, these findings demonstrate the role of DNA binding by XPC in the assembly of subsequent NER intermediate complexes.

The role of CSA in the response to oxidative DNA damage in human cells

Cockayne syndrome (CS) is a rare genetic disease characterized by severe growth, mental retardation and pronounced cachexia. CS is most frequently due to mutations in either of two genes, CSB and CSA. Evidence for a role of CSB protein in the repair of oxidative DNA damage has been provided recently. Here, we show that CSA is also involved in the response to oxidative stress. CS-A human primary fibroblasts and keratinocytes showed hypersensitivity to potassium bromate, a specific inducer of oxidative damage. This was associated with inefficient repair of oxidatively induced DNA lesions, namely 8-hydroxyguanine (8-OH-Gua) and (5'S)-8,5'-cyclo 2'-deoxyadenosine. Expression of the wild-type CSA in the CS-A cell line CS3BE significantly decreased the steady-state level of 8-OH-Gua and increased its repair rate following oxidant treatment. CS-A cell extracts showed normal 8-OH-Gua cleavage activity in an in vitro assay, whereas CS-B cell extracts were confirmed to be defective. Our data provide the first in vivo evidence that CSA protein contributes to prevent accumulation of various oxidized DNA bases and underline specific functions of CSB not shared with CSA. These findings support the hypothesis that defective repair of oxidative DNA damage is involved in the clinical features of CS patients.

Mutations in theC7orf11(TTDN1) gene in six nonphotosensitive trichothiodystrophy patients: no obvious genotype-phenotype relationships

Trichothiodystrophy (TTD) is a rare autosomal recessive disorder whose defining feature is brittle hair. Associated clinical symptoms include physical and mental retardation of different severity, ichthyosis, premature aging, and, in half of the patients, photosensitivity. Recently, C7orf11 (TTDN1) was identified as the first disease gene for the nonphotosensitive form of TTD, being mutated in two unrelated cases and in an Amish kindred. We have evaluated the involvement of TTDN1 in 44 unrelated nonphotosensitive TTD cases of different geographic origin and with different disease severity. Mutations were found in six patients, five of whom are homozygous and one of whom is a compound heterozygote. All five identified mutations are deletions that have not been described before. Three are deletions of a few bases, resulting in frameshifts and premature termination codons. The other two include the whole TTDN1 gene, suggesting that TTDN1 is not essential for cell proliferation and viability. The severity of the clinical features does not correlate with the type of mutation, indicating that other factors besides TTDN1 mutations influence the severity of the disorder. Since only a small proportion of the analyzed cases were mutated in TTDN1, the nonphotosensitive form of TTD is genetically heterogeneous. Mutations in TTDN1 do not affect the response to ultraviolet (UV) light or the steady state level of the repair/transcription factor IIH (TFIIH), which is central to the onset of the photosensitive form of TTD.

DNA nucleotide excision repair-dependent signaling to checkpoint activation

Eukaryotic cells respond to a variety of DNA insults by triggering a common signal transduction cascade, known as checkpoint response, which temporarily halts cell-cycle progression. Although the main players involved in the cascade have been identified, there is still uncertainty about the nature of the structures that activate these surveillance mechanisms. To understand the role of nucleotide excision repair (NER) in checkpoint activation, we analyzed the UV-induced phosphorylation of the key checkpoint proteins Chk1 and p53, in primary fibroblasts from patients with xeroderma pigmentosum (XP), Cockayne syndrome (CS), trichothiodystrophy (TTD), or UV light-sensitive syndrome. These disorders are due to defects in transcription-coupled NER (TC-NER) and/or global genome NER (GG-NER), the NER subpathways repairing the transcribed strand of active genes or the rest of the genome, respectively. We show here that in G0/G1 and G2/M phases of the cell cycle, triggering of the DNA damage cascade requires recognition and processing of the lesions by the GG-NER. Loss of TC-NER does not affect checkpoint activation. Mutations in XPD, XPB, and in TTDA, encoding subunits of the TFIIH complex, involved in both transcription and NER, impair checkpoint triggering. The only exception is represented by mutations in XPD, resulting in combined features of XP and CS (XP/CS) that lead to activation of the checkpoint cascade after UV radiation. Inhibition of RNA polymerase II transcription significantly reduces the phosphorylation of key checkpoint factors in XP/CS fibroblasts on exposure to UV damage.

A novel mutation in the XPA gene associated with unusually mild clinical features in a patient who developed a spindle cell melanoma

BACKGROUND

Xeroderma pigmentosum (XP) is an autosomal recessive disorder of, in most cases, defective nucleotide excision repair (NER) of ultraviolet radiation (UV)- and chemical-induced DNA damage. The condition is characterized by an increased sensitivity of the skin to UV radiation, with early development of pigmentary changes and premalignant lesions in sun-exposed areas of the skin, signs of photoageing and a greatly increased incidence from a young age of skin tumours including melanoma. Approximately 20% of patients with XP show neurological abnormalities of varying severity due to primary neuronal degeneration. Genetic analysis by somatic cell hybridization has led to the identification in the NER-defective form of XP of seven complementation groups, designated XP-A to XP-G. These complementation groups correspond to different proteins involved in the NER process. XP-A classically includes some of the most severely affected patients.

OBJECTIVES

We describe a 61-year-old Punjabi woman with XP. Remarkably she had only mild cutaneous abnormalities, minimal neurological features and unusual longevity, and developed a malignant spindle cell melanoma. There are few previous reports of spindle cell melanoma associated with XP. To gain insight into the aetiology of these unusual features, we sought to analyse the DNA repair properties of the patient and identify the complementation group and the causative mutation in the defective gene.

METHODS

Unscheduled DNA synthesis and the inhibition of RNA synthesis were measured. The complementation group was assigned by fusing the cells of our patient with XP cells of known complementation groups and determining the ability to carry out unscheduled DNA repair. Molecular analysis of the cDNA was carried out by polymerase chain reaction and DNA sequencing.

RESULTS

Levels of DNA repair were extremely low and complementation analysis assigned the defect to the XP-A group. Sequencing of the XPA gene revealed a novel homozygous mutation of A-->G at the eighth nucleotide of intron 4 causing aberrant splicing and a nonfunctional truncated XP-A protein. However, a small amount of normally spliced mRNA was detected at <5% the level in normal cells.

CONCLUSIONS

The small amount of normally spliced mRNA detected may be sufficient to explain the relatively mild clinical features in our patient.