Hanoch Slor

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

UV-sensitive syndrome (UVSS) is a genodermatosis characterized by cutaneous photosensitivity without skin carcinoma. Despite mild clinical features, cells from individuals with UVSS, 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 UVSS 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 UVSS-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 UVSS-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.

Autoantibodies to DNA in multicase families with schizophrenia

In an attempt to define the autoimmune status of members of multicase families with schizophrenia, sera of both patients and healthy relatives from 28 such cases were tested for antinuclear antibodies, anti-double-stranded DNA, and anti-single-stranded DNA autoantibodies. These autoantibodies were significantly more frequent in both schizophrenic patients and healthy relatives than in normal subjects. Immunoglobulin (Ig) M anti-DNA antibodies were more common in patients, whereas in healthy relatives, IgG anti-DNA antibodies were more common. No significant differences were found between schizophrenic patients and their healthy relatives. The data indicate that an autoimmune process may be involved in the etiology of a subset of patients with schizophrenia.

Xeroderma Pigmentosum-Variant Patients from America, Europe, and Asia

Xeroderma pigmentosum-variant (XP-V) patients have sun sensitivity and increased skin cancer risk. Their cells have normal nucleotide excision repair, but have defects in the POLH gene encoding an error-prone polymerase, DNA polymerase eta (pol eta). To survey the molecular basis of XP-V worldwide, we measured pol eta protein in skin fibroblasts from putative XP-V patients (aged 8-66 years) from 10 families in North America, Turkey, Israel, Germany, and Korea. Pol eta was undetectable in cells from patients in eight families, whereas two showed faint bands. DNA sequencing identified 10 different POLH mutations. There were two splicing, one nonsense, five frameshift (3 deletion and 2 insertion), and two missense mutations. Nine of these mutations involved the catalytic domain. Although affected siblings had similar clinical features, the relation between the clinical features and the mutations was not clear. POLH mRNA levels were normal or reduced by 50% in three cell strains with undetectable levels of pol eta protein, indicating that nonsense-mediated message decay was limited. We found a wide spectrum of mutations in the POLH gene among XP-V patients in different countries, suggesting that many of these mutations arose independently.

Shuttling of the autoantigen La between nucleus and cell surface after uv irradiation of human keratinocytes

During the past years we have established that the nuclear autoantigen La shuttles between the nucleus and the cytoplasm in tumor cells after inhibition of transcription or virus infection. We reinvestigated this shuttling using primary human keratinocytes from both healthy donors and patients with xeroderma pigmentosum. Ultraviolet irradiation resulted in both an inhibition of transcription and a translocation of La protein from the nucleus to the cytoplasm. After a prolonged inhibition of transcription La protein relocated into the nucleus and assembled with nuclear storage regions. The uv-induced shuttling included a translocation to the cell surface, where La protein colocalized with epidermal growth factor receptors.

Anticardiolipin antibodies are elevated in drug-free, multiply affected families with schizophrenia

The objective of this study was to measure anticardiolipin antibodies in patients and healthy relatives in multicase families with schizophrenia. Twenty-eight (28) multicase families with schizophrenia were examined. One hundred three drug-free patients and 66 first-degree relatives consented to evaluation by DSM-III-R criteria. Criteria for patient definition included the following: age ≥16, a confirmed hospital diagnosis of schizophrenia, knowledge of biological parents, and consent to participate. Additional data were drawn from family history and medical records. Serum samples were tested separately for IgG and IgM anticardiolipin by enzyme-linked immunosorbent assay (ELISA) and designated positive/negative by comparison to the reactivity of an age-matched control group. IgG anticardiolipin antibodies were significantly more common in both patients and relatives compared to controls. IgM anticardiolipin antibodies were significantly more common in patients. In 75% of families at least one member was anticardiolipin positive and this positivity correlated with patient positivity. The relevance of anticardiolipin antibodies in both patients and healthy relatives of some multicase families to the pathogenesis of schizophrenia is discussed.

Induction of unscheduled DNA synthesis by the carcinogen 7-bromomethylbenz(A)anthracene and its removal from the DNA of normal and xeroderma pigmentosum lymphocytes

Abstract The carcinogen 7-bromomethylbenz( a )anthracene (BBA), which can bind strongly to DNA, induces unscheduled DNA synthesis (DNA repair) in normal lymphocytes but almost none in lymphocytes from patients with Xeroderma pigmentosum (XP), and inherited disease known to be defective in excision repair of ultraviolet-damaged DNA. We studied [ 3 H]BBAs ability to bind to DNA of normal and XP lymphocytes, its influence on unscheduled DNA synthesis, and its removal from the DNA of both cell types. We found that 20–30% of the BBA is bound to macromolecules other than DNA and that its binding to DNA is essentially complete after 30 min. The induction of unscheduled DNA synthesis by the carcinogen in XP lymphocytes was approximately 10% of that induced in normal lymphocytes. While 15–20% of the BBA was removed from the DNA of normal cells 6 h after treatment, only 1–2% was removed from the DNA of XP cells. Thus, XP cells not only are defective in repairing ultraviolet-damaged DNA and excising thymine dimers but also fail to repair DNA damaged by certain carcinogens, and, most importantly, fail to remove the DNA-bound carcinogen, BBA.

Increased anti-Sm antibodies in schizophrenic patients and their families

1. Autoantibodies in the Sm complex have become a useful serologic aid in the diagnosis of systemic lupus erythematosus (SLE) and have rarely been observed in other diseases. 2. A subset of SLE patients have a variety of psychiatric abnormalities, including schizophrenia. 3. The authors have recently observed that schizophrenic patients have a high incidence of autoantibodies suggesting that autoimmune phenomena may play a role in the pathogenesis of this disease. 4. In the present study the authors investigated multicase families with schizophrenia for the presence of anti-Sm antibodies and showed that these autoantibodies are elevated both in patients and in their healthy relatives. 5. An autoimmune process may be involved in the pathology of schizophrenia.

Cockayne syndrome type II in a Druze isolate in Northern Israel in association with an insertion mutation in ERCC6

Cockayne syndrome (CS) (OMIM #133540) is a rare autosomal recessive disease characterized by severe growth and developmental retardation, progressive neurological dysfunction and symptoms of premature aging. The underlying cause of the disease is a defect in transcription‐coupled DNA repair, specifically the nucleotide excision repair (NER) pathway. To date, about half of the reported CS cases have an altered cellular response to UV resulting from mutations in either the CSA or the CSB genes. We have identified a large, highly consanguineous, Druze kindred descended from a single ancestor, with six CS cases. All six of them presented with the congenital severe phenotype that includes severe failure to thrive, severe mental retardation, congenital cataracts, loss of adipose tissue, joint contractures, distinctive face with small, deep‐set eyes and prominent nasal bridge, and kyphosis. They had no language skills, could not sit or walk independently, and died by the age of 5 years. Cellular studies of the fibroblasts from three patients showed a significant defect in transcription‐coupled DNA repair (TCR) and a marked correction of the abnormal cellular phenotype with a plasmid containing the cDNA of the ERCC6 gene. Molecular studies led to identification of a novel insertion mutation, c.1034‐1035insT in exon 5 of the ERCC6 gene (p.Lys345Asnfs*24). This mutation was identified in 1:15 healthy individuals from the same village, indicating an extremely high carrier frequency. Identification of the causative mutation enables comprehensive genetic counseling among the population at risk from this village.

Quantitative evaluation of hepatic cytochrome P4501A transcript, protein, and catalytic activity in the striped sea bream (Lithognathus mormyrus)

Hepatic cytochrome P4501A (CYP1A) expression was partially characterized in the striped sea bream (Lithognathus mormyrus) from the Mediterranean coast of Israel as part of the process of establishing the CYP1A gene as an environmental biomarker. Reverse transcription-competitive polymerase chain reaction, competitive enzyme-linked immunosorbent assay, and ethoxyresorufin O-deethylase (EROD) assay were used for evaluating transcript, protein, and catalytic activity levels, respectively, in absolute units. Highest elucidated transcript, protein, and catalytic activity levels were 0.264 +/- SD 0.084 fmol/microg total RNA, 0.88 +/- 0.52 pmol/microg total protein, and 1.11 +/- 0.52 pmol resorufin/min/microg total protein, respectively, and the lower levels were 0.009 +/- 0.007 fmol/microg total RNA, 0.17 +/- 0.08 pmol/microg total protein, and 0.11 +/- 0.06 pmol resorufin/min/microg total protein, respectively, demonstrating substantial induction potential. All alternate pairs of seven examined field samples, revealing a transcript-level ratio higher than 1.7, also demonstrated a significant difference between their transcript levels, indicating a potential to detect relatively small biomarker changes (1.7-fold) caused by environmental effects. Simultaneous triple measurements of transcript, protein, and catalytic activity were carried out in individuals from two field samples and during a 318-d decay experiment. Fish from the field samples revealed significant alternate bivariate correlation between transcript, protein, and enzymatic activity. Conflicting results were found when analyzing the decay experiment, in which both protein and catalytic activity levels decreased significantly to basal levels, in contrast to no significant change in transcript levels throughout the experiment. No significant difference was observed between males and females regarding the levels of CYP1A transcript, protein, and EROD.

Detection of Antimitochondrial Antibodies: Characterization by Enzyme Immunoassay and Immunoblotting

Mitochondrial antigens were purified from rat liver and characterized by immunoblotting. Sera from 19 well defined patients with primary biliary cirrhosis (PBC) reacted with two mitochondrial polypeptides of 68 Kd and 45 Kd. Antibodies to these antigens were not detected in any of the sera of patients with cirrhosis of the liver, chronic active hepatitis or other autoimmune diseases. The two polypeptides were derived from the soluble fraction of the mitochondrial matrix. An enzyme-linked immunosorbent assay (ELISA) employing these rat liver mitochondrial antigens is described. Positive results were obtained with all except one PBC sera (95%), five out of 47 patients with cirrhosis (11%), one out of 20 patients with chronic active hepatitis (5%), and two out of 19 patients with various autoimmune disorders (11%). The titers detected in PBC were markedly higher than those recorded in patients with other liver and autoimmune diseases. Strong correlation was found between immunoblotting and the ELISA in determining antimitochondrial antibodies. The ELISA presented is easily performed and seems to be a useful diagnostic tool for antimitochondrial antibodies in patients with PBC.