A small, portable RNA device for the control of exon skipping in mammalian cells.

Splicing is an essential and highly regulated process in mammalian cells. We developed a synthetic riboswitch that efficiently controls alternative splicing of a cassette exon in response to the small molecule ligand tetracycline. The riboswitch was designed to control the accessibility of the 3' splice site by placing the latter inside the closing stem of a conformationally controlled tetracycline aptamer. In the presence of tetracycline, the cassette exon is skipped, whereas it is included in the ligand's absence. The design allows for an easy, context-independent integration of the regulatory device into any gene of interest. Portability of the device was shown through its functionality in four different systems: a synthetic minigene, a reporter gene and two endogenous genes. Furthermore, riboswitch functionality to control cellular signaling cascades was demonstrated by using it to specifically induce cell death through the conditionally controlled expression of CD20, which is a target in cancer therapy.

Jmjd3 controls mesodermal and cardiovascular differentiation of embryonic stem cells.

RATIONALE: The developmental role of the H3K27 demethylases Jmjd3, especially its epigenetic regulation at target genes in response to upstream developmental signaling, is unclear. OBJECTIVE: To determine the role of Jmjd3 during mesoderm and cardiovascular lineage commitment. METHODS AND RESULTS: Ablation of Jmjd3 in mouse embryonic stem cells does not affect the maintenance of pluripotency and self-renewal but compromised mesoderm and subsequent endothelial and cardiac differentiation. Jmjd3 reduces H3K27me3 marks at the Brachyury promoter and facilitates the recruitment of ß-catenin, which is critical for Wnt signal-induced mesoderm differentiation. CONCLUSIONS: These data demonstrate that Jmjd3 is required for mesoderm differentiation and cardiovascular lineage commitment.

Klinefelter twins presenting with discordant aneuploidies, acardia, forked umbilical cord and with different gonadal sex despite monozygosity.

OBJECTIVE: A higher frequency of twin births in sibships of Klinefelter syndrome patients and also monozygotic or dizygotic twins, themselves being affected by Klinefelter syndrome have been noted repeatedly. To address this issue, we evaluated type and frequency of twinning among Klinefelter fetuses that we had received for autopsy within a 'Prenatal Diagnosis' program. METHOD: We performed fetal autopsies, and genetic analyses on DNA extracted from stained histological slides. RESULTS: Among 41 prenatal diagnoses of a 47, XXY karyotype we observed four twin pairs. One was dizygotic with discordant Klinefelter and Down syndrome. Three twin pairs were monozygotic as concluded from monochorial placentation. In two monozygotic pairs one twin partner was an acardiac monster and in one of these the acardiac twin showed a female gonadal sex and missing Y-chromosomal SRY-sequences as confirmed by polymerase chain reaction. CONCLUSIONS: There is a high rate of twinning and twin reversed arterial perfusion sequence among our Klinefelter fetuses. Forked umbilical cords at the placental insertion site in one case allowed classification as conjoined twins in the sense of a 'funiculopagus'. Anaphase lagging or semidizygosity by second polar body twinning are proposed as explanations for the gonadal sex discordance and the excessive developmental disadvantage in the one acardiac. Problems may arise with regard to non-invasive prenatal diagnosis of aneuploidies in twin pregnancies.

Variations of frataxin protein levels in normal individuals.

Friedreich's ataxia (FRDA) is the most common of the inherited ataxias and is associated with GAA trinucleotide repeat expansions within the first intron of the frataxin (FXN) gene. There are expanded FXN alleles from 66 to 1,700 GAA·TTC repeats in FRDA patients and correlations between number of GAA repeats and frataxin protein levels are assumed. Here, we present for the first time frataxin protein levels as well as analysis of GAA triplet repeats in the FXN gene in a population of 50 healthy Austrian people. Frataxin protein levels were measured in lymphocytes from blood samples by ELISA and GAA repeats were analyzed by capillary electrophoresis. Rather unexpectedly, we found a high variation of frataxin protein levels among the individuals. In addition, there was no correlation between frataxin levels, GAA repeats, age and sex in this group. However, these findings are of great importance for better characterization of the disease.

DNA repair polymorphisms associated with cytogenetic subgroups in B-cell chronic lymphocytic leukemia.

Genetic polymorphisms in DNA repair genes can affect the risk of developing different forms of cancer. Therefore, we have studied the putative association of seven single nucleotide polymorphisms (SNPs) in five DNA repair genes with the incidence of chronic lymphocytic leukemia (CLL). We included 461 CLL patients and the same number of age- and sex-matched controls. As chromosomal aberrations are important prognostic markers in CLL, we additionally correlated the SNPs with the occurrence of favorable and unfavorable cytogenetic aberrations in CLL patients. Patients with del(13q) as a sole aberration were allocated to the favorable cytogenetic risk group, and patients with del(17p) and/or del(11q) to the unfavorable cytogenetic risk group. All investigated SNPs were equally distributed between patients with the favorable cytogenetic aberration and controls. However, differences were observed in the distribution of rs13181 in ERCC2 between all CLL patients and controls. Moreover, the clearest differences were found for rs13181 in ERCC2 and rs25487 in XRCC1 between CLL patients with unfavorable cytogenetic aberrations and controls. These data suggest that inborn genetic polymorphisms may predict the outcome of CLL.

Smith-Lemli-Opitz syndrome - Fetal phenotypes with special reference to the syndrome-specific internal malformation pattern.

BACKGROUND: Autosomal-recessive SLOS is caused by mutations in the DHCR7 gene. It is defined as a highly variable complex of microcephaly with intellectual disability, characteristic facies, hypospadias, and polysyndactyly. Syndrome diagnosis is often missed at prenatal ultrasound and fetal autopsy METHODS: We performed autopsies and DHCR7 gene analyses in eight fetuses suspected of having SLOS and measured cholesterol values in long-term formalin-fixed tissues of an additional museum exhibit RESULTS: Five of the nine fetuses presented classical features of SLOS, including four cases with atrial/atrioventricular septal defects and renal anomalies, and one with additional bilateral renal agenesis and a Dandy-Walker cyst. These cases allowed for diagnosis at autopsy and subsequent SLOS diagnosis in two siblings. Two fetuses were mildly affected and two fetuses showed additional holoprosencephaly. These four cases and the exhibit had escaped diagnosis at autopsy. The case with bilateral renal agenesis presented a novel combination of a null allele and a putative C-terminus missense mutation in the DHCR7 gene CONCLUSIONS: In view of the discrepancy between the prevalence of SLOS among newborns and the carrier frequency of a heterozygous DHCR7 gene mutation, the syndrome-specific internal malformation pattern may be helpful not to miss SLOS diagnosis in fetuses at prenatal ultrasound and fetal autopsy.

Acanthocytosis and the c.680 A>G Mutation in the PANK2 Gene: A Study Enrolling a Cohort of PKAN Patients from the Dominican Republic.

Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a form of Neurodegeneration with Brain Iron Accumulation (NBIA) associated with mutations in the pantothenate kinase 2 gene (PANK2). Pantothenate kinases catalyze the rate-limiting step of coenzyme A synthesis and Pank2 is the only pantothenate kinase isoform in humans that is localized to mitochondria. Acanthocytosis, the occurrence of spiculated erythrocytes, is observed in about 10% of the PKAN patients. Therefore PKAN is also classified together with other rare neurodegenerative diseases like Chorea Acanthocytosis (ChAc) and McLeod syndrome (MLS) into the Neuroacanthocytosis (NA) syndromes. It has not been investigated yet whether acanthocytosis in PKAN is associated with a specific subset of Pank2 mutations. In this study, we analyzed acanthocytosis of a cohort of 25 PKAN patients from the Dominican Republic that are homozygous for the c.680 A>G mutation in the PANK2 gene as compared to control donors that are heterozygous or wild-type with respect to this mutation. 3D modeling of this mutation indicated that the replacement of a tyrosine by a cysteine at position 227 in Pank2 disrupts a polar interaction within the A domain of the enzyme. Mean acanthocyte count was elevated in the cohort of patients, however, acanthocytosis varied among the patients with nearly half of them showing high (>20%) or elevated acanthocytosis and the rest showing mild (6-10%) or no (<6%) acanthocytosis. Heterozygous control donors revealed a tendency to mild acanthocytosis. Based on the insight that Pank2 is a normal constituent of red blood cells and de novo biosynthesis of coenzyme A is likely to take place in the erythrocyte cytosol we propose a hypothetical model that accounts for the variability in the occurrence of acanthocytic cells in PKAN.

MMP-9 polymorphisms are not associated with spontaneous cervical artery dissection.

BACKGROUND AND PURPOSE: Cervical artery dissection (CAD) is a common cause of ischemic stroke in young adults. Alteration in the structure of the vascular extracellular matrix has been described in CAD. Matrix metalloproteinases (MMPs) degrade extracellular matrix proteins and can lead to vascular damage. METHODS: We tested 2 different MMP-9 DNA polymorphisms, a CA repeat and a cytosine to thymidine transition in the promotor sequence, for frequency in 52 patients with CAD. We compared the results with those of 52 healthy controls. RESULTS: No differences were found in the allelic distribution of either polymorphism. CONCLUSIONS: Alleles of these well-characterized functional polymorphisms of MMP-9 gene are not associated with structural alterations in the matrix of vessels of patients with CAD.

Topographically graded postischemic presence of metalloproteinases is inhibited by hypothermia.

To test the hypothesis that presence of metalloproteases (MMPs), their inhibitors (TIMPs) and their substrate laminin-5 differs between the ischemic core and the surrounding tissue, we examined the impact of middle cerebral artery occlusion/reperfusion (MCA:O/R) on these molecules in different regions of the infarct. We also investigated the influence of hypothermia on the progression of the ischemic lesion and MMP activity. Brain sections from 64 Wistar rats subjected to MCA:O/R were examined by means of cytohistochemistry and zymography. The artery was occluded for 2 h followed by 3, 5, 8 and 12 h of reperfusion. Well characterized antibodies against laminin-5, MMPs and TIMP-2 were used. A total of 32 rats were treated with hypothermia. The presence of each antigen was related to the following regions of interest: ischemic core with BBB breakdown (I(c)), surrounding ischemic tissue without BBB breakdown (I(r)), and the contralateral non-ischemic region (N). Regions of interest were defined by MRI. The I(c) increased over time at the cost of the I(r). BBB breakdown occurred early in the ischemic core and increased over time. Hypothermia reduced the BBB breakdown at all time points. A graded decreased presence of laminin-5 was observed with 16.5+/-3.7(N)>10+/-2.8(I(r))>4+/-1.4(I(c)) immunopositive microvessels/mm(2) at 3 h of reperfusion. MMP-9 showed a reverse pattern with 0 (N)<4+/-0.8(I(r))<10+/-1.5(I(c)) immunopositive microvessels/mm(2). Hypothermia decreased the MMP activity measured by zymography. Laminin-5 and MMP presence relate directly to the degree of postischemic injury. Hypothermia reduces the conversion from the I(r) to ischemic core and the degree of BBB as well as MMP abundance.

Volumetric evaluation of the ischemic lesion size with serial MRI in a transient MCAO model of the rat: comparison of DWI and T1WI.

Magnetic resonance imaging (MRI) is applied in many studies on experimental cerebral ischemia in rodents to monitor the temporal evolution of ischemic damage. We report a protocol to evaluate the infarct size after middle cerebral artery occlusion with reperfusion (MCAO/R) in male Wistar rats. Imaging was performed with a 2.35 T scanner and we focused on diffusion-weighted imaging (DWI), T2-weighted imaging (T2WI) and postcontrast T1-weighted imaging (T1WI). We show the detailed procedure of volumetry, the contrast-to-noise ratio (CNR) and the intraindividual variability of infarct and hemispheric volumes at different reperfusion times. The presented method is of low variability if image contrast between ischemic and nonischemic tissue is very high, which is the case not only for all sequences at 8 and 12 h of reperfusion but also for DWI after 3 and 5 h of reperfusion. Furthermore, we describe the so-called mismatch region of lesion sizes depicted on DWI and postcontrast T1WI that suffers from cytotoxic edema but lacks contrast enhancement.

Desbuquois dysplasia type I and fetal hydrops due to novel mutations in the CANT1 gene.

We report on three hydropic fetuses of 17, 22 and 25 gestational weeks from three distinct families presenting with Desbuquois dysplasia type 1. All fetuses showed brachymelia and characteristic dysmorphic features. X-ray studies revealed δ-shaped extraphalangeal bones and disease-specific prominence of the lesser trochanter, varying in severity with fetal age. Early lethal manifestation of the disorder was reflected in lung hypoplasia and in early death of similarly affected siblings in cases 1 and 2. All families were German Caucasians by descent. Sequence analysis of the CANT1 gene revealed two frameshift mutations, c.228_229insC and c.277_278delCT, in homozygous and compound heterozygous configuration, respectively, and a homozygously novel missense mutation, c.336C>A (p.D112E), located within a highly conserved region of exon 2. Haplotype analyses by high-resolution single-nucleotide polymorphism array showed that the haplotype associated with c.228_229insC may be traced to a single founder in the German population.

Determination of the minimal distance between the matrix and transmembrane domains of the large hepatitis B virus envelope protein.

The cytosolic matrix domain (MD) located between amino acids (aa) 103 and 124 of the large hepatitis B virus envelope protein L is essential for virion formation. We reduced the distance between MD and the transmembrane domain (TD; aa 254 to 272) by deletions starting at aa 132. Six mutants with deletions of up to aa 234 were wild type, and four mutants with slightly larger deletions were blocked with respect to virion morphogenesis. Thus, the minimal distance between MD and TD was around 26 aa. This spacer might be required by MD to reach contact sites on the capsid.