Somatic cell mutation in pediatric patients undergoing allogeneic bone marrow transplantation

In order to examine whether bone marrow transplantation (BMT) has genotoxic effects in vivo, mutant frequencies (Mfs) at the hypoxanthine-guanine phosphoribosyl transferase (Hprt) locus were evaluated. Thirty-seven pediatric patients who had received allogeneic BMT for various hematologic or immunologic disorders were enrolled. Nine out of the 37 patients (24.3%) were found to have Hprt-Mfs exceeding the 99% confidence limits calculated from observation of healthy controls. Among factors including gender, primary disease of the patient, donor-recipient histocompatibility relationship, age of donor, and total body irradiation as conditioning regimen, none was associated with an increased Hprt-Mf. In three patients who had chimerism in their peripheral blood after BMT, Hprt mutant clones turned out to be of donor- or recipient-origin. Mfs at the T-cell receptor (TCR) locus were examined in 28 patients. Four patients (14.3%) were found to have increased TCR-Mfs. However, there were not any patients who showed elevation of both Hprt-and TCR-Mfs. These data, taken together, suggest that BMT may cause genotoxicity in vivo in some patients.     

Interaction with GM130 during HERG ion channel trafficking. Disruption by type 2 congenital long QT syndrome mutations. Human Ether-à-go-go-Related Gene

Many mutations in the Human Ether-à-go-go-Related Gene (HERG) cause type 2 congenital long QT syndrome (LQT2) by disrupting trafficking of the HERG-encoded potassium channel. Beyond observations that some mutations trap channels in the endoplasmic reticulum, little is known about how trafficking fails. Even less is known about what checkpoints are encountered in normal trafficking. To identify protein partners encountered as HERG channels are transported among subcellular compartments, we screened a human heart library with the C terminus of HERG using yeast two-hybrid technology. Among the proteins isolated was GM130, a Golgi-associated protein involved in vesicular transport. The interaction mapped to two non-contiguous regions of HERG and to a region just upstream of the GRASP-65 interaction domain of GM130. GM130 did not interact with the N or C terminus of either KvLQT1 or Shaker channels. LQT2-causing mutations in the HERG C terminus selectively disrupted interactions with GM130 but not Tara, another HERG-interacting protein. Native GM130 and stably expressed HERG were co-immunoprecipitated from HEK-293 cells using GM130 antibodies. In rat cardiac myocytes and HEK-293 cells, confocal immunocytochemistry showed co-localization of GM130 and HERG to the Golgi apparatus. Overexpression of GM130 suppressed HERG current amplitude in Xenopus oocytes, as if by providing an excess of substrate at the Golgi checkpoint. These findings indicate that GM130 plays a previously undefined role in cargo transport. We propose that the cytoplasmic C terminus of HERG participates in the tethering or possibly targeting of HERG-containing vesicles within the Golgi via its interaction with GM130.     

Y-chromosome analysis in Egypt suggests a genetic regional continuity in Northeastern Africa

The geographic location of Egypt, at the interface between North Africa, the Middle East, and southern Europe, prompted us to investigate the genetic diversity of this population and its relationship with neighboring populations. To assess the extent to which the modern Egyptian population reflects this intermediate geographic position, ten Unique Event Polymorphisms (UEPs), mapping to the nonrecombining portion of the Y chromosome, have been typed in 164 Y chromosomes from three North African populations. The analysis of these binary markers, which define 11 Y-chromosome lineages, were used to determine the haplogroup frequencies in Egyptians, Moroccan Arabs, and Moroccan Berbers and thereby define the Y-chromosome background in these regions. Pairwise comparisons with a set of 15 different populations from neighboring European, North African, and Middle Eastern populations and geographic analysis showed the absence of any significant genetic barrier in the eastern part of the Mediterranean area, suggesting that genetic variation and gene flow in this area follow the "isolation-by-distance" model. These results are in sharp contrast with the observation of a strong north-south genetic barrier in the western Mediterranean basin, defined by the Gibraltar Strait. Thus, the Y-chromosome gene pool in the modern Egyptian population reflects a mixture of European, Middle Eastern, and African characteristics, highlighting the importance of ancient and recent migration waves, followed by gene flow, in the region.     

Mycobacterium tuberculosis induces differential cytokine production from dendritic cells and macrophages with divergent effects on naive T cell polarization

Th1-mediated cellular responses are important for protection in tuberculosis. However, the mechanisms and APC types responsible for initiating Th1 responses are not well understood. These studies show that macrophages and dendritic cells, albeit both being APC, respond differently following Mycobacterium tuberculosis infection and thereby have different consequences for the development of naive T cells. We report that M. tuberculosis-infected dendritic cells bias the polarization of OVA peptide-specific naive transgenic T cells to the Th1 phenotype, and, in contrast, in the presence of infected macrophages naive T cells do not develop a Th1 phenotype. Comparison of the cytokine profile expressed by the infected dendritic cells and macrophages revealed several differences, the most striking being that infected macrophages did not express the Th1-promoting cytokine IL-12. These studies also show that IL-10 is responsible for the failure of IL-12 production by M. tuberculosis-infected macrophages, and that the effects of IL-10 can be overcome by IFN-gamma priming. We speculate that the observed difference in response of the two APC types to M. tuberculosis infection may be a reflection of their respective roles in immune initiation and granuloma regulation.     

Cancer cell dynamics in presence of telomerase inhibitors: analysis of in vitro data

The inhibition of telomerase activity in actively dividing cells leads to suppression of cell growth after a time delay (inhibitory delay) required to reach a threshold telomeric DNA size. We developed a mathematical model of the dynamics of telomere size distribution and cell growth in the presence of telomere inhibitors that allowed quantification of the inhibitory delay. The model based on the solution of a system of differential equations described quantitatively recent experimental data on dynamics of cultured cells in presence of telomerase inhibitors. The analysis of the data by this model suggested the existence of at least two distinct subpopulations of cells with different proliferative activity. Size distribution of telomeres, fraction of proliferating cells, and tumor doubling times are of critical importance for the dynamics of cancer cells growth in presence of telomerase inhibitors. Rapidly growing cells with large telomeric DNA heterogeneity and small proliferating fractions as well as those with very short homogeneous telomeres would be the most sensitive to telomerase inhibitors.     

Enantioselective addition of diethylzinc to aldehydes catalyzed by optically active C2-symmetrical bis-beta-amino alcohols

The syntheses of new optically active C(2)-symmetrical bis-beta-amino alcohols 1-6 from (S)-2-(1-hydroxy-1,1-diphenylmethyl)-pyrrolidine are described. Especially attention is focused on bridges, which link the two beta-amino alcohol units. These new chiral ligands have been successfully applied in the catalytic enantioselective addition of diethylzinc to aldehydes to give sec-alcohols in good yields with up to 95% enantiomeric excess.     

Differential responses of temporal and nasal retinal neurites to regional-specific cues in the mouse retinofugal pathway

Retinal explants of mouse embryos were cultured together with explants of different regions in the retinofugal pathway in order to investigate whether ventral temporal (VT) and dorsal nasal (DN) retinal neurites showed differential responses to regional-specific cues in the pathway. In the presence of the chiasm, biased outgrowth of retinal neurites was found in explants of both retinal regions, which was accompanied by a reduction in total neurite growth in the VT but not the DN retina. Such differential responses to the diffusible negative influence were also observed when explants of two retinal origins were cocultured with the ventral diencephalon, but were not found with the dorsal diencephalon that contains targets of the optic axons. Indeed, extensive neurite invasion was found in the dorsal diencephalic explants and this ingrowth was more prominent for VT than DN neurites, showing a difference in axons from a distinct position in the retina to contact-mediated stimulatory activity within the target nuclei. We conclude that neurites from different regions of the retina show differential responses to the regional-specific cues in the diencephalon. These cues exist in both diffusible and contact-mediated forms that may shape the characteristic course and organization of retinal axons in decision regions of the optic pathway and the visual targets.     

Congenital fibrosis of the vertically acting extraocular muscles maps to the <Emphasis Type="Italic">FEOM3</Emphasis> locus

The diagnosis of congenital fibrosis of the extraocular muscles (CFEOM) encompasses several different inherited strabismus syndromes characterized by congenital restrictive ophthalmoplegia affecting extraocular muscles innervated by the oculomotor and/or trochlear nerves. The OMIM database (http://www.ncbi.nlm.nih.gov/Omim/) currently contains four familial CFEOM phenotypes: CFEOM1-3, which map to the FEOM1-3 loci (MIM 135600, 602078, 604361), respectively, and congenital fibrosis of the vertically acting extraocular muscles (MIM 600638), reported in a single family without a corresponding genotype. We have had the opportunity to study the reported family with this fourth phenotype and now demonstrate that their phenotype can be reclassified as CFEOM3 and that it maps to FEOM3, flanked by D16S498 to 16qter, with a maximum lod score of 6.0.     

Using nuclear targeting signals to enhance non-viral gene transfer

Summary Gene therapy involves the introduction of DNA-encoding therapeutic gene products into appropriate cells of an affected individual. The limitations of the approach relate largely to the poor efficiency of the delivery of the therapeutic DNA to the nucleus. This review examines recent work in the area of non-viral gene transfer, building on developments in the field of nuclear protein import and their application in the field of non-viral gene transfer. In particular, advances in the area of enhancing DNA targeting to the nucleus are discussed, including the use of modular nuclear targeting signals recognised by the cellular nuclear import machinery and DNA condensing agents to facilitate passage through the nuclear pore. Optimising nuclear DNA delivery through these and other strategies should assist greatly in rendering gene therapy a viable and realistic possibility for treating disease.