Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed

Genetic studies on telomere length are important for understanding age-related diseases. Prior GWASs for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally diverse individuals (European, African, Asian, and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole-genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n = 109,122 individuals. We identified 59 sentinel variants (p < 5 × 10−9) in 36 loci associated with telomere length, including 20 newly associated loci (13 were replicated in external datasets). There was little evidence of effect size heterogeneity across populations. Fine-mapping at OBFC1 indicated that the independent signals colocalized with cell-type-specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated that our TL polygenic trait scores (PTSs) were associated with an increased risk of cancer-related phenotypes

Effect of tryptophan insertions on the properties of the human group IIA phospholipase A2: mutagesesis produces an enzyme with characteristics similar to those of the human group V phospholipase A2

An important characteristic of the human group IIA secreted phospholipase A(2) (IIA PLA(2)) is the extremely low activity of this enzyme with phosphatidylcholine (PC) vesicles, mammalian cell membranes, and serum lipoproteins. This characteristic is reflected in the lack of ability of this enzyme to bind productively to zwitterionic interfaces. Part of the molecular basis for this lack of activity is an absence of tryptophan, a residue with a known preference for residing in the interfacial region of zwitterionic phospholipid bilayers. In this paper we have replaced the eight residues that make up the hydrophobic collar on the interfacial binding surface of the enzyme with tryptophan. The catalytic and interfacial binding properties of these mutants have been investigated, particularly those properties associated with binding to and hydrolysis of zwitterionic interfaces. Only the insertion of a tryptophan at position 3 or 31 produces mutants that significantly enhance the activity of the human IIA enzyme against zwitterionic interfaces and intact cell membranes. Importantly, the ability of the enzyme mutants to hydrolyze PC- rich interfaces such as the outer plasma membrane of mammalian cells was paralleled by enhanced interfacial binding to zwitterionic interfaces. The corresponding double tryptophan mutant (V3,31W) displays a specific activity on PC vesicles comparable to that of the human group V sPLA2. This enhanced activity includes the ability to interact with human embryonic kidney HEK293 cells, previously reported for the group V enzyme [Kim, Y. J., Kim, K. P., Rhee, H. J., Das, S., Rafter, J. D., Oh, Y. S., and Cho, W. (2002) J. Biol. Chem. 277, 9358-9365

The antibacterial properties of secreted phospholipases A(2) - A major physiological role for the group IIA enzyme that depends on the very high pI of the enzyme to allow penetration of the bacterial cell wall

The antibacterial properties of human group IIA secreted phospholipase A(2) against Gram-positive bacteria as a result of membrane hydrolysis have been reported. Using Micrococcus luteus as a model system, we demonstrate the very high specificity of this human enzyme for such hydrolysis compared with the group IB, IIE, lIF, V, and X human secreted phospholipase A(2)s. A unique feature of the group IIA enzyme is its very high pI due to a large excess of cationic residues on the enzyme surface. The importance of this global positive charge in bacterial cell membrane hydrolysis and bacterial killing has been examined using charge reversal mutagenesis. The global positive charge on the enzyme surface allows penetration through the bacterial cell wall, thus allowing access of this enzyme to the cell membrane. Reduced bacterial killing was associated with the loss of positive charge and reduced cell membrane hydrolysis. All mutants were highly effective in hydrolyzing the bacterial membrane of cells in which the cell wall was permeabilized with lysozyme. These same overall characteristics were also seen with suspensions of Staphylococcus aureus and Listeria innocua, where cell membrane hydrolysis and antibacterial activity of human group IIA enzyme was also lost as a result of charge reversal mutagenesis

Isothiazole dioxides: Synthesis and inhibition of Trypanosoma brucei protein farnesyltransferase

A series of isothiazole dioxides was synthesized and evaluated as inhibitors of protein farnesyltransferase from the parasite that causes African sleeping sickness (Trypanosoma brucei). The most potent compound in the series inhibited the parasite enzyme with an IC50 of 2 \u3bcM and blocked the growth of the bloodstream parasite in vitro with an ED50 of 10 \u3bcM. The same compound inhibited rat protein farnesyltransferase and protein geranylgeranyltransferase type I only at much higher concentration. \ua9 2002 Elsevier Science Ltd. All rights reserved

The pharmacological control of the mevalonate pathway regulates arterial smooth muscle cell proliferation

none8The aim of the present study was to analyze the frequency and mechanism of cell death in atherosclerotic plaques with a recent history ( 70% diameter reduction undergoing carotid endarterectomy. In situ tailing and nick translation of fragmented DNA, agarose gel electrophoresis of plaque DNA and electron microscopy were used to identify cell death by apoptosis (programmed cell death) and oncosis. The mean number of cells containing fragmented DNA in the plaques was 12.7 ± 3.5% (n = 15). Focal accumulations of cells with DNA fragmentation occurred in the fibrous cap, at sites of rupture, close to lipid deposits and necrosis and was always accompanied by the presence of inflammatory cells. Electrophoretic separation of DNA isolated from part of plaques, where the presence of DNA fragmentation had previously been demonstrated by in situ DNA nick translation, resulted in multiple ladders of 180-200 base pairs characteristic of apoptosis. Electron microscopic analysis revealed presence of cells with morphological signs of degeneration in a frequency even higher than that found by in situ nick translation. Some of these cells had a characteristic apoptotic appearance with condensed chromatin and cytoplasm, but the large majority of the cells had an ultrastructure typical for cells undergoing cell death by oncosis with membrane disruption and swollen, disintegrating organelles. Thus, although apoptosis clearly takes place in atherosclerotic plaques, oncosis appears to be a much more common mechanism for cell death.noneA. Corsini; L. Arnaboldi; P. McGeady; M.H. Gelb; P. Quarato; N. Ferri; R. Paoletti; R. FumagalliA., Corsini; L., Arnaboldi; P., Mcgeady; M. H., Gelb; P., Quarato; Ferri, Nicola; R., Paoletti; R., Fumagall

The pharmacological control of the mevalonate pathway regulates arterial smooth muscle cell proliferation

The aim of the present study was to analyze the frequency and mechanism of cell death in atherosclerotic plaques with a recent history ( 70% diameter reduction undergoing carotid endarterectomy. In situ tailing and nick translation of fragmented DNA, agarose gel electrophoresis of plaque DNA and electron microscopy were used to identify cell death by apoptosis (programmed cell death) and oncosis. The mean number of cells containing fragmented DNA in the plaques was 12.7 \ub1 3.5% (n = 15). Focal accumulations of cells with DNA fragmentation occurred in the fibrous cap, at sites of rupture, close to lipid deposits and necrosis and was always accompanied by the presence of inflammatory cells. Electrophoretic separation of DNA isolated from part of plaques, where the presence of DNA fragmentation had previously been demonstrated by in situ DNA nick translation, resulted in multiple ladders of 180-200 base pairs characteristic of apoptosis. Electron microscopic analysis revealed presence of cells with morphological signs of degeneration in a frequency even higher than that found by in situ nick translation. Some of these cells had a characteristic apoptotic appearance with condensed chromatin and cytoplasm, but the large majority of the cells had an ultrastructure typical for cells undergoing cell death by oncosis with membrane disruption and swollen, disintegrating organelles. Thus, although apoptosis clearly takes place in atherosclerotic plaques, oncosis appears to be a much more common mechanism for cell death