Calcium-dependent regulation of the cell cycle via a novel MAPK–NF-κB pathway in Swiss 3T3 cells

Nuclear factor kappa B (NF-κB) has been implicated in the regulation of cell proliferation and transformation. We investigated the role of the serum-induced intracellular calcium increase in the NF-κB–dependent cell cycle progression in Swiss 3T3 fibroblasts. Noninvasive photoactivation of a calcium chelator (Diazo-2) was used to specifically disrupt the transient rise in calcium induced by serum stimulation of starved Swiss 3T3 cells. The serum-induced intracellular calcium peak was essential for subsequent NF-κB activation (measured by real-time imaging of the dynamic p65 and IκBα fluorescent fusion proteins), cyclin D1 (CD1) promoter-directed transcription (measured by real-time luminescence imaging of CD1 promoter-directed firefly luciferase activity), and progression to cell division. We further showed that the serum-induced mitogen-activated protein kinase (MAPK) phosphorylation is calcium dependent. Inhibition of the MAPK- but not the PtdIns3K-dependent pathway inhibited NF-κB signaling, and further, CD1 transcription and cell cycle progression. These data suggest that a serum-dependent calcium signal regulates the cell cycle via a MAPK–NF-κB pathway in Swiss 3T3 cells

Unregulated actin polymerization by WASp causes defects of mitosis and cytokinesis in X-linked neutropenia

Specific mutations in the human gene encoding the Wiskott-Aldrich syndrome protein (WASp) that compromise normal auto-inhibition of WASp result in unregulated activation of the actin-related protein 2/3 complex and increased actin polymerizing activity. These activating mutations are associated with an X-linked form of neutropenia with an intrinsic failure of myelopoiesis and an increase in the incidence of cytogenetic abnormalities. To study the underlying mechanisms, active mutant WASpI294T was expressed by gene transfer. This caused enhanced and delocalized actin polymerization throughout the cell, decreased proliferation, and increased apoptosis. Cells became binucleated, suggesting a failure of cytokinesis, and micronuclei were formed, indicative of genomic instability. Live cell imaging demonstrated a delay in mitosis from prometaphase to anaphase and confirmed that multinucleation was a result of aborted cytokinesis. During mitosis, filamentous actin was abnormally localized around the spindle and chromosomes throughout their alignment and separation, and it accumulated within the cleavage furrow around the spindle midzone. These findings reveal a novel mechanism for inhibition of myelopoiesis through defective mitosis and cytokinesis due to hyperactivation and mislocalization of actin polymerization

The effects of lower-body compression garments on walking performance and perceived exertion in adults with CVD risk factors

Objectives Compression garments are used by athletes in attempts to enhance performance and recovery, although evidence to support their use is equivocal. Reducing the exertion experienced during exercise may encourage sedentary individuals to increase physical activity. The aim of this study was to assess the effect of compression garments on walking performance (self-paced and enforced pace) and rate of perceived exertion (RPE) in adults who presented with two or more CVD risk factors. Participants (n = 15, 10 female, 58.9 ± 11.5 years, BMI 27.5 ± 4.5 kg m2) were recruited. Design A repeated measures design. Methods Participants were randomised to Modified Bruce Protocol (enforced pace), or the 6 min walk test (self-paced), and completed the test wearing compression garments or normal exercise clothes (Control). Outcome measures included stage completed, gross efficiency (%) and RPE in Modified Bruce Protocol, and distance walked (m) and RPE in 6 min walk test. Results In the Modified Bruce Protcol participants had a higher RPE (15.5 ± 2.5 vs 14.3 ± 2.2) and a lower efficiency (19.1 ± 5.9 vs 21.1 ± 6.7) in the compression garment condition compared with control, p < 0.05. In the 6 min walk test participants walked 9% less in the compression garment condition (p < 0.05) but did not have a lower RPE. Conclusions Compared with previous studies reporting enhanced or no effects of compression garments on performance or RPE, this study shows adverse effects of such clothing in untrained individuals with CVD risk factors. The mechanisms underlying this negative effect require further exploration. Use of garments designed for the athletic individuals may not be suitable for the wider population

Transcription factor Pit-1 affects transcriptional timing in the dual-promoter human prolactin gene

Gene transcription occurs in short bursts interspersed with silent periods, and these kinetics can be altered by promoter structure. The effect of alternate promoter architecture on transcription bursting is not known. We studied the human prolactin (hPRL) gene that contains two promoters, a pituitary-specific promoter that requires the transcription factor Pit-1, and displays dramatic transcriptional bursting activity, and an alternate upstream promoter that is active in non-pituitary tissues. We studied large hPRL genomic fragments with luciferase reporters, and used bacterial artificial chromosome (BAC) recombineering to manipulate critical promoter regions. Stochastic switch mathematical modelling of single-cell time-lapse luminescence image data revealed that the Pit-1-dependent promoter showed longer, higher-amplitude transcriptional bursts. Knockdown studies confirmed that the presence of Pit-1 stabilised and prolonged periods of active transcription. Pit-1 therefore plays an active role in establishing the timing of transcription cycles, in addition to its cell-specific functions

Detectability of Tensor Perturbations Through CBR Anisotropy (final published version)

Detection of the tensor perturbations predicted in inflationary models is important for testing inflation as well as for reconstructing the inflationary potential. We show that because of cosmic variance the tensor contribution to the square of the CBR quadrupole anisotropy must be greater than about 20\% of the scalar contribution to ensure a statistically significant detection of tensor perturbations. This sensitivity could be achieved by full-sky measurements on angular scales of $3^{\circ}$ and $0.5^\circ$.Comment: 10 pages, uu-encoded postscript file, FERMILAB-PUB-94/175-

Cosmological parameters from SDSS and WMAP

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS information more than halves the WMAP-only error bars on some parameters, tightening 1 sigma constraints on the Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when dropping prior assumptions about curvature, neutrinos, tensor modes and the equation of state. Our results are in substantial agreement with the joint analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive consistency check with independent redshift survey data and analysis techniques. In this paper, we place particular emphasis on clarifying the physical origin of the constraints, i.e., what we do and do not know when using different data sets and prior assumptions. For instance, dropping the assumption that space is perfectly flat, the WMAP-only constraint on the measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running tilt, neutrino mass and equation of state in the list of free parameters, many constraints are still quite weak, but future cosmological measurements from SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt figures available at http://www.hep.upenn.edu/~max/sdsspars.htm

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease