The rockefeller university

Increased caloric intake has been associated with increased risk for cancer of the large intestine. We studied caloric intake effect on tumor formation in Apc1638(N/+) mice, a preclinical model for human familial adenomatous polyposis. Mice were fed a controlled AIN-76A diet or a new Western-style diet (NWD). Intestinal tumor development was evaluated after 6 mu of feeding 1) AIN-76A diet (fed ad libitum) vs. AIN-76A (caloric intake reduced 30%); 2) NWD (led ad libitum) vs. NWD (caloric intake reduced 30%); and 3) AIN-76A (fed ad libitum) vs. NWD (paired-fed with NWD providing equal caloric intakes to AIN-76A). Intestinal tumor incidences were 78-100% with intergroup variation P > 0.05; however, tumor multiplicity responded differently to dietary treatment: 1) Tumor multiplicity was unchanged after AIN-76A (caloric intake reduced 30% vs. mice fed AIN-76A ad libitum); 2) tumor multiplicity was unchanged after NWD (caloric intake reduced 30% vs. NWD ad libitum); and 3) tumor multiplicity increased 130% after NWD was paired-fed with the same caloric intake as mice fed AIN-76A ad libitum (P < 0.05). Body weights showed no association with tumor development. Findings indicated modified nutrients in NWD were mainly responsible for increased tumors in mice fed NWD vs. AIN-76A in this preclinical mouse model for human FAP.

T follicular helper (Tfh) cells are critical for providing the necessary signals to induce differentiation of B cells into memory and Ab-secreting cells. Accordingly, it is important to identify the molecular requirements for Tfh cell development and function. We previously found that IL-12 mediates the differentiation of human CD4(+) T cells to the Tfh lineage, because IL-12 induces naive human CD4(+) T cells to acquire expression of IL-21, BCL6, ICOS, and CXCR5, which typify Tfh cells. We have now examined CD4(+) T cells from patients deficient in IL-12R beta 1, TYK2, STAT1, and STAT3 to further explore the pathways involved in human Tfh cell differentiation. Although STAT1 was dispensable, mutations in IL12RB1, TYK2, or STAT3 compromised IL-12-induced expression of IL-21 by human CD4(+) T cells. Defective expression of IL-21 by STAT3-deficient CD4(+) T cells resulted in diminished B-cell helper activity in vitro. Importantly, mutations in STAT3, but not IL12RB1 or TYK2, also reduced Tfh cell generation in vivo, evidenced by decreased circulating CD4(+)CXCR5(+) T cells. These results highlight the nonredundant role of STAT3 in human Tfh cell differentiation and suggest that defective Tfh cell development and/or function contributes to the humoral defects observed in STAT3-deficient patients. (Blood. 2012;119(17):3997-4008)

Populations vary in time and in space, and temporal variation may differ from spatial variation. Yet, in the past half century, field data have confirmed both the temporal and spatial forms of Taylor's power Law, a linear relationship between log(variance) and log(mean) of population size. Recent theory predicted that competitive species interactions should reduce the slope of the temporal version of Taylor's Law. We tested whether this prediction applied to the spatial version of Taylor's Law using simple, well-controlled laboratory populations of two species of bacteria that were cultured either separately or together for 24 h in media of widely varying nutrient richness. Experimentally, the spatial form of Taylor's Law with a slope of 2 held for these simple bacterial communities, but competitive interactions between the two species did not reduce the spatial Taylor's Law slope. These results contribute to the widespread usefulness of Taylor's Law in population ecology, epidemiology and pest control.

Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies.

Developmental signaling networks are composed of dozens of components whose interactions are very difficult to quantify in an embryo. Geometric reasoning enumerates a discrete hierarchy of phenotypic models with a few composite variables whose parameters may be defined by in vivo data. Vulval development in the nematode Caenorhabditis elegans is a classic model for the integration of two signaling pathways; induction by EGF and lateral signaling through Notch. Existing data for the relative probabilities of the three possible terminal cell types in diverse genetic backgrounds as well as timed ablation of the inductive signal favor one geometric model and suffice to fit most of its parameters. The model is fully dynamic and encompasses both signaling and commitment. It then predicts the correlated cell fate probabilities for a cross between any two backgrounds/conditions. The two signaling pathways are combined additively, without interactions, and epistasis only arises from the nonlinear dynamical flow in the landscape defined by the geometric model. In this way, the model quantitatively fits genetic experiments purporting to show mutual pathway repression. The model quantifies the contributions of extrinsic vs. intrinsic sources of noise in the penetrance of mutant phenotypes in signaling hypomorphs and explains available experiments with no additional parameters. Data for anchor cell ablation fix the parameters needed to define Notch autocrine signaling.

The Mediator subunit MED1 is essential for mammary gland development and lactation, whose contribution through direct interaction with estrogen receptors (ERs) is restricted to involvement in pubertal mammary gland development and luminal cell differentiation. Here, we provide evidence that the MED24-containing submodule of Mediator functionally communicates specifically with MED1 in pubertal mammary gland development. Mammary glands from MED1/MED24 double heterozygous knockout mice showed profound retardation in ductal branching during puberty, while single haploinsufficient glands developed normally. DNA synthesis of both luminal and basal cells were impaired in double mutant mice, and the expression of ER-targeted genes encoding E2F1 and cyclin D1, which promote progression through the G(1)/S phase of the cell cycle, was attenuated. Luciferase reporter assays employing double mutant mouse embryonic fibroblasts showed selective impairment in ER functions. Various breast carcinoma cell lines expressed abundant amounts of MED1, MED24, and MED30, and attenuated expression of MED1 and MED24 in breast carcinoma cells led to attenuated DNA synthesis and growth. These results indicate functional communications between the MED1 subunit and the MED24-containing submodule that mediate estrogen receptor functions and growth of both normal mammary epithelial cells and breast carcinoma cells.

Staphylococcus haemolyticus is one of the most clinically relevant coagulase-negative staphylococci (CoNS), particularly in immunocompromised patients; however, little is known regarding its molecular epidemiology. In this work, we characterized the genetic background and the SCCmec region of 36 methicillin-resistant S. haemolyticus (MRSHae) and 10 methicillin-susceptible S. haemolyticus (MSSHae) collected from neutropenic patients in Tunisia between 2002 and 2004. The molecular characterization of MRSHae by pulsed-field gel electrophoresis (PFGE) showed that the great majority of the isolates (77.8%) belonged to only four types. SCCmec typing by polymerase chain reaction (PCR) and Southern hybridization showed that isolates belonging to each PFGE type could carry either one or two SCCmec types. SCCmec V was the most common, but mec complex C was frequently associated to ccr allotypes other than ccrC. The mec complex class C was predominant in MRSHae (47%) and ccrC was predominant among both methicillin-resistant and -susceptible isolates (31 and 50%, respectively). Interestingly, one half (50%) of the MRSHae isolates analyzed lacked the known ccr complexes (ccrand ccrC), although they carried the mecA. Conversely, all MSSHae carrying a ccrC complex were multidrug-resistant, although they lack the mecA. The results suggest that ccrC and mec complex C are frequent and may exist autonomously and independently of SCCmec type V in S. haemolyticus. Moreover, the data obtained suggest that small chromosomal rearrangements promoting the loss or structural variation of mec and ccr complex appear to occur frequently, which probably provide S. haemolyticus with a specialized means for SCCmec trapping and/or diversification.

Dendritic cells (DC) are antigen-presenting cells found in both lymphoid and nonlymphoid organs, including the brain (bDC) of Cd11c/eyfp transgenic C57BL/6 mice. Using an intranasal vesicular stomatitis virus infection, we demonstrated that EYFP+ cells amass in areas associated with viral antigens, take on an activated morphology, and project their processes into infected neuronal tissue within the olfactory bulb. These bDC separated into three EYFP+ CD45(+) CD11b(+) populations, all but one being able to functionally promote both T lymphocyte proliferation and T(H)1 cytokine production. One population was shown to emanate from the brain and a second population was peripherally derived. The third population was of indeterminate origin, being both radiosensitive and not replenished by donor bone marrow. Finally, each EYFP+ population contained CD11b(+) CD103(+) subpopulations and could be distinguished in terms of CD115, Gr-1, and Ly-6C expression, highlighting mucosal and monocyte-derived DC lineages.

To investigate the effects of visible light on the retinal development, we established an early-light-exposure model in neonatal mice. An incision was made on the right-sided eyelids of mice on postnatal day 4 (P4), and so that the right eyes were exposed to visible light (4000 lux) for 12 h per day. The population in the retinal ganglion cells (RGCs), cellular apoptosis and lumican expression were analyzed in the retinae. The loss of the RGCs was moderately alleviated and dramatically increased by early light exposure on P9 and P12, respectively. In the light-exposed retinae, the immunoactivities of caspase-9 (p39), an active isoform of caspase-9 marking the cellular apoptosis, dropped to nearly 30% of those in the control specimens on P6; thereafter the light-induced lower levels of caspase-9 (p39) remained, while those in the control specimens dropped to the values less than 50% of the light-exposed retinae. Lumican was first ectopically detected on P9, and distributed in the inner layers of the light-exposed retinae, with the most significant accumulation in the ganglion cell layer by P12. The ectopic expression of lumican was both temporarily and spatially parallel with the aggravated loss of the RGCs. In conclusion, early light exposure inflicts a profound effect on the immature retina. Our studies may have implications for premature infant care. (C) 2012 Elsevier Inc. All rights reserved.

Psoriasis is a chronic, debilitating, immune-mediated inflammatory skin disease. As IFN-gamma is involved in many cellular processes, including activation of dendritic cells (DCs), antigen processing and presentation, cell adhesion and trafficking, and cytokine and chemokine production, IFN-gamma-producing Th1 cells were proposed to be integral to the pathogenesis of psoriasis. Recently, IFN-gamma was shown to enhance IL-23 and IL-1 production by DCs and subsequently induce Th17 cells, which are important contributors to the inflammatory cascade in psoriatic lesions. To determine whether IFN-gamma indeed induces the pathways expressed in psoriatic lesions, a single intradermal injection of IFN-gamma was administered to an area of clinically normal, non-lesional (NL) skin of psoriasis patients and biopsies were collected 24 hours later. Although there were no visible changes in the skin, IFN-gamma induced many molecular and histological features characteristic of psoriatic lesions. IFN-gamma increased a number of differentially expressed genes in the skin, including many chemokines concomitant with an influx of T cells and inflammatory DCs. Furthermore, inflammatory DC products tumor necrosis factor (TNF), inducible nitric oxide synthase, IL-23, and TNF-related apoptosis-inducing ligand were present in IFN-gamma-treated skin. Thus, IFN-gamma, which is significantly elevated in NL skin compared with healthy skin, appears to be a key pathogenic cytokine that can induce many features of the inflammatory cascade of psoriasis.