Paradoxical effects of a stress signal on pro- and anti-apoptotic machinery in HTLV-1 tax expressing cells

Adult T-cell leukemia (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) are associated with Human T-cell lymphotropic virus type 1 (HTLV-1) infection. The viral transactivator, Tax is able to mediate the cell cycle progression by targeting key regulators of the cell cycle such as p21/waf1, p16/ink4a, p53, cyclins D1-3/cdk complexes, and the mitotic spindle checkpoint MAD apparatus, thereby deregulating cellular DNA damage and checkpoint control. Genome expression profiling of infected cells exemplified by the development of DNA microarrays represents a major advance in genome-wide functional analysis. Utilizing cDNA microarray analysis, we have observed an apparent opposing and paradoxical regulatory network of host cell gene expression upon the introduction of DNA damage stress signal. We find the apparent induction of cell cycle inhibitors, and pro- as well as anti-apoptotic gene expression is directly linked to whether cells are at either G1, S, or G2/M phases of the cell cycle. Specifically, a G1/S block is induced by p21/waf1 and p16/ink4a, while pro-apoptotic expression at S, and G2/M is associated with caspase activation, and anti-apoptotic gene expression is associated with up regulation of Bcl-2 family member, namely bfl-1 gene. Therefore, the microarray results indicating expression of both pro- and anti-apoptotic genes could easily be explained by the particular stage of the cell cycle. Mechanism and the functional outcome of induction for both pathways are discussed.     

Three-dimensional adipose tissue model using low shear bioreactors

Summary Presented here are techniques developed to culture and analyze three-dimensional (3-D) adipose-like tissues as a means to bridge the gap between current liminations in culturing preadipocytes (PAs) and that of providing clinically relevant volumes of adipose tissue useful for soft tissue engineering stratgies in reconstructive surgery. Pilot studies were performed to determine techniques to visualize and analyze 3-D PA-like tissues as well as to develop successful strategies to culture 3T3-L1 cells in a high aspect ratio vessel rotating-wall bioreactor both with and without microcarriers. Next, a series of cultures were accessed to verify these techniques as well as to compare the culture of the cells with and without microcarriers. Finally, a perfused rotating-wall bioreactor was used to further investigate the nature of the aggregates or tissues being generated. The aggregates that formed in the perfused system were analyzed via histology and in vivo animal studies. PA-like tissues as large as 4–5 mm in diameter without microcarriers that were capable of lipid-loading and composed of viable cells were achieved. We have successfully demonstrated that large tissue aggregates can be grown in bioreactor culture systems.     

A comparison of phenotypic plasticity in the native dandelion Taraxacum ceratophorum and its invasive congener T. officinale

We compared plastic responses to variation in the light environment for sympatric populations of native and exotic dandelion species, Taraxacum ceratophorum and Taraxacum officinale. Plasticity in leaf size, inflorescence height, reproductive phenology and dispersal-related traits were measured under experimentally altered light quality (red : far-red light ratio, R : FR) and light intensity (photosynthetically active radiation, PAR). To test whether differences in means and reaction norms of dispersal-related traits between species affected colonization potential, we created seed-dispersal models based on seed-fall rate and release height. Differences in plasticity between species were not systematic, but varied in direction and magnitude among traits. Taraxacum officinale produced larger leaves that exhibited greater plasticity in size under variable light intensity than T. ceratophorum. Plasticity in scape length at flowering occurred in relation to R : FR ratio in both species, but tended to be greater in T. ceratophorum. Seed-bearing scapes of T. officinale were taller and more canalized in height across light regimes than scapes of T. ceratophorum. Seeds of T. officinale were smaller than seeds of T. ceratophorum. Models predict greater dispersal in T. officinale within open and vegetated habitats. In contrast to the idea that plasticity promotes invasiveness, results suggest that the lack of plasticity in dispersal-related traits enhances the colonization potential of T. officinale.     

Bovine T cell receptor gamma variable and constant genes: combinatorial usage by circulating γδ T cells

Studies here describe expression and sequence of several new bovine T cell receptor gamma (TRG) genes to yield a total of 11 TRG variable (TRGV) genes (in eight subgroups) and six TRG constant (TRGC) genes. Publicly available genomic sequences were annotated to show their placement. Homologous TRG genes in cattle and sheep were assigned, using four accepted criteria. New genes described here include the bovine TRGC6, TRGV2, and TRGV4, homologues of ovine TRGC4, TRGV2, and TRGV4, respectively. The bovine Vγ7 and BTGV1 clones (previously TRGV4 and TRGV2, respectively) were reassigned to new subgroups TRGV7 and TRGV8, respectively, with approval by the IMGT Nomenclature Committee. Three TRGV subgroups (TRGV5, TRGV6, and TRGV8) were further designated as TRGV5-1 and TRGV5-2, TRGV6-1 and TRGV6-2, and TRGV8-1 and TRGV8-2 because each subgroup is comprised of two mapped genes. The complete sequence of bovine TRGC5 is also reported, for which a limited number of nucleotides was previously available, and shown to be most closely related to ovine TRGC5. Analysis of circulating γδ T cells revealed that rearrangement of TRGV genes with TRGC genes is largely dictated by their proximity within one of the six genomic V-J-C cassettes, with all TRG genes expressed by bovine peripheral blood γδ T cells. Cattle are useful models for γδ T cell biology because they have γδ T cells that respond to isopentenylpyrophosphate (IPP) antigens, while mice do not, and some bovine TRGV genes cluster closely with human genes.Nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank database under the accession numbers DQ179591, DQ179592, DQ179593, and DQ179594.     

Interaction between active Pak1 and Raf-1 is necessary for phosphorylation and activation of Raf-1.

Activation of Raf-1 is a complex process in which phosphorylation of Ser(338)-Tyr(341) is a critical step. Previous studies have shown that Pak1/2 is implicated in both Ras-dependent and -independent activation of Raf-1 by phosphorylating Raf Ser(338). The present study explores the structural basis of Raf-1 phosphorylation by Pak1. We found that Pak directly associates with Raf-1 under both physiological and overexpressed conditions. The association is greatly stimulated by 4beta-12-O-tetradecanoylphorbol-13-acetate and nocodazole and by expression of the active mutants of Rac and Ras. The active forms of Pak generated by mutation of Thr(423) to Glu or truncation of the amino-terminal moiety exhibit a greater binding to Raf than the wild type, whereas the kinase-dead mutant Pak barely binds Raf. The extent of binding to Raf-1 is correlated with the ability of Pak to phosphorylate Raf and induce mitogen-activated protein kinase activation. Furthermore, the Raf-1 binding site is defined to the carboxyl terminus of the Pak catalytic domain. In addition, our results suggest that the amino-terminal regulatory region of Raf inhibits the interaction. Taken together, the results indicate that the interaction depends on the active conformations of Pak and Raf. They also argue that Pak1 is a physiological candidate for phosphorylation of Raf Ser(338) during the course of Raf activation.     

Alcohol Use among Adolescent Youth: The Role of Friendship Networks and Family Factors in Multiple School Studies

To explore the co-evolution of friendship tie choice and alcohol use behavior among 1,284 adolescents from 12 small schools and 976 adolescents from one big school sampled in the National Longitudinal Study of Adolescent to Adult Health (AddHealth), we apply a Stochastic Actor-Based (SAB) approach implemented in the R-based Simulation Investigation for Empirical Network Analysis (RSiena) package. Our results indicate the salience of both peer selection and peer influence effects for friendship tie choice and adolescent drinking behavior. Concurrently, the main effect models indicate that parental monitoring and the parental home drinking environment affected adolescent alcohol use in the small school sample, and that parental home drinking environment affected adolescent drinking in the large school sample. In the small school sample, we detect an interaction between the parental home drinking environment and choosing friends that drink as they multiplicatively affect friendship tie choice. Our findings suggest that future research should investigate the synergistic effects of both peer and parental influences for adolescent friendship tie choices and drinking behavior. And given the tendency of adolescents to form ties with their friends'' friends, and the evidence of local hierarchy in these networks, popular youth who do not drink may be uniquely positioned and uniquely salient as the highest rank of the hierarchy to cause anti-drinking peer influences to diffuse down the social hierarchy to less popular youth. As such, future interventions should harness prosocial peer influences simultaneously with strategies to increase parental support and monitoring among parents to promote affiliation with prosocial peers.     

Women Are Seen More than Heard in Online Newspapers

Feminist news media researchers have long contended that masculine news values shape journalists’ quotidian decisions about what is newsworthy. As a result, it is argued, topics and issues traditionally regarded as primarily of interest and relevance to women are routinely marginalised in the news, while men’s views and voices are given privileged space. When women do show up in the news, it is often as “eye candy,” thus reinforcing women’s value as sources of visual pleasure rather than residing in the content of their views. To date, evidence to support such claims has tended to be based on small-scale, manual analyses of news content. In this article, we report on findings from our large-scale, data-driven study of gender representation in online English language news media. We analysed both words and images so as to give a broader picture of how gender is represented in online news. The corpus of news content examined consists of 2,353,652 articles collected over a period of six months from more than 950 different news outlets. From this initial dataset, we extracted 2,171,239 references to named persons and 1,376,824 images resolving the gender of names and faces using automated computational methods. We found that males were represented more often than females in both images and text, but in proportions that changed across topics, news outlets and mode. Moreover, the proportion of females was consistently higher in images than in text, for virtually all topics and news outlets; women were more likely to be represented visually than they were mentioned as a news actor or source. Our large-scale, data-driven analysis offers important empirical evidence of macroscopic patterns in news content concerning the way men and women are represented.     

Dual Targeting of MEK and PI3K Pathways Attenuates Established and Progressive Pulmonary Fibrosis

Pulmonary fibrosis is often triggered by an epithelial injury resulting in the formation of fibrotic lesions in the lung, which progress to impair gas exchange and ultimately cause death. Recent clinical trials using drugs that target either inflammation or a specific molecule have failed, suggesting that multiple pathways and cellular processes need to be attenuated for effective reversal of established and progressive fibrosis. Although activation of MAPK and PI3K pathways have been detected in human fibrotic lung samples, the therapeutic benefits of in vivo modulation of the MAPK and PI3K pathways in combination are unknown. Overexpression of TGFα in the lung epithelium of transgenic mice results in the formation of fibrotic lesions similar to those found in human pulmonary fibrosis, and previous work from our group shows that inhibitors of either the MAPK or PI3K pathway can alter the progression of fibrosis. In this study, we sought to determine whether simultaneous inhibition of the MAPK and PI3K signaling pathways is a more effective therapeutic strategy for established and progressive pulmonary fibrosis. Our results showed that inhibiting both pathways had additive effects compared to inhibiting either pathway alone in reducing fibrotic burden, including reducing lung weight, pleural thickness, and total collagen in the lungs of TGFα mice. This study demonstrates that inhibiting MEK and PI3K in combination abolishes proliferative changes associated with fibrosis and myfibroblast accumulation and thus may serve as a therapeutic option in the treatment of human fibrotic lung disease where these pathways play a role.