Commitment to splice site pairing coincides with A complex formation

Differential recognition of exons by the spliceosome regulates gene expression and exponentially increases the complexity of metazoan proteomes. After definition of the exons, the spliceosome is activated by a series of sequential structural rearrangements. Formation of the first ATP-independent spliceosomal complex commits the pre-mRNA to the general splicing pathway. However, the time at which a commitment to a specific splice site choice and pairing is made is unknown. Here, we demonstrate that alternative splicing patterns are irreversibly chosen at a kinetic step different from the ATP-independent commitment to splicing. Splice sites become committed at the first ATP-dependent spliceosomal complex when rearrangements lock U2 snRNP onto the pre-mRNA. Thus, commitment to the splicing pathway and commitment to splice site pairing are separate steps during spliceosomal assembly, and ATP hydrolysis drives the irreversible juxtaposition of exons within the spliceosome.     

Investigation of interleukin 1β-mediated regulation of NF-κB activation in colonic cells reveals divergence between PKB and PDK-transduced events

Recent work has highlighted a role for PDK1 in adaptive immunity, however its contribution to innate immunity has not been addressed. We have investigated the role of PKB and PDK1 in IL-1β-induced NF-κB activation. Over-expression of either in HCT 116 and HEK 293T cells, effected a reproducible NF-κB activation. This was validated in a one-hybrid assay utilizing Gal4-RelA and Gal4-luciferase assay. N-tosyl phenylalanyl chloromethyl ketone (TPCK), wortmannin and Ly294002 inhibited IL-1β-induced NF-κB activation in both systems indicating involvement of the PI3K axis in this response. p65 (Rel A) Ser536 phosphorylation was not affected by the PI3K inhibitors but was dose-dependently attenuated by TPCK. Evaluation of IKK-associated activity using GST-p65 substrate phosphorylation in immune complex assays, revealed that whilst TPCK attenuated this, neither of the PI3K inhibitors had any effect. Furthermore whilst TPCK inhibited IL-1β-induced p65 DNA binding, this was not apparent with either of wortmannin or Ly294002. Similarly, over-expression of PDK1 but not PKB resulted in promotion of p65 DNA binding. Using a p65-S536A reporter construct, we found inhibition of only PDK1 over-expression-induced, but not PKB over-expression-induced NF-κB activation. This was supported using biochemical analysis in which immunoprecipitated IKKγ from IL-1β-activated cells was unable to phosphorylate a p65-S536A substrate, confirming this as the dominant IKK-dependent site. In further support of a dissociated response, we observed an attenuation of the Ser177/181 IKK phosphorylation by TPCK but not in response to PI3K inhibition. Our data reveals for the first time that PDK1 and PKB may differentially activate NF-κB, and that TPCK may subserve a useful anti-inflammatory function by inhibiting IKKβ. This study was supported in part by grants from the Crohn’s and Colitis Foundation of Canada (BS) and the Canadian Society for Intestinal Research (BS) and funds from the Geraldine Dow Foundation to B. S. K.P. was supported by a Michael Smith Graduate Studentship. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked, “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.     

Neural bases of syntax–semantics interface processing

The binding problem—question of how information between the modules of the linguistic system is integrated during language processing—is as yet unresolved. The remarkable speed of language processing and comprehension (Pulvermüller et al. 2009) suggests that at least coarse semantic information (e.g. noun animacy) and syntactically-relevant information (e.g. verbal template) are integrated rapidly to allow for coarse comprehension. This EEG study investigated syntax–semantics interface processing during word-by-word sentence reading. As alpha-band neural activity serves as an inhibition mechanism for local networks, we used topographical distribution of alpha power to help identify the timecourse of the binding process. We manipulated the syntactic parameter of verbal event structure, and semantic parameter of noun animacy in reduced relative clauses (RRCs, e.g. “The witness/mansion seized/protected by the agent was in danger”), to investigate the neural bases of interaction between syntactic and semantic networks during sentence processing. The word-by-word stimulus presentation method in the present experiment required manipulation of both syntactic structure and semantic features in the working memory. The results demonstrated a gradient distribution of early components (biphasic posterior P1–N2 and anterior N1–P2) over function words “by” and “the”, and the verb, corresponding to facilitation or conflict resulting from the syntactic (telicity) and semantic (animacy) cues in the preceding portion of the sentence. This was followed by assimilation of power distribution in the α band at the second noun. The flattened distribution of α power during the mental manipulation with high demand on working memory—thematic role re-assignment—demonstrates a state of α equilibrium with strong functional coupling between posterior and anterior regions. These results demonstrate that the processing of semantic and syntactic features during sentence comprehension proceeds in highly integrated fashion using gating of attentional resources to facilitate rapid comprehension, with attentional suppression of global alpha power to facilitate interaction of local networks.     

17‐α estradiol ameliorates age‐associated sarcopenia and improves late‐life physical function in male mice but not in females or castrated males

Pharmacological treatments can extend mouse lifespan, but lifespan effects often differ between sexes. 17‐α estradiol (17aE2), a less feminizing structural isomer of 17‐β estradiol, produces lifespan extension only in male mice, suggesting a sexually dimorphic mechanism of lifespan regulation. We tested whether these anti‐aging effects extend to anatomical and functional aging—important in late‐life health—and whether gonadally derived hormones control aging responses to 17aE2 in either sex. While 17aE2 started at 4 months of age diminishes body weight in both sexes during adulthood, in late‐life 17aE2‐treated mice better maintain body weight. In 17aE2‐treated male mice, the higher body weight is associated with heavier skeletal muscles and larger muscle fibers compared with untreated mice during aging, while treated females have heavier subcutaneous fat. Maintenance of skeletal muscle in male mice is associated with improved grip strength and rotarod capacity at 25 months, in addition to higher levels of most amino acids in quadriceps muscle. We further show that sex‐specific responses to 17aE2—metabolomic, structural, and functional—are regulated by gonadal hormones in male mice. Castrated males have heavier quadriceps than intact males at 25 months, but do not respond to 17aE2, suggesting 17aE2 promotes an anti‐aging skeletal muscle phenotype similar to castration. Finally, 17aE2 treatment benefits can be recapitulated in mice when treatment is started at 16 months, suggesting that 17aE2 may be able to improve aspects of late‐life function even when started after middle age.     

Ectopic expression of the Stabilin2 gene triggered by an intracisternal A particle (IAP) element in DBA/2J strain of mice

Mammalian Genome - Stabilin2 (Stab2) encodes a large transmembrane protein which is predominantly expressed in the liver sinusoidal endothelial cells (LSECs) and functions as a scavenger receptor...     

A Systematic Review Exploring the Social Cognitive Theory of Self-Regulation as a Framework for Chronic Health Condition Interventions

Background

Theory is often recommended as a framework for guiding hypothesized mechanisms of treatment effect. However, there is limited guidance about how to use theory in intervention development.

Methods

We conducted a systematic review to provide an exemplar review evaluating the extent to which use of theory is identified and incorporated within existing interventions. We searched electronic databases PubMed, PsycINFO, CENTRAL, and EMBASE from inception to May 2014. We searched clinicaltrials.gov for registered protocols, reference lists of relevant systematic reviews and included studies, and conducted a citation search in Web of Science. We included peer-reviewed publications of interventions that referenced the social cognitive theory of self-regulation as a framework for interventions to manage chronic health conditions. Two reviewers independently assessed articles for eligibility. We contacted all authors of included studies for information detailing intervention content. We describe how often theory mechanisms were addressed by interventions, and report intervention characteristics used to address theory.

Results

Of 202 articles that reported using the social cognitive theory of self-regulation, 52% failed to incorporate self-monitoring, a main theory component, and were therefore excluded. We included 35 interventions that adequately used the theory framework. Intervention characteristics were often poorly reported in peer-reviewed publications, 21 of 35 interventions incorporated characteristics that addressed each of the main theory components. Each intervention addressed, on average, six of eight self-monitoring mechanisms, two of five self-judgement mechanisms, and one of three self-evaluation mechanisms. The self-monitoring mechanisms ‘Feedback’ and ‘Consistency’ were addressed by all interventions, whereas the self-evaluation mechanisms ‘Self-incentives’ and ‘External rewards’ were addressed by six and four interventions, respectively. The present review establishes that systematic review is a feasible method of identifying use of theory as a conceptual framework for existing interventions. We identified the social cognitive theory of self-regulation as a feasible framework to guide intervention development for chronic health conditions.     

A Krüppel-like factor is required for development and regeneration of germline and yolk cells from somatic stem cells in planarians

Sexually reproducing animals segregate their germline from their soma. In addition to gamete-producing gonads, planarian and parasitic flatworm reproduction relies on yolk cell–generating accessory reproductive organs (vitellaria) supporting development of yolkless oocytes. Despite the importance of vitellaria for flatworm reproduction (and parasite transmission), little is known about this unique evolutionary innovation. Here, we examine reproductive system development in the planarian Schmidtea mediterranea, in which pluripotent stem cells generate both somatic and germ cell lineages. We show that a homolog of the pluripotency factor Klf4 is expressed in primordial germ cells (PGCs), presumptive germline stem cells (GSCs), and yolk cell progenitors. Knockdown of this klf4-like (klf4l) gene results in animals that fail to specify or maintain germ cells; surprisingly, they also fail to maintain yolk cells. We find that yolk cells display germ cell–like attributes and that vitellaria are structurally analogous to gonads. In addition to identifying a new proliferative cell population in planarians (yolk cell progenitors) and defining its niche, our work provides evidence supporting the hypothesis that flatworm germ cells and yolk cells share a common evolutionary origin.