Mitogen-Dependent Regulation of DUSP1 Governs ERK and p38 Signaling During Early 3T3-L1 Adipocyte Differentiation

© 2015 Wiley Periodicals, Inc. Knowledge concerning mechanisms that control proliferation and differentiation of preadipocytes is essential to our understanding of adipocyte hyperplasia and the development of obesity. Evidence has shown that temporal regulation of mitogen-activated protein kinase (MAPK) phosphorylation and dephosphorylation is critical for coupling extracellular stimuli to cellular growth and differentiation. Using differentiating 3T3-L1 preadipocytes as a model of adipocyte hyperplasia, we examined a role for dual-specificity phosphatase 1 (DUSP1) on the timely modulation of MAPK signaling during states of growth arrest, proliferation, and differentiation. Using real-time reverse transcription PCR (qRT-PCR), we report that DUSP1 is induced during early preadipocyte proliferation concomitant with ERK and p38 dephosphorylation. As deactivation of ERK and p38 is essential for the progression of adipocyte differentiation, we further showed that de novo mRNA synthesis was required for ERK and p38 dephosphorylation, suggesting a role for inducible phosphatases in regulating MAPK signaling. Pharmacological and genetic inhibition of DUSP1 markedly increased ERK and p38 phosphorylation during early adipocyte differentiation. Based on these findings, we postulated that loss of DUSP1 would block adipocyte hyperplasia. However, genetic loss of DUSP1 was not sufficient to prevent preadipocyte proliferation or differentiation, suggesting a role for other phosphatases in the regulation of adipogenesis. In support of this, qRT-PCR identified several MAPK-specific DUSPs induced during early (DUSP2, -4, -5, & -6), mid (DUSP4 & -16) and late (DUSP9) stages of adipocyte differentiation. Collectively, these data suggest an important role for DUSPs in regulating MAPK dephosphorylation, with an emphasis on DUSP1, during early adipogenesis

Impact of obesity on IL-12 family gene expression in insulin responsive tissues

Mounting evidence has established a role for chronic inflammation in the development of obesity-induced insulin resistance, as genetic ablation of pro-inflammatory cytokines and chemokines elevated in obesity improves insulin signaling in vitro and in vivo. Recent evidence further highlights interleukin (IL)-12 family cytokines as prospective inflammatory mediators linking obesity to insulin resistance. In this study, we present empirical evidence demonstrating that IL-12 family related genes are expressed and regulated in insulin-responsive tissues under conditions of obesity. First, we report that respective mRNAs for each of the known members of this cytokine family are expressed within detectable ranges in WAT, skeletal muscle, liver and heart. Second, we show that these cytokines and their cognate receptors are divergently regulated with genetic obesity in a tissue-specific manner. Third, we demonstrate that select IL-12 family cytokines are regulated in WAT in a manner that is dependent on the developmental stage of obesity as well as the inflammatory progression associated with obesity. Fourth, we report that respective mRNAs for IL-12 cytokines and receptors are also expressed and divergently regulated in cultured adipocytes under conditions of inflammatory stress. To our knowledge, this report is the first study to systemically evaluated mRNA expression of all IL-12 family cytokines and receptors in any tissue under conditions of obesity highlighting select family members as potential mediators linking excess nutrient intake to metabolic diseases such as insulin resistance, diabetes and heart disease. © 2012 Elsevier B.V

Role for dual-specificity phosphatases on mitogen-activated protein kinase signaling in adipocytes

Obesity and diabetes are major public health concerns that contribute to cardiovascular disease, hypertension, and stroke. It is now widely accepted that chronic inflammation is an important element of pathogenic mechanisms linking obesity to diabetes. Moreover, clinical and experimental evidence has established the mitogen-activated protein kinase (MAPK) signaling pathway as a pivotal mediator during inflammatory stress in coupling obesity to insulin resistance (IR). While numerous studies have examined the upstream kinase activation of MAPKs, few have examined mechanisms that dephosphorylate, and thus, deactivate these pathways, potentially affording protection against adipose tissue (AT) inflammation and obesity-induced IR. Data presented in this dissertation demonstrate that several MAPK-specific dual-specificity phosphatases (DUSPs) are induced in AT under conditions of genetic and diet-induced obesity that is associated with increased inflammation and IR. While AT is composed of multiple cell types, evidence suggests an essential role for preadipocytes (PAs) and adipocytes (ADs) in the development of AT inflammation and IR. Therefore, we further report phenotypic differences in DUSP expression where four of the ten MAPK-specific DUSPs are more abundant in PAs compared to ADs while two of the ten DUSPs are more abundant in ADs compared to PAs, suggesting a regulatory role for these phosphatases that is cell type specific. Moreover, phenotypic differences were observed regarding MAPK signaling and DUSP expression in PAs and ADs exposed to TNFalpha-mediated inflammatory stress, where ERK, JNK, and p38 phosphorylation was markedly elevated and transient in PAs while ERK and JNK phosphorylation was prolonged in ADs concomitant with the phenotypic differences in inducible DUSPs. As induction of DUSPs in PAs kinetically mirrored MAPK dephosphorylation, we further show that de novo mRNA synthesis was essential for MAPK dephosphorylation, suggesting a role for inducible DUSPs in the modulation of MAPK signaling. Based on these data, we present empirical evidence that DUSP knockdown markedly increased the magnitude and duration of ERK, JNK, and p38 phosphorylation in response to inflammatory stress, subsequently elevating MAPK-dependent pro-inflammatory cytokine and chemokine gene expression. Collectively, these findings demonstrate an essential role for DUSPs in the timely modulation of MAPK signaling, highlighting prospective therapeutic targets linking obesity with metabolic inflammatory diseases

Promiscuous actions of small molecule inhibitors of the protein kinase D-class IIa HDAC axis in striated muscle

AbstractPKD-mediated phosphorylation of class IIa HDACs frees the MEF2 transcription factor to activate genes that govern muscle differentiation and growth. Studies of the regulation and function of this signaling axis have involved MC1568 and Gö-6976, which are small molecule inhibitors of class IIa HDAC and PKD catalytic activity, respectively. We describe unanticipated effects of these compounds. MC1568 failed to inhibit class IIa HDAC catalytic activity in vitro, and exerted divergent effects on skeletal muscle differentiation compared to a bona fide inhibitor of these HDACs. In cardiomyocytes, Gö-6976 triggered calcium signaling and activated stress-inducible kinases. Based on these findings, caution is warranted when employing MC1568 and Gö-6976 as pharmacological tool compounds to assess functions of class IIa HDACs and PKD

When the relatively poor prosper: the Underdog Effect on charitable donations

In fundraising, it is common for the donor to see how much a charity has received so far. What is the impact of this information on a) how much people choose to donate and b) which charity they choose to donate to? Conditional cooperation suggests that people will donate to the charity that has received the most prior support, while the Underdog Effect suggests increased donations to the charity with the least support. Across 2 laboratory experiments, an online study (combined N = 494) and a qualitative survey (N = 60), a consistent preference to donate to the charity with the least prior support was observed. Thus, the Underdog Effect was supported. We suggest people will show a preference for the underdog if there are two or more charities to donate to, one of the charities is at a disadvantage and people have little pre-existing loyalty to either charity

Duration of hospital participation in a nationwide stroke registry is associated with improved quality of care

BACKGROUND: There are several proven therapies for patients with ischemic stroke or transient ischemic attack (TIA), including prophylaxis of deep venous thrombosis (DVT) and initiation of antithrombotic medications within 48 h and at discharge. Stroke registries have been promoted as a means of increasing use of such interventions, which are currently underutilized. METHODS: From 1999 through 2003, 86 U.S. hospitals participated in Ethos, a voluntary web-based acute stroke treatment registry. Detailed data were collected on all patients admitted with a diagnosis of TIA or ischemic stroke. Rates of optimal treatment (defined as either receipt or a valid contraindication) were examined within each hospital as a function of its length of time in registry. Generalized estimating equations were used to adjust for patient and hospital characteristics. RESULTS: A total of 16,301 patients were discharged with a diagnosis of stroke or TIA from 50 hospitals that participated for more than 1 year. Rates of optimal treatment during the first 3 months of participation were as follows: 92.5% for antithrombotic medication within 48 h, 84.6% for antithrombotic medications at discharge, and 77.1% for DVT prophylaxis. Rates for all treatments improved with duration of participation in the registry (p < 0.05), with the most dramatic improvements in the first year. CONCLUSION: In a large cohort of patients with stroke or TIA, three targeted quality-improvement measures improved among hospitals participating in a disease-specific registry. Although the changes could be attributed to interventions other than the registry, these findings demonstrate the potential for hospital-level interventions to improve care for patients with stroke and TIA

Type Ia Supernova Rate Measurements To Redshift 2.5 From CANDELS: Searching For Prompt Explosions In The Early Universe

dThe Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of -0.25 deg2 with -900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z 2.5. We classify -24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z =- 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only -3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation ( 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions-though further analysis and larger samples will be needed to examine that suggestion. Key words: infrared: general - supernovae:Astronom

The Influence of Physiological Status on age Prediction of Anopheles Arabiensis Using Near Infra-red spectroscopy

Determining the age of malaria vectors is essential for evaluating the impact of interventions that reduce the survival of wild mosquito populations and for estimating changes in vectorial capacity. Near infra-red spectroscopy (NIRS) is a simple and non-destructive method that has been used to determine the age and species of Anopheles gambiae s.l. by analyzing differences in absorption spectra. The spectra are affected by biochemical changes that occur during the life of a mosquito and could be influenced by senescence and also the life history of the mosquito, i.e., mating, blood feeding and egg-laying events. To better understand these changes, we evaluated the influence of mosquito physiological status on NIR energy absorption spectra. Mosquitoes were kept in individual cups to permit record keeping of each individual insect’s life history. Mosquitoes of the same chronological age, but at different physiological stages, were scanned and compared using cross-validations. We observed a slight trend within some physiological stages that suggest older insects tend to be predicted as being physiologically more mature. It was advantageous to include mosquitoes of different chronological ages and physiological stages in calibrations, as it increases the robustness of the model resulting in better age predictions. Progression through different physiological statuses of An. arabiensis influences the chronological age prediction by the NIRS. Entomologists that wish to use NIR technology to predict the age of field-caught An. gambiae s.l from their study area should use a calibration developed from their field strain using mosquitoes of diverse chronological ages and physiological stages to increase the robustness and accuracy of the predictions.\u

The Birth of an Ultra-Luminous X-ray Source in M83

A previously undetected X-ray source (L_X<10**36 erg/s) in the strongly star-forming galaxy M83 entered an ultraluminous state between August 2009 and December 2010. It was first seen with Chandra on 23 December 2010 at L_X ~ 4 10**39 ergs/s, and has remained ultraluminous through our most recent observations in December 2011, with typical flux variation of a factor of two. The spectrum is well fitted by a combination of absorbed power-law and disk black-body models. While the relative contributions of the models varies with time, we have seen no evidence for a canonical state transition. The luminosity and spectral properties are consistent with accretion powered by a black hole with M_BH ~ 40-100 solar masses. In July 2011 we found a luminous, blue optical counterpart which had not been seen in deep HST observations obtained in August 2009. These optical observations suggest that the donor star is a low-mass star undergoing Roche-lobe overflow, and that the blue optical emission seen during the outburst is coming from an irradiated accretion disk. This source shows that ultraluminous X-ray sources (ULXs) with low-mass companions are an important component of the ULX population in star-forming galaxies, and provides further evidence that the blue optical counterparts of some ULXs need not indicate a young, high-mass companion, but rather that they may indicate X-ray reprocessing.Comment: 40 pages, 7 figures, accepted for publication in Ap