Localization of Giα proteins in the centrosomes and at the midbody: implication for their role in cell division

At the plasma membrane, heterotrimeric G proteins act as molecular switches to relay signals from G protein–coupled receptors; however, Gα subunits also have receptor-independent functions at intracellular sites. Regulator of G protein signaling (RGS) 14, which enhances the intrinsic GTPase activity of Giα proteins, localizes in centrosomes, which suggests the coexpression of Giα. We show expression of Giα1, Giα2, and Giα3 in the centrosomes and at the midbody. Fluorescence resonance energy transfer analysis confirms a direct interaction between RGS14 and Giα1 in centrosomes. Expression of GTPase-deficient Giα1 results in defective cytokinesis, whereas that of wild-type or GTPase-deficient Giα3 causes prolonged mitosis. Cells treated with pertussis toxin, with reduced expression of Giα1, Giα2, and Giα3 or with decreased expression of RGS14 also exhibit cytokinesis defects. These results suggest that Giα proteins and their regulators at these sites may play essential roles during mammalian cell division

Inhibitory G-protein Modulation of CNS Excitability.

Epilepsy represents a major health burden upon society. Approximately 30% of patients still remain symptomatic despite therapy. While not a current medicinal target for epilepsy, the family of inhibitory G-proteins appears to play an important role in this disease, as blocking their function in animal models increases both acute seizure susceptibility and the rate of spontaneous seizure development in kindling, a research model with parallels to epilepsy. The most abundant inhibitory G-protein in the brain is Go, composing roughly 2% of membrane bound protein. To further clarify the role of Go in epilepsy a Gnao1 gain-of-function mouse line (RGSi/G184S) was employed. Hippocampal slices from Gnao1 +/RGSi mice show enhanced epinephrine-mediated suppression of epileptiform burst firing of neurons demonstrating that Gnao1 +/RGSi mice have enhanced Go signaling. The aforementioned work lead me to hypothesize that C57BL/6J Gnao1 +/RGSi mice would be protected from kindling. In fact, the mice experience premature death, enhanced kindling susceptibility and over a ten-fold increase in frequency of electrical disturbances within their brain. C57BL/6J Gnao1 +/RGSi mice also display an unexpected loss of inhibitory signaling within specific brain regions. Interestingly, the mutation is only lethal on the C57BL/6J background. The progenitor 129S1/SvImJ strain demonstrates no change in seizure susceptibility or viability. A genome-wide SNP analysis identified a region on chromosome 17 between 41-70 megabases that affords protection from spontaneous lethality. Further, this region also reduces the rate at which mice develop seizures in response to kindling. This region was further refined to a subregion from 41-51 megabases which was found sufficient to afford protection to kindling. Consequently, I have identified two genomic loci, Gnao1 and the Chr17 modifier which I term Mogs1 (modifier of G-protein seizures), that should be examined as candidates in human epilepsy. Additionally, future use of this model should prove informative in assessing the utility of novel therapeutics to prevent the progression of epilepsy.PHDPharmacologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107120/1/jkehrl_1.pd

Glacimarine Sedimentation Processes at Kronebreen and Kongsvegen, Svalbard

Tidewater glaciers deposit sediment at their terminus, thereby reducing the relative water depth. Reduced water depth can lead to increased glacier stability through decreased rates of iceberg calving, glacier thinning and submarine melting. Here we investigate sedimentation processes at the termini of Kronebreen and Kongsvegen, Svalbard. We mapped the fjord floor bathymetry in August 2009 and calculate sedimentation rates based on our bathymetry and that from a similar study in 2005. A grounding-line fan is developing near the current position of the subglacial stream. An older, abandoned grounding-line fan that likely formed between ~1987 and 2001 is degrading near the middle of the ice front. Our findings indicate that sediment gravity flows reduce the height of the sediment mound forming at the glacier terminus. The future impact of glacimarine sedimentation processes on glacier stability will depend on the net balance between the observed gravity flows and sediment deposition

Review Article Autophagy in Macrophages: Impacting Inflammation and Bacterial Infection

Macrophages are on the front line of host defense. They possess an array of germline-encoded pattern recognition receptors/sensors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs) and which activate downstream effectors/pathways to help mediate innate immune responses and host defense. Innate immune responses include the rapid induction of transcriptional networks that trigger the production of cytokines, chemokines, and cytotoxic molecules; the mobilization of cells including neutrophils and other leukocytes; the engulfment of pathogens by phagocytosis and their delivery to lysosome for degradation; and the induction of autophagy. Autophagy is a catabolic process that normally maintains cellular homeostasis in a lysosome-dependent manner, but it also functions as a cytoprotective response that intersects with a variety of general stress-response pathways. This review focuses on the intimately linked molecular mechanisms that help govern the autophagic pathway and macrophage innate immune responses

Safety and effectiveness of acetadote for acetaminophen toxicity.

BACKGROUND: Acetaminophen (APAP) toxicity is commonly encountered in the Emergency Department. Until 2004, treatment consisted of either oral N-acetylcysteine (NAC) or filtered oral NAC administered intravenously (i.v.). Intravenous acetylcysteine (Acetadote) is a new Food and Drug Administration-approved i.v. formulation of acetylcysteine manufactured by Cumberland Pharmaceuticals in Nashville, Tennessee. Little post-marketing data exists on the effectiveness and safety of i.v. acetylcysteine. OBJECTIVES: We evaluated the clinical presentations and outcomes of patients treated with i.v. acetylcysteine for APAP toxicity. METHODS: We performed a retrospective chart review of patients treated with i.v. acetylcysteine for APAP ingestion. The primary outcome measures were: adverse reactions to and effectiveness of i.v. acetylcysteine, as defined by elevation of transaminases, liver failure, renal failure, death, and hospital length of stay (LOS). Data collected included: comorbidities, allergies, intentionality, timing and dosing of i.v. acetylcysteine, hospital LOS, transaminases \u3e 1000 IU/L, development of liver failure requiring transplant, development of renal failure requiring hemodialysis, death, and anaphylactoid reactions. RESULTS: Sixty-four patients met our study criteria. Overall, 16 (25%) patients developed transaminases \u3e 1000 IU/L, 4 (6%) of them died and 2 (3%) received liver transplants. Of the 15 patients (23%) treated within 8 h, none died or developed liver or renal failure, and only 1 developed transient transaminase elevation \u3e 1000 IU/L. In the patients treated outside of 8 h, the median LOS was 3 days, whereas the group treated within 8 h had a median LOS of only 1 day. Six (9%) patients developed anaphylactoid reactions, 2 of whom received the i.v. acetylcysteine bolus over 15 min. Five of these patients were treated pharmacologically and completed treatment, and one had treatment discontinued for undocumented reasons. CONCLUSION: Intravenous acetylcysteine seemed to be a safe and effective formulation of N-acetylcysteine

A regulator of G Protein signaling, RGS3, inhibits gonadotropin-releasing hormone (GnRH)-stimulated luteinizing hormone (LH) secretion

BACKGROUND: Luteinizing hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing hormone and by alterations in gonadotropin releasing hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Gα proteins with effectors such as phospholipase Cβ. Previously, we reported that gonadotropin releasing hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing hormone-induced luteinizing hormone secretion from cultured rat pituitary cells. RESULTS: A truncated version of RGS3 (RGS3T = RGS3 314–519) inhibited gonadotropin releasing hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more (35)S-Gqα than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing hormone-stimulated luteinizing hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing hormone stimulated (3)H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqα protein. CONCLUSIONS: RGS3 inhibits gonadotropin releasing hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqα protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing hormone-stimulated inositol trisphosphate production

Volume Loss from Lower Peyto Glacier, Alberta, Canada, between 1966 and 2010

Mass loss from mountain glaciers contributes to sea-level rise and reduces freshwater availability in glacier-fed river basins, with negative effects on hydropower generation, agriculture and the health of aquatic ecosystems. In this study, we determine the volume of lower Peyto Glacier, Alberta, Canada, from ground-penetrating radar surveys in 2008–10, and compare our volume estimate with previous estimates from 1966 and 1984. The long-term record of mass-balance estimates on Peyto Glacier highlights Peyto’s importance as an ‘index’ glacier for the region. We calculate a mean volume of (3.39 0.30) 10m for the glacier snout for the period 2008–10. Glacier volume decreased linearly from 1966 to 2010. If this trend persists, the glacier snout will disappear by 2019 and Peyto Glacier will have retreated by 1 km. Our results agree with modelling studies, which suggest that Peyto Glacier and other nearby glaciers along the eastern slopes of the Canadian Rocky Mountains will likely lose 80–90% of their present-day volume by 2100

Rgs1 and Gnai2 Regulate the Entrance of B Lymphocytes into Lymph Nodes and B Cell Motility within Lymph Node Follicles

SummarySignaling by G protein-coupled receptors coupled to Gαi assists in triggering lymphocyte movement into and out of lymph nodes. Here, we show that modulating the signaling output from these receptors dramatically alters B cell trafficking. Intravital microscopy of adoptively transferred B cells from wild-type and Rgs1−/− mice revealed that Rgs1−/− B cells stick better to lymph node high endothelial venules, home better to lymph nodes, and move more rapidly within lymph node follicles than do wild-type B cells. In contrast, B cells from Gnai2−/− mice enter lymph nodes poorly and move more slowly than do wild-type B cells. The Gnai2−/− mice often lack multiple peripheral lymph nodes, and their B cells respond poorly to chemokines, indicating that Gαi1 and Gαi3 poorly compensate for the loss of Gαi2. These results demonstrate opposing roles for Rgs1 and Gnai2 in B cell trafficking into and within lymph nodes

Recent Accumulation Variability in Northwest Greenland from Ground-Penetrating Radar and Shallow Cores along the Greenland Inland Traverse

Accumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along the 1009 km route of the Greenland Inland Traverse from Thule to Summit during April and May of 2011, to image continuous internal reflecting horizons. We dated these horizons using ice-core chemistry at each end of the traverse. Using density profiles measured along the traverse, we determined the depth to the horizons and the corresponding water-equivalent accumulation rates. The measured accumulation rates vary from ~0.1 m w.e. a–1 in the interior to ~0.7 m w.e. a–1 near the coast, and correspond broadly with existing published model results, though there are some excursions. Comparison of our recent accumulation rates with those collected along a similar route in the 1950s shows a ~10% increase in accumulation rates over the past 52 years along most of the traverse route. This implies that the increased water vapor capacity of warmer air is increasing accumulation in the interior of Greenland