A human embryonic kidney 293T cell line mutated at the Golgi -mannosidase II locus

Disruption of Golgi -mannosidase II activity can result in type II congenital dyserythropoietic anemia and can induce lupus-like autoimmunity in mice. Here, we isolate a mutant human embryonic kidney (HEK) 293T cell line, called Lec36, that displays sensitivity to ricin that lies between the parental HEK 293T cells, whose secreted and membrane-expressed proteins are dominated by complex-type glycosylation, and 293S Lec1 cells, which only produce oligomannose-type N-linked glycans. The stem cell marker, 19A, was transiently expressed in the HEK 293T Lec36 cells, and in parental HEK 293T cells with and without the potent Golgi -mannosidase II inhibitor, swainsonine. Negative-ion nano-electrospray ionization mass spectra of the 19A N-linked glycans from HEK 293T Lec36 and swainsonine-treated HEK 293T cells were qualitatively indistinguishable and, as shown by collision-induced dissociation spectra, dominated by hybrid-type glycosylation. Nucleotide sequencing revealed mutations in each allele of MAN2A1, the gene encoding Golgi -mannosidase II: a point mutation in one allele mapping to the active site and an in-frame deletion of twelve-nucleotides in the other. Expression of wild-type but not the mutant MAN2A1 alleles in Lec36 cells restored processing of the 19A reporter glycoprotein to complex-type glycosylation. The Lec36 cell line will be useful for expressing therapeutic glycoproteins with hybrid-type glycans and provides a sensitive host for detecting mutations in human MAN2A1 causing type II congenital dyserythropoietic anemia

Endogenous Technological Change under Uncertainty

How does risk or uncertainty in the productivity of research affect the growth rate of the economy? To answer this question, a model of endogenous technological change is used where sustained growth stems from intentional investments in R&D from profit-maximizing firms. The uncertainty arises from the productivity of these investments in R&D. The main result of this analysis is that the relationship between long-run growth and uncertainty (on the productivity of knowledge creation) depends on two main factors - the returns to scale in knowledge creation (increasing or non-increasing) and the value of the elasticity of intertemporal substitution (higher or lower than some critical value). Based on empirical studies on the returns to scale in knowledge creation (”non-increasing”) and the value of the elasticity of intertemporal substitution (”higher than the critical value”), we expect a negative relationship between long-run growth and uncertainty regarding the productivity of knowledge creation.Long-run growth, Technological change, Uncertainty

On Growth and Fluctuations: The Option to Adobt New Technology

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On Taxation in a Two-Sector Endogenous Growth Model with Endogenous Labor Supply

This paper studies the effects of taxation on long-run growth in a two-sector endogenous growth model with (i) physical capital as an input in the education sector and (ii) leisure as an additional argument in the utility function. Due to the flexibility of labor supply, taxation of income may induce agents to spend more or less time on leisure activities. Income taxation - the same rate applies for capital and labor income - reduces the growth rate. The contribution of endogenous leisure in this case is confined to reducing or increasing the size of the effect on the growth rate. The same is true if only labor income is taxed. However, if only capital income is taxed, the sign of the effect may reverse. In that case, the positive effect of the increase in total non-leisure time dominates the direct negative effect, implying that capital taxation increases the long-run growth rate.

Hexose-6-phosphate dehydrogenase modulates the effect of inhibitors and alternative substrates of 11[beta]-hydroxysteroid dehydrogenase 1

Intracellular glucocorticoid reactivation is catalyzed by 11[beta]-hydroxysteroid dehydrogenase 1 (11[beta]-HSD1), which functions predominantly as a reductase in cells expressing hexose-6-phosphate dehydrogenase (H6PDH). We recently showed that the ratios of cortisone to cortisol and 7-keto- to 7-hydroxy-neurosteroids are regulated by 11[beta]-HSD1 and very much depend on co-expression with H6PDH, providing cosubstrate NADPH. Here, we investigated the impact of H6PDH on the modulation of 11[beta]-HSD1-dependent inter-conversion of cortisone and cortisol by inhibitors and alternative substrates. Using HEK-293 cells expressing 11[beta]-HSD1 or co-expressing 11[beta]-HSD1 and H6PDH, we observed significant differences of 11[beta]-HSD1 inhibition by natural and pharmaceutical compounds as well as endogenous hormone metabolites. Furthermore, we show potent and dose-dependent inhibition of 11[beta]-HSD1 by 7-keto-DHEA in differentiated human THP-1 macrophages and in HEK-293 cells over-expressing 11[beta]-HSD1 with or without H6PDH. In contrast, 7-ketocholesterol (7-KC) did not inhibit 11[beta]-HSD1 in HEK-293 cells, even in the presence of H6PDH, but inhibited 11[beta]-HSD1 reductase activity in differentiated THP-1 macrophages (IC~50~ = 8.1 +/- 0.9 [mu]M). 7-keto-DHEA but not 7-KC inhibited 11[beta]-HSD1 in HEK-293 cell lysates. In conclusion, cellular factors such as H6PDH can significantly modulate the effect of inhibitors and alternative 7-oxygenated substrates on intracellular glucocorticoid availability

Ebola virus VP35 induces high-level production of recombinant TPL-2–ABIN-2–NF-κB1 p105 complex in co-transfected HEK-293 cells

Activation of PKR (double-stranded-RNA-dependent protein kinase) by DNA plasmids decreases translation, and limits the amount of recombinant protein produced by transiently transfected HEK (human embryonic kidney)-293 cells. Co-expression with Ebola virus VP35 (virus protein 35), which blocked plasmid activation of PKR, substantially increased production of recombinant TPL-2 (tumour progression locus 2)–ABIN-2 [A20-binding inhibitor of NF-κB (nuclear factor κB) 2]–NF-κB1 p105 complex. VP35 also increased expression of other co-transfected proteins, suggesting that VP35 could be employed generally to boost recombinant protein production by HEK-293 cells

Heliophysics Event Knowledgebase for the Solar Dynamics Observatory and Beyond

The immense volume of data generated by the suite of instruments on SDO requires new tools for efficient identifying and accessing data that is most relevant to research investigations. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.Comment: 17 pages, 4 figure

Are older workers overpaid? A literature review

It is widely believed that wage and productivity profiles of individual workers do not coincide at all ages. We give an overview of the theories which provide a rationale for this, and discuss the empirical literature. Human capital theories typically imply that wages rise with tenure, so that job reallocation at old age would imply a wage cut. Incentive theories typically imply that wages exceed productivity at the end of a worker's career. Bargaining power of unions may also lead to 'overpayment' of older workers. Some general conclusions regarding the wages of older workers are formulated on the basis of the authors' reading of the empirical literature.

Analyzing labour supply of elderly people: a life-cycle approach

In light of the ageing of the Dutch society, policy measures aim at increasing the participation rate of elderly workers, particularly in the age-group between 55 and 64. This paper develops a stylized numerical simulation model. This model describes consumption, savings and labour supply behaviour over the life cycle to analyze the labour-market implications of such proposals. For example, we simulate a shift in the (normal) retirement age from 65 to 67, the elimination of the Social Security premium exemption after age 65, and a premium on first-tier pension benefits if the commencement date of these benefits is postponed. Each of these reforms affect the economic outcomes via wealth effects, income effects and inter- and intratemporal substitution effects. The stylized model offers a profound theoretical underpinning which helps us to understand these policy effects over the entire life cycle of individuals. However, the numerical outcomes should be taken with some caution as the model ignores insights of behavioural economics (such as ‘framing effects’).