Calmodulin activates nuclear protein import: A link between signal transduction and nuclear transport

In addition to the well-characterized GTP-dependent nuclear transport observed in permeabilized cells, we detected a mode of nuclear transport that was GTP-independent at elevated cytoplasmic calcium concentrations. Nuclear transport under these conditions was blocked by calmodulin inhibitors. Recombinant calmodulin restored ATP-dependent nuclear transport in the absence of cytosol. Calmodulin-dependent transport was inhibited by wheat germ agglutinin consistent with transport proceeding through nuclear pores. We propose that release of intracellular calcium stores upon cell activation inhibits GTP-dependent nuclear transport; the elevated cytosolic calcium then acts through calmodulin to stimulate the novel GTP-independent mode of import.

Translation initiation of ornithine decarboxylase and nucleocytoplasmic transport of cyclin D1 mRNA are increased in cells overexpressing eukaryotic initiation factor 4E.

The structure of m7GpppN (where N is any nucleotide), termed cap, is present at the 5' end of all eukaryotic cellular mRNAs (except organellar). The eukaryotic initiation factor 4E (eIF-4E) binds to the cap and facilitates the formation of translation initiation complexes. eIF-4E is implicated in control of cell growth, as its overexpression causes malignant transformation of rodent cells and deregulates HeLa cell growth. It was suggested that overexpression of eIF-4E results in the enhanced translation of poorly translated mRNAs that encode growth-promoting proteins. Indeed, enhanced expression of several proteins, including cyclin D1 and ornithine decarboxylase (ODC), was documented in eIF-4E-overexpressing NTH 3T3 cells. However, the mechanism underlying this increase has not been elucidated. Here, we studied the mode by which eIF-4E increases the expression of cyclin D1 and ODC. We show that the increase in the amount of cyclin D1 and ODC is directly proportional to the degree of eIF-4E overexpression. Two mechanisms, which are not mutually exclusive, are responsible for the increase. In eIF-4E-overexpressing cells the rate of translation initiation of ODC mRNA was increased inasmuch as the mRNA sedimented with heavier polysomes. For cyclin D1 mRNA, translation initiation was not increased, but rather its amount in the cytoplasm increased, without a significant increase in total mRNA. Whereas, in the parental NIH 3T3 cell line, a large proportion of the cyclin D1 mRNA was confined to the nucleus, in eIF-4E-overexpressing cells the vast majority of the mRNA was present in the cytoplasm. These results indicate that eIF-4E affects directly or indirectly mRNA nucleocytoplasmic transport, in addition to its role in translation initiation.

Impacts on particles and ozone by transport processes recorded at urban and high-altitude monitoring stations

In order to evaluate the influence of particle transport episodes on particle number concentration temporal trends at both urban and high-altitude (Aitana peak-1558 m a.s.l.) stations, a simultaneous sampling campaign from October 2011 to September 2012 was performed. The monitoring stations are located in southeastern Spain, close to the Mediterranean coast. The annual average value of particle concentration obtained in the larger accumulation mode (size range 0.25–1 μm) at the mountain site, 55.0 ± 3.0 cm− 3, was practically half that of the value obtained at the urban station (112.0 ± 4.0 cm− 3). The largest difference between both stations was recorded during December 2011 and January 2012, when particles at the mountain station registered the lowest values. It was observed that during urban stagnant episodes, particle transport from urban sites to the mountain station could take place under specific atmospheric conditions. During these transports, the major particle transfer is produced in the 0.5–2 μm size range. The minimum difference between stations was recorded in summer, particularly in July 2012, which is most likely due to several particle transport events that affected only the mountain station. The particle concentration in the coarse mode was very similar at both monitoring sites, with the biggest difference being recorded during the summer months, 0.4 ± 0.1 cm− 3 at the urban site and 0.9 ± 0.1 cm− 3 at the Aitana peak in August 2012. Saharan dust outbreaks were the main factor responsible for these values during summer time. The regional station was affected more by these outbreaks, recording values of > 4.0 cm− 3, than the urban site. This long-range particle transport from the Sahara desert also had an effect upon O3 levels measured at the mountain station. During periods affected by Saharan dust outbreaks, ozone levels underwent a significant decrease (3–17%) with respect to its mean value.

Rôle de l'isoforme p35 de la chaîne invariante humaine dans la formation et le transport de complexes de CMH II

La présentation antigénique par les molécules de classe II du complexe majeur d’histocompatibilité (CMH II) est un mécanisme essentiel au contrôle des pathogènes par le système immunitaire. Le CMH II humain existe en trois isotypes, HLA-DP, DQ et DR, tous des hétérodimères composés d’une chaîne α et d’une chaîne β. Le CMH II est entre autres exprimé à la surface des cellules présentatrices d’antigènes (APCs) et des cellules épithéliales activées et a pour fonction de présenter des peptides d’origine exogène aux lymphocytes T CD4+. L’oligomérisation et le trafic intracellulaire du CMH II sont largement facilités par une chaperone, la chaîne invariante (Ii). Il s’agit d’une protéine non-polymorphique de type II. Après sa biosynthèse dans le réticulum endoplasmique (ER), Ii hétéro- ou homotrimérise, puis interagit via sa région CLIP avec le CMH II pour former un complexe αβIi. Le complexe sort du ER pour entamer son chemin vers différents compartiments et la surface cellulaire. Chez l’homme, quatre isoformes d’Ii sont répertoriées : p33, p35, p41 et p43. Les deux isoformes exprimées de manière prédominante, Iip33 et p35, diffèrent par une extension N-terminale de 16 acides aminés portée par Iip35. Cette extension présente un motif de rétention au réticulum endoplasmique (ERM) composé des résidus RXR. Ce motif doit être masqué par la chaîne β du CMH II pour permettre au complexe de quitter le ER. Notre groupe s’est intéressé au mécanisme du masquage et au mode de sortie du ER des complexes αβIi. Nous montrons ici que l’interaction directe, ou en cis, entre la chaîne β du CMH II et Iip35 dans une structure αβIi est essentielle pour sa sortie du ER, promouvant la formation de structures de haut niveau de complexité. Par ailleurs, nous démontrons que NleA, un facteur de virulence bactérien, permet d’altérer le trafic de complexes αβIi comportant Iip35. Ce phénotype est médié par l’interaction entre p35 et les sous-unités de COPII. Bref, Iip35 joue un rôle central dans la formation des complexes αβIi et leur transport hors du ER. Ceci fait d’Iip35 un régulateur clef de la présentation antigénique par le CMH II.

Movable-bed laboratory experiments comparing radiation stress and energy flux factor as predictors of longshore transport rate /

"April 1981."

Analysis of coastal sediment transport processes from Wrightsville Beach to Fort Fisher, North Carolina /

A comprehensive engineering analysis of the coastal sediment transport processes along a 42-kilometer segment of the North Carolina shoreline from Wrightsville Beach to Fort Fisher is presented. Included in the analysis is an interpretation of the littoral processes, longshore transport, and the behavior and success of beach nourishment projects at Wrightsville Beach and Carolina Beach, North Carolina. The historical position of the MLW, MSL, and MHW contours, relative to a fixed base line, is plotted for the period between 1964 and 1975. An equivalent volumetric erosion or accretion between successive surveys is determined by multiplying the average excursion distance of the contours by a constant of proportionality. The plots of excursion distance versus time for the MLW, MSL, and MHW contours also show the time response of the beach fills. This response is described by a mathematical function. The alongshore components of wave-induced energy flux are also determined within the study area through wave refraction analysis. This information, together with the information on volumetric change, is used in a sediment budget analysis to determine the coefficient of alongshore sediment transport and the inlet trapping characteristics. (Author).

Transport and fate of contaminants in the subsurface.

Mode of access: Internet.

Source assessment : transport of sand and gravel /

Mode of access: Internet.

Red clay turbidity and its transport in Lake Superior /

"EPA-905/9-79-004."

Results of a joint U.S.A./U.S.S.R. hydrodynamic and transport modeling project /

"February 1979."

An initial assessment of the literature on the measurement, control, transport, transformation and health effects of urregulated diesel engine emissions /

Final report, January 1979.

Transport and communication:

At head of title, no. 1- : Official statistics, commonwealth of Australia. Commonwealth Bureau of census and statistics, Melbourne.

Historical development of transport coordination & integration in the United States.

"This study was prepared principally by James A. Little ... Henry M. Cunningham...and Chester E. Stiles."

Instrumentation for measuring pavement-vehicle interaction. Volume III: Kennedy Co. operation and maintenance manual, formatter and digital tape transport. Final report.

Federal Highway Administration, Structures and Applied Mechanics Division, Washington, D.C.

San Diego region wind transport and wave overwash report : Coast of California Storm and Tidal Waves Study /

Mode of access: Internet.