IP3R3 silencing induced actin cytoskeletal reorganization through ARHGAP18/RhoA/mDia1/FAK pathway in breast cancer cell lines

Cell morphology is altered in the migration process, and the underlying cytoskeleton remodeling is highly dependent of intracellular Ca²⁺ concentration. Many calcium channels are known to be involved in migration. Inositol 1,4,5-trisphosphate receptor (IP₃R) was demonstrated to be implicated in breast cancer cells migration, but its involvement in morphological changes during the migration process remains unclear. In the present work, we showed that IP₃R3 expression was correlated to cell morphology. IP₃R3 silencing induced rounding shape and decreased adhesion in invasive breast cancer cell lines. Moreover, IP₃R3 silencing decreased ARHGAP18 expression, RhoA activity, Cdc42 expression and ^Y861FAK phosphorylation. Interestingly, IP₃R3 was able to regulate profilin remodeling, without inducing any myosin II reorganization. IP₃R3 silencing revealed an oscillatory calcium signature, with a predominant oscillating profile occurring in early wound repair. To summarize, we demonstrated that IP₃R3 is able to modulate intracellular Ca²⁺ availability and to coordinate the remodeling of profilin cytoskeleton organization through the ARHGAP18/RhoA/mDia1/FAK pathway.     

Linking above- and belowground phenology of hybrid walnut growing along a climatic gradient in temperate agroforestry systems

Background and aims

Plant phenology is a sensitive indicator of plant response to climate change. Observations of phenological events belowground for most ecosystems are difficult to obtain and very little is known about the relationship between tree shoot and root phenology. We examined the influence of environmental factors on fine root production and mortality in relation with shoot phenology in hybrid walnut trees (Juglans sp.) growing in three different climates (oceanic, continental and Mediterranean) along a latitudinal gradient in France.

Methods

Eight rhizotrons were installed at each site for 21 months to monitor tree root dynamics. Root elongation rate (RER), root initiation quantity (RIQ) and root mortality quantity (RMQ) were recorded frequently using a scanner and time-lapse camera. Leaf phenology and stem radial growth were also measured. Fine roots were classified by topological order and 0–1 mm, 1–2 mm and 2–5 mm diameter classes and fine root longevity and risk of mortality were calculated during different periods over the year.

Results

Root growth was not synchronous with leaf phenology in any climate or either year, but was synchronous with stem growth during the late growing season. A distinct bimodal pattern of root growth was observed during the aerial growing season. Mean RER was driven by soil temperature measured in the month preceding root growth in the oceanic climate site only. However, mean RER was significantly correlated with mean soil water potential measured in the month preceding root growth at both Mediterranean (positive relationship) and oceanic (negative relationship) sites. Mean RIQ was significantly higher at both continental and Mediterranean sites compared to the oceanic site. Soil temperature was a driver of mean RIQ during the late growing season at continental and Mediterranean sites only. Mean RMQ increased significantly with decreasing soil water potential during the late aerial growing season at the continental site only. Mean root longevity at the continental site was significantly greater than for roots at the oceanic and Mediterranean sites. Roots in the 0–1 mm and 1–2 mm diameter classes lived for significantly shorter periods compared to those in the 2–5 mm diameter class. First order roots (i.e. the primary or parents roots) lived longer than lateral branch roots at the Mediterranean site only and first order roots in the 0–1 mm diameter class had 44.5% less risk of mortality than that of lateral roots for the same class of diameter.

Conclusions

We conclude that factors driving root RER were not the same between climates. Soil temperature was the best predictor of root initiation at continental and Mediterranean sites only, but drivers of root mortality remained largely undetermined.

     

Holdfasts of Sargassum swartzii are resistant to herbivory and resilient to damage

Coral Reefs - The importance of herbivory in both preventing and reversing shifts to macroalgae dominance on coral reefs has been extensively investigated. However, most studies examining the...     

Lifelong treatment with atenolol decreases membrane fatty acid unsaturation and oxidative stress in heart and skeletal muscle mitochondria and improves immunity and behavior,without changing mice longevity

The membrane fatty acid unsaturation hypothesis of aging and longevity is experimentally tested for the first time in mammals. Lifelong treatment of mice with the β1‐blocker atenolol increased the amount of the extracellular‐signal‐regulated kinase signaling protein and successfully decreased one of the two traits appropriately correlating with animal longevity, the membrane fatty acid unsaturation degree of cardiac and skeletal muscle mitochondria, changing their lipid profile toward that present in much more longer‐lived mammals. This was mainly due to decreases in 22:6n‐3 and increases in 18:1n‐9 fatty acids. The atenolol treatment also lowered visceral adiposity (by 24%), decreased mitochondrial protein oxidative, glycoxidative, and lipoxidative damage in both organs, and lowered oxidative damage in heart mitochondrial DNA. Atenolol also improved various immune (chemotaxis and natural killer activities) and behavioral functions (equilibrium, motor coordination, and muscular vigor). It also totally or partially prevented the aging‐related detrimental changes observed in mitochondrial membrane unsaturation, protein oxidative modifications, and immune and behavioral functions, without changing longevity. The controls reached 3.93 years of age, a substantially higher maximum longevity than the best previously described for this strain (3.0 years). Side effects of the drug could have masked a likely lowering of the endogenous aging rate induced by the decrease in membrane fatty acid unsaturation. We conclude that it is atenolol that failed to increase longevity, and likely not the decrease in membrane unsaturation induced by the drug.     

Risk perception and specific behaviors of anglers concerning mercury contamination of fish

Abstract

In recent years, mercury levels in some predatory fishes of several lakes of South-West France, exceeding the European Union nutritional recommendations threshold for safe consumption have been noticed. This led to a decision by regional authorities to ban consumption of those species. We conducted a questionnaire-based study on 276 users of four lakes of the region, two of which were affected by the ban, in order to better understand how it had affected perception of the risk and the associated behaviors. Our study revealed that anglers were the major fish consumers. It also showed that the ban had a poor impact on anglers’ actual fish consumption, despite their being globally well informed about its existence. We conclude that the ban has had a weak impact on anglers’ perception of risk, and that safety nutrition policies should better take into account this factor in the future.     

Notch signaling induces either apoptosis or cell fate change in multiciliated cells during mucociliary tissue remodeling

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Properties of the kainate channel in rat brain mRNA injected Xenopus oocytes: ionic selectivity and blockage

The properties of kainate receptor/channels were studied in Xenopus oocytes injected with mRNA that was isolated from adult rat striatum and cerebellum and partially purified by sucrose gradient fractionation. Kainate (3-1000 microM) induced a smooth inward current that was competitively inhibited by gamma-D-glutamyl-aminomethanesulfonate (GAMS, 300 microM). In striatal mRNA-injected oocytes, the kainate current displayed nearly linear voltage-dependence and mean reversal potential (Er) of -6.1 +/- 0.5 mV. In cerebellar mRNA-injected oocytes; Er was nearly identical (-5.1 +/- 1.2 mV) but there was marked inward rectification of the kainate current. Ion replacement studies reveal that the kainate channel is selective for cations over anions, but relatively non-selective among small monovalent cations. Large monovalent cations such as tetrabutylammonium are impermeant and induce a non-competitive block of kainate current that is strongly voltage-dependent. Divalent cations are relatively impermeant in the kainate channel and Cd++ and other polyvalent metals were shown to block kainate current by a mechanism that is only weakly voltage-dependent. A model of the kainate channel is proposed based upon these observations.