Cell cycle arrest or survival signaling through αv integrins,activation of PKC and ERK1/2 lead to anoikis resistance of ovarian cancer spheroids

Ovarian cancer is the most lethal gynecologic cancer mainly due to spheroids organization of cancer cells that disseminate within the peritoneal cavity. We have investigated the molecular mechanisms by which ovarian cancer spheroids resist anoikis, choosing as models the 2 well-characterized human ovarian cancer cell lines IGROV1 and SKOV3. These cell lines have the propensity to float as clusters, and were isolated from tumor tissue and ascites, respectively. To form spheroids, IGROV1 and SKOV3 ovarian adenocarcinoma cells were maintained under anchorage-independent culture conditions, in which both lines survive at least a week. A short apoptotic period prior to a survival signaling commitment was observed for IGROV1 cells whereas SKOV3 cells entered G0/G1 phase of the cell cycle. This difference in behavior was due to different signals. With regard to SKOV3 cells, activation of p38 and an increase in p130/Rb occurred once anchorage-independent culture was established. Analyses of the survival signaling pathway switched on by IGROV1 cells showed that activation of ERK1/2 was required to evade apoptosis, an effect partly dependent on PKC activation and αv integrins. αv-integrin expression is essential for survival through activation of ERK1/2 phosphorylation.     

Effects of seasonal and climate variations on calves’ thermal comfort and behaviour

The aim of this study was to measure the effect of season and climate variations on thermal comfort and behaviour of 6-month-old dairy calves housed in a semi-opened shelter to develop animal-based indicators for assessing animal thermal comfort. The ultimate purpose was to further exploit the use of those indicators to prevent thermal stress by providing appropriate care to the animals. Measurements were taken for winter and summer seasons. Results showed that season significantly influenced (P?≤?0.01) the lying down behaviour of calves by reducing the time spent lying, from 679.9 min in winter to 554.1 min in summer. Moreover, season had a significant influence (P?≤?0.01) on feeding behaviour. In detail, the total length of feeding periods was shorter in winter, 442.1 min in comparison to 543.5 min in summer. Time spent drinking increased significantly (P?≤?0.001), from 11.9 min in winter to 26.9 min in summer. Furthermore, season had a significant influence (P?≤?0.001) on self grooming behaviour which was 5.5 times longer in duration in winter than in summer (1,336 s vs 244 s). It was concluded that calves’ thermal comfort is affected by seasonal and climate variations and that this can be assessed by measuring behaviour with animal-based indicators, such as lying down, resting, standing up, feeding, rumination, drinking and self grooming. The indicators developed may be a useful tool to prevent animal thermal stress by providing appropriate housing and handling to calves under seasonal and climate challenge.     

Promoter diversity in multigene transformation

Multigene transformation (MGT) is becoming routine in plant biotechnology as researchers seek to generate more complex and ambitious phenotypes in transgenic plants. Every nuclear transgene requires its own promoter, so when coordinated expression is required, the introduction of multiple genes leads inevitably to two opposing strategies: different promoters may be used for each transgene, or the same promoter may be used over and over again. In the former case, there may be a shortage of different promoters with matching activities, but repetitious promoter use may in some cases have a negative impact on transgene stability and expression. Using illustrative case studies, we discuss promoter deployment strategies in transgenic plants that increase the likelihood of successful and stable multiple transgene expression.     

Role of Spatial and Temporal Refuges in the Evolution of Pest Resistance to Toxic Crops

Toxic plants have been used for years in agriculture to control major crop pests. However, the continuous exposure of targeted pests to toxins dramatically increases the rate of resistance evolution (Gassman et al. in Annu Rev Entomol 54:147–163, 2009a; Tabashnik et al. Nat Biotechnol 26:199–202, 2008). To prevent or delay resistance, non toxic host plants can be used as refuges. Our study considers spatial and temporal refuges that are respectively implemented concurrently or alternatively a toxic crop. A conceptual model based on impulsive differential equations is proposed to describe the dynamics of the susceptible and resistant pest populations over time. The mathematical study enlightens threshold values of the proportion of the spatial refuge and key parameters that should help to understand evolution of pest resistance to toxic crop.     

Chemically-induced resistance on soybean inhibits nodulation and mycorrhization

Induced plant resistance (IR) against pathogen infection can be triggered by various chemical and biological elicitors. The effectiveness of elicitors to induce resistance as a practical means to control plant disease makes use of the plant’s own defence mechanisms triggered by resistance inducing agents. The aim of the present study was to examine the possible side effects of IR on the establishment and the efficiency of a rhizobial symbioses (Bradyrhizobium japonicum-soybean) and an arbuscular mycorrhizal symbioses (Glomus mosseae —soybean). IR was triggered by applying, acibenzolar S-methyl (ASM) at 80 mg a.i. L^?1 by two ways: seed soaking or foliar spray. Chitinase activity, used as a biochemical marker of IR, increased when ASM was applied both as seed soaking or as foliar spray. In vitro ASM showed no direct effect on the growth of B. japonicum and induced, only at a high concentration, a slight inhibition effect on spore germination of G. mosseae. ASM caused after both treatments a significant decrease in the number of nodules. Nitrogen content in aerial parts and roots decreased. On the other hand, ASM showed no significant effect on the frequency of colonization by G.mosseae but reduced the intensity of colonization and the proportion of arbuscules. The possible interaction between IR and the induction and suppression of defence-like mechanisms during symbiotic processes is discussed.     

Codominance of TLR2-dependent and TLR2-independent modulation of MHC class II in Mycobacterium tuberculosis infection in vivo

Mycobacterium tuberculosis is an exceptionally successful human pathogen. A major component of this success is the ability of the bacteria to infect immunocompetent individuals and to evade eradication by an adaptive immune response that includes production of the macrophage-activating cytokine, IFN-gamma. Although IFN-gamma is essential for arrest of progressive tuberculosis, it is insufficient for efficacious macrophage killing of the bacteria, which may be due to the ability of M. tuberculosis to inhibit selected macrophage responses to IFN-gamma. In vitro studies have determined that mycobacterial lipoproteins and other components of the M. tuberculosis cell envelope, acting as agonists for TLR2, inhibit IFN-gamma induction of MHC class II. In addition, M. tuberculosis peptidoglycan and IL-6 secreted by infected macrophages inhibit IFN-gamma induction of MHC class II in a TLR2-independent manner. To determine whether TLR2-dependent inhibition of macrophage responses to IFN-gamma is quantitatively dominant over the TLR2-independent mechanisms in vivo, we prepared mixed bone marrow chimeric mice in which the hemopoietic compartment was reconstituted with a mixture of TLR(+/+) and TLR2(-/-) cells. When the chimeric mice were infected with M. tuberculosis, the expression of MHC class II on TLR2(+/+) and TLR2(-/-) macrophages from the lungs of individual infected chimeric mice was indistinguishable. These results indicate that TLR2-dependent and -independent mechanisms of inhibition of responses to IFN-gamma are equivalent in vivo, and that M. tuberculosis uses multiple pathways to abrogate the action of an important effector of adaptive immunity. This work was supported by National Institutes of Health Grants AI 065357-AI 020010.     

Characterization of p43(ARF), a derivative of the p43 component of multiaminoacyl-tRNA synthetase complex released during apoptosis

In human, nine aminoacyl tRNA synthetases are associated with the three auxiliary proteins, p18, p38, and p43, to form a stable multiprotein complex. The p43 component, which has a potent tRNA binding capacity, is associated to the complex via its N-terminal moiety. This protein is also the precursor of the endothelial monocyte-activating polypeptide II (p43(EMAPII), corresponding to the C-terminal moiety of p43), a cytokine generated during apoptosis. Here we examined the cellular pathway that, starting from the p43 subunit of the complex, leads to this extracellular cytokine. We identified a new intermediate in this pathway, named p43(ARF) for Apoptosis-released Factor. This intermediate is produced in cellulo by proteolytic cleavage of endogenous p43 and is rapidly recovered in the culture medium. This p43 derivative was purified from the medium of human U937 cells subjected to serum starvation. It contains 40 additional N-terminal amino acid residues as compared with the cytokine p43(EMAPII) and may be generated by a member of the matrix metalloproteinase family. Recombinant p43(ARF) is a monomer in solution and binds tRNA with a Kd of approximately 6 nM, 30-fold lower than that of p43. Highly purified p43(ARF) or p43(EMAPII) do not stimulate the expression of E-selectin by human umbilical vein endothelial cells. Our results suggest that the cleavage of p43 and its cellular delocalization, and thus the release of this tRNA binding subunit from the complex, is one of the molecular mechanisms leading to the shut down of protein synthesis in apoptosis.     

Neurotrophic effects of PACAP in the cerebellar cortex

In the rodent cerebellum, PACAP is expressed by Purkinje neurons and PAC1 receptors are present on granule cells during both the development period and in adulthood. Treatment of granule neurons with PACAP inhibits proliferation, slows migration, promotes survival and induces differentiation. PACAP also protects cerebellar granule cells against the deleterious effects of neurotoxic agents. Most of the neurotrophic effects of PACAP are mediated through the cAMP/PKA signaling pathway and often involve the ERK MAPkinase. Caspase-3 is one of the key enzymes implicated in the neuroprotective action of PACAP but PACAP also inhibits caspase-9 activity and increases Bcl-2 expression. PACAP and functional PAC1 receptors are expressed in the monkey and human cerebellar cortex with a pattern of expression very similar to that described in rodents, suggesting that PACAP could also exert neurodevelopmental and neuroprotective functions in the cerebellum of primates including human.     

Solution structure of the region 51-160 of human KIN17 reveals an atypical winged helix domain

Human KIN17 is a 45-kDa eukaryotic DNA- and RNA-binding protein that plays an important role in nuclear metabolism and in particular in the general response to genotoxics. Its amino acids sequence contains a zinc finger motif (residues 28-50) within a 30-kDa N-terminal region conserved from yeast to human, and a 15-kDa C-terminal tandem of SH3-like subdomains (residues 268-393) only found in higher eukaryotes. Here we report the solution structure of the region 51-160 of human KIN17. We show that this fragment folds into a three-alpha-helix bundle packed against a three-stranded beta-sheet. It belongs to the winged helix (WH) family. Structural comparison with analogous WH domains reveals that KIN17 WH module presents an additional and highly conserved 3(10)-helix. Moreover, KIN17 WH helix H3 is not positively charged as in classical DNA-binding WH domains. Thus, human KIN17 region 51-160 might rather be involved in protein-protein interaction through its conserved surface centered on the 3(10)-helix.