Nuclear envelope budding and its cellular functions.

The nuclear pore complex (NPC) has long been assumed to be the sole route across the nuclear envelope, and under normal homeostatic conditions it is indeed the main mechanism of nucleo-cytoplasmic transport. However, it has also been known that e.g. herpesviruses cross the nuclear envelope utilizing a pathway entitled nuclear egress or envelopment/de-envelopment. Despite this, a thread of observations suggests that mechanisms similar to viral egress may be transiently used also in healthy cells. It has since been proposed that mechanisms like nuclear envelope budding (NEB) can facilitate the transport of RNA granules, aggregated proteins, inner nuclear membrane proteins, and mis-assembled NPCs. Herein, we will summarize the known roles of NEB as a physiological and intrinsic cellular feature and highlight the many unanswered questions surrounding these intriguing nuclear events.

Sphingosine 1-phosphate mediates adiponectin receptor signaling essential for lipid homeostasis and embryogenesis.

Cells and organisms require proper membrane composition to function and develop. Phospholipids are the major component of membranes and are primarily acquired through the diet. Given great variability in diet composition, cells must be able to deploy mechanisms that correct deviations from optimal membrane composition and properties. Here, using lipidomics and unbiased proteomics, we found that the embryonic lethality in mice lacking the fluidity regulators Adiponectin Receptors 1 and 2 (AdipoR1/2) is associated with aberrant high saturation of the membrane phospholipids. Using mouse embryonic fibroblasts (MEFs) derived from AdipoR1/2-KO embryos, human cell lines and the model organism C. elegans we found that, mechanistically, AdipoR1/2-derived sphingosine 1-phosphate (S1P) signals in parallel through S1PR3-SREBP1 and PPARγ to sustain the expression of the fatty acid desaturase SCD and maintain membrane properties. Thus, our work identifies an evolutionary conserved pathway by which cells and organisms achieve membrane homeostasis and adapt to a variable environment.

Nuclear envelope budding is a response to cellular stress.

Nuclear envelope budding (NEB) is a recently discovered alternative pathway for nucleocytoplasmic communication distinct from the movement of material through the nuclear pore complex. Through quantitative electron microscopy and tomography, we demonstrate how NEB is evolutionarily conserved from early protists to human cells. In the yeast Saccharomyces cerevisiae, NEB events occur with higher frequency during heat shock, upon exposure to arsenite or hydrogen peroxide, and when the proteasome is inhibited. Yeast cells treated with azetidine-2-carboxylic acid, a proline analog that induces protein misfolding, display the most dramatic increase in NEB, suggesting a causal link to protein quality control. This link was further supported by both localization of ubiquitin and Hsp104 to protein aggregates and NEB events, and the evolution of these structures during heat shock. We hypothesize that NEB is part of normal cellular physiology in a vast range of species and that in S. cerevisiae NEB comprises a stress response aiding the transport of protein aggregates across the nuclear envelope.

RNA sequencing data describing transcriptional changes in aorta of ApoE-/- mice after alpha 7 nicotinic acetylcholine receptor (α7nAChR) stimulation.

This manuscript is a companion paper to Ulleryd M.U. et al., "Stimulation of alpha 7 nicotinic acetylcholine receptor (α7nAChR) inhibits atherosclerosis via immunomodulatory effects on myeloid cells" Atherosclerosis, 2019 [1]. Data shown here include RNA sequencing data from whole aorta of ApoE-/- mice fed high fat diet and treated with the alpha 7 nicotinic acetylcholine receptor (α7nAChR) agonist AZ6983 for 8 weeks using subcutaneously implanted osmotic minipumps. Here we present the top gene networks affected by treatment with AZ6983, as well as the up- and down-regulated genes in aorta after treatment. Further, a URL link to the RNA sequencing datasets submitted to GEO is included.

Stimulation of alpha 7 nicotinic acetylcholine receptor (α7nAChR) inhibits atherosclerosis via immunomodulatory effects on myeloid cells.

BACKGROUND AND AIMS: Alpha 7 nicotinic acetylcholine receptor (α7nAChR) stimulation can regulate acute inflammation, and lack of α7nAChR accelerates atherosclerosis in mice. In this study, we aimed to investigate the effects of the novel α7nAChR agonist, AZ6983, on atherosclerosis and assess its possible immunomodulating effects. METHODS: AZ6983 was tested in vitro in LPS-challenged mouse and human blood and in vivo using the acute inflammatory air pouch model. Thereafter, long-term effects of AZ6983 treatment on atherosclerosis and immune responses were assessed in apoE-/- mice after 8 and 12 weeks. Atherosclerosis was investigated in the aortic root and thoracic aorta, serum levels of cytokines were analysed and RNAseq was used to study aortic gene expression. Further, bone-marrow-derived macrophages were used to assess phagocytosis in vitro. RESULTS: α7nAChR activation by AZ6983 decreased pro-inflammatory cytokines in acute stimulations of human and mouse blood in vitro, as well as in vivo using the air pouch model. Treating apoE-/- mice with AZ6983 decreased atherosclerosis by 37-49% and decreased serum cytokine levels. RNAseq analysis of aortae suggested the involvement of several specific myeloid cell functions, including phagocytosis. In line with this, AZ6983 significantly increased phagocytosis in bone marrow-derived macrophages. CONCLUSIONS: This study demonstrates that activation of α7nAChR with AZ6983 inhibits atherosclerosis in apoE-/-mice and that immunomodulating effects on myeloid cells, such as enhanced phagocytosis and suppression of inflammatory cytokines, could be part of the athero-protective mechanisms. The observed anti-inflammatory effect in human blood supports the idea that AZ6983 may decrease disease also in humans.

Genotoxic and Antigenotoxic Assessment of Chios Mastic Oil by the In Vitro Micronucleus Test on Human Lymphocytes and the In Vivo Wing Somatic Test on Drosophila.

Chios mastic oil (CMO), the essential oil derived from Pistacia lentiscus (L.) var. chia (Duham), has generated considerable interest because of its antimicrobial, anticancer, antioxidant and other beneficial properties. In the present study, the potential genotoxic activity of CMO as well as its antigenotoxic properties against the mutagenic agent mitomycin-C (MMC) were evaluated by employing the in vitro Cytokinesis Block MicroNucleus (CBMN) assay and the in vivo Somatic Mutation And Recombination Test (SMART). In the in vitro experiments, lymphocytes were treated with 0.01, 0.05 and 0.10% (v/v) of CMO with or without 0.05 µg/ml MMC, while in the in vivo assay Drosophila larvae were fed with 0.05, 0.10, 0.50 and 1.00% (v/v) of CMO with or without 2.50 µg/ml MMC. CMO did not significantly increase the frequency of micronuclei (MN) or total wing spots, indicating lack of mutagenic or recombinogenic activity. However, the in vitro analysis suggested cytotoxic activity of CMO. The simultaneous administration of MMC with CMO did not alter considerably the frequencies of MMC-induced MN and wing spots showing that CMO doesn't exert antigenotoxic or antirecombinogenic action. Therefore, CMO could be considered as a safe product in terms of genotoxic potential. Even though it could not afford any protection against DNA damage, at least under our experimental conditions, its cytotoxic potential could be of interest.