Search results for "apparatus"

A homemade cytospin apparatus

2006

Endothelial Nitric Oxide Synthase Regulates T Cell Receptor Signaling at the Immunological Synapse

2006

The role of nitric oxide (NO) in T cells remains controversial, and the origin and localization of endogenous NO and whether it regulates lymphocyte activation are unclear. We show here that, within minutes of binding to antigen, T cells produce NO via endothelial nitric oxide synthase (eNOS). This process required increased intracellular Ca2+ and phosphoinositide3-kinase activity. By using an eNOS-green fluorescent fusion protein and fluorescent probes to detect NO, we show that eNOS translocates with the Golgi apparatus to the immune synapse of T helper cells engaged with antigen-presenting cells (APC), where it was fully activated. Overexpression of eNOS prevented the central coalescence…

Microtubule organization and distribution of gamma-tubulin in male meiosis of lepidoptera

1996

Meiotic spindles in males of higher Lepidotera are unusual in that the bulk of the spindle micro-tubules (MTs) ends about halfway between the equatorial plate and the centrosomes in metaphase. It appears worthwhile to determine how the MTs are nucleated, while their pole proximal ends are distant from the centrosomes. To this end, spermatocytes of Phragmatobia fuliginosa (Arctiidae), collected in the field, were double-labeled with antibodies to beta- and gamma-tubulin. The former antibody reveals the entire microtubular cytoskeleton, and the latter is directed against a newly-discovered tublin isoform that is prevalent in microtubule-organizing centers (MTOCs). The immunocytochemical work …

eNOS S-nitrosylates β-actin on Cys374 and regulates PKC-θ at the immune synapse by impairing actin binding to profilin-1.

2017

The actin cytoskeleton coordinates the organization of signaling microclusters at the immune synapse (IS); however, the mechanisms involved remain poorly understood. We show here that nitric oxide (NO) generated by endothelial nitric oxide synthase (eNOS) controls the coalescence of protein kinase C-¿ (PKC-¿) at the central supramolecular activation cluster (c-SMAC) of the IS. eNOS translocated with the Golgi to the IS and partially colocalized with F-actin around the c-SMAC. This resulted in reduced actin polymerization and centripetal retrograde flow of ß-actin and PKC-¿ from the lamellipodium-like distal (d)-SMAC, promoting PKC-¿ activation. Furthermore, eNOS-derived NO S-nitrosylated ß-…

Optogenetically blocking sharp wave ripple events in sleep does not interfere with the formation of stable spatial representation in the CA1 area of …

2016

During hippocampal sharp wave/ripple (SWR) events, previously occurring, sensory inputdriven neuronal firing patterns are replayed. Such replay is thought to be important for plasticity-related processes and consolidation of memory traces. It has previously been shown that the electrical stimulation-induced disruption of SWR events interferes with learning in rodents in different experimental paradigms. On the other hand, the cognitive map theory posits that the plastic changes of the firing of hippocampal place cells constitute the electrophysiological counterpart of the spatial learning, observable at the behavioral level. Therefore, we tested whether intact SWR events occurring during th…

Stx5 is a novel interactor of VLDL-R to affect its intracellular trafficking and processing

2012

We identified syntaxin 5 (Stx5), a protein involved in intracellular vesicle trafficking, as a novel interaction partner of the very low density lipoprotein (VLDL)-receptor (VLDL-R), a member of the LDL-receptor family. In addition, we investigated the effect of Stx5 on VLDL-R maturation, trafficking and processing. Here, we demonstrated mutual association of both proteins using several in vitro approaches. Furthermore, we detected a special maturation phenotype of VLDL-R resulting from Stx5 overexpression. We found that Stx5 prevented advanced Golgi-maturation of VLDL-R, but did not cause accumulation of the immature protein in ER, ER to Golgi compartments, or cis-Golgi ribbon, the main ex…

A new insight into the three-dimensional architecture of the Golgi complex: Characterization of unusual structures in epididymal principal cells.

2017

Principal epididymal cells have one of the largest and more developed Golgi complex of mammalian cells. In the present study, we have used this cell as model for the study of the three-dimensional architecture of the Golgi complex of highly secretory and endocytic cells. Electron tomography demonstrated the presence in this cell type of some unknown or very unusual Golgi structures such as branched cisternae, pocket-like cisternal invaginations or tubular connections. In addition, we have used this methodology and immunoelectron microscopy to analyze the close relationship between this organelle and both the endoplasmic reticulum and microtubules, and to describe in detail how these element…

Chronic administration of green tea extract to TRAMP mice induces the collapse of Golgi apparatus in prostate secretory cells and results in alterati…

2011

Considering its long latency, prostate cancer (PCa) represents an ideal target for chemoprevention strategies. Green tea extract (GTE) has been proved to be one of the most promising natural substances capable of inhibiting PCa progression in animal models (transgenic adenocarcinoma of mouse prostate), as well as in humans. However, the cellular targets of the GTE action are mostly unknown. The main objective of this work was to investigate whether the endoplasmic reticulum (ER) and the Golgi apparatus (GA), known to be actively involved in sensing stress stimuli and initiating and propagating cell death signalling, may represent the subcellular targets of GTE action. To this end, 42 TRAMP …

Unique pharmacology of KAR-2, a potential anti-cancer agent: absorption modelling and selective mitotic spindle targeting.

2008

Abstract Bis-indols are a large group of the anti-cancer agents, which effectively arrest the uncontrolled division of the cancerous cells. Their use in clinical chemotherapy is still limited because of: (i) the non-specific targeting of the mitotic cells; (ii) low bioavailability of the drugs. KAR-2 has been identified as a tubulin binding agent which displays significantly lower cytotoxicity but favourable anti-cancer potency than its mother molecule, vinblastine. The objective of this paper, on one hand, was to show that the human intestinal epithelial Caco-2 cells, used for pharmacokinetic studies display distinct sensitivity against KAR-2 and vinblastine due to their distinct targeting…

Testis differentiation in the glowworm,Lampyris noctiluca, with special reference to the apical tissue

2001

The gonads of Lampyris noctiluca are sexually undifferentiated during the first larval instars. They consist of many gonadal follicles that include the germ stem cells enclosed by the somatic cells of the follicle wall. Follicle wall cells are more numerous at the follicle apices than at the distal parts, but different cell types cannot be distinguished. In male larvae, the appearance of apical follicle tissue, derived from follicle wall cells, marks the onset of testis differentiation. When maximally expressed, the apical tissue occupies about the upper half of the testis follicles and can be observed in larvae of the fifth and sixth instar. The apical tissue is characterized by its “light…