Bovine microvascular endothelial cells of separate morphology differ in growth and response to the action of interferon-γ

Five cell types recently isolated from the bovine corpus luteum differed in their epithelioid morphology and their cytoskeleton, but shared common criteria of microvascular endothelial cells^1,2. To give strong evidence for the separate entity, the growth rate of the 5 phenotypically different cells was studied. They were seeded at low density on day 0. Most of these cells were treated with 200 to 1000 U recombinant bovine interferon- (IFN-) for 3 days. The untreated remainder served as controls. Cell counts were made for all cultures on days 4, 7, 10 and 13. morphology: 13 d after treatment with IFN- senescent cells as well as intact cells occurred in cultures of cell types 1 to 4. Cultures of cell type 5 were apparently unchanged and resembled their untreated counterparts. Desminpositive cells in cultures of cell type 2 developed cell processes. Growth rate: In the absence of IFN-, the growth rate was high for cell types 3 and 4, moderate for cell type 1, and low for cell types 2 and 5. The presence of IFN- caused anti-proliferative effects. These were higher for cell types 3 and 4 than for cell types 1 and 2. IFN- could be cytotoxic on cell type 3. In contrast, the cytokine tended to support the cell growth of cell type 5. These findings substantiate the postulate that endothelial cells exhibiting separate morphology in culture also function differently.     

Does an initial phasic response exist in the receptor potential of taste cells?

The depolarizing receptor potentials to 0.5 M NaCl recorded from frog taste cells did not exhibit any phasic response, even when the rectangular waveform of stimulus onset was employed. The quickest depolarizations recorded reached the peak in 50 msec. On the other hand, the gustatory neural response showed initial overshoot of the impulse discharge even when 0.5 M NaCl was delivered at the slower rate of 0.06 ml/sec. It is concluded that the initial neural response may be associated with the rate of rise of the receptor potential before its plateau level is reached.     

Dissection of the molecular mechanisms that control the nuclear accumulation of transport factors importin-α and CAS in stressed cells

The physiological state of eukaryotic cells controls nuclear trafficking of numerous cargos. For example, stress results in the inhibition of classical protein import, which is characterized by the redistribution of several transport factors. As such, importin-alpha and cellular apoptosis susceptibility protein (CAS) accumulate in nuclei of heat-shocked cells; however, the mechanisms underlying this relocation are not fully understood. We now show that heat upregulates the initial docking of importin-alpha at the nuclear envelope and stimulates the translocation of CAS into the nuclear interior. Moreover, heat exposure compromises the exit of importin-alpha from nuclei and drastically increases its retention in the nucleoplasm, whereas CAS nuclear exit and retention are less affected. Taken together, our results support the idea that heat shock regulates importin-alpha and CAS nuclear accumulation at several levels. The combination of different stress-induced changes leads to the nuclear concentration of both transport factors in heat-stressed cells.     

Neutrophil uptake of nitrogen-bisphosphonates leads to the suppression of human peripheral blood γδ T cells

Nitrogen-bisphosphonates (n-BP), such as zoledronate, are the main class of drugs used for the prevention of osteoporotic fractures and the management of cancer-associated bone disease. However, long-term or high-dose use has been associated with certain adverse drug effects, such as osteonecrosis of the jaw and the loss of peripheral of blood Vγ9Vδ2 T cells, which appear to be linked to drug-induced immune dysfunction. In this report we show that neutrophils present in human peripheral blood readily take up zoledronate, and this phenomenon is associated with the potent immune suppression of human peripheral blood Vγ9Vδ2 T cells. Furthermore, we found this zoledronate-mediated inhibition by neutrophils could be overcome to fully reconstitute Vγ9Vδ2 T cell proliferation by concomitantly targeting neutrophil-derived hydrogen peroxide, serine proteases, and arginase I activity. These findings will enable the development of targeted strategies to mitigate some of the adverse effects of n-BP treatment on immune homeostasis and to improve the success of immunotherapy trials based on harnessing the anticancer potential of peripheral blood γδ T cells in the context of n-BP treatment.     

Heavy incorporation of3H-prostaglandin F2α in the neoplastic cells as revealed by autoradiographic studies

Summary A marked uptake (9-fold) of the³H-PGF₂ was found specifically over heterochromatin in the nuclei of neoplastic cells. Lower but significant uptakes of³H-PGF₂ were also found in the nuclei of control epidermal cells, which indicate the presence of nuclear receptors in the epidermal neoplastic cells.     

Multidrug-resistant cancer cells and cancer stem cells hijack cellular systems to circumvent systemic therapies,can natural products reverse this?

Chemotherapy is one of the most effective and broadly used approaches for cancer management and many modern regimes can eliminate the bulk of the cancer cells. However, recurrence and metastasis still remain a major obstacle leading to the failure of systemic cancer treatments. Therefore, to improve the long-term eradication of cancer, the cellular and molecular pathways that provide targets which play crucial roles in drug resistance should be identified and characterised. Multidrug resistance (MDR) and the existence of tumor-initiating cells, also referred to as cancer stem cells (CSCs), are two major contributors to the failure of chemotherapy. MDR describes cancer cells that become resistant to structurally and functionally unrelated anti-cancer agents. CSCs are a small population of cells within cancer cells with the capacity of self-renewal, tumor metastasis, and cell differentiation. CSCs are also believed to be associated with chemoresistance. Thus, MDR and CSCs are the greatest challenges for cancer chemotherapy. A significant effort has been made to identify agents that specifically target MDR cells and CSCs. Consequently, some agents derived from nature have been developed with a view that they may overcome MDR and/or target CSCs. In this review, natural products-targeting MDR cancer cells and CSCs are summarized and clustered by their targets in different signaling pathways.     

Cadherin 22 participates in the self-renewal of mouse female germ line stem cells via interaction with JAK2 and β-catenin

The self-renewal capacity of the stem cell pool determines tissue function and health. Cadherin-22 (Cdh22), a member of the cadherin superfamily, has two splicing patterns in rats, and the short type that lacks a catenin binding domain is closely related to spermatogonial stem cell self-renewal. Previously, we reported that CDH22 was highly expressed in mouse ovary germ cells, especially in female germ line stem cells (FGSCs). However, its underlying function in FGSCs is still not clear. Here, we found that Cdh22 encodes only one type of protein product in mice and demonstrated that CDH22 was required for FGSC self-renewal. In addition, JAK2 and β-catenin were found to interact with CDH22 and be involved in CDH22 signaling in mouse FGSCs. Moreover, extrinsic CDH22 was identified as a potential molecule that participates in FGSC adhesion and is pivotal for FGSC maintenance and self-renewal. These results reveal that CDH22 functions as an essential molecule in FGSC maintenance and self-renewal via different mechanisms, including interaction with the JAK-STAT signaling pathway and β-catenin.     

Light-dependent phosphorylation of Bardet–Biedl syndrome 5 in photoreceptor cells modulates its interaction with arrestin1

Arrestins are dynamic proteins that move between cell compartments triggered by stimulation of G-protein-coupled receptors. Even more dynamically in vertebrate photoreceptors, arrestin1 (Arr1) moves between the inner and outer segments according to the light conditions. Previous studies have shown that the light-driven translocation of Arr1 in rod photoreceptors is initiated by rhodopsin through a phospholipase C/protein kinase C (PKC) signaling cascade. The purpose of this study is to identify the PKC substrate that regulates the translocation of Arr1. Mass spectrometry was used to identify the primary phosphorylated proteins in extracts prepared from PKC-stimulated mouse eye cups, confirming the finding with in vitro phosphorylation assays. Our results show that Bardet–Biedl syndrome 5 (BBS5) is the principal protein phosphorylated either by phorbol ester stimulation or by light stimulation of PKC. Via immunoprecipitation of BBS5 in rod outer segments, Arr1 was pulled down; phosphorylation of BBS5 reduced this co-precipitation of Arr1. Immunofluorescence and immunoelectron microscopy showed that BBS5 principally localizes along the axonemes of rods and cones, but also in photoreceptor inner segments, and synaptic regions. Our principal findings in this study are threefold. First, we demonstrate that BBS5 is post-translationally regulated by phosphorylation via PKC, an event that is triggered by light in photoreceptor cells. Second, we find a direct interaction between BBS5 and Arr1, an interaction that is modulated by phosphorylation of BBS5. Finally, we show that BBS5 is distributed along the photoreceptor axoneme, co-localizing with Arr1 in the dark. These findings suggest a role for BBS5 in regulating light-dependent translocation of Arr1 and a model describing its role in Arr1 translocation is proposed.     

Dynamics of the interaction of γδ T cells with their neighbors in vivo

γδ T cells are a diverse component of the immune system in humans and mice with presumably important but still largely unknown functions. Understanding the dynamic interaction of γδ T cells with their neighbors should help to understand their physiological role. This review addresses recent advances and strategies to visualize the dynamic interactions of γδ T cells with their neighbors in vivo. Current knowledge regarding the dynamic contacts of tissue resident γδ T cells and epithelial cells, but also of the communication between circulating γδ T cells and DCs, monocytes and FoxP3⁺ regulatory T cells is revisited with emphasis on the role of γδ T cell motility.     

The influence of N-methyl-N-β-chloroethyl hydrazines on the mitotic index of Ehrlich ascites tumor cells and the leukopoiesis of the mouse

Summary The cytostatic activity of N-methyl-N--chloroethylbenzaldehyd hydrazone, (B1) is at least equal to that of procarbazine when its effect is tested with the Ehrlich ascites tumor cells of the mouse and the Yoshida sarcoma of the rat. B1 causes a slighter decrease of mitotic cells and no shift from prophase to metaphase. These results suggest that the cytostatic effect of B1 is due to interference with cell metabolism or an effect at the cell membrane and not to an effect on cell proliferation. This assumption is supported by a considerable depression, of lymphocytes and a minor effect on granulopoiesis, which is especially sensitive towards proliferation toxins. All these findings suggest a different mechanism of action of B1 and procarbazine.     

Age-related differences in the urinary excretion of prostaglandin F2α catabolites in the rat

Summary Tritium-labelled PGF₂ was administered i.v. into rats of varying ages (2, 4, 6 weeks and adult). Urine was collected and assayed for radioactive products by thin-layer-chromatography. Results showed a distinctly different urinary profile between the 2-week-old and the adult rat. While the urinary pattern from the 2-week-old rat gave a single less polar product than PGF₂, the pattern from the adult rat gave products more polar than PGF₂. Urine from the 4- and 6-week-old rats gave a mixture of these types of products. These results indicate that some prostaglandin catabolic pathway (likely the -oxidative system) is activated in vivo within the 4–6-week postnatal period in the rat.Supported by a grant (MT-4181) to C.P.-A. from the Medical Research Council of Canada.This study is in partial fulfillment of the requirements for a Ph.D. degree in the Department of Pharmacology, University of Toronto.