EGF-induced programmed cell death of human mammary carcinoma MDA-MB-468 cells is preceded by activation of AP-1

MDA-MB-468 is a human mammary adenocarcinoma cell line that overexpresses the epidermal growth factor (EGF) receptor and undergoes programmed cell death (apoptosis) in response to EGF treatment. Programmed cell death was shown to be greatly enhanced when cells were growth-arrested prior to EGF treatment. Apoptosis was characterized by an initial rounding up and detachment of the cells from their substrate starting about 12 h after EGF treatment, followed by chromatin condensation, nuclear fragmentation and oligonucleosomal fragmentation of the DNA at about 24 to 48 h. Cell death was dependent on de novo protein synthesis. We found a rapid induction of c-fos, c-jun and junB at the mRNA level after about 30 min of EGF treatment and a more delayed upregulation of fosB and fra-1. The junD gene was expressed in the absence of EGF, and it was moderately induced within 30 min of growth factor addition. The increase of the different fos and jun mRNAs were paralleled by an increase of activator protein-1 (AP-1) DNA binding activity. A characterization of the AP-1 complex revealed similar levels of several Fos and Jun proteins. Based on the kinetics of AP-1 accumulation and cell death, it seems likely that AP-1 contributes to the apoptotic cell death of EGF receptor-overexpressing MDA-MB-468 cells. Received 21 July 1997; received after revision 6 November 1997; accepted 6 November 1997     

Central IL-1 differentially regulates peripheral IL-6 and TNF synthesis

Centrally given interleukin (IL)-1 is known to induce a rapid rises in blood IL-6. To extend this and to examine the mechanism by which this occurs, the effects of intracerebroventricular (icv) injection of human recombinant IL-1β on mRNA expression of IL-6 and tumour necrosis factor (TNF) in the spleen and liver were examined in rats. Icv injection of IL-1 produced a rapid rise of the tissue mRNA levels of IL-6 and TNF in both organs, prior to and/or in parallel with an increase in their serum levels. Pretreatment with chlorisondamine, a ganglionic blocking agent, inhibited the IL-6 responses, while it had little influence on the TNF responses. The results suggest that brain IL-1 induces peripheral production of IL-6, but not of TNF, through autonomic nervous system activation. Received 27 October 1997; received after revision 15 December 1997; accepted 12 January 1998     

Nitric oxide mediates histamine induced down-regulation of H<Subscript>2</Subscript> receptor mRNA and internalization of the receptor protein (R1)

During agonist-dependent long-term stimulation of cells, histamine receptor subtypes are frequently down-regulated. However, the mechanisms underlying the modulation of receptor expression during long-term histamine stimulation have yet to be resolved. Based on our recently reported results showing an H₁-mediated down-regulation of histamine H₂ receptor mRNA in endothelial cells, our aim was to characterize the mechanism controlling rapid and long-term histamine-mediated modulation of H₂ receptor expression in more detail. We were able to show that the histamine-induced down-regulation of H₂ receptor mRNA and cell surface expression lasting for 24 h was accompanied by augmentation of the receptor protein level in the cytoplasmatic fraction of endothelial cells for this time period. Furthermore, changes in receptor protein levels in whole-cell lysate were negligible, indicating that the rapid and prolonged modulation of cell surface H₂ receptor levels by histamine was regulated solely via internalization. The role of nitric oxide (NO) as a key mediator in histamine-stimulated cell responses was underlined by subsequent studies showing the attenuation of histamine-induced H₂ receptor mRNA down-regulation and protein trafficking following NO synthase isozyme inhibition.Received 11 March 2003; received after revision 11 June 2003; accepted 17 June 2003     

Drosophila unconventional myosin VI is involved in intra- and intercellular transport during oogenesis

During mid-oogenesis of Drosophila, cyto plasmic particles are transported within the nurse cells and through ring canals (cytoplasmic bridges) into the oocyte by means of a microfilament-dependent mecha nism. Video-intensified fluorescence timelapse mi croscopy, in combination with microinjections of antibodies directed against Drosophila 95F myosin, have revealed that this unconventional myosin of class VI is involved in the transport processes. The results indicate that certain cytoplasmic particles in the nurse cells move along microfilaments due to their direct association with myosin VI motors. Additional myosin- VI molecules located at the rim of the ring canals seem to be involved in particle transport into the oocyte. Microinjected mitochondria-specific dyes have revealed that some of these particles are mitochondria. Received 3 April 1997; received after revision 5 May 1997; accepted 27 May 1997     

Augmentation of natural antiganglioside IgM antibodies in lower motor neuron disease (LMND) and role of CD5+ B cells

IgM antibodies directed against neuronal gangliosides GM₁ , GM₂ , GD_1a , GD_1b and GT_1b occur in normal individuals and their level significantly decreases with age. Patients with lower motor neuron disease (LMND) produce high levels of these autoantibodies. AntiGM₁ IgM is selectively augmented. In these patients, the CD5+ (B1) and CD5− (B2) subsets of B cells are not distinct entities but range from those without detectable CD5 marker to those with high CD5+ expression. B1 B cells were sorted to homogeneity, but B2 B cell cannot be isolated to homogeneity because of the presence of B1 cells with low CD5 expression. In short term cultures both the subsets produced IgM antibodies, but the antibodies reacted better with desialylated GM₁ than with GM₁ . Cycloheximide (Cx) (0.35 mM) largely blocked IgM synthesis of the B1 B cells but inhibition of the B2 B cells was incomplete, possibly due to shedding of cytophilic antibodies as well as to the presence of B1 phenotype with loss of CD5 expression. CD5+ B cells may be involved in the production of antiglycolipid IgM. Received 9 June 1997; received after revision 21 July 1997; accepted 28 July 1997     

Heat shock protein gene expression during Xenopus development

Stress-induced heat shock protein gene expression is developmentally regulated during early embryogen esis of the frog, Xenopus laevis. For example, a number of heat shock protein genes, such as hsp70, hsp90, and ubiquitin are not heat-inducible until after the midblastula stage of embryogenesis. Furthermore, the family of small heat shock protein genes, hsp30, are differentially expressed after the midblastula stage as well as being regulated at the level of mRNA stability. Many of these stress proteins are also synthesized constitutively during oogenesis and embryogenesis during which they may act as molecular chaperones as well as being involved in sequestering proteins in an inactive state until required by the developing embryo. Furthermore the induction of these stress protein genes has been correlated with enhanced thermoresistance. During stressful conditions heat shock proteins probably prevent aggregation or misfolding of damaged protei ns within the embryo.     

Production of insulin-like growth factor I (IGF-I) and IGF-binding proteins by rat intestinal stromal cells in vitro

To determine if intestinal stromal cells secrete diffusible factors such as insulin-like growth factors (IGFs) capable of regulating epithelial cell growth in vitro, stromal cells were isolated by enzymatic digestion of rat intestine. Incorporation of [³H]thymidine into DNA and [¹⁴C]leucine into protein of IEC-6 cells, a model intestinal epithelial cell line, was significantly increased (two- to threefold) when the IEC-6 cells were co-cultured with stromal cells, relative to IEC-6 cells grown alone. Medium conditioned by stromal cells stimulated DNA synthesis of IEC-6 cells in a dose-dependent manner. Analysis of the conditioned medium revealed that intestinal stromal cells secreted IGF-I, but little IGF-II, in addition to an M _r 32,000 IGF-binding protein (IGFBP-2) and an IGFBP having M _r∼ 24,000. We conclude that rat intestinal stromal cells secrete one or more diffusible factors, which may include IGF-I and IGFBPs, capable of stimulating proliferation of IEC-6 cells in vitro. Received 25 August 1997; received after revision 7 November 1997; accepted 20 November 1997     

The distribution of α2β1, α3β1 and α6β4 integrins identifies distinct subpopulations of basal keratinocytes in the outer root sheath of the human anagen hair follicle

The human hair follicle is composed of different concentric compartments, which reflect different programmes of differentiation. Using monoclonal antibodies against α2β1 and α3β1 integrins we demonstrated a shift in their expression, from a basolateral distribution in the basal cells of the lower outer root sheath, to an apicolateral expression in the upper outer root sheath, as in epidermis. This shift takes place in a transition zone, localized to the midpart of the follicle. The distinct basolateral distribution of α2β1 and α3β1 integrins in the lower portion of the outer root sheath coincides with the presence of basal cell protrusions and is probably linked to the presence of the vitreous membrane which surrounds the bottom part of the anagen human hair follicle. Moreover, we showed that the expression of α6β4 integrin is discontinuous along the hair follicle and coincides with that of laminin 5. Together these results establish that within a given compartment – namely the outer root sheath – several domains can be clearly identified, which probably reflect the onset of successive differentiation pathways along the hair follicle. Received 17 January 1997; received after revision 18 February 1997; accepted 24 February 1997     

Protein kinase-dependent overexpression of the nuclear protein pirin in c-JUN and RAS transformed fibroblasts

Signalling via the protein kinase Raf-MEK-ERK pathway is of major importance for transformation by oncogenes. To identify genes affected by inhibition of this pathway, c-JUN transformed rat fibroblasts were treated with a MEK1 inhibitor (PD98059) and subjected to two-dimensional gel electrophoresis after cell lysis. Gene products with expression influenced by MEK1 inhibition were determined by mass spectrometry of fragments from in-gel tryptic digestions. The expression of pirin, a nuclear factor I-interacting protein, was lowered after inhibition of MEK1. Western blot analysis revealed increased expression of pirin in RAS and c-JUN transformed cells in the absence of PD98059. Inhibition of MEK1 also led to reduced expression of α-enolase, phosphoglycerate kinase, elongation factor 2 and heterogeneous nuclear ribonucleoprotein A3, the latter two being detected as truncated proteins. In contrast, the level of ornithine aminotransferase was increased. We conclude that inhibition of MEK1 results in major alterations of protein expression in c-JUN transformed cells, suggesting that this pathway is important for oncogene-induced phenotypic changes. Received 30 December 1998; accepted 12 January 1999     

A role for the hinge/ear domain of the β chains in the incorporation of AP complexes into clathrin-coated pits and coated vesicles

The clathrin-associated adaptor protein (AP) complexes drive the polymerization of clathrin in coated pits to form coated vesicles. It has previously been shown that the carboxyl-terminal hinge/ear domain of the β2 chain contains a binding site for clathrin and that removal of this domain from APs or from isolated β2 chains abrogates their ability to form clathrin coats in vitro. We show here that the hinge/ear domain is necessary for efficient incorporation of AP complexes into coated pits and coated vesicles in cells, a result that is consistent with the view that the β chains indeed provide an important interaction between the AP complexes and clathrin. Received 7 April 1997; received after revision 22 May 1997; accepted 28 May 1997     

Cell death proteins as markers of early postmortem interval

Estimation of time since death is one of the challenges in forensic science. There are many approaches to estimate the postmortem interval, including both physical and thanatochemistry methods. Decomposition is triggered by a process called autolysis, which induces destructive changes in the cell leading to cell death. Based on the process of cell death signaling, this study analyzed the early postmortem interval (2–8 h since death) using the study of the mRNA expression of Fas Ligand (FasL) and phosphatase and tensin homologue deleted on chromosome 10 (PTEN) by Quantitative-PCR. Results of the study indicate a time-dependent increase in the mRNA levels of both proteins up until 6 h after death. Using a regression analysis in these first 6 h, a positive linear correlation was found between the mRNA expression of these proteins and the time since death. Since PTEN and FasL are implicated in signaling pathways, both proteins are potential candidates to analyze the time since death in time intervals of 6 h or less. Further research is needed to find additional cell death markers and expand the time period for time since death estimation.     

Sialyl Lewisx-liposomes as vehicles for site-directed, E-selectin-mediated drug transfer into activated endothelial cells

E-selectin, exclusively expressed on activated endothelial cells, is a potential target for site-directed delivery of agents. We and others have shown that sialyl Lewis^x-liposomes (sLe^x-liposomes) are recognized by E-selectin. We now report an approach employing sLe^x-liposomes to deliver antisense oligonucleotides (AS-ODNs) directed against the adhesion molecule ICAM-1 to activated vascular endothelial cells. ICAM-1 expression was analyzed at the protein level by immunofluorescence and a cell surface ELISA, and at the RNA level by RT-PCR. We have investigated two different AS-ODNs complementary to the 3′ untranslated region and the AUG translation initiation codon of ICAM-1 mRNA. Both inhibited protein expression, but did not influence the mRNA level, pointing to a hybridization of AS-ODNs with the mRNA in the cytoplasm. Our results demonstrate the feasibility of a novel approach for the delivery of agents to activated endothelial cells by glycoliposomes targeted to E-selectin. Received 16 October 2000; revised 29 November 2000; accepted 29 November 2000     

Oxidative stress and hypoxia-like injury cause Alzheimer-type molecular abnormalities in central nervous system neurons

Neuronal loss and neuritic/cytoskeletal lesions (synaptic disconnection and proliferation of dystrophic neurites) represent major dementia-associated abnormalities in Alzheimer’s disease (AD). This study examined the role of oxidative stress as a factor contributing to both the cell death and neuritic degeneration cascades in AD. Primary neuron cultures were treated with H₂O₂ (9–90 μM) or desferrioxamine (2–25 μM) for 24 h and then analyzed for viability, mitochondrial mass, mitochondrial function, and pro-apoptosis and sprouting gene expression. H₂O₂ treatment causes free-radical injury and desferrioxamine causes hypoxia-type injury without free radical generation. The H₂O₂-treated cells exhibited sustained viability but neurite retraction, impaired mitochondrial function, increased levels of the pro-apoptosis gene product CD95/Fas, reduced expression of N2J1-immunoreactive neuronal thread protein and synaptophysin, and reduced distribution of mitochondria in neuritic processes. Desferrioxamine treatment resulted in dose-dependent neuronal loss associated with impaired mitochondrial function, proliferation of neurites, and reduced expression of GAP-43, which has a role in path-finding during neurite outgrowth. The results suggest that oxidative stress can cause neurodegeneration associated with enhanced susceptibility to apoptosis due to activation of pro-apoptosis genes, neurite retraction (synaptic disconnection), and impaired transport of mitochondria to cell processes where they are likely required for synaptic function. In contrast, hypoxia-type injury causes neuronal loss with proliferation of neurites (sprouting), impaired mitochondrial function, and reduced expression of molecules required to form and maintain synaptic connections. Since similar abnormalities occur in AD, both oxidative stress and hypoxic injury can contribute to AD neurodegeneration. Received 24 May 2000; received after revision 7 July 2000; accepted 27 July 2000     

Kinetics of BRCA1 regulation in response to UVC radiation

To investigate changes in BRCA1 following DNA damage, we exposed MCF-7 cells to increasing doses of ultraviolet C. We observed an increase in BRCA1 protein levels above 78 J/m². This increase was observed as early as 5 min after irradiation. BRCA1 levels were then observed to decrease after 2 h, consistent with the previously published data. By pretreating with cycloheximide prior to irradiation, we observed a decrease in the protein half-life, from 3.5 h to 53 min, suggesting that a decrease in protein half-life may cause the lower levels of BRCA1 after irradiation. We also observed an increase in BRCA1 mRNA within 15 min of irradiation, followed by a decrease after 4 h. These data suggest that newly translated protein may contribute to increases in BRCA1 protein levels. The very rapid changes in BRCA1 support its role as a sensor of DNA damage, as opposed to being a repair gene. Received 6 April 2000; received after revision 23 May 2000; accepted 23 May 2000     

Identification and characterization of a highly thermostable bacteriophage lysozyme

Pseudomonas aeruginosa bacteriophage KMV is a T7-like lytic phage. Liquid chromatography-mass spectrometry of the structural proteins revealed gene product 36 (gp36) as part of the KMV phage particle. The presence of a lysozyme domain in the C terminal of this protein (gp36C) was verified by turbidimetric assays on chloroform-treated P. aeruginosa PAO1 and Escherichia coli WK6 cells. The molecular mass (20,884 Da) and pI (6.4) of recombinant gp36C were determined, as were the optimal enzymatic conditions (pH 6.0 in 16.7 mM phosphate buffer) and activity (4800 U/mg). Recombinant gp36C is a highly thermostable lysozyme, retaining 26% of its activity after 2 h at 100°C and 21% after autoclaving. This thermostability could prove an interesting characteristic for food conservation technology.Received 13 July 2004; received after revision 31 August 2004; accepted 6 September 2004     

Melatonin antagonizes colchicine-induced mitotic arrest

Summary Melatonin, in concentrations up to 10^–3 M, showed no effect on mitosis in cultures of HeLa or KB cells. However, when melatonin at 10^–4 M was preincubated with HeLa cells prior to addition of 10^–7 M colchicine, a reduction in the mitotic index, in comparison to colchicine alone, was observed.This work was supported by PHS Grant No. CA 16425.