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  • 1
    Electronic Resource
    Electronic Resource
    Metabolic depletion inhibits the uptake of nontransferrin-bound iron by K562 cells (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 177 (1998), S. 585-592 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of metabolic inhibitors on nontransferrin bound iron transport by K562 cells was investigated. Incubation with 1 μM rotenone, 10 μM antimycin, or 0.5 mM 2,4-dinitrophenol effectively reduced ATP levels by ∼50%. Both the rate and extent of Fe+3 uptake were impaired in ATP-depleted cells, which display a reduced Vmax for uptake. K562 cell ferrireductase activity was also lowered by metabolic inhibitors, suggesting that the apparent energy requirements for transport reside in the reduction of Fe+3 to Fe+2. However, ATP depletion was found to inhibit the rate and extent of Fe+2 uptake as well. Thus, the transbilayer passage of Fe+2 and/or Fe+3 appears to be an energy-requiring process. These features possibly reflect properties of the transport mechanism associated with a recently identified K562 cell transport protein, called SFT for “Stimulator of Fe Transport,” since exogenous expression of its activity is also affected by ATP depletion. J Cell Physiol 177:585-592, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Tumor necrosis factor and interleukin 1 inhibit parathyroid hormone-responsive adenylate cyclase in clonal osteoblast-like cell by down-regulating parathyroid hormone receptors (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 153 (1992), S. 206-213 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of the monokines tumor necrosis factor α (TNF) and interleukin 1 (IL 1) on parathyroid hormone (PTH)-responsive adenylate cyclase were examined in clonal rat osteosarcoma cells (UMR-106) with the osteoblast phenotype. Recombinant TNF and IL 1 incubated with UMR-106 cells for 48 hr each produced concentration-dependent inhibition of PTH-sensitive adeylate cyclase, with maximal inhibition of PTH response (40% for TNF. 24% for IL 1) occuring at 10-8 M of either monikine. Both monokines also decreased adenylate cyclase stimulation by the tumor-derived PTH-related Protein (PTHrP). In contrast, TNF and IL 1 had little or no inhibitory effect on receptor-mediated stimulation of adenylate cyclase by isoproterenol and nonreceptors-mediated enzyme activation by cholera toxin forskolin; both monokines increased prostaglandin E2 stimulation of adenylate cyclase. Binding of the radiodinated agonistt mono-[125I]-[Nle3, 18, Tyr34]bPTH-(1-34)NH2 to UMR-106 cells in the presence of increasing concentrations of unlabeled [Nle8,18, Tyr34]bPTH-(1-34)NH2 revealed a decline in PTH receptor density (Bmax) without change in receptor binding affinity (dissociation constant, Kd) after treatment with TNF or IL 1. Pertusis toxin increased PTH-sensitive adenylate cyclase activity but did not attenuate monokine-induced inhibiton of PTH response. In time course studies, brief (1hr) exposure of cells to TNF or IL 1 during early culture was sufficient to decrease PTH response but only after exposed cells were subsequently allowed to grow for prolonged periods. Inhibition of PTH response by monokines was blocked by cycloheximide. The results and indicate that TNF and IL 1 impair responsiveness to PTH (and PTHrP) by a time protein synthesis-dependent down-regulation of PTH receptors linked to adenylate cyclase. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041530125
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  • 3
    Electronic Resource
    Electronic Resource
    Retinoic acid nuclear receptor β inhibits breast carcinoma anchorage independent growth (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 165 (1995), S. 449-458 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Retinoids modulate cellular proliferation and mediate gene function through a series of nuclear receptors. The retinoic acid nuclear receptor β (RARβ) plays an important role in the differentiation of a number of cell types. We now demonstrate that RARβ expresion is confined to normal mammary tissue and is not expressed in either immortalized normal or malignant cell lines. Treatment of RARβ-transfected MDA-MB-231 cells with 1 μM all-trans-retinoic acid (RA) significantly inhibited monolayer growth of the cells which express recombinant RARβ. RARβ-expressing MDA-MB-231 cells formed significantly smaller and fewer colonies soft agar than the mock-transfected cells. Addition of 1 μM RA stimulated colony size and number in the RARβ-transfected MDA-MB-231 cells. In contast to the RARβ-expressing cells, colony formation by the RARβ-expressing cells was similar to the mock-transfected controls and the addition of 1 μM RA to the RARα-transfected cells inhibited colony formation. While demonstrating decreased colony formation in agar, RARβ-expressing MDA-MB-231 cells failed to exhibit decreased growth in SCID mice. Our results show that RARβ functions as a negative regulator of growth in breast epithelial cells. In addition, the growth of these cells is differentially regulated by RARα and RARβ which is most likely the result to the modulation of different genes. © 1995 Wiley-Liss Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041650302
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  • 4
    Electronic Resource
    Electronic Resource
    Transforming growth factor β enhances parathyroid hormone stimulation of adenylate cyclase in clonal osteoblast-like cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 144 (1990), S. 438-447 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of transforming growth factor β (TGFβ) on parathyroid hormone (PTH)-responsive adenylate cyclase were examined in clonal rat osteosarcoma cells (UMR-106) with the osteoblast phenotype. Purified TGFβ incubated with UMR-106 cells for 48 hr produced a concentration-dependent increase in PTH stimulation of adenylate cyclase, with maximal increase in PTH response (37%) occurring at 1 ng/ml TGFβ. TGFβ also enhanced receptor-mediated activation of adenylate cyclase by isoproterenol and prostaglandin E2 (PGE2) and nonreceptormediated enzyme activation by cholera toxin and forskolin. In cells in which PTH-stimulated adenylate cyclase activity was augmented by treatment with pertussis toxin, the incremental increase in PTH response produced by TGFβ was reduced by 33%. However, TGFβ neither mimicked nor altered the ability of pertussis toxin to catalyze the ADP-ribosylation of a 41, 000-Da protein, presumably the α subunit of the inhibitory guanine nucleotide-binding regulatory component (Gi) of adenylate cyclase, in cholate-extracted UMR-106 cell membranes. TGFβ also had no effect on the levels of α or β subunits of Gi, as assessed by immunotransfer blotting. In time course studies, brief (≥ 30 min) exposure of cells to TGFβ during early culture was sufficient to increase PTH response but only after exposed cells were subsquently allowed to grow for prolonged periods. TGFβ enhancement of PTH and isoproterenol responses was blocked by prior treatment of cells with cycloheximide but not indomethacin. The results suggest that TGFβ enhances PTH response in osteoblast-like cells by action(s) exerted at nonreceptor components of adenylate cyclase. The effect of TGFβ may involve Gi, although in a manner unrelated to either pertussis toxin-catalyzed ADP-ribosylation of the α subunit of Gi or changes in levels of Gi subunits. The regulatory action of TGFβ on adenylate cyclase is likely to be mediated by the rapid generation of cellular signals excluding prostaglandins, followed by a prolonged sequence of events involving protein synthesis. These observations suggest a mechanism by which TGFβ may regulate osteoblast responses to systemic hormones.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041440311
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic characterization of Tetrahymena thermophila mutants unable to secrete capsules (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 160-166 
    Details
    ISSN: 0192-253X
    Keywords: Deletion mapping ; exocytosis ; genetic complementation ; genomic exclusion ; mucocyst ; nullisomic strains ; regulated secretion ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Under appropriate conditions, Alcian Blue-induced exocytosis of Tetrahymena mucocysts leads to formation of a capsule that surrounds the cell. This phenomenon is an example of regulated secretion, a mechanism of fundamental significance in eukaryotic cells. In order to dissect genetically the mechanism of mucocyst biogenesis and regulated exocytosis, mutants unable to form capsules (Caps-) were isolated. In this paper we report a genetic characterization of Caps- mutants in this collection. The mutations in mutants SB255 and SB281 behave as single recessive Men-delian mutations. The mutation in SB251 is restricted to the macronucleus, and could not be further characterized by the genetic methods we used. Complementation tests suggest the existence of at least 2 genes, named exoA and exoB; additional mutant loci are likely to be included in the mutant collection. Deletion mapping using nulli-somic strains showed that exoA and exoB are located on the left arm of chromosome 4. The exo-3 mutation, which behaves as recessive and complements with exoA1 in SB255 and exoB2 in SB281, maps to chromosome 3. These Caps- mutants may be useful for the elucidation of the developmental pathway of mucocyst biogenesis and the control of regulated secretion in eukaryotic cells. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130210
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  • 6
    Electronic Resource
    Electronic Resource
    Genetic determination of sporangiophore development in Phycomyces (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 733-741 
    Details
    ISSN: 0192-253X
    Keywords: Phycomyces blakesleeanus ; developmental mutants ; phorogenesis ; sexual reproduction ; light ; carotene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mycelium of the fungus Phycomyces. essentially a giant multinucleate cell, produces two kinds of asexual reproductive structures, called macrophores and microphores, and a succession of structures for sexual reproduction. Following the treatment of spores with N-methyl-N′ -nitro-N-nitrosoguanidine, conditional imb mutants have been isolated that form no macrophores at 26°C, but do at 14°C. At the restrictive temperature, few imb mutants (2 of 13) develop microphores, and none is able to complete the sexual cycle. This suggests that genes responsible for macrophorogenesis are involved in microphorogenesis and in sexual development as well. Light reduces macrophorogenesis and totally abolishes microphorogenesis in the wild type under the conditions of our experiments. These photomorphogenetic effects require the normal function of genes madA and madB, which are responsible for phototropism. Light inhibits microphorogenesis in the two imb mutants that form microphores at the restrictive temperature. Genetic alterations of carotenogenesis lead to an excess of microphores and a scarcity of macrophores in the dark, but they have little influence on vegetative reproduction in the light.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090605
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  • 7
    Electronic Resource
    Electronic Resource
    Cloning and dosage compensation of the 6-phosphogluconate dehydrogenase gene (Pgd+) of Drosophila melanogaster (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 155-161 
    Details
    ISSN: 0192-253X
    Keywords: 6PGD ; 6-phosphogluconate dehydrogenase ; X chromosome ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Using a heterologous rat cDNA probe, we have identified a 14.7 kbp Drosophila melanogaster genomic clone containing the X-linked gene Pgd+, which encodes the enzyme 6-phosphogluconate dehydrogenase (6PGD). We used in situ hybridization to larval polytene chromosomes, a somatic transient expression assay for enzyme activity, and the rescue of the lethal Pgd- phenotype by germline transformation to verify the identity of the gene. A 7.4 kbp fragment including the gene and approximately 1.2 kbp of upstream and 1.8 kbp of downstream sequences was relocated to autosomal ectopic sites by germline transformation; this transduced gene exhibits levels of enhanced activity in males comparable to those of the indigenous gene at its normal X chromosome locus. We conclude that the sequences responsible for dosage compensation of Pgd+ are included in this fragment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100305
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular mechanisms of the antihormonal and antiimplantation effects of norethisterone and its a-ring reduced metabolites (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 157-163 
    Details
    ISSN: 1040-452X
    Keywords: Synthetic progestins ; Uteroglobin ; Pregnancy ; Rabbit endometrium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Norethisterone (NET) has been used as a contragestational postcoital agent. It is biotrans-formed to 5α dihydro-NET (5α-NET) and 3β,5α tetrahydro-NET (3β,5α-NET) in target tissues. The participation of these metabolites in NET effects is unknown. We have examined the antiimplantation and antiprogestational effects of NET and its metabolites, in adult mated female rabbits, by assessing the number of implantation sites and the expression products of the uteroglobin (UTG) gene in the uterus, and by comparing them with those of RU-486 and estradiol. Steroids were daily administered s.c. at several doses for 7 consecutive days, starting 24 hr after coitus. To assure that fertilization occurred in all animals, the presence of early pregnancy factor was determined. The results demonstrated that high doses (5 mg/kg) of NET reduced both implantation and the expression of the UTG gene. On the other hand, lower doses (1.5 mg/kg) of 5α-NET produced an antiimplantation effect and suppressed UTG synthesis and its mRNA. These effects were similar to those of RU-486. At lower doses (1 mg/kg), both estradiol and the estrogenic metabolite 3β,5α-NET were also effective in inhibiting implantation and UTG gene expression. The overall results suggest that NET metabolites exert antiimplantation and antiprogestational effects through their interaction with progesterone and estrogen receptors, and provide an explanation for the molecular mechanisms involved in the postcoital contraceptive action of NET. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080400204
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  • 9
    Electronic Resource
    Electronic Resource
    Nickel nitrate: A new junction permeability tracer for the study of the blood-testis barrier (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 20 (1992), S. 34-42 
    Details
    ISSN: 1059-910X
    Keywords: Intercellular tracer ; Lanthanum ; Testis ; Galea ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: With the purpose of evaluating a new intercellular tracer, nickel-K ferrocyanide, we compared results yielded by lanthanum with information provided by nickel. This was done in the seminiferous epithelium of Holtzman rats of several postnatal ages and in a wild local seasonal breeder Galea musteloides. Tissues were studied with transmission electron microscopy and freezefracture replications. Nickel tracing proved to delineate cell contours more intensely and less interruptedly than lanthanum. With regard to seasonal variations in adult galea, the limits of the barrier were similar to those described in other mammals: spermatogonia, preleptotene, and leptotene spermatocytes were surrounded by the tracer in the basal compartment. The zygotenepachytenes were contained in the lumenal compartment and tracers were stopped at the inter - Sertoli cell tight junctions. During the inactive spermatogenic phase in winter, the seminiferous epithelium contained Sertoli cells and occasional germ cells, never beyond the spermatocyte stage. The tracer filled intercellular spaces, indicating that the barrier was incompetent. Some resting germ cells showed nuclear hyperchromasia, karyolysis, organelle loss, cell shrinkage, and cell fusion leading to a multinucleated cells. The inter-Sertoli tight junctions were scanty and had randomly oriented and discontinuous junctional strands. Moreover, inter - Sertoli cell gap junctions proliferated. During the active spermatogenic phase in summer, junctions were numerous. Their junctional strands were parallel to each other, and continuous.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070200105
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  • 10
    Electronic Resource
    Electronic Resource
    Endometrial expression of progesterone receptor and uteroglobin genes during early pregnancy in the rabbit (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 244-249 
    Details
    ISSN: 1040-452X
    Keywords: Steroid receptors ; Rabbit endometrium ; Hormone regulation ; Gene expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The progesterone receptor (PR) plays a pivotal role in the maturation process of the secretory endometrium, implantation and maintenance of pregnancy in rabbits. To determine the dynamics of PR gene expression and its physiological significance, the endometrial expression of PR and PR mRNA were evaluated and compared with the expression of the progesterone-regulated uteroglobin (UG) gene during 0-5 days post-coitus in rabbits. The results of immunoblot experiments indicated the presence of PR in endometrial cell extracts from days 1-4 of pregnancy with maximum PR immunostaining on day 2, followed by a marked diminution until its complete disappearance on day 5. When endometrial PR mRNA content was assessed by Northern blots, the results were similar to those of PR immunostaining, with maximal concentrations on the second day after mating. However, PR mRNA levels were still high on day 3, despite the concomitant decrease in immunostainable PR. Endometrial UG gene expression, on the other hand, exhibited a different time sequence. Thus, the UG content in uterine flushings progressively increased from day 3 after mating, reaching maximal levels on the fifth day. The endometrial UG mRNA content presented a similar profile, as its maximum concentration occurred on days 4-5. The overall results indicate that endometrial PR is down-regulated at both the mRNA and protein levels, possibly by endogenous progesterone during early pregnancy. The striking observation that maximal expression of endometrial UG gene products occurred when PR and its mRNA are no longer detectable suggests an important role for this progesterone-binding uterine protein during the preimplantation period. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080340303
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