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Sheila Andreatta-Van Leyen Joan R. Hembree Richard L. Eckert 《Journal of cellular physiology》1994,160(2):265-274
Insulin-like growth factors (IGFs) are important regulators of epithelial cell growth. The mitogenic activity of these factors is influenced by the levels of extracellular IGF binding proteins, including insulin-like growth factor binding protein 3 (IGFBP-3). In the present report we study the effects of epidermal growth factor (EGF) and all-trans-retinoic acid (RA) on IGFBP-3 RNA and protein levels in human papillomavirus-immortalized cervical epithelial cells. Treatment of ECE16-1 cells with 3–20 ng/ml EGF causes a marked reduction in IGFBP-3 levels. In contrast, 1 μM RA increases IGFBP-3 mRNA and protein levels in the presence or absence of 20 ng/ml EGF. The response is concentration dependent with a half-maximal increase observed at 1 nM RA. RA is able to reverse the EGF suppression when added simultaneously or 3 days after initiation of EGF treatment. Conversely, when cells are treated with RA, IGFBP-3 levels increase within 24 h and subsequent addition of EGF is without effect. Thus, the RA-dependent increase in IGFBP-3 levels is dominant over the EGF suppression. The increased IGFBP-3 levels are correlated with RA suppression of proliferation. Similar RA effects on IGFBP-3 mRNA levels were observed in other cervical epithelial cell lines (i.e., ECE16-D1, ECE16-D2, and CaSki). These results suggest that RA may act to inhibit cervical cell growth by increasing IGFBP-3 levels and reducing the extracellular concentration of free insulin-like growth factor I (IGFI) and/or, alternatively, IGFBP-3 may inhibit cell growth by direct effects on the cell, independent of IGFI. © 1994 Wiley-Liss, Inc. 相似文献
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Sheila L. Vrana Kent E. Vrana Timothy R. Koves James E. Smith Steven I. Dworkin 《Journal of neurochemistry》1993,61(6):2262-2268
Cocaine is an inhibitor of dopamine and serotonin reuptake by synaptic terminals and has potent reinforcing effects that lead to its abuse. Tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) catalyze the rate-limiting steps in dopamine and serotonin biosynthesis, respectively, and are the subject of dynamic regulatory mechanisms that could be sensitive to the actions of cocaine. This study assessed the effects of chronic cocaine on brain TH and TPH activities. Cocaine was administered (0.33 mg/infusion, i.v.) to rats for 7 days every 8 min for 6 h per day. This administration schedule is similar to patterns of self-administration by rats when given ad libitum access to this dose. This chronic, response-independent administration increased TH enzyme activity in the substantia nigra (30%) and ventral tegmental area (43%). Moreover, TH mRNA levels were also increased (45 and 50%, respectively). In contrast to the enzymatic and molecular biological changes in the cell bodies, TH activity was unchanged in the terminal fields (corpus striaturn and nucleus accumbens). Similarly, TPH activity was increased by 50% in the raphe nucleus (serotonergic cell bodies). In summary, the chronic response-independent administration of cocaine produces increases in the expression of TH mRNA and activity in both the cell bodies of motor (nigrostriatal) and reinforcement (mesolimbic) dopamine pathways. These increases are not manifested in the terminal fields of these pathways. 相似文献
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Carina Ämmälä Krister Bokvist Sheila Galt Patrik Rorsman 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1991,1092(3):347-349
The effects of a photoactivatable (DMNPE-caged) ATP-analogue on ATP-regulated K+-channels (KATP-channel) in mouse pancreatic β-cells were investigated using the inside-out patch configuration of the patch-clamp technique. The caged precursor caused a concentration-dependent reduction of channel activity with a Ki of 17 μM; similar to the 11 μM obtained for standard Mg-ATP. The small difference in the blocking capacity between the precursor and ATP is probably the reason why no change in channel activity was observed upon photolysis of the caged molecule and liberation of ATP. It is suggested that the part of the ATP molecule involved in the blocking reaction of the KATP-channel is not sufficiently protected in DMNPE-caged ATP making this compound unsuitable for studying the rapid kinetics of ATP-induced KATP-channel inhibition. 相似文献
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More than 90% of people with AIDS develop circulating immune complexes (CICs) and lymphocytotoxic antibodies (LCTAs). Animals infected with HIV, however, never display CICs or LCTAs, and remain healthy. Similarly, HIV-infected people who do not develop CICs or LCTAs also do not progress to AIDS. The appearance of CICs and LCTAs is, however, highly prognostic for AIDS and death. Since HIV infection does not,per se, lead to the development of CICs and LCTAs, other causes are likely. One such cause, for which both epidemiologic and experimental evidence exists, is semen. Semen components include sperm, seminal fluid, lymphocytes, and sometimes infectious agents, including HIV, mycoplasmas, and herpes and hepatitis viruses, all of which independently cause immune suppression. Extensive evidence demonstrates sperm (and various viruses) contains many proteins mimicking the CD4 protein of T-helper cells, while HIV, mycoplasmas, and seminal fluid mimic class II MHC proteins of other lymphocytes. We identify a large number of protein sequences that display such mimicry using computer homology searching, and demonstrate experimentally that sperm antibodies specifically precipitate antibodies against class II MHC mimics such as mycoplasmas, which in turn precipitate antibodies to lymphocyte antigens. These data prove that immunologic exposure to sperm and lymphocytes (as may occur in receptive anal intercourse, needle sharing, or blood transfusions) is theoretically capable of initiating lymphocytotoxic autoimmunity. Such autoimmunity may play a significant role in the pathogenesis of AIDS, and will need to be addressed clinically in high risk individuals regardless of HIV status and regardless of the success of anti-HIV prophylaxis and treatment. 相似文献
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Sheila Kemplay 《Cell and tissue research》1980,207(1):155-163
Summary The sprouting of parasympathetic axons into the submandibular sympathetic nerve trunk following sympathetic denervation has been investigated. It was found that a permanent sympathetic denervation was necessary in order for the sprouting to develop and be maintained: if reinnervation by adrenergic nerves was delayed, the sprouting developed but was reduced at longer survival times when the original innervation was reestablished. The evidence for suppression of the cholinergic sprouting by the adrenergic axons is discussed, as is the evidence that these sprouts arise from the submandibular gland. 相似文献
29.
Inhibition of dihydropteridine reductase by dopamine 总被引:1,自引:1,他引:0
Dihydropteridine reductase has been purified 900-fold from rat liver. Dopamine inhibited the enzyme up to 50% at a concentration of 0.11mm. In the presence of dopamine the enzyme gave non-hyperbolic v-against-[S] plots. This enzyme may have a role in control of dopamine biosynthesis. 相似文献
30.
rme1 Mutation of Saccharomyces cerevisiae: map position and bypass of mating type locus control of sporulation. 总被引:16,自引:7,他引:9
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Sporulation in Saccharomyces cerevisiae normally occurs only in MATa/MAT alpha diploids. We show that mutations in RME1 bypassed the requirements for both a and alpha mating type information in sporulation and therefore allowed MATa/MATa and MAT alpha/MAT alpha diploids to sporulate. RME1 was located on chromosome VII, between LEU1 and ADE6. 相似文献