scholarly journals Social Fear Memory Requires Two Stages of Protein Synthesis in Mice

2020 ◽  
Vol 21 (15) ◽  
pp. 5537
Author(s):  
Johannes Kornhuber ◽  
Iulia Zoicas

It is well known that long-term consolidation of newly acquired information, including information related to social fear, require de novo protein synthesis. However, the temporal dynamics of protein synthesis during the consolidation of social fear memories is unclear. To address this question, mice received a single systemic injection with the protein synthesis inhibitor, anisomycin, at different time-points before or after social fear conditioning (SFC), and memory was assessed 24 h later. We showed that anisomycin impaired the consolidation of social fear memories in a time-point-dependent manner. Mice that received anisomycin 20 min before, immediately after, 6 h, or 8 h after SFC showed reduced expression of social fear, indicating impaired social fear memory, whereas anisomycin caused no effects when administered 4 h after SFC. These results suggest that consolidation of social fear memories requires two stages of protein synthesis: (1) an initial stage starting during or immediately after SFC, and (2) a second stage starting around 6 h after SFC and lasting for at least 5 h.

1990 ◽  
Vol 110 (4) ◽  
pp. 1427-1438 ◽  
Author(s):  
S Aznavoorian ◽  
M L Stracke ◽  
H Krutzsch ◽  
E Schiffmann ◽  
L A Liotta

Transduction of signals initiating motility by extracellular matrix (ECM) molecules differed depending on the type of matrix molecule and whether the ligand was in solution or bound to a substratum. Laminin, fibronectin, and type IV collagen stimulated both chemotaxis and haptotaxis of the A2058 human melanoma cell line. Peak chemotactic responses were reached at 50-200 nM for laminin, 50-100 nM for fibronectin, and 200-370 nM for type IV collagen. Checkerboard analysis of each attractant in solution demonstrated a predominantly directional (chemotactic) response, with a minor chemokinetic component. The cells also migrated in a concentration-dependent manner to insoluble step gradients of substratum-bound attractant (haptotaxis). The haptotactic responses reached maximal levels at coating concentrations of 20 nM for laminin and type IV collagen, and from 30 to 45 nM for fibronectin. Pretreatment of cells with the protein synthesis inhibitor, cycloheximide (5 micrograms/ml), resulted in a 5-30% inhibition of both chemotactic and haptotactic responses to each matrix protein, indicating that de novo protein synthesis was not required for a significant motility response. Pretreatment of cells with 50-500 micrograms/ml of synthetic peptides containing the fibronectin cell-recognition sequence GRGDS resulted in a concentration-dependent inhibition of fibronectin-mediated chemotaxis and haptotaxis (70-80% inhibition compared to control motility); negative control peptide GRGES had only a minimal effect. Neither GRGDS nor GRGES significantly inhibited motility to laminin or type IV collagen. Therefore, these results support a role for the RGD-directed integrin receptor in both types of motility response to fibronectin. After pretreatment with pertussis toxin (PT), chemotactic responses to laminin, fibronectin, and type IV collagen were distinctly different. Chemotaxis to laminin was intermediate in sensitivity; chemotaxis to fibronectin was completely insensitive; and chemotaxis to type IV collagen was profoundly inhibited by PT. In marked contrast to the inhibition of chemotaxis, the hepatotactic responses to all three ligands were unaffected by any of the tested concentrations of PT. High concentrations of cholera toxin (CT; 10 micrograms/ml) or the cAMP analogue, 8-Br-cAMP (0.5 mM), did not significantly affect chemotactic or haptotactic motility to any of the attractant proteins, ruling out the involvement of cAMP in the biochemical pathway initiating motility in these cells. The sensitivity of chemotaxis induced by laminin and type IV collagen, but not fibronectin, to PT indicates the involvement of a PT-sensitive G protein in transduction of the signals initiating motility to soluble laminin and type IV collagen.(ABSTRACT TRUNCATED AT 400 WORDS)


1998 ◽  
Vol 274 (1) ◽  
pp. R120-R125 ◽  
Author(s):  
Tohru Sakakibara ◽  
Thomas H. Hintze ◽  
Alberto Nasjletti

We studied the determinants of kinin release into the venous effluent of rat hindquarters perfused with Krebs bicarbonate buffer. Kinin release in preparations perfused with control media (14.6 ± 2.5–20.7 ± 6.7 pg/15 min) was surpassed by that in preparations perfused with media containing kininase inhibitors (243 ± 53 to 276 ± 78 pg/15 min). Kinin release increased when purified kininogen (from 242 ± 43 to 3,365 ± 725 pg/15 min) or kallikrein (from 270 ± 49 to 30,649 ± 8,040 pg/15 min) was added to the perfusate. Conversely, kinin release fell when the kallikrein inhibitor aprotinin (from 272 ± 58 to 122 ± 27 pg/15 min) or soybean trypsin inhibitor (from 273 ± 52 to 195 ± 25 pg/15 min) was added. Both basal and kininogen-induced kinin release were attenuated in preparations perfused with media containing cycloheximide, a protein synthesis inhibitor, but kallikrein-induced kinin release was not. These data suggest that kinin release from perfused rat hindquarters reflects the activity of both the kinin-degrading and kinin-generating pathways and that the latter is sustained by a kallikrein manufactured de novo and by preexistent kininogen(s).


1994 ◽  
Vol 179 (4) ◽  
pp. 1225-1232 ◽  
Author(s):  
M Pouliot ◽  
P P McDonald ◽  
P Borgeat ◽  
S R McColl

The synthesis of leukotrienes in human blood neutrophils chiefly relies on the activity of two enzymes, phospholipase A2 and 5-lipoxygenase (5-LO). In turn, the activation of the 5-LO requires the participation of a recently characterized membrane-bound protein, the 5-LO-activating protein (FLAP). In this study, we have investigated conditions under which FLAP expression in neutrophils may be modulated. Of several cytokines tested, only granulocyte/macrophage colony-stimulating factor (GM-CSF) (and to a lesser extent tumor necrosis factor alpha) significantly increased expression of FLAP. GM-CSF increased FLAP mRNA steady-state levels in a time- and dose-dependent manner. The stimulatory effect of GM-CSF on FLAP mRNA was inhibited by prior treatment of the cells with the transcription inhibitor, actinomycin D, and pretreatment of the cells with the protein synthesis inhibitor, cycloheximide, failed to prevent the increase in FLAP mRNA induced by GM-CSF. The accumulation of newly synthesized FLAP, as determined by immunoprecipitation after incorporation of 35S-labeled amino acids, was also increased after incubation of neutrophils with GM-CSF. In addition, the total level of FLAP protein was increased in GM-CSF-treated neutrophils, as determined by two-dimensional gel electrophoresis, followed by Western blot. GM-CSF did not alter the stability of the FLAP protein, indicating that the effect of GM-CSF on FLAP accumulation was the consequence of increased de novo synthesis as opposed to decreased degradation of FLAP. Finally, incubation of neutrophils with the synthetic glucocorticoid dexamethasone directly stimulated the upregulation of FLAP mRNA and protein, and enhanced the effect of GM-CSF. Taken together, these data demonstrate that FLAP expression may be upmodulated after appropriate stimulation of neutrophils. The increase in FLAP expression induced by GM-CSF in inflammatory conditions could confer upon neutrophils a prolonged capacity to synthesize leukotrienes.


1980 ◽  
Vol 84 (1) ◽  
pp. 1-15
Author(s):  
J. W. Jacklet

1. The circadian rhythm of compound action potentials (CAP) frequency recorded from the isolated eye of Aplysia in culture medium and darkness was subjected to step and pulse treatments with anisomycin, a protein synthesis inhibitor. 2. The step application of anisomycin and its continued presence in the culture medium lengthened the period of the rhythm in a dose-dependent manner. At 10(−8) M the period was increased from the normal 26.5 h to about 28 h and at 10(−7) M the period was lengthened to 31 h or longer. At 10(−6) M the rhythm was suppressed but the CAP activity continued without the cyclic variations in CAP frequency. 3. Six-hour pulses of anisomycin at 10(−6) M caused phase-dependent phase-shifts of the rhythm. Maximum phase delays of 15 h were obtained at CT (circadian time) 2 and maximum phase advances of 4 h were obtained at CT 6. The phase response curves at 12, 15 and 17 degrees C were essentially identical. 4. Anisomycin appears to act rather selectively on the circadian clock mechanism. It does not alter the CAP amplitude and duration and it does not alter the bursting pacemaker mechanism of the optic nerve CAP or central neurones. 5. The results support the hypothesis that the synthesis of a protein or polypeptide on eucaryotic ribosomes is an essential part of the circadian clock timing mechanism. The sensitivity of the clock to anisomycin is the same at three different temperatures (12, 15 and 17 degrees C) within the physiological range of temperatures for Aplysia, as expected for a clock whose period length is temperature compensated (Q10 1.02) over that same range. 6. At the critical phases of CT 1-4, anisomycin pulses often caused unusual perturbations of the rhythm. These effects are consistent with the hypothesis that the circadian rhythm is a multioscillator system.


2002 ◽  
Vol 282 (1) ◽  
pp. E24-E30 ◽  
Author(s):  
Ricky Cheung ◽  
Jane Mitchell

We have previously demonstrated that glucocorticoids increased Gq/11α protein expression and phospholipase C activity in the rat osteosarcoma cell line UMR 106–01. In this study, we demonstrated that G11α is the primary Gq-subtype family member expressed in UMR cells. Dexamethasone treatment increased the expression of G11α protein in both a time- and a dose-dependent manner. Glucocorticoid treatment significantly increased the half-life of G11α protein from 20.3 to 63 h. Steady-state G11α mRNA level was also increased by glucocorticoid treatment by ∼70%. This change was not the result of changes in RNA stability but rather the result of increased transcription, because the glucocorticoid-mediated upregulation of G11α mRNA was blocked by the transcription inhibitor actinomycin D. The dexamethasone induction of G11α mRNA occurred after a time lag of 12–24 h and was blocked by the protein synthesis inhibitor cycloheximide. These results suggest that the dexamethasone-induced rise in G11α protein results primarily from changes in the degradation rate of the protein, whereas changes in G11α mRNA play a smaller role and require de novo synthesis of regulatory protein(s).


2006 ◽  
Vol 23 (2) ◽  
pp. 43-46
Author(s):  
Kiyotaka Matsumura ◽  
Manami Nagano ◽  
Sachiko Tsukamoto ◽  
Haruko Kato ◽  
Nobuhiro Fusetani

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