192 Micro RNA induction by interferon alpha and their potential role to interfere in the negative feedback pathway

Abstract Background: Red blood cells regulate tissue circulation and O2 delivery by releasing the vasodilator adenosine triphosphate (ATP) in response to hypoxia. When released extracellularly, ATP is rapidly degraded to adenosine diphosphate (ADP) in the circulation by ectonucleotidases. ATP and ADP activate subtypes of the large P2 receptor family (15 subtypes). Here we show that ADP acting on P2Y13 receptors on red blood cells serves as a negative feedback pathway for the inhibition of ATP release. Methods: mRNA was quantified with real-time PCR. Western blot was used to detect P2 receptors with available antibodies. cAMP levels were determined with an enzyme immunoassay. ATP release was measured in incubated red blood cells using microdialysis and a luciferase assay. In a pig model, catheters were inserted through the carotid artery to place a catheter in the left coronary artery, and through the jugular vein to place a microdialysis probe in the coronary vein. 2-MeSADP was injected in the artery and ATP levels were measured in the coronary vein. Results: mRNA of the ADP receptor P2Y13 was highly expressed in human red blood cells and reticulocytes, whilst other ADP receptors were not (Fig.1). Figure Figure The stable ADP analogue 2-MeSADP decreased ATP release from red blood cells by inhibition of cAMP. The P2Y12 and P2Y13 receptor antagonist AR-C67085 (30 mM), but not the P2Y1 blocker MRS2179, inhibited the effects of 2-MeSADP. At doses where AR-C67085 only blocks P2Y12 (100 nM), it had no effect. AR-C67085 and the nucleotidase apyrase increased cAMP per se, indicating a constant cAMP inhibitory effect of endogenous extracellular ADP. 2-MeSADP reduced plasma ATP concentrations in an in vivo pig model. Furthermore, a missense polymorphism in the coding region of P2Y13 has been found that is in total disequilibrium with 5 polymorphisms in P2Y12 (the important ADP receptor in platelets) forming a haplotype that could contribute to vascular disease. Conclusion: Our results show that P2Y13 is selectively expressed in human red blood cells. The ATP degradation product ADP inhibited ATP release by acting on this receptor. This negative feedback system could be important in the control of plasma ATP levels and tissue circulation. Because blood consists of approximately 40% red blood cells, containing a 1000-fold higher ATP concentration than plasma (mM vs. uM), even a minor release of ATP from the high intracellular concentrations could have major circulatory effects. A negative system may therefore be of great physiological importance to mitigate ATP release. In addition, this finding could be of interest for efforts to preserve intracellular ATP in red blood cells during storage.

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Integrin-αIIbβ3-mediated outside-in signalling activates a negative feedback pathway to suppress platelet activation

Thrombosis and Haemostasis ◽

10.1160/th16-02-0096 ◽

2016 ◽

Vol 116 (11) ◽

pp. 918-930 ◽

Cited By ~ 8

Author(s):

Baiyun Dai ◽

Peng Wu ◽

Feng Xue ◽

Renchi Yang ◽

Ziqiang Yu ◽

...

Keyword(s):

Flow Cytometry ◽

Platelet Activation ◽

Negative Feedback ◽

Human Platelets ◽

Wild Type ◽

Integrin Αiibβ3 ◽

Atp Secretion ◽

Platelet Disaggregation ◽

Feedback Pathway

SummaryIntegrin-αIIbβ3-mediated outside-in signalling is widely accepted as an amplifier of platelet activation; accumulating evidence suggests that outside-in signalling can, under certain conditions, also function as an inhibitor of platelet activation. The role of integrin-αIIbβ3-mediated outside-in signalling in platelet activation is disputable. We employed flow cytometry, aggregometry, immunoprecipitation, and immunoblotting to investigate the role of integrin-αIIbβ3-mediated outside-in signalling in platelet activation. Integrin αIIbβ3 inhibition enhances agonist-induced platelet ATP secretion. Human platelets lacking expression of αIIbβ3 exhibited more platelet ATP secretion than their wild-type counterparts. Moreover, integrin-αIIbβ3-mediated outside-in signals activate SHIP-1, which in turn mediates p-Akt dep-hosphorylation, leading to inactivation of PI3K/Akt signalling. Furthermore, 3AC (SHIP-1 inhibitor) inhibits platelet disaggregation, and promotes platelet ATP secretion. Upon ADP stimulation, Talin is recruited to αIIbβ3, and it is dissociated from αIIbβ3 when platelets disaggregate. In addition, treatment with RUC2, an inhibitor of αIIbβ3, which blocks αIIbβ3-mediated outside-in signalling, can markedly prevent the dissociation of talin from integrin. SHIP1 Inhibitor 3AC inhibits the dissociation of talin from integrin-β3. These results suggest that integrin-αIIbβ3-mediated outside-in signalling can serve as a brake to restrict unnecessary platelet activation by activated SHIP-1, which mediated the disassociation of talin from β3, leading to integrin inactivation and blocking of PI3K/Akt signalling to restrict platelet ATP secretion.

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Faculty Opinions recommendation of FoxO3a regulates hematopoietic homeostasis through a negative feedback pathway in conditions of stress or aging.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1136884.593980 ◽

2008 ◽

Author(s):

Nelson Chao ◽

John Chute

Keyword(s):

Negative Feedback ◽

Feedback Pathway

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1699-P: Mechanisms and Roles of Foxo1-Akt Negative Feedback Pathway in Adipocytes

Diabetes ◽

10.2337/db20-1699-p ◽

2020 ◽

Vol 69 (Supplement 1) ◽

pp. 1699-P

Author(s):

TOMOHIRO OHNO ◽

HIRAKU ONO ◽

KOUTARO YOKOTE

Keyword(s):

Negative Feedback ◽

Feedback Pathway

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A horizontal cell selectively contacts blue-sensitive cones in cyprinid fish retina : intracellular staining with horseradish peroxidase

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1988.0076 ◽

1988 ◽

Vol 235 (1280) ◽

pp. 281-287 ◽

Cited By ~ 8

Keyword(s):

Horseradish Peroxidase ◽

Negative Feedback ◽

Horizontal Cell ◽

Cyprinid Fish ◽

Horizontal Cells ◽

Intracellular Staining ◽

Yellow Orange ◽

Fish Retina ◽

Feedback Pathway

A horizontal cell selectively contacting blue-sensitive cones has been intracellularly stained with horseradish peroxidase in the retina of a cyprinid fish, the roach. The light microscopical morphology of the cell belonged to the H3 category of horizontal cells found in cyprinid fish retinae. In response to spectral stimuli, the cell generated chromaticity-type S-potentials that were hyperpolarizing to blue and depolarizing to yellow-orange. A red-sensitive hyperpolarizing component was absent possibly because of suppression of the negative feedback pathway between luminosity-type (H1) horizontal cells and green-sensitive cones.

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The growth hormone response to repeated bouts of sprint exercise with and without suppression of lipolysis in men

Journal of Applied Physiology ◽

10.1152/japplphysiol.00534.2007 ◽

2008 ◽

Vol 104 (3) ◽

pp. 724-728 ◽

Cited By ~ 9

Author(s):

Keith A. Stokes ◽

Christopher Tyler ◽

Kate L. Gilbert

Keyword(s):

Growth Hormone ◽

Negative Feedback ◽

Potential Role ◽

Cycle Ergometer ◽

The Other ◽

Hormone Response ◽

Healthy Men ◽

Repeated Exercise ◽

Negative Feedback Control ◽

Response To Exercise

A single 30-s sprint is a potent physiological stimulus for growth hormone (GH) release. However, repeated bouts of sprinting attenuate the GH response, possibly due to negative feedback via elevated systemic free fatty acids (FFA). The aim of the study was to use nicotinic acid (NA) to suppress lipolysis to investigate whether serum FFA can modulate the GH response to exercise. Seven nonobese, healthy men performed two trials, consisting of two maximal 30-s cycle ergometer sprints separated by 4 h of recovery. In one trial (NA), participants ingested NA (1 g 60 min before, and 0.5 g 60 and 180 min after sprint 1); the other was a control (Con) trial. Serum FFA was not significantly different between trials before sprint 1 but was significantly lower in the NA trial immediately before sprint 2 [NA vs. Con: mean (SD); 0.08 (0.05) vs. 0.75 (0.34) mmol/l, P < 0.05]. Peak and integrated GH were significantly greater following sprint 2 compared with sprint 1 in the NA trial [peak GH: 23.3 (7.0) vs. 7.7 (11.9) μg/l, P < 0.05; integrated GH: 1,076 (350) vs. 316 (527) μg·l−1·60 min−1, P < 0.05] and compared with sprint 2 in the Con trial [peak GH: 23.3 (7.0) vs. 5.2 (2.3) μg/l, P < 0.05; integrated GH: 1,076 (350) vs. 206 (118) μg·l−1·60 min−1, P < 0.05]. In conclusion, suppressing lipolysis resulted in a significantly greater GH response to the second of two sprints, suggesting a potential role for serum FFA in negative feedback control of the GH response to repeated exercise.

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