The role of blood platelets in nucleoside metabolism: regulation of megakaryocyte development and platelet production

1988 ◽  
Vol 200 (1-2) ◽  
pp. 67-97 ◽  
Author(s):  
T. Shaw
Keyword(s):  
Blood Platelets ◽  
Platelet Production ◽  
Metabolism Regulation ◽  
Nucleoside Metabolism

scholarly journals Regulation of Platelet Production and Life Span: Role of Bcl-xL and Potential Implications for Human Platelet Diseases

2020 ◽  
Vol 21 (20) ◽  
pp. 7591
Author(s):  
Emma C. Josefsson ◽  
William Vainchenker ◽  
Chloe James
Keyword(s):  
Life Span ◽  
Human Platelet ◽  
Inflammatory Diseases ◽  
Blood Platelets ◽  
Intrinsic Apoptosis ◽  
Tumour Angiogenesis ◽  
Platelet Production ◽  
Family Protein ◽  
Platelet Number

Blood platelets have important roles in haemostasis, where they quickly stop bleeding in response to vascular damage. They have also recognised functions in thrombosis, immunity, antimicrobal defense, cancer growth and metastasis, tumour angiogenesis, lymphangiogenesis, inflammatory diseases, wound healing, liver regeneration and neurodegeneration. Their brief life span in circulation is strictly controlled by intrinsic apoptosis, where the prosurvival Bcl-2 family protein, Bcl-xL, has a major role. Blood platelets are produced by large polyploid precursor cells, megakaryocytes, residing mainly in the bone marrow. Together with Mcl-1, Bcl-xL regulates megakaryocyte survival. This review describes megakaryocyte maturation and survival, platelet production, platelet life span and diseases of abnormal platelet number with a focus on the role of Bcl-xL during these processes.

scholarly journals Regulating billions of blood platelets: glycans and beyond

Blood ◽  
2015 ◽  
Vol 126 (16) ◽  
pp. 1877-1884 ◽  
Author(s):  
Renata Grozovsky ◽  
Silvia Giannini ◽  
Hervé Falet ◽  
Karin M. Hoffmeister
Keyword(s):  
Platelet Count ◽  
Posttranslational Modifications ◽  
Platelet Transfusion ◽  
Blood Platelets ◽  
Arterial Occlusion ◽  
Organ Damage ◽  
Spontaneous Bleeding ◽  
Platelet Production ◽  
Pathological Conditions

Abstract The human body produces and removes 1011 platelets daily to maintain a normal steady state platelet count. Platelet production must be regulated to avoid spontaneous bleeding or arterial occlusion and organ damage. Multifaceted and complex mechanisms control platelet production and removal in physiological and pathological conditions. This review will focus on different mechanisms of platelet senescence and clearance with specific emphasis on the role of posttranslational modifications. It will also briefly address platelet transfusion and the role of glycans in the clearance of stored platelets.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

The Effect of Partial Splenectomy on Platelet Production in Mice

1981 ◽  
Vol 46 (03) ◽  
pp. 602-603 ◽  
Author(s):  
H Bessler ◽  
I Notti ◽  
M Djaldetti
Keyword(s):  
Peripheral Blood ◽  
Blood Platelets ◽  
Operative Procedures ◽  
Partial Splenectomy ◽  
Splenic Lymphocytes ◽  
Platelet Production ◽  
Platelet Number ◽  
Spleen Lymphocytes

SummaryThe effect of total and partial splenectomy on the number and production of circulating platelets was studied in mice. Five days after total and partial splenectomy the number of the peripheral blood platelets increased by 87% and 60%, respectively and the incorporation of 75selenium methionine (75Se-Met) into platelets was enhanced indicating that the thrombocytosis was due to increased platelet production. The results obtained by the two operative procedures were compared.Since previous work from our laboratory has shown that a factor produced by splenic lymphocytes affects the platelet number in mice, it is suggested that the differences in the number of circulating platelets observed in animals after total and partial splenectomy may reflect a difference in the number of spleen lymphocytes removed.

scholarly journals Role of 5-HT7 receptors in the immune system in health and disease

2019 ◽  
Vol 26 (1) ◽  
Author(s):  
Alejandro Quintero-Villegas ◽  
Sergio Iván Valdés-Ferrer
Keyword(s):  
Central Nervous System ◽  
Immune Response ◽  
Nervous System ◽  
Immune System ◽  
Blood Platelets ◽  
Pain Tolerance ◽  
Immune Mediated ◽  
The Central Nervous System ◽  
Health And Disease

AbstractIn mammalians, serotonin (5-HT) has critical roles in the central nervous system (CNS), including mood stability, pain tolerance, or sleep patterns. However, the vast majority of serotonin is produced by intestinal enterochromaffin cells of the gastrointestinal tract and circulating blood platelets, also acting outside of the CNS. Serotonin effects are mediated through its interaction with 5-HT receptors (5-HTRs), a superfamily with a repertoire of at least fourteen well-characterized members. 5-HT7 receptors are the last 5-HTR member to be identified, with well-defined functions in the nervous, gastrointestinal, and vascular systems. The effects of serotonin on the immune response are less well understood. Mast cells are known to produce serotonin, while T cells, dendritic cells, monocytes, macrophages and microglia express 5-HT7 receptor. Here, we review the known roles of 5-HT7 receptors in the immune system, as well as their potential therapeutic implication in inflammatory and immune-mediated disorders.

scholarly journals Intestinal miRNAs regulated in response to dietary lipids

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Judit Gil-Zamorano ◽  
João Tomé-Carneiro ◽  
María-Carmen Lopez de las Hazas ◽  
Lorena del Pozo-Acebo ◽  
M. Carmen Crespo ◽  
...  
Keyword(s):  
Small Intestine ◽  
Lipid Metabolism ◽  
Chronic Exposure ◽  
Potential Role ◽  
In Vitro Models ◽  
Dietary Lipids ◽  
Metabolism Regulation

Abstract The role of miRNAs in intestinal lipid metabolism is poorly described. The small intestine is constantly exposed to high amounts of dietary lipids, and it is under conditions of stress that the functions of miRNAs become especially pronounced. Approaches consisting in either a chronic exposure to cholesterol and triglyceride rich diets (for several days or weeks) or an acute lipid challenge were employed in the search for intestinal miRNAs with a potential role in lipid metabolism regulation. According to our results, changes in miRNA expression in response to fat ingestion are dependent on factors such as time upon exposure, gender and small intestine section. Classic and recent intestinal in vitro models (i.e. differentiated Caco-2 cells and murine organoids) partially mirror miRNA modulation in response to lipid challenges in vivo. Moreover, intestinal miRNAs might play a role in triglyceride absorption and produce changes in lipid accumulation in intestinal tissues as seen in a generated intestinal Dicer1-deletion murine model. Overall, despite some variability between the different experimental cohorts and in vitro models, results show that some miRNAs analysed here are modulated in response to dietary lipids, hence likely to participate in the regulation of lipid metabolism, and call for further research.

scholarly journals Flow-accelerated platelet biogenesis is due to an elasto-hydrodynamic instability

2020 ◽  
Vol 117 (32) ◽  
pp. 18969-18976 ◽  
Author(s):  
Christian Bächer ◽  
Markus Bender ◽  
Stephan Gekle
Keyword(s):  
Hydrodynamic Instability ◽  
Blood Platelets ◽  
Three Dimensional ◽  
Immersed Boundary ◽  
Fusion Event ◽  
Specific Flow ◽  
Actomyosin Contractility ◽  
Biophysical Mechanism ◽  
Three Dimensional Simulations

Blood platelets are formed by fragmentation of long membrane extensions from bone marrow megakaryocytes in the blood flow. Using lattice-Boltzmann/immersed boundary simulations we propose a biological Rayleigh–Plateau instability as the biophysical mechanism behind this fragmentation process. This instability is akin to the surface tension-induced breakup of a liquid jet but is driven by active cortical processes including actomyosin contractility and microtubule sliding. Our fully three-dimensional simulations highlight the crucial role of actomyosin contractility, which is required to trigger the instability, and illustrate how the wavelength of the instability determines the size of the final platelets. The elasto-hydrodynamic origin of the fragmentation explains the strong acceleration of platelet biogenesis in the presence of an external flow, which we observe in agreement with experiments. Our simulations then allow us to disentangle the influence of specific flow conditions: While a homogeneous flow with uniform velocity leads to the strongest acceleration, a shear flow with a linear velocity gradient can cause fusion events of two developing platelet-sized swellings during fragmentation. A fusion event may lead to the release of larger structures which are observable as preplatelets in experiments. Together, our findings strongly indicate a mainly physical origin of fragmentation and regulation of platelet size in flow-accelerated platelet biogenesis.

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