Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estrogen has an important role in the reconstruction of a new vascular network in the endometrium during each menstrual cycle; however, the underlying mechanisms are incompletely understood. Angiopoietin-1 (Ang-1) promotes vessel assembly, whereas Ang-2 and thrombospondin-1 (TSP-1) cause vessel breakdown. To determine the potential effect of estrogen on the expression of these angioregulatory factors in the endometrium, Ang-1, Ang-2, TSP-1, and Tie-2 receptor mRNA levels were assessed by real-time reverse transcriptase polymerase chain reaction in glandular epithelial and stromal cells isolated from the endometrium of ovariectomized baboons treated acutely with estradiol. Corresponding protein expression was assessed by immunocytochemistry and the proximity ligation assay (PLA) during advancing stages of the baboon menstrual cycle. Serum estradiol levels in ovariectomized baboons were 400 pg/ml within 4-6 hr of estradiol treatment. Ang-1 mRNA levels in glandular epithelial cells increased threefold (P < 0.01) within 4 hr of estradiol administration. In contrast, TSP-1 mRNA levels decreased four- to fivefold (P < 0.01) in endometrial glandular epithelial and stromal cells 4-6 hr after estradiol, whereas Ang-2 and Tie-2 expression was unaltered. Immunostaining for Ang-1 increased, TSP-1 decreased, and Ang-2 and Tie-2 were unaltered in the endometrium during the secretory compared with the proliferative phase of the cycle. Endometrial Ang-1 protein expression, quantified by PLA, increased 10-fold (P < 0.05) between the early proliferative and late proliferative/mid-secretory phases of the menstrual cycle in association with the rise in estrogen. In summary, estrogen induced a rapid, divergent, and cell-specific change in expression of angiostimulatory and angioinhibitory growth factors in the endometrium of the nonhuman primate.
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PMID:Divergent regulation of angiopoietin-1 and -2, Tie-2, and thrombospondin-1 expression by estrogen in the baboon endometrium. 2014 Sep 67

Hematopoietic processes, especially megakaryocytopoiesis and thrombopoiesis, are highly sensitive to extracellular oxidative stresses such as ionizing radiation and chemotherapeutic agents. This study examined the terminal maturation of megakaryocytes and platelet production in hematopoietic stem/progenitor cells (HSPCs) exposed to ionizing radiation. Highly purified CD34(+) cells derived from human placental/umbilical cord blood were exposed to X rays (2 Gy, 150 kVp, 20 mA; 0.5-mm aluminum and 0.3-mm copper filters) at a dose rate of approximately 1 Gy/min and then cultured in a serum-free medium supplemented with thrombopoietin and interleukin-3. The number of cells generated from X-irradiated CD34(+) cells decreased with the time in culture. However, the fraction of CD34(+)Tie-2(+) and CD41(+)Tie-2(+) cells among the total cells generated from X-irradiated cells increased significantly in comparison to nonirradiated controls on day 7. In addition, the CD42a(+) particles, which appeared to be platelets, generated from the X-irradiated HSPCs appeared to be normal. Quantitative real-time reverse transcriptase-polymerase chain reaction analysis of the expression of various genes in cells harvested from the cultures showed that the early hematopoiesis-related genes FLI1, HOXB4 and Tie-2, the cytokine receptor genes KIT and IL3RA, and the oxidative stress-related genes HO1 and NQO1 were upregulated on day 7. These results suggest that normal terminal maturation of megakaryocytes and platelet production occur in residual HSPCs after exposure to ionizing radiation despite the adverse effect of radiation on proliferation and differentiation of HSPCs. Ionizing radiation may have the potential to promote both megakaryocytopoiesis and thrombopoiesis.
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PMID:Megakaryocytopoiesis and thrombopoiesis in hematopoietic stem cells exposed to ionizing radiation. 2202 86


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