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Objective To explore whether microRNAs (miRNA) in astrocytes participate in regulating the phenotypic switch in the developing central nervous system (CNS). Methods The hGFAP-CreERT; Dicer fl/fl; mT/mG and Dicer fl/fl; mT/mG mice were generated and induced by tamoxifen (TMF). The)' were divided into 7 days, 10 days, 14 days Dicer conditional knock out (Dicer CKO) group and control group according to their age and the expression of hGFAP-CreERT. These 24 mice were divided into six groups and each group contained four mice. Then the change of astrocytes in the developing CNS was observed by immunofluorescenct staining. Results Both of the densities of astrocytes and microglial cells increased in the Dicer CKO mice brains as compared to littermate controls. Conclusion Dicer and miRNA of astrocytes are important for astrocytes quiescence in developing brains.
ABSTRACT
Increasing evidence has shown that astrocytes are implicated in regulating oligodendrocyte myelination, but the underlying mechanisms remain largely unknown. To understand whether microRNAs in astrocytes function in regulating oligodendroglial differentiation and myelination in the developing and adult CNS, we generated inducible astrocyte-specific Dicer conditional knockout mice (hGFAP-CreERT; Dicer fl/fl). By using a reporter mouse line (mT/mG), we confirmed that hGFAP-CreERT drives an efficient and astrocyte-specific recombination in the developing CNS, upon tamoxifen treatment from postnatal day 3 (P3) to P7. The Dicer deletion in astrocytes resulted in inhibited oligodendroglial differentiation and myelination in the developing CNS of Dicer cKO mice at P10 and P14, and did not alter the densities of neurons or axons, indicating that Dicer in astrocytes is required for oligodendrocyte myelination. Consequently, the Dicer deletion in astrocytes at P3 resulted in impaired spatial memory and motor coordination at the age of 9 weeks. To understand whether Dicer in astrocytes is also required for remyelination, we induced Dicer deletion in 3-month-old mice and then injected lysolecithin into the corpus callosum to induce demyelination. The Dicer deletion in astrocytes blocked remyelination in the corpus callosum 14 days after induced demyelination. Together, our results indicate that Dicer in astrocytes is required for oligodendroglia myelination in both the developing and adult CNS.
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Exposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreER
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Exposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreER
Subject(s)
Animals , Mice , Clemastine , Hypoxia/complications , Mice, Inbred C57BL , Mice, Transgenic , Myelin Sheath , OligodendrogliaABSTRACT
Objective To provide data reference for later researchers to visually and conveniently recognize the key research areas of coronavirus, quickly find important literature and influential research partners by analyzing the research literature on coronavirus. Methods Data from the Web of Science Core Collection database were selected to systematically collate the literature on coronavirus research from 1968 to 2019, and the literature type distribution, annual number of papers, countries, institutions, journals, authors, literature co citation, and emerging key words were analyzed using Microsoft Excel 2019 and CiteSpace 5.5.R2 software. Results As of December 31, 2019, a total of 13,959 papers on coronavirus have been published. Global coronavirus research is divided into three periods: The initial research period (1968-2003), the first golden development period (2004-2012) and the second golden development period (2013-2019). United States is the country with the largest number of publications; the University of Hong Kong is the institution with the largest number of publications, and the Journal of Virology ranks first in the number and influence of publications. Peiris JSM, Drosten C and Ksiazek TG are good partners in the field of coronavirus research. Conclusions "SARS-CoV", "infectious disease", "coronavirus spike protein" may attract close attention in the field of coronavirus research.
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<p><b>OBJECTIVE</b>To explore the expression of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in early stage of diabetic retinopathy (DR) in Macaca mulatta.</p><p><b>METHODS</b>Three diabetic Macaca mulattas induced by high-fat diet were identified for early stage of diabetic retinopathy according to the fasting plasma glucose, hemoglobin Alc (HbA1c), fundus photograph and duration of diabetes, with another 3 age-matched healthy Macaca mulattas as control. The expression of VEGF and PEDF in the retinas of Macaca mulatta were detected by quantitative real-time PCR and immunohistochemistry.</p><p><b>RESULT</b>In early stage of diabetic retinopathy, VEGF mRNA and protein of the diabetic group were both significantly increased compared with the control group (P<0.05). PEDF expression at both mRNA and protein levels was significantly decreased in diabetic Macaca mulattas compared with the control group (P<0.01 and 0.05 respectively).</p><p><b>CONCLUSION</b>Retinal VEGF expression is increased and PEDF expression is decreased in early stage of diabetic retinopathy, suggesting their involvement in the occurrence of diabetic retinopathy and their value in assisting in the early diagnosis.</p>