For many years, hematopoietic stem cell kinetics and/or cell signaling pathway activity has been studied through fluorescent in vitro or in vivo models. However, inaccurate measurement of the... Show moreFor many years, hematopoietic stem cell kinetics and/or cell signaling pathway activity has been studied through fluorescent in vitro or in vivo models. However, inaccurate measurement of the fluorescent proteins or lack of knowlegde about the genetic design of these models lead to incomplete conclusions. In the present thesis, in vivo fluorescent models are improved and new models are proposed together with analysis protocols to ensure precise measurement of fluorescent protein dynamics. Show less
The immune system of mammals is responsible for protecting our body against pathogensand foreign substances (antigens), and it consists of two discrete lines of defense. The firstline called innate... Show moreThe immune system of mammals is responsible for protecting our body against pathogensand foreign substances (antigens), and it consists of two discrete lines of defense. The firstline called innate immunity and provide a quick and nonspecific defense. The innate immunityincludes different cells types, such as mast cells, macrophages, neutrophils, eosinophils,dendritic cells and natural killer (NK) cells. The second line of defense called adaptive immunityresponds in an antigen-specific manner, and comprised of B and T lymphocyte cells.This thesis focuses on one of the signals which are known to play an important role duringHSC repopulation and T cell development that is Wnt signaling pathway. Dependingon the tissue/cell types (microenvironment) and specific class of Wnt proteins binding tothe corresponding receptors on the developing lymphocytes, two discrete downstreampathways will be activated namely canonical or non-canonical Wnt pathway. The main aimof this thesis is to dissect the roles of these two distinct pathways during hematopoiesisand lymphocyte development in murine as a physiologically relevant animal model. Show less
Fallik, N.; Bar-Lavan, Y.; Greenshpan, Y.; Goldstein, O.; Grosch, M.; Drukker, M.E.; Gazit, R. 2017
Hematopoietic Stem Cells (HSCs) generate blood and immune cells through a hierarchical process of differentiation. Genes that regulate this process are of great interest for understanding normal... Show moreHematopoietic Stem Cells (HSCs) generate blood and immune cells through a hierarchical process of differentiation. Genes that regulate this process are of great interest for understanding normal and also malignant hematopoiesis. Surprisingly, however, very little is known about long-non-coding RNAs (lncRNA) in HSCs. Neat1 is a lncRNA that plays a major role in the formation of sub-nuclear structures called paraspeckles, and was reported to regulate proliferation and differentiation in other cells types. We detected Neat1 expression using RNA-seq data and RT-qPCR in HSCs, progenitors and effector immune cells, by specific detection of its isoforms. Neat1 is highly expressed in stem and progenitor cells, yet it shows significant reduction in granulocytes. Microscopically, Neat1 is detected as sharp nuclear foci. Paraspeckle proteins NONO and PSPC1 are detected as aggregated nuclear foci in fresh primary hematopoietic cells, and in cultured cells. Induction of differentiation in vitro was found to enhance Neat1 expression. Taken together, our data demonstrate for the first time the expression of Neat1 and paraspeckles formation in HSCs and along hematopoiesis. Show less
