Department of Immunohematology and Blood Transfusion (IHB), Leiden University Medical Center, Leiden, the Netherlands.
Ann N Y Acad Sci. 2012 Aug;1266:78-93. doi: 10.1111/j.1749-6632.2012.06626.x.
All blood cells are derived from multipotent stem cells, the so-called hematopoietic stem cells (HSCs), that in adults reside in the bone marrow. Most types of blood cells also develop there, with the notable exception of T lymphocytes that develop in the thymus. For both HSCs and developing T cells, interactions with the surrounding microenvironment are critical in regulating maintenance, differentiation, apoptosis, and proliferation. Such specialized regulatory microenvironments are referred to as niches and provide both soluble factors as well as cell-cell interactions between niche component cells and blood cells. Two pathways that are critical for early T cell development in the thymic niche are Wnt and Notch signaling. These signals also play important but controversial roles in the HSC niche. Here, we review the differences and similarities between the thymic and hematopoietic niches, with particular focus on Wnt and Notch signals, as well as the latest insights into regulation of these developmentally important pathways.
所有的血细胞都来源于多能干细胞，即所谓的造血干细胞（HSCs），在成年人中，造血干细胞存在于骨髓中。大多数类型的血细胞也在那里发育，只有 T 淋巴细胞在胸腺中发育是个例外。对于 HSCs 和正在发育的 T 细胞来说，与周围微环境的相互作用对于调节其维持、分化、凋亡和增殖至关重要。这种专门的调节微环境被称为龛，提供龛内细胞与血细胞之间的可溶性因子以及细胞-细胞相互作用。Wnt 和 Notch 信号通路是胸腺龛中早期 T 细胞发育所必需的两条通路。这些信号在造血龛中也发挥着重要但有争议的作用。在这里，我们将回顾胸腺龛和造血龛之间的差异和相似之处，特别关注 Wnt 和 Notch 信号，以及对这些对发育至关重要的通路的最新调控见解。
