Niches of Stem Cells

Abstract

In niches, stem cells are associated with adhesion extracellular matrix molecules (ECM). This gives rise to cells that retain their ‘stemness’, control their self-renewal and their progeny production, by using asymmetric or symmetric divisions. The adhesion molecules include N-cadherin/β-catenin, VCAM/integrin, and osteopontin /β1 integrin. They create a microenvironment that favor cell division, and interactions leading to cell differentiation. Asymmetric division contributes to self-renewal (a single division) and produce daughter cells that conduct to terminal differentiation. C-Myc is involved in controlling the balance between stem cell maintenance and proliferation. Daughter cells are expressing low levels of c-Myc. They are retained in the niche in a quiescent state, whereas, high levels of c-Myc expression in the remaining daughter cells supports the proliferation of cells and the displacement of dividing transit cells and their replacement leading to terminal differentiation.