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The balance between stem cell self-renewal and differentiation is ultimately controlled by the integration of intrinsic factors with extrinsic cues supplied by the surrounding microenvironment, known as the stem cell niche. How much do we know about this intriguing microenvironment?
The family of Argonaute proteins has important roles in RNA-mediated gene silencing. Argonaute proteins form complexes with small non-coding RNAs such as small interfering RNAs and microRNAs, control protein synthesis and mRNA stability, and participate in the production of a new class of small RNAs, Piwi-interacting RNAs.
Kinetochores are large proteinaceous structures that link centromeric DNA to spindle microtubules. More than 80 kinetochore proteins have been identified so far, and recent analyses are revealing how these proteins function to direct kinetochore specification and assembly, bind to microtubules and regulate chromosome segregation.
BCL-2 family proteins have either pro- or anti-apoptotic activities that are crucial for the regulation of apoptosis, tumorigenesis and cellular responses to anti-cancer therapy. Recent advances suggest that interactions between BCL-2 family proteins affect their localization and conformation and regulate their bioactivity.
Extracellular signals can be transduced across the plasma membrane by activating G-protein-coupled receptors. The conformational changes induced in the receptor on ligand binding and how this causes the activation of the associated G protein are beginning to be understood.
Mammalian iron homeostasis is achieved through iron acquisition and storage. Intestinal iron absorption and macrophage-mediated recycling of iron from red blood cells are highly regulated. The discovery of iron transporters and insight into their regulation has provided important information about iron-related disorders.
Studies of epidermisin vivohave revealed that a committed progenitor cell population can maintain normal adult tissue in the long term without support from a stem-cell population. Here, the stem-cell theories that explain epidermal homeostasis are challenged.
