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How do signals from neighboring cells affect which genes a stem cell expresses?
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stem cell
Stem cells of neural and hematopoietic origin have tremendous potential in the development of therapies for certain diseases, such as diabetes and Parkinson disease. Neural stem cells occur in the spinal cord and in specific regions of the brain, and hematopoietic stem cells occur in the blood and bone marrow.
Signals from neighboring cells play a critical role in directing stem cell fate by influencing gene expression. This process typically occurs through the following mechanisms:
- Receptor Interaction: Signaling molecules secreted by neighboring cells bind to specific receptors on the stem cell surface. These interactions trigger intracellular cascades that activate or repress transcription factors, which in turn dictate which genes are turned on or off to drive cell specialization.1
- Induction: In this process, substances secreted by one group of cells instruct neighboring cells to adopt a different state of commitment. These signals often form concentration gradients that evoke varied responses depending on the local concentration of the signaling substance.2
- Lateral Inhibition: This system allows cells to influence their neighbors to follow a different developmental pathway. For example, a cell may express a surface molecule (such as Delta) that binds to a receptor (such as Notch) on an adjacent cell. This activation suppresses specific differentiation pathways in the neighbor, ensuring that the population generates a diverse array of cell types rather than identical ones.2
Through these interactions, cells integrate environmental cues to achieve stable and persistent states of cell differentiation.21