Cell differentiation and biology of stem cells Flashcards
What two properties define stem cells?
- Unspecialized and can self-renew
2. Can be induced to differentiate into cells with special functions
Self-renewal in asymmetric vs. symmetric division
asymmetric - recreate self and differentiate (maintains balance between differentiated and undifferentiated cells)
symmetric - recreate 2 copies of self (predominates when stem cells must mutliply in number, like during development or after an injury)
How do cells divide asymmetrically?
Cells segregate factors - ones for stem cell kept by stem cell, other half does not have those factors. OR - depends on whether the new cell stays in the niche (microenvironment) and doesn’t differentiate or whether it leaves this microenvironment and does differentiate.
What is cell-intrinsic regulation? What factors involved in whether cell should be a differentiated or stem cell?
Promotes stem cell - Sox2 and oct4 are transcription factors that negatively regulate the expression of differentiating promoting genes.
DNA binding protein Ronin suppresses transcription of differentiating inducing genes.
What is cell-extrinsic regulation?
MAPK pathway commonly used to block differentiation. - signals can block this pathway so that the cell stays as a stem cell.
What comprises of the niche environment?
Various interactions, including cell-cell, cell-matrix/substratum, growth factors, cytokines…
During tissue injury, what happens to the niche environment?
Niche environment goes away and stem cells become differentiated as needed.
Define potency
potential to differentiate
Pluiropotent are descendents of totipotent cells, they can differentiate from ecto, endo & mesoderm. Where do you find these?
Inner cell mass of blastocyst
Multipotent cells give rise to
different cells in a closely related family of cells, i.e. hematapoetic stem cells
Oligopotent
these cells can only differentiate into a couple of cell types
Unipotent cells
can produce only one cell type, their own, but have the property of self-renewal. Muscle from muscle. Muscle stem cells, for example, could differentiate into muscle cells only.
