Stem Cells Flashcards
What Properties Define Stem Cells?
- unspecialized (undifferentiated)
- can self-renew
- can be induced to differentiate into cells with special functions.
Asymmetric stem cell division:
- predominates under steady-state conditions.
- serves to maintain a balance between differentiated and undifferentiated cells.
- Gives rise to one stem cell and one cell that will differentiate.
Symmetric stem cell division:
- predominates when stem cells must expand in number, such as during development or after injury.
- Gives rise to two identical stem cells.
Asymmetric Division may be due to (2):
- asymmetrical segregation of “steaminess” factors.
- one cell placed in different microenvironment and differentiates.
What are two ways to keep stem cells in an undifferentiated state intrinsically?
- transcription factors
- DNA-binding proteins
What transcription factors negatively regulate the expression of differentiation-promoting genes?
- Sox2
- Oct4
- Nanog
What DNA-binding protein suppresses transcription of differentiation-inducing genes such as GATA4 and
GATA6?
Ronin
What molecules can extrinsically block stem cell differentiation and what are their pathways?
- LIF works through STAT3 pathway
- BMP work through SMAD-Id pathway
BOTH BLOCK MAPK PATHWAY
What is the stem cell niche?
- the microenvironment in which stem cells reside in their undifferentiated state.
- a chemical and/or mechanical environment
The intestinal crypt niche:
- Intestinal crypt stem cells give rise to TA cells that can differentiate into all cell types required in the vili and also to Paneth cells.
- Paneth cells remain in close proximity to the stem cells
- stem cells will not divide if Paneth cells are removed
The three types of stem cells:
- Adult stem cells
- Embryonic stem cells
- Cancer stem cells (CSCs)
Embryonic stem cells:
- Undifferentiated cells derived from a 5-day preimplantation embryo
- pluripotent
- have potential to differentiate into a wide variety of specialized cell types.
Cancer stem cells (CSCs):
- Cells that drive tumorigenesis and also give rise to differentiated progeny.
Adult stem cells:
- undifferentiated cells found in a differentiated tissue
- can self-renew and differentiate into all the specialized cell types of the tissue from which it originated.
- induced pluripotent stem cells
Differentiated Cells:
- a cell that through the process of differentiation has acquired specialized structure and function.