Foty - Stem Cells

Question 1

Cell Intrinsic Regulation

Answer 1

Sox2-Oct4-Nanog - negative transcription factors, repress differentiation genes
Ronin: DNA binding protein that also represses

Question 2

Cell Extrinsic Pathway

Answer 2

LIF (leukimia inhibitory factor) and BMP use JAK-STAT3 pathway and SMAD-ID pathway (respectively) to block MAPK pathway, preventing environment from causing differentiation

Question 3

Stem Cell Niche

Answer 3

Microenvironment within which stem cells live undifferentiated (chemical, physical, molecular..)
ex: Intestinal crypt niche, stem cells differentiate to TA & Paneth, paneth remains in niche with stem while TA go out to become new cells; can’t divide without paneth present

Question 4

Stem Cell properties

Answer 4

Undifferentiated, self-renewal.
Symmetric Division: under stress, need to form a ton of stem cells
Assymetric division: Normal, when stem cell forms differentiated and new stem cell

Question 5

Types of Stem Cells (3)

Answer 5

1) Adult Stem Cell (germline)
2) Embryonic Stem Cell (embryo)
3) Cancer Stem Cells (drive tumorigenesis)

Question 6

De-Differentiation

Answer 6

i.e. induced pluripotency, make stem cell from differentiated cell by working backwards

Question 7

Gold Standard for Stem Cell sorting?

Answer 7

FACS Fluorescence-activated cell sorting (uses fluorescent flow cytometry to separate stem cells based on tagged surface markers)

Question 8

Maintenance of Differentiation (4)

Answer 8

All + Feedback:

1) transcription factors activated by differentiation bind their own enhancer (+ feedback)
2) synthesize proteins that affect chromatin to keep gene accessible
3) cell makes more of differentiating signal molecule and receptor
4) neighboring cells stimulate each other to remain differentiated

Question 9

Induced Pluripotent Stem Cell key genes (SOCK)

Answer 9

Oct4, Sox2, Klf4, cMyc

Question 10

Cancer Stem Cells

Answer 10

Unlike previously thought, cancer develops from cancer stem cells (CSCs). If chemo targets tumor but ignores stem cells (since they proliferate slower, have multidrug resistance, etc.), tumor will return. New cancer therapies aim to target CSCs