Ch. 5 pt 1 Flashcards
Stem cells are undifferentiated pluripotent/totipotent cells housed in particular “_______” within a body that are able to _______ indefinitely and give rise to more specialized cells
niches
divide
Asymmetrical divisions of stem cells produces what 2 cells?
1) another stem cell
2) a more specialized cell
_______: can form all cells of the adult and trophoblast cells
totipotent
What is an example of a totipotent stem cell?
zygote (zygote through 4-8 cell stage)
_______: can form all cells of the adult
pluripotent
What is an example of a pluripotent stem cell?
inner cell mass of blastocyst
_______: usually adult stem cells with fates restricted to a subset of cells (a COMMITTED cell type)
multipotent
What are the 2 examples of multipotent stem cells?
1) hematopoietic stem cells
2) mammary stem cells
_______ cells cannot divide indefinitely, limited reproduction before final differentiation
progenitor cells
- sometimes referred to as transit-amplifying cells
Where are embryonic stem cells located?
inner cell mass of mammalian embryos
Where are adult stem cells found?
stem cell niches
_______ stem cells: function to generate only ONE cell type in the organism
unipotent
What is an example of a unipotent stem cell?
spermatatonia
What are the external regulators of stem cells?
1) physical contact
2) chemical regulation
What are the 2 physical contacts for stem cell regulation externally?
1) cell to cell contacts
2) ECM contacts
What are the 3 chemical process that externally regulate stem cells?
1) paracrine
2) juxtacrine
3) endocrine
What are the 3 internal regulators for stem cells?
1) cytoplasmic determinants
2) transcriptional regulation (TF)
3) epigenetic regulation (chromatin state)
Inner cell mass cells adhere to the side of the _______ and is capable for forming all cells of the embryo and associated membranes
trophectoderm
_______ along with the trophectoderm will generate extraembryonic membranes
primitive endoderm
- forms placenta, chorion, yolk sac
_______ forms all the cell types of the embryo proper and finally adult mammal
epiblast
- pluripotent
Cultured ICM or epiblast cells are called _______. These retain their potency and can generate all cell types of the body. Divide indefinitely in culture.
embryonic stem cells (ESCs)
_____ transcription factors maintain the pluripotency and uncommitted state of the ICM
3
- oct 4, Nanog, Sox2
Symmetric division of trophectoderm cells leads to _______, while asymmetric divisions lead to _______
trophectoderm expansion
2 layer (ICM cell created)
During asymmetrical division, there is _______ partitioning of cytoplasmic determinants, and _______ localize between ICM and trophectodermal cells
uneven
E-cadherins
- causes differential gene expression
_______ are compartments where continually proliferating stem cells are housed
stem cell niches
- once they leave, they begin differentiation
Stem cell niches provide physical structures, mechanical, hormonal, and chemical signals that regulate stem cell differentiation and proliferation. These niches are also known as _______
micro-regulatory environments
- maintenance of these niches is important to health and appearance
In drosophila ovarian niche, Germinal stem cells (GSC) divide into what 2 cells?
1) germinal stem cell
2) cystoblast
Germinal stem cells maintain contact to Cap cells via _______
E-cadherins
Germinal stem cells are maintained by _______ signals that activate _______ signal cascade inside GSC and prevent differentiation
TGF-β
BMP
_______ prevents diffusion of TGF-β ligands very far, which allows transcription of _______
ECM
BAM (bag of marbles)
Neural stem cells (NSC’s) retain much of the molecular and physical characteristics of their embryonic progenitor cell the _______
radial glial cell
- polarized epithelial cells
NSC’s have only been identified in TWO regions in the adult mammalian brain:
1) subgranular zone (hippocampus)
2) ventricular-subventricular zone (V-SVZ)(lateral ventricles)
What is the order of cells for the neural stem cell niche of the V-SVZ?
B1–> B2–> B3 –> C–> A
- 3 cell divisions of C before A
Fundamental cellular constituents:
- Layer of ependymal cells _______ along the ventricular wall
- Neural stem cell called the _______
- progenitor (tansit-amplifying) _______
- migrating neuroblast _______
E cells
B cells (1,2,3)
C cells
A cells
distinctive _______ structure are retained throughout mammalian life, although the number of pinwheels and neural cells contain decreases with age
Rosette
_______: cell surface adhesion molecule that helps maintain architecture and differential state of Rosette
VCAM1
The more closely associated B cells are with ependymal cells the more quiescent they are (_______) the more this association loosens, the more active in proliferation they are (_______)
B1 cells (outside)
B2 and B3 cells (middle)
_______ family transmembrane receptors are cleaved through cell-to-cell interactions
Notch
The _______ is cleaved off and functions as part of a transcription factor complex repressing proneural gene expression
Notch intracellular domain (NICD)
_______ signals promotes neurogenesis by upregulating _______ which in turn inhibits Notch signals
EGFR
NUMB
___1___ generally promotes gliogenesis. In the V-SVZ, the ___1___ inhibitor ___2___ keeps ___1___ levels low.
1) BMP
2) Noggin
As developing B cells move away from ependymal cells, they experience increasing levels of _______, which promotes neurogenesis with a preference for glial cells
BMP
- (less Noggin)
_______ is in contact with the niche and can influence NSC behavior through paracrine factors. This allows response to injury, physiologic state, exercise, and circadian rhythms
Cerebral spinal fluid
The neurotransmitter _______ secreted by nearby neuronal precursors negatively feeds back on proliferation
GABA
Explain the sonic hedgehog gradient in V-SVZ niche
low (basal, endothelial) –> high (apical, ependymal)
